// dear imgui, v1.60 WIP
// (headers)

// See imgui.cpp file for documentation.
// Call and read ImGui::ShowDemoWindow() in imgui_demo.cpp for demo code.
// Read 'Programmer guide' in imgui.cpp for notes on how to setup ImGui in your codebase.
// Get latest version at https://github.com/ocornut/imgui

#pragma once

// User-editable configuration files (edit stock imconfig.h or define IMGUI_USER_CONFIG to your own filename)
#ifdef IMGUI_USER_CONFIG
#include IMGUI_USER_CONFIG
#endif
#if !defined(IMGUI_DISABLE_INCLUDE_IMCONFIG_H) || defined(IMGUI_INCLUDE_IMCONFIG_H)
#include "imconfig.h"
#endif

#include <float.h>          // FLT_MAX
#include <stdarg.h>         // va_list
#include <stddef.h>         // ptrdiff_t, NULL
#include <string.h>         // memset, memmove, memcpy, strlen, strchr, strcpy, strcmp

#define IMGUI_VERSION       "1.60 WIP"

// Define attributes of all API symbols declarations, e.g. for DLL under Windows.
#ifndef IMGUI_API
#define IMGUI_API
#endif

// Define assertion handler.
#ifndef IM_ASSERT
#include <assert.h>
#define IM_ASSERT(_EXPR)    assert(_EXPR)
#endif

// Helpers
// Some compilers support applying printf-style warnings to user functions.
#if defined(__clang__) || defined(__GNUC__)
#define IM_FMTARGS(FMT)             __attribute__((format(printf, FMT, FMT+1)))
#define IM_FMTLIST(FMT)             __attribute__((format(printf, FMT, 0)))
#else
#define IM_FMTARGS(FMT)
#define IM_FMTLIST(FMT)
#endif
#define IM_ARRAYSIZE(_ARR)          ((int)(sizeof(_ARR)/sizeof(*_ARR)))
#define IM_OFFSETOF(_TYPE,_MEMBER)  ((size_t)&(((_TYPE*)0)->_MEMBER))       // Offset of _MEMBER within _TYPE. Standardized as offsetof() in modern C++.

#if defined(__clang__)
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wold-style-cast"
#endif

// Forward declarations
struct ImDrawChannel;               // Temporary storage for outputting drawing commands out of order, used by ImDrawList::ChannelsSplit()
struct ImDrawCmd;                   // A single draw command within a parent ImDrawList (generally maps to 1 GPU draw call)
struct ImDrawData;                  // All draw command lists required to render the frame
struct ImDrawList;                  // A single draw command list (generally one per window)
struct ImDrawListSharedData;        // Data shared among multiple draw lists (typically owned by parent ImGui context, but you may create one yourself)
struct ImDrawVert;                  // A single vertex (20 bytes by default, override layout with IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT)
struct ImFont;                      // Runtime data for a single font within a parent ImFontAtlas
struct ImFontAtlas;                 // Runtime data for multiple fonts, bake multiple fonts into a single texture, TTF/OTF font loader
struct ImFontConfig;                // Configuration data when adding a font or merging fonts
struct ImColor;                     // Helper functions to create a color that can be converted to either u32 or float4
struct ImGuiIO;                     // Main configuration and I/O between your application and ImGui
struct ImGuiOnceUponAFrame;         // Simple helper for running a block of code not more than once a frame, used by IMGUI_ONCE_UPON_A_FRAME macro
struct ImGuiStorage;                // Simple custom key value storage
struct ImGuiStyle;                  // Runtime data for styling/colors
struct ImGuiTextFilter;             // Parse and apply text filters. In format "aaaaa[,bbbb][,ccccc]"
struct ImGuiTextBuffer;             // Text buffer for logging/accumulating text
struct ImGuiTextEditCallbackData;   // Shared state of ImGui::InputText() when using custom ImGuiTextEditCallback (rare/advanced use)
struct ImGuiSizeCallbackData;       // Structure used to constraint window size in custom ways when using custom ImGuiSizeCallback (rare/advanced use)
struct ImGuiListClipper;            // Helper to manually clip large list of items
struct ImGuiPayload;                // User data payload for drag and drop operations
struct ImGuiContext;                // ImGui context (opaque)

// Typedefs and Enumerations (declared as int for compatibility and to not pollute the top of this file)
typedef unsigned int ImU32;         // 32-bit unsigned integer (typically used to store packed colors)
typedef unsigned int ImGuiID;       // unique ID used by widgets (typically hashed from a stack of string)
typedef unsigned short ImWchar;     // character for keyboard input/display
typedef void* ImTextureID;          // user data to identify a texture (this is whatever to you want it to be! read the FAQ about ImTextureID in imgui.cpp)
typedef int ImGuiCol;               // enum: a color identifier for styling     // enum ImGuiCol_
typedef int ImGuiCond;              // enum: a condition for Set*()             // enum ImGuiCond_
typedef int ImGuiKey;               // enum: a key identifier (ImGui-side enum) // enum ImGuiKey_
typedef int ImGuiNavInput;          // enum: an input identifier for navigation // enum ImGuiNavInput_
typedef int ImGuiMouseCursor;       // enum: a mouse cursor identifier          // enum ImGuiMouseCursor_
typedef int ImGuiStyleVar;          // enum: a variable identifier for styling  // enum ImGuiStyleVar_
typedef int ImDrawCornerFlags;      // flags: for ImDrawList::AddRect*() etc.   // enum ImDrawCornerFlags_
typedef int ImDrawListFlags;        // flags: for ImDrawList                    // enum ImDrawListFlags_
typedef int ImFontAtlasFlags;       // flags: for ImFontAtlas                   // enum ImFontAtlasFlags_
typedef int ImGuiColorEditFlags;    // flags: for ColorEdit*(), ColorPicker*()  // enum ImGuiColorEditFlags_
typedef int ImGuiColumnsFlags;      // flags: for *Columns*()                   // enum ImGuiColumnsFlags_
typedef int ImGuiDragDropFlags;     // flags: for *DragDrop*()                  // enum ImGuiDragDropFlags_
typedef int ImGuiComboFlags;        // flags: for BeginCombo()                  // enum ImGuiComboFlags_
typedef int ImGuiFocusedFlags;      // flags: for IsWindowFocused()             // enum ImGuiFocusedFlags_
typedef int ImGuiHoveredFlags;      // flags: for IsItemHovered() etc.          // enum ImGuiHoveredFlags_
typedef int ImGuiInputTextFlags;    // flags: for InputText*()                  // enum ImGuiInputTextFlags_
typedef int ImGuiNavFlags;          // flags: for io.NavFlags                   // enum ImGuiNavFlags_
typedef int ImGuiSelectableFlags;   // flags: for Selectable()                  // enum ImGuiSelectableFlags_
typedef int ImGuiTreeNodeFlags;     // flags: for TreeNode*(),CollapsingHeader()// enum ImGuiTreeNodeFlags_
typedef int ImGuiWindowFlags;       // flags: for Begin*()                      // enum ImGuiWindowFlags_
typedef int (*ImGuiTextEditCallback)(ImGuiTextEditCallbackData *data);
typedef void (*ImGuiSizeCallback)(ImGuiSizeCallbackData* data);
#if defined(_MSC_VER) && !defined(__clang__)
typedef unsigned __int64 ImU64;     // 64-bit unsigned integer
#else
typedef unsigned long long ImU64;   // 64-bit unsigned integer
#endif 

// Others helpers at bottom of the file:
// class ImVector<>                 // Lightweight std::vector like class.
// IMGUI_ONCE_UPON_A_FRAME          // Execute a block of code once per frame only (convenient for creating UI within deep-nested code that runs multiple times)

struct ImVec2
{
    float x, y;
    ImVec2() { x = y = 0.0f; }
    ImVec2(float _x, float _y) { x = _x; y = _y; }
    float  operator[] (size_t idx) const { IM_ASSERT(idx == 0 || idx == 1); return (&x)[idx]; }    // We very rarely use this [] operator, thus an assert is fine.
#ifdef IM_VEC2_CLASS_EXTRA          // Define constructor and implicit cast operators in imconfig.h to convert back<>forth from your math types and ImVec2.
    IM_VEC2_CLASS_EXTRA
#endif
};

struct ImVec4
{
    float x, y, z, w;
    ImVec4() { x = y = z = w = 0.0f; }
    ImVec4(float _x, float _y, float _z, float _w) { x = _x; y = _y; z = _z; w = _w; }
#ifdef IM_VEC4_CLASS_EXTRA          // Define constructor and implicit cast operators in imconfig.h to convert back<>forth from your math types and ImVec4.
    IM_VEC4_CLASS_EXTRA
#endif
};

// ImGui end-user API
// In a namespace so that user can add extra functions in a separate file (e.g. Value() helpers for your vector or common types)
namespace ImGui
{
    // Context creation and access, if you want to use multiple context, share context between modules (e.g. DLL). 
    // All contexts share a same ImFontAtlas by default. If you want different font atlas, you can new() them and overwrite the GetIO().Fonts variable of an ImGui context.
    // All those functions are not reliant on the current context.
    IMGUI_API ImGuiContext* CreateContext(ImFontAtlas* shared_font_atlas = NULL);
    IMGUI_API void          DestroyContext(ImGuiContext* ctx = NULL);   // NULL = Destroy current context
    IMGUI_API ImGuiContext* GetCurrentContext();
    IMGUI_API void          SetCurrentContext(ImGuiContext* ctx);

    // Main
    IMGUI_API ImGuiIO&      GetIO();
    IMGUI_API ImGuiStyle&   GetStyle();
    IMGUI_API void          NewFrame();                                 // start a new ImGui frame, you can submit any command from this point until Render()/EndFrame().
    IMGUI_API void          Render();                                   // ends the ImGui frame, finalize the draw data. (Obsolete: optionally call io.RenderDrawListsFn if set. Nowadays, prefer calling your render function yourself.)
    IMGUI_API ImDrawData*   GetDrawData();                              // valid after Render() and until the next call to NewFrame(). this is what you have to render. (Obsolete: this used to be passed to your io.RenderDrawListsFn() function.)
    IMGUI_API void          EndFrame();                                 // ends the ImGui frame. automatically called by Render(), so most likely don't need to ever call that yourself directly. If you don't need to render you may call EndFrame() but you'll have wasted CPU already. If you don't need to render, better to not create any imgui windows instead!

    // Demo, Debug, Informations
    IMGUI_API void          ShowDemoWindow(bool* p_open = NULL);        // create demo/test window (previously called ShowTestWindow). demonstrate most ImGui features. call this to learn about the library! try to make it always available in your application!
    IMGUI_API void          ShowMetricsWindow(bool* p_open = NULL);     // create metrics window. display ImGui internals: draw commands (with individual draw calls and vertices), window list, basic internal state, etc.
    IMGUI_API void          ShowStyleEditor(ImGuiStyle* ref = NULL);    // add style editor block (not a window). you can pass in a reference ImGuiStyle structure to compare to, revert to and save to (else it uses the default style)
    IMGUI_API bool          ShowStyleSelector(const char* label);
    IMGUI_API void          ShowFontSelector(const char* label);
    IMGUI_API void          ShowUserGuide();                            // add basic help/info block (not a window): how to manipulate ImGui as a end-user (mouse/keyboard controls).
    IMGUI_API const char*   GetVersion();

    // Styles
    IMGUI_API void          StyleColorsDark(ImGuiStyle* dst = NULL);    // New, recommended style
    IMGUI_API void          StyleColorsClassic(ImGuiStyle* dst = NULL); // Classic imgui style (default)
    IMGUI_API void          StyleColorsLight(ImGuiStyle* dst = NULL);   // Best used with borders and a custom, thicker font

    // Window
    IMGUI_API bool          Begin(const char* name, bool* p_open = NULL, ImGuiWindowFlags flags = 0);   // push window to the stack and start appending to it. see .cpp for details. return false when window is collapsed (so you can early out in your code) but you always need to call End() regardless. 'bool* p_open' creates a widget on the upper-right to close the window (which sets your bool to false).
    IMGUI_API void          End();                                                              // always call even if Begin() return false (which indicates a collapsed window)! finish appending to current window, pop it off the window stack.
    IMGUI_API bool          BeginChild(const char* str_id, const ImVec2& size = ImVec2(0,0), bool border = false, ImGuiWindowFlags flags = 0);  // begin a scrolling region. size==0.0f: use remaining window size, size<0.0f: use remaining window size minus abs(size). size>0.0f: fixed size. each axis can use a different mode, e.g. ImVec2(0,400).
    IMGUI_API bool          BeginChild(ImGuiID id, const ImVec2& size = ImVec2(0,0), bool border = false, ImGuiWindowFlags flags = 0);          // "
    IMGUI_API void          EndChild();                                                         // always call even if BeginChild() return false (which indicates a collapsed or clipping child window)
    IMGUI_API ImVec2        GetContentRegionMax();                                              // current content boundaries (typically window boundaries including scrolling, or current column boundaries), in windows coordinates
    IMGUI_API ImVec2        GetContentRegionAvail();                                            // == GetContentRegionMax() - GetCursorPos()
    IMGUI_API float         GetContentRegionAvailWidth();                                       //
    IMGUI_API ImVec2        GetWindowContentRegionMin();                                        // content boundaries min (roughly (0,0)-Scroll), in window coordinates
    IMGUI_API ImVec2        GetWindowContentRegionMax();                                        // content boundaries max (roughly (0,0)+Size-Scroll) where Size can be override with SetNextWindowContentSize(), in window coordinates
    IMGUI_API float         GetWindowContentRegionWidth();                                      //
    IMGUI_API ImDrawList*   GetWindowDrawList();                                                // get rendering command-list if you want to append your own draw primitives
    IMGUI_API ImVec2        GetWindowPos();                                                     // get current window position in screen space (useful if you want to do your own drawing via the DrawList api)
    IMGUI_API ImVec2        GetWindowSize();                                                    // get current window size
    IMGUI_API float         GetWindowWidth();
    IMGUI_API float         GetWindowHeight();
    IMGUI_API bool          IsWindowCollapsed();
    IMGUI_API bool          IsWindowAppearing();
    IMGUI_API void          SetWindowFontScale(float scale);                                    // per-window font scale. Adjust IO.FontGlobalScale if you want to scale all windows

    IMGUI_API void          SetNextWindowPos(const ImVec2& pos, ImGuiCond cond = 0, const ImVec2& pivot = ImVec2(0,0)); // set next window position. call before Begin(). use pivot=(0.5f,0.5f) to center on given point, etc.
    IMGUI_API void          SetNextWindowSize(const ImVec2& size, ImGuiCond cond = 0);          // set next window size. set axis to 0.0f to force an auto-fit on this axis. call before Begin()
    IMGUI_API void          SetNextWindowSizeConstraints(const ImVec2& size_min, const ImVec2& size_max, ImGuiSizeCallback custom_callback = NULL, void* custom_callback_data = NULL); // set next window size limits. use -1,-1 on either X/Y axis to preserve the current size. Use callback to apply non-trivial programmatic constraints.
    IMGUI_API void          SetNextWindowContentSize(const ImVec2& size);                       // set next window content size (~ enforce the range of scrollbars). not including window decorations (title bar, menu bar, etc.). set an axis to 0.0f to leave it automatic. call before Begin()
    IMGUI_API void          SetNextWindowCollapsed(bool collapsed, ImGuiCond cond = 0);         // set next window collapsed state. call before Begin()
    IMGUI_API void          SetNextWindowFocus();                                               // set next window to be focused / front-most. call before Begin()
    IMGUI_API void          SetNextWindowBgAlpha(float alpha);                                  // set next window background color alpha. helper to easily modify ImGuiCol_WindowBg/ChildBg/PopupBg.
    IMGUI_API void          SetWindowPos(const ImVec2& pos, ImGuiCond cond = 0);                // (not recommended) set current window position - call within Begin()/End(). prefer using SetNextWindowPos(), as this may incur tearing and side-effects.
    IMGUI_API void          SetWindowSize(const ImVec2& size, ImGuiCond cond = 0);              // (not recommended) set current window size - call within Begin()/End(). set to ImVec2(0,0) to force an auto-fit. prefer using SetNextWindowSize(), as this may incur tearing and minor side-effects.    
    IMGUI_API void          SetWindowCollapsed(bool collapsed, ImGuiCond cond = 0);             // (not recommended) set current window collapsed state. prefer using SetNextWindowCollapsed().
    IMGUI_API void          SetWindowFocus();                                                   // (not recommended) set current window to be focused / front-most. prefer using SetNextWindowFocus().
    IMGUI_API void          SetWindowPos(const char* name, const ImVec2& pos, ImGuiCond cond = 0);      // set named window position.
    IMGUI_API void          SetWindowSize(const char* name, const ImVec2& size, ImGuiCond cond = 0);    // set named window size. set axis to 0.0f to force an auto-fit on this axis.
    IMGUI_API void          SetWindowCollapsed(const char* name, bool collapsed, ImGuiCond cond = 0);   // set named window collapsed state
    IMGUI_API void          SetWindowFocus(const char* name);                                           // set named window to be focused / front-most. use NULL to remove focus.

    IMGUI_API float         GetScrollX();                                                       // get scrolling amount [0..GetScrollMaxX()]
    IMGUI_API float         GetScrollY();                                                       // get scrolling amount [0..GetScrollMaxY()]
    IMGUI_API float         GetScrollMaxX();                                                    // get maximum scrolling amount ~~ ContentSize.X - WindowSize.X
    IMGUI_API float         GetScrollMaxY();                                                    // get maximum scrolling amount ~~ ContentSize.Y - WindowSize.Y
    IMGUI_API void          SetScrollX(float scroll_x);                                         // set scrolling amount [0..GetScrollMaxX()]
    IMGUI_API void          SetScrollY(float scroll_y);                                         // set scrolling amount [0..GetScrollMaxY()]
    IMGUI_API void          SetScrollHere(float center_y_ratio = 0.5f);                         // adjust scrolling amount to make current cursor position visible. center_y_ratio=0.0: top, 0.5: center, 1.0: bottom. When using to make a "default/current item" visible, consider using SetItemDefaultFocus() instead.
    IMGUI_API void          SetScrollFromPosY(float pos_y, float center_y_ratio = 0.5f);        // adjust scrolling amount to make given position valid. use GetCursorPos() or GetCursorStartPos()+offset to get valid positions.
    IMGUI_API void          SetStateStorage(ImGuiStorage* tree);                                // replace tree state storage with our own (if you want to manipulate it yourself, typically clear subsection of it)
    IMGUI_API ImGuiStorage* GetStateStorage();

    // Parameters stacks (shared)
    IMGUI_API void          PushFont(ImFont* font);                                             // use NULL as a shortcut to push default font
    IMGUI_API void          PopFont();
    IMGUI_API void          PushStyleColor(ImGuiCol idx, ImU32 col);
    IMGUI_API void          PushStyleColor(ImGuiCol idx, const ImVec4& col);
    IMGUI_API void          PopStyleColor(int count = 1);
    IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, float val);
    IMGUI_API void          PushStyleVar(ImGuiStyleVar idx, const ImVec2& val);
    IMGUI_API void          PopStyleVar(int count = 1);
    IMGUI_API const ImVec4& GetStyleColorVec4(ImGuiCol idx);                                    // retrieve style color as stored in ImGuiStyle structure. use to feed back into PushStyleColor(), otherwhise use GetColorU32() to get style color + style alpha.
    IMGUI_API ImFont*       GetFont();                                                          // get current font
    IMGUI_API float         GetFontSize();                                                      // get current font size (= height in pixels) of current font with current scale applied
    IMGUI_API ImVec2        GetFontTexUvWhitePixel();                                           // get UV coordinate for a while pixel, useful to draw custom shapes via the ImDrawList API
    IMGUI_API ImU32         GetColorU32(ImGuiCol idx, float alpha_mul = 1.0f);                  // retrieve given style color with style alpha applied and optional extra alpha multiplier
    IMGUI_API ImU32         GetColorU32(const ImVec4& col);                                     // retrieve given color with style alpha applied
    IMGUI_API ImU32         GetColorU32(ImU32 col);                                             // retrieve given color with style alpha applied

    // Parameters stacks (current window)
    IMGUI_API void          PushItemWidth(float item_width);                                    // width of items for the common item+label case, pixels. 0.0f = default to ~2/3 of windows width, >0.0f: width in pixels, <0.0f align xx pixels to the right of window (so -1.0f always align width to the right side)
    IMGUI_API void          PopItemWidth();
    IMGUI_API float         CalcItemWidth();                                                    // width of item given pushed settings and current cursor position
    IMGUI_API void          PushTextWrapPos(float wrap_pos_x = 0.0f);                           // word-wrapping for Text*() commands. < 0.0f: no wrapping; 0.0f: wrap to end of window (or column); > 0.0f: wrap at 'wrap_pos_x' position in window local space
    IMGUI_API void          PopTextWrapPos();
    IMGUI_API void          PushAllowKeyboardFocus(bool allow_keyboard_focus);                  // allow focusing using TAB/Shift-TAB, enabled by default but you can disable it for certain widgets
    IMGUI_API void          PopAllowKeyboardFocus();
    IMGUI_API void          PushButtonRepeat(bool repeat);                                      // in 'repeat' mode, Button*() functions return repeated true in a typematic manner (using io.KeyRepeatDelay/io.KeyRepeatRate setting). Note that you can call IsItemActive() after any Button() to tell if the button is held in the current frame.
    IMGUI_API void          PopButtonRepeat();

    // Cursor / Layout
    IMGUI_API void          Separator();                                                        // separator, generally horizontal. inside a menu bar or in horizontal layout mode, this becomes a vertical separator.
    IMGUI_API void          SameLine(float pos_x = 0.0f, float spacing_w = -1.0f);              // call between widgets or groups to layout them horizontally
    IMGUI_API void          NewLine();                                                          // undo a SameLine()
    IMGUI_API void          Spacing();                                                          // add vertical spacing
    IMGUI_API void          Dummy(const ImVec2& size);                                          // add a dummy item of given size
    IMGUI_API void          Indent(float indent_w = 0.0f);                                      // move content position toward the right, by style.IndentSpacing or indent_w if != 0
    IMGUI_API void          Unindent(float indent_w = 0.0f);                                    // move content position back to the left, by style.IndentSpacing or indent_w if != 0
    IMGUI_API void          BeginGroup();                                                       // lock horizontal starting position + capture group bounding box into one "item" (so you can use IsItemHovered() or layout primitives such as SameLine() on whole group, etc.)
    IMGUI_API void          EndGroup();
    IMGUI_API ImVec2        GetCursorPos();                                                     // cursor position is relative to window position
    IMGUI_API float         GetCursorPosX();                                                    // "
    IMGUI_API float         GetCursorPosY();                                                    // "
    IMGUI_API void          SetCursorPos(const ImVec2& local_pos);                              // "
    IMGUI_API void          SetCursorPosX(float x);                                             // "
    IMGUI_API void          SetCursorPosY(float y);                                             // "
    IMGUI_API ImVec2        GetCursorStartPos();                                                // initial cursor position
    IMGUI_API ImVec2        GetCursorScreenPos();                                               // cursor position in absolute screen coordinates [0..io.DisplaySize] (useful to work with ImDrawList API)
    IMGUI_API void          SetCursorScreenPos(const ImVec2& pos);                              // cursor position in absolute screen coordinates [0..io.DisplaySize]
    IMGUI_API void          AlignTextToFramePadding();                                          // vertically align/lower upcoming text to FramePadding.y so that it will aligns to upcoming widgets (call if you have text on a line before regular widgets)
    IMGUI_API float         GetTextLineHeight();                                                // ~ FontSize
    IMGUI_API float         GetTextLineHeightWithSpacing();                                     // ~ FontSize + style.ItemSpacing.y (distance in pixels between 2 consecutive lines of text)
    IMGUI_API float         GetFrameHeight();                                                   // ~ FontSize + style.FramePadding.y * 2
    IMGUI_API float         GetFrameHeightWithSpacing();                                        // ~ FontSize + style.FramePadding.y * 2 + style.ItemSpacing.y (distance in pixels between 2 consecutive lines of framed widgets)

    // Columns
    // You can also use SameLine(pos_x) for simplified columns. The columns API is still work-in-progress and rather lacking.
    IMGUI_API void          Columns(int count = 1, const char* id = NULL, bool border = true);
    IMGUI_API void          NextColumn();                                                       // next column, defaults to current row or next row if the current row is finished
    IMGUI_API int           GetColumnIndex();                                                   // get current column index
    IMGUI_API float         GetColumnWidth(int column_index = -1);                              // get column width (in pixels). pass -1 to use current column
    IMGUI_API void          SetColumnWidth(int column_index, float width);                      // set column width (in pixels). pass -1 to use current column
    IMGUI_API float         GetColumnOffset(int column_index = -1);                             // get position of column line (in pixels, from the left side of the contents region). pass -1 to use current column, otherwise 0..GetColumnsCount() inclusive. column 0 is typically 0.0f
    IMGUI_API void          SetColumnOffset(int column_index, float offset_x);                  // set position of column line (in pixels, from the left side of the contents region). pass -1 to use current column
    IMGUI_API int           GetColumnsCount();

    // ID scopes
    // If you are creating widgets in a loop you most likely want to push a unique identifier (e.g. object pointer, loop index) so ImGui can differentiate them.
    // You can also use the "##foobar" syntax within widget label to distinguish them from each others. Read "A primer on the use of labels/IDs" in the FAQ for more details.
    IMGUI_API void          PushID(const char* str_id);                                         // push identifier into the ID stack. IDs are hash of the entire stack!
    IMGUI_API void          PushID(const char* str_id_begin, const char* str_id_end);
    IMGUI_API void          PushID(const void* ptr_id);
    IMGUI_API void          PushID(int int_id);
    IMGUI_API void          PopID();
    IMGUI_API ImGuiID       GetID(const char* str_id);                                          // calculate unique ID (hash of whole ID stack + given parameter). e.g. if you want to query into ImGuiStorage yourself
    IMGUI_API ImGuiID       GetID(const char* str_id_begin, const char* str_id_end);
    IMGUI_API ImGuiID       GetID(const void* ptr_id);

    // Widgets: Text
    IMGUI_API void          TextUnformatted(const char* text, const char* text_end = NULL);               // raw text without formatting. Roughly equivalent to Text("%s", text) but: A) doesn't require null terminated string if 'text_end' is specified, B) it's faster, no memory copy is done, no buffer size limits, recommended for long chunks of text.
    IMGUI_API void          Text(const char* fmt, ...)                                     IM_FMTARGS(1); // simple formatted text
    IMGUI_API void          TextV(const char* fmt, va_list args)                           IM_FMTLIST(1);
    IMGUI_API void          TextColored(const ImVec4& col, const char* fmt, ...)           IM_FMTARGS(2); // shortcut for PushStyleColor(ImGuiCol_Text, col); Text(fmt, ...); PopStyleColor();
    IMGUI_API void          TextColoredV(const ImVec4& col, const char* fmt, va_list args) IM_FMTLIST(2);
    IMGUI_API void          TextDisabled(const char* fmt, ...)                             IM_FMTARGS(1); // shortcut for PushStyleColor(ImGuiCol_Text, style.Colors[ImGuiCol_TextDisabled]); Text(fmt, ...); PopStyleColor();
    IMGUI_API void          TextDisabledV(const char* fmt, va_list args)                   IM_FMTLIST(1);
    IMGUI_API void          TextWrapped(const char* fmt, ...)                              IM_FMTARGS(1); // shortcut for PushTextWrapPos(0.0f); Text(fmt, ...); PopTextWrapPos();. Note that this won't work on an auto-resizing window if there's no other widgets to extend the window width, yoy may need to set a size using SetNextWindowSize().
    IMGUI_API void          TextWrappedV(const char* fmt, va_list args)                    IM_FMTLIST(1);
    IMGUI_API void          LabelText(const char* label, const char* fmt, ...)             IM_FMTARGS(2); // display text+label aligned the same way as value+label widgets
    IMGUI_API void          LabelTextV(const char* label, const char* fmt, va_list args)   IM_FMTLIST(2);
    IMGUI_API void          BulletText(const char* fmt, ...)                               IM_FMTARGS(1); // shortcut for Bullet()+Text()
    IMGUI_API void          BulletTextV(const char* fmt, va_list args)                     IM_FMTLIST(1);
    IMGUI_API void          Bullet();                                                                     // draw a small circle and keep the cursor on the same line. advance cursor x position by GetTreeNodeToLabelSpacing(), same distance that TreeNode() uses

    // Widgets: Main
    IMGUI_API bool          Button(const char* label, const ImVec2& size = ImVec2(0,0));            // button
    IMGUI_API bool          SmallButton(const char* label);                                         // button with FramePadding=(0,0) to easily embed within text
    IMGUI_API bool          InvisibleButton(const char* str_id, const ImVec2& size);                // button behavior without the visuals, useful to build custom behaviors using the public api (along with IsItemActive, IsItemHovered, etc.)
    IMGUI_API void          Image(ImTextureID user_texture_id, const ImVec2& size, const ImVec2& uv0 = ImVec2(0,0), const ImVec2& uv1 = ImVec2(1,1), const ImVec4& tint_col = ImVec4(1,1,1,1), const ImVec4& border_col = ImVec4(0,0,0,0));
    IMGUI_API bool          ImageButton(ImTextureID user_texture_id, const ImVec2& size, const ImVec2& uv0 = ImVec2(0,0),  const ImVec2& uv1 = ImVec2(1,1), int frame_padding = -1, const ImVec4& bg_col = ImVec4(0,0,0,0), const ImVec4& tint_col = ImVec4(1,1,1,1));    // <0 frame_padding uses default frame padding settings. 0 for no padding
    IMGUI_API bool          Checkbox(const char* label, bool* v);
    IMGUI_API bool          CheckboxFlags(const char* label, unsigned int* flags, unsigned int flags_value);
    IMGUI_API bool          RadioButton(const char* label, bool active);
    IMGUI_API bool          RadioButton(const char* label, int* v, int v_button);
    IMGUI_API void          PlotLines(const char* label, const float* values, int values_count, int values_offset = 0, const char* overlay_text = NULL, float scale_min = FLT_MAX, float scale_max = FLT_MAX, ImVec2 graph_size = ImVec2(0,0), int stride = sizeof(float));
    IMGUI_API void          PlotLines(const char* label, float (*values_getter)(void* data, int idx), void* data, int values_count, int values_offset = 0, const char* overlay_text = NULL, float scale_min = FLT_MAX, float scale_max = FLT_MAX, ImVec2 graph_size = ImVec2(0,0));
    IMGUI_API void          PlotHistogram(const char* label, const float* values, int values_count, int values_offset = 0, const char* overlay_text = NULL, float scale_min = FLT_MAX, float scale_max = FLT_MAX, ImVec2 graph_size = ImVec2(0,0), int stride = sizeof(float));
    IMGUI_API void          PlotHistogram(const char* label, float (*values_getter)(void* data, int idx), void* data, int values_count, int values_offset = 0, const char* overlay_text = NULL, float scale_min = FLT_MAX, float scale_max = FLT_MAX, ImVec2 graph_size = ImVec2(0,0));
    IMGUI_API void          ProgressBar(float fraction, const ImVec2& size_arg = ImVec2(-1,0), const char* overlay = NULL);

    // Widgets: Combo Box
    // The new BeginCombo()/EndCombo() api allows you to manage your contents and selection state however you want it. 
    // The old Combo() api are helpers over BeginCombo()/EndCombo() which are kept available for convenience purpose.
    IMGUI_API bool          BeginCombo(const char* label, const char* preview_value, ImGuiComboFlags flags = 0);
    IMGUI_API void          EndCombo(); // only call EndCombo() if BeginCombo() returns true!
    IMGUI_API bool          Combo(const char* label, int* current_item, const char* const items[], int items_count, int popup_max_height_in_items = -1);
    IMGUI_API bool          Combo(const char* label, int* current_item, const char* items_separated_by_zeros, int popup_max_height_in_items = -1);      // Separate items with \0 within a string, end item-list with \0\0. e.g. "One\0Two\0Three\0"
    IMGUI_API bool          Combo(const char* label, int* current_item, bool(*items_getter)(void* data, int idx, const char** out_text), void* data, int items_count, int popup_max_height_in_items = -1);

    // Widgets: Drags (tip: ctrl+click on a drag box to input with keyboard. manually input values aren't clamped, can go off-bounds)
    // For all the Float2/Float3/Float4/Int2/Int3/Int4 versions of every functions, note that a 'float v[X]' function argument is the same as 'float* v', the array syntax is just a way to document the number of elements that are expected to be accessible. You can pass address of your first element out of a contiguous set, e.g. &myvector.x
    // Speed are per-pixel of mouse movement (v_speed=0.2f: mouse needs to move by 5 pixels to increase value by 1). For gamepad/keyboard navigation, minimum speed is Max(v_speed, minimum_step_at_given_precision).
    IMGUI_API bool          DragFloat(const char* label, float* v, float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f);     // If v_min >= v_max we have no bound
    IMGUI_API bool          DragFloat2(const char* label, float v[2], float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          DragFloat3(const char* label, float v[3], float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          DragFloat4(const char* label, float v[4], float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          DragFloatRange2(const char* label, float* v_current_min, float* v_current_max, float v_speed = 1.0f, float v_min = 0.0f, float v_max = 0.0f, const char* display_format = "%.3f", const char* display_format_max = NULL, float power = 1.0f);
    IMGUI_API bool          DragInt(const char* label, int* v, float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f");                                       // If v_min >= v_max we have no bound
    IMGUI_API bool          DragInt2(const char* label, int v[2], float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f");
    IMGUI_API bool          DragInt3(const char* label, int v[3], float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f");
    IMGUI_API bool          DragInt4(const char* label, int v[4], float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f");
    IMGUI_API bool          DragIntRange2(const char* label, int* v_current_min, int* v_current_max, float v_speed = 1.0f, int v_min = 0, int v_max = 0, const char* display_format = "%.0f", const char* display_format_max = NULL);

    // Widgets: Input with Keyboard
    IMGUI_API bool          InputText(const char* label, char* buf, size_t buf_size, ImGuiInputTextFlags flags = 0, ImGuiTextEditCallback callback = NULL, void* user_data = NULL);
    IMGUI_API bool          InputTextMultiline(const char* label, char* buf, size_t buf_size, const ImVec2& size = ImVec2(0,0), ImGuiInputTextFlags flags = 0, ImGuiTextEditCallback callback = NULL, void* user_data = NULL);
    IMGUI_API bool          InputFloat(const char* label, float* v, float step = 0.0f, float step_fast = 0.0f, int decimal_precision = -1, ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputFloat2(const char* label, float v[2], int decimal_precision = -1, ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputFloat3(const char* label, float v[3], int decimal_precision = -1, ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputFloat4(const char* label, float v[4], int decimal_precision = -1, ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputInt(const char* label, int* v, int step = 1, int step_fast = 100, ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputInt2(const char* label, int v[2], ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputInt3(const char* label, int v[3], ImGuiInputTextFlags extra_flags = 0);
    IMGUI_API bool          InputInt4(const char* label, int v[4], ImGuiInputTextFlags extra_flags = 0);

    // Widgets: Sliders (tip: ctrl+click on a slider to input with keyboard. manually input values aren't clamped, can go off-bounds)
    IMGUI_API bool          SliderFloat(const char* label, float* v, float v_min, float v_max, const char* display_format = "%.3f", float power = 1.0f);     // adjust display_format to decorate the value with a prefix or a suffix for in-slider labels or unit display. Use power!=1.0 for logarithmic sliders
    IMGUI_API bool          SliderFloat2(const char* label, float v[2], float v_min, float v_max, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          SliderFloat3(const char* label, float v[3], float v_min, float v_max, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          SliderFloat4(const char* label, float v[4], float v_min, float v_max, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          SliderAngle(const char* label, float* v_rad, float v_degrees_min = -360.0f, float v_degrees_max = +360.0f);
    IMGUI_API bool          SliderInt(const char* label, int* v, int v_min, int v_max, const char* display_format = "%.0f");
    IMGUI_API bool          SliderInt2(const char* label, int v[2], int v_min, int v_max, const char* display_format = "%.0f");
    IMGUI_API bool          SliderInt3(const char* label, int v[3], int v_min, int v_max, const char* display_format = "%.0f");
    IMGUI_API bool          SliderInt4(const char* label, int v[4], int v_min, int v_max, const char* display_format = "%.0f");
    IMGUI_API bool          VSliderFloat(const char* label, const ImVec2& size, float* v, float v_min, float v_max, const char* display_format = "%.3f", float power = 1.0f);
    IMGUI_API bool          VSliderInt(const char* label, const ImVec2& size, int* v, int v_min, int v_max, const char* display_format = "%.0f");

    // Widgets: Color Editor/Picker (tip: the ColorEdit* functions have a little colored preview square that can be left-clicked to open a picker, and right-clicked to open an option menu.)
    // Note that a 'float v[X]' function argument is the same as 'float* v', the array syntax is just a way to document the number of elements that are expected to be accessible. You can the pass the address of a first float element out of a contiguous structure, e.g. &myvector.x
    IMGUI_API bool          ColorEdit3(const char* label, float col[3], ImGuiColorEditFlags flags = 0);
    IMGUI_API bool          ColorEdit4(const char* label, float col[4], ImGuiColorEditFlags flags = 0);
    IMGUI_API bool          ColorPicker3(const char* label, float col[3], ImGuiColorEditFlags flags = 0);
    IMGUI_API bool          ColorPicker4(const char* label, float col[4], ImGuiColorEditFlags flags = 0, const float* ref_col = NULL);
    IMGUI_API bool          ColorButton(const char* desc_id, const ImVec4& col, ImGuiColorEditFlags flags = 0, ImVec2 size = ImVec2(0,0));  // display a colored square/button, hover for details, return true when pressed.
    IMGUI_API void          SetColorEditOptions(ImGuiColorEditFlags flags);                         // initialize current options (generally on application startup) if you want to select a default format, picker type, etc. User will be able to change many settings, unless you pass the _NoOptions flag to your calls.

    // Widgets: Trees
    IMGUI_API bool          TreeNode(const char* label);                                            // if returning 'true' the node is open and the tree id is pushed into the id stack. user is responsible for calling TreePop().
    IMGUI_API bool          TreeNode(const char* str_id, const char* fmt, ...) IM_FMTARGS(2);       // read the FAQ about why and how to use ID. to align arbitrary text at the same level as a TreeNode() you can use Bullet().
    IMGUI_API bool          TreeNode(const void* ptr_id, const char* fmt, ...) IM_FMTARGS(2);       // "
    IMGUI_API bool          TreeNodeV(const char* str_id, const char* fmt, va_list args) IM_FMTLIST(2);
    IMGUI_API bool          TreeNodeV(const void* ptr_id, const char* fmt, va_list args) IM_FMTLIST(2);
    IMGUI_API bool          TreeNodeEx(const char* label, ImGuiTreeNodeFlags flags = 0);
    IMGUI_API bool          TreeNodeEx(const char* str_id, ImGuiTreeNodeFlags flags, const char* fmt, ...) IM_FMTARGS(3);
    IMGUI_API bool          TreeNodeEx(const void* ptr_id, ImGuiTreeNodeFlags flags, const char* fmt, ...) IM_FMTARGS(3);
    IMGUI_API bool          TreeNodeExV(const char* str_id, ImGuiTreeNodeFlags flags, const char* fmt, va_list args) IM_FMTLIST(3);
    IMGUI_API bool          TreeNodeExV(const void* ptr_id, ImGuiTreeNodeFlags flags, const char* fmt, va_list args) IM_FMTLIST(3);
    IMGUI_API void          TreePush(const char* str_id);                                           // ~ Indent()+PushId(). Already called by TreeNode() when returning true, but you can call Push/Pop yourself for layout purpose
    IMGUI_API void          TreePush(const void* ptr_id = NULL);                                    // "
    IMGUI_API void          TreePop();                                                              // ~ Unindent()+PopId()
    IMGUI_API void          TreeAdvanceToLabelPos();                                                // advance cursor x position by GetTreeNodeToLabelSpacing()
    IMGUI_API float         GetTreeNodeToLabelSpacing();                                            // horizontal distance preceding label when using TreeNode*() or Bullet() == (g.FontSize + style.FramePadding.x*2) for a regular unframed TreeNode
    IMGUI_API void          SetNextTreeNodeOpen(bool is_open, ImGuiCond cond = 0);                  // set next TreeNode/CollapsingHeader open state.
    IMGUI_API bool          CollapsingHeader(const char* label, ImGuiTreeNodeFlags flags = 0);      // if returning 'true' the header is open. doesn't indent nor push on ID stack. user doesn't have to call TreePop().
    IMGUI_API bool          CollapsingHeader(const char* label, bool* p_open, ImGuiTreeNodeFlags flags = 0); // when 'p_open' isn't NULL, display an additional small close button on upper right of the header

    // Widgets: Selectable / Lists
    IMGUI_API bool          Selectable(const char* label, bool selected = false, ImGuiSelectableFlags flags = 0, const ImVec2& size = ImVec2(0,0));  // "bool selected" carry the selection state (read-only). Selectable() is clicked is returns true so you can modify your selection state. size.x==0.0: use remaining width, size.x>0.0: specify width. size.y==0.0: use label height, size.y>0.0: specify height
    IMGUI_API bool          Selectable(const char* label, bool* p_selected, ImGuiSelectableFlags flags = 0, const ImVec2& size = ImVec2(0,0));       // "bool* p_selected" point to the selection state (read-write), as a convenient helper.
    IMGUI_API bool          ListBox(const char* label, int* current_item, const char* const items[], int items_count, int height_in_items = -1);
    IMGUI_API bool          ListBox(const char* label, int* current_item, bool (*items_getter)(void* data, int idx, const char** out_text), void* data, int items_count, int height_in_items = -1);
    IMGUI_API bool          ListBoxHeader(const char* label, const ImVec2& size = ImVec2(0,0));     // use if you want to reimplement ListBox() will custom data or interactions. make sure to call ListBoxFooter() afterwards.
    IMGUI_API bool          ListBoxHeader(const char* label, int items_count, int height_in_items = -1); // "
    IMGUI_API void          ListBoxFooter();                                                        // terminate the scrolling region

    // Widgets: Value() Helpers. Output single value in "name: value" format (tip: freely declare more in your code to handle your types. you can add functions to the ImGui namespace)
    IMGUI_API void          Value(const char* prefix, bool b);
    IMGUI_API void          Value(const char* prefix, int v);
    IMGUI_API void          Value(const char* prefix, unsigned int v);
    IMGUI_API void          Value(const char* prefix, float v, const char* float_format = NULL);

    // Tooltips
    IMGUI_API void          SetTooltip(const char* fmt, ...) IM_FMTARGS(1);                     // set text tooltip under mouse-cursor, typically use with ImGui::IsItemHovered(). overidde any previous call to SetTooltip().
    IMGUI_API void          SetTooltipV(const char* fmt, va_list args) IM_FMTLIST(1);
    IMGUI_API void          BeginTooltip();                                                     // begin/append a tooltip window. to create full-featured tooltip (with any kind of contents).
    IMGUI_API void          EndTooltip();

    // Menus
    IMGUI_API bool          BeginMainMenuBar();                                                 // create and append to a full screen menu-bar.
    IMGUI_API void          EndMainMenuBar();                                                   // only call EndMainMenuBar() if BeginMainMenuBar() returns true!
    IMGUI_API bool          BeginMenuBar();                                                     // append to menu-bar of current window (requires ImGuiWindowFlags_MenuBar flag set on parent window).
    IMGUI_API void          EndMenuBar();                                                       // only call EndMenuBar() if BeginMenuBar() returns true!
    IMGUI_API bool          BeginMenu(const char* label, bool enabled = true);                  // create a sub-menu entry. only call EndMenu() if this returns true!
    IMGUI_API void          EndMenu();                                                          // only call EndBegin() if BeginMenu() returns true!
    IMGUI_API bool          MenuItem(const char* label, const char* shortcut = NULL, bool selected = false, bool enabled = true);  // return true when activated. shortcuts are displayed for convenience but not processed by ImGui at the moment
    IMGUI_API bool          MenuItem(const char* label, const char* shortcut, bool* p_selected, bool enabled = true);              // return true when activated + toggle (*p_selected) if p_selected != NULL

    // Popups
    IMGUI_API void          OpenPopup(const char* str_id);                                      // call to mark popup as open (don't call every frame!). popups are closed when user click outside, or if CloseCurrentPopup() is called within a BeginPopup()/EndPopup() block. By default, Selectable()/MenuItem() are calling CloseCurrentPopup(). Popup identifiers are relative to the current ID-stack (so OpenPopup and BeginPopup needs to be at the same level).
    IMGUI_API bool          BeginPopup(const char* str_id, ImGuiWindowFlags flags = 0);                                             // return true if the popup is open, and you can start outputting to it. only call EndPopup() if BeginPopup() returns true!
    IMGUI_API bool          BeginPopupContextItem(const char* str_id = NULL, int mouse_button = 1);                                 // helper to open and begin popup when clicked on last item. if you can pass a NULL str_id only if the previous item had an id. If you want to use that on a non-interactive item such as Text() you need to pass in an explicit ID here. read comments in .cpp!
    IMGUI_API bool          BeginPopupContextWindow(const char* str_id = NULL, int mouse_button = 1, bool also_over_items = true);  // helper to open and begin popup when clicked on current window.
    IMGUI_API bool          BeginPopupContextVoid(const char* str_id = NULL, int mouse_button = 1);                                 // helper to open and begin popup when clicked in void (where there are no imgui windows).
    IMGUI_API bool          BeginPopupModal(const char* name, bool* p_open = NULL, ImGuiWindowFlags flags = 0);                     // modal dialog (regular window with title bar, block interactions behind the modal window, can't close the modal window by clicking outside)
    IMGUI_API void          EndPopup();                                                                                             // only call EndPopup() if BeginPopupXXX() returns true!
    IMGUI_API bool          OpenPopupOnItemClick(const char* str_id = NULL, int mouse_button = 1);                                  // helper to open popup when clicked on last item. return true when just opened.
    IMGUI_API bool          IsPopupOpen(const char* str_id);                                    // return true if the popup is open
    IMGUI_API void          CloseCurrentPopup();                                                // close the popup we have begin-ed into. clicking on a MenuItem or Selectable automatically close the current popup.

    // Logging/Capture: all text output from interface is captured to tty/file/clipboard. By default, tree nodes are automatically opened during logging.
    IMGUI_API void          LogToTTY(int max_depth = -1);                                       // start logging to tty
    IMGUI_API void          LogToFile(int max_depth = -1, const char* filename = NULL);         // start logging to file
    IMGUI_API void          LogToClipboard(int max_depth = -1);                                 // start logging to OS clipboard
    IMGUI_API void          LogFinish();                                                        // stop logging (close file, etc.)
    IMGUI_API void          LogButtons();                                                       // helper to display buttons for logging to tty/file/clipboard
    IMGUI_API void          LogText(const char* fmt, ...) IM_FMTARGS(1);                        // pass text data straight to log (without being displayed)

    // Drag and Drop
    // [BETA API] Missing Demo code. API may evolve.
    IMGUI_API bool          BeginDragDropSource(ImGuiDragDropFlags flags = 0);                                      // call when the current item is active. If this return true, you can call SetDragDropPayload() + EndDragDropSource()
    IMGUI_API bool          SetDragDropPayload(const char* type, const void* data, size_t size, ImGuiCond cond = 0);// type is a user defined string of maximum 12 characters. Strings starting with '_' are reserved for dear imgui internal types. Data is copied and held by imgui.
    IMGUI_API void          EndDragDropSource();                                                                    // only call EndDragDropSource() if BeginDragDropSource() returns true!
    IMGUI_API bool          BeginDragDropTarget();                                                                  // call after submitting an item that may receive an item. If this returns true, you can call AcceptDragDropPayload() + EndDragDropTarget()
    IMGUI_API const ImGuiPayload* AcceptDragDropPayload(const char* type, ImGuiDragDropFlags flags = 0);            // accept contents of a given type. If ImGuiDragDropFlags_AcceptBeforeDelivery is set you can peek into the payload before the mouse button is released.
    IMGUI_API void          EndDragDropTarget();                                                                    // only call EndDragDropTarget() if BeginDragDropTarget() returns true!

    // Clipping
    IMGUI_API void          PushClipRect(const ImVec2& clip_rect_min, const ImVec2& clip_rect_max, bool intersect_with_current_clip_rect);
    IMGUI_API void          PopClipRect();

    // Focus, Activation
    // (Prefer using "SetItemDefaultFocus()" over "if (IsWindowAppearing()) SetScrollHere()" when applicable, to make your code more forward compatible when navigation branch is merged)
    IMGUI_API void          SetItemDefaultFocus();                                              // make last item the default focused item of a window. Please use instead of "if (IsWindowAppearing()) SetScrollHere()" to signify "default item".
    IMGUI_API void          SetKeyboardFocusHere(int offset = 0);                               // focus keyboard on the next widget. Use positive 'offset' to access sub components of a multiple component widget. Use -1 to access previous widget.

    // Utilities
    IMGUI_API bool          IsItemHovered(ImGuiHoveredFlags flags = 0);                         // is the last item hovered? (and usable, aka not blocked by a popup, etc.). See ImGuiHoveredFlags for more options.
    IMGUI_API bool          IsItemActive();                                                     // is the last item active? (e.g. button being held, text field being edited- items that don't interact will always return false)
    IMGUI_API bool          IsItemFocused();                                                    // is the last item focused for keyboard/gamepad navigation?
    IMGUI_API bool          IsItemClicked(int mouse_button = 0);                                // is the last item clicked? (e.g. button/node just clicked on)
    IMGUI_API bool          IsItemVisible();                                                    // is the last item visible? (aka not out of sight due to clipping/scrolling.)
    IMGUI_API bool          IsAnyItemHovered();
    IMGUI_API bool          IsAnyItemActive();
    IMGUI_API bool          IsAnyItemFocused();
    IMGUI_API ImVec2        GetItemRectMin();                                                   // get bounding rectangle of last item, in screen space
    IMGUI_API ImVec2        GetItemRectMax();                                                   // "
    IMGUI_API ImVec2        GetItemRectSize();                                                  // get size of last item, in screen space
    IMGUI_API void          SetItemAllowOverlap();                                              // allow last item to be overlapped by a subsequent item. sometimes useful with invisible buttons, selectables, etc. to catch unused area.
    IMGUI_API bool          IsWindowFocused(ImGuiFocusedFlags flags = 0);                       // is current window focused? or its root/child, depending on flags. see flags for options.
    IMGUI_API bool          IsWindowHovered(ImGuiHoveredFlags flags = 0);                       // is current window hovered (and typically: not blocked by a popup/modal)? see flags for options.
    IMGUI_API bool          IsRectVisible(const ImVec2& size);                                  // test if rectangle (of given size, starting from cursor position) is visible / not clipped.
    IMGUI_API bool          IsRectVisible(const ImVec2& rect_min, const ImVec2& rect_max);      // test if rectangle (in screen space) is visible / not clipped. to perform coarse clipping on user's side.
    IMGUI_API float         GetTime();
    IMGUI_API int           GetFrameCount();
    IMGUI_API ImDrawList*   GetOverlayDrawList();                                               // this draw list will be the last rendered one, useful to quickly draw overlays shapes/text
    IMGUI_API ImDrawListSharedData* GetDrawListSharedData();
    IMGUI_API const char*   GetStyleColorName(ImGuiCol idx);
    IMGUI_API ImVec2        CalcTextSize(const char* text, const char* text_end = NULL, bool hide_text_after_double_hash = false, float wrap_width = -1.0f);
    IMGUI_API void          CalcListClipping(int items_count, float items_height, int* out_items_display_start, int* out_items_display_end);    // calculate coarse clipping for large list of evenly sized items. Prefer using the ImGuiListClipper higher-level helper if you can.

    IMGUI_API bool          BeginChildFrame(ImGuiID id, const ImVec2& size, ImGuiWindowFlags flags = 0); // helper to create a child window / scrolling region that looks like a normal widget frame
    IMGUI_API void          EndChildFrame();                                                    // always call EndChildFrame() regardless of BeginChildFrame() return values (which indicates a collapsed/clipped window)

    IMGUI_API ImVec4        ColorConvertU32ToFloat4(ImU32 in);
    IMGUI_API ImU32         ColorConvertFloat4ToU32(const ImVec4& in);
    IMGUI_API void          ColorConvertRGBtoHSV(float r, float g, float b, float& out_h, float& out_s, float& out_v);
    IMGUI_API void          ColorConvertHSVtoRGB(float h, float s, float v, float& out_r, float& out_g, float& out_b);

    // Inputs
    IMGUI_API int           GetKeyIndex(ImGuiKey imgui_key);                                    // map ImGuiKey_* values into user's key index. == io.KeyMap[key]
    IMGUI_API bool          IsKeyDown(int user_key_index);                                      // is key being held. == io.KeysDown[user_key_index]. note that imgui doesn't know the semantic of each entry of io.KeyDown[]. Use your own indices/enums according to how your backend/engine stored them into KeyDown[]!
    IMGUI_API bool          IsKeyPressed(int user_key_index, bool repeat = true);               // was key pressed (went from !Down to Down). if repeat=true, uses io.KeyRepeatDelay / KeyRepeatRate
    IMGUI_API bool          IsKeyReleased(int user_key_index);                                  // was key released (went from Down to !Down)..
    IMGUI_API int           GetKeyPressedAmount(int key_index, float repeat_delay, float rate); // uses provided repeat rate/delay. return a count, most often 0 or 1 but might be >1 if RepeatRate is small enough that DeltaTime > RepeatRate
    IMGUI_API bool          IsMouseDown(int button);                                            // is mouse button held
    IMGUI_API bool          IsAnyMouseDown();                                                   // is any mouse button held
    IMGUI_API bool          IsMouseClicked(int button, bool repeat = false);                    // did mouse button clicked (went from !Down to Down)
    IMGUI_API bool          IsMouseDoubleClicked(int button);                                   // did mouse button double-clicked. a double-click returns false in IsMouseClicked(). uses io.MouseDoubleClickTime.
    IMGUI_API bool          IsMouseReleased(int button);                                        // did mouse button released (went from Down to !Down)
    IMGUI_API bool          IsMouseDragging(int button = 0, float lock_threshold = -1.0f);      // is mouse dragging. if lock_threshold < -1.0f uses io.MouseDraggingThreshold
    IMGUI_API bool          IsMouseHoveringRect(const ImVec2& r_min, const ImVec2& r_max, bool clip = true);  // is mouse hovering given bounding rect (in screen space). clipped by current clipping settings. disregarding of consideration of focus/window ordering/blocked by a popup.
    IMGUI_API bool          IsMousePosValid(const ImVec2* mouse_pos = NULL);                    //
    IMGUI_API ImVec2        GetMousePos();                                                      // shortcut to ImGui::GetIO().MousePos provided by user, to be consistent with other calls
    IMGUI_API ImVec2        GetMousePosOnOpeningCurrentPopup();                                 // retrieve backup of mouse positioning at the time of opening popup we have BeginPopup() into
    IMGUI_API ImVec2        GetMouseDragDelta(int button = 0, float lock_threshold = -1.0f);    // dragging amount since clicking. if lock_threshold < -1.0f uses io.MouseDraggingThreshold
    IMGUI_API void          ResetMouseDragDelta(int button = 0);                                //
    IMGUI_API ImGuiMouseCursor GetMouseCursor();                                                // get desired cursor type, reset in ImGui::NewFrame(), this is updated during the frame. valid before Render(). If you use software rendering by setting io.MouseDrawCursor ImGui will render those for you
    IMGUI_API void          SetMouseCursor(ImGuiMouseCursor type);                              // set desired cursor type
    IMGUI_API void          CaptureKeyboardFromApp(bool capture = true);                        // manually override io.WantCaptureKeyboard flag next frame (said flag is entirely left for your application handle). e.g. force capture keyboard when your widget is being hovered.
    IMGUI_API void          CaptureMouseFromApp(bool capture = true);                           // manually override io.WantCaptureMouse flag next frame (said flag is entirely left for your application handle).

    // Clipboard Utilities (also see the LogToClipboard() function to capture or output text data to the clipboard)
    IMGUI_API const char*   GetClipboardText();
    IMGUI_API void          SetClipboardText(const char* text);

    // Memory Utilities
    // All those functions are not reliant on the current context.
    // If you reload the contents of imgui.cpp at runtime, you may need to call SetCurrentContext() + SetAllocatorFunctions() again.
    IMGUI_API void          SetAllocatorFunctions(void* (*alloc_func)(size_t sz, void* user_data), void(*free_func)(void* ptr, void* user_data), void* user_data = NULL);
    IMGUI_API void*         MemAlloc(size_t size);
    IMGUI_API void          MemFree(void* ptr);

} // namespace ImGui

// Flags for ImGui::Begin()
enum ImGuiWindowFlags_
{
    ImGuiWindowFlags_NoTitleBar             = 1 << 0,   // Disable title-bar
    ImGuiWindowFlags_NoResize               = 1 << 1,   // Disable user resizing with the lower-right grip
    ImGuiWindowFlags_NoMove                 = 1 << 2,   // Disable user moving the window
    ImGuiWindowFlags_NoScrollbar            = 1 << 3,   // Disable scrollbars (window can still scroll with mouse or programatically)
    ImGuiWindowFlags_NoScrollWithMouse      = 1 << 4,   // Disable user vertically scrolling with mouse wheel. On child window, mouse wheel will be forwarded to the parent unless NoScrollbar is also set.
    ImGuiWindowFlags_NoCollapse             = 1 << 5,   // Disable user collapsing window by double-clicking on it
    ImGuiWindowFlags_AlwaysAutoResize       = 1 << 6,   // Resize every window to its content every frame
    //ImGuiWindowFlags_ShowBorders          = 1 << 7,   // Show borders around windows and items (OBSOLETE! Use e.g. style.FrameBorderSize=1.0f to enable borders).
    ImGuiWindowFlags_NoSavedSettings        = 1 << 8,   // Never load/save settings in .ini file
    ImGuiWindowFlags_NoInputs               = 1 << 9,   // Disable catching mouse or keyboard inputs, hovering test with pass through.
    ImGuiWindowFlags_MenuBar                = 1 << 10,  // Has a menu-bar
    ImGuiWindowFlags_HorizontalScrollbar    = 1 << 11,  // Allow horizontal scrollbar to appear (off by default). You may use SetNextWindowContentSize(ImVec2(width,0.0f)); prior to calling Begin() to specify width. Read code in imgui_demo in the "Horizontal Scrolling" section.
    ImGuiWindowFlags_NoFocusOnAppearing     = 1 << 12,  // Disable taking focus when transitioning from hidden to visible state
    ImGuiWindowFlags_NoBringToFrontOnFocus  = 1 << 13,  // Disable bringing window to front when taking focus (e.g. clicking on it or programatically giving it focus)
    ImGuiWindowFlags_AlwaysVerticalScrollbar= 1 << 14,  // Always show vertical scrollbar (even if ContentSize.y < Size.y)
    ImGuiWindowFlags_AlwaysHorizontalScrollbar=1<< 15,  // Always show horizontal scrollbar (even if ContentSize.x < Size.x)
    ImGuiWindowFlags_AlwaysUseWindowPadding = 1 << 16,  // Ensure child windows without border uses style.WindowPadding (ignored by default for non-bordered child windows, because more convenient)
    ImGuiWindowFlags_ResizeFromAnySide      = 1 << 17,  // (WIP) Enable resize from any corners and borders. Your back-end needs to honor the different values of io.MouseCursor set by imgui.
    ImGuiWindowFlags_NoNavInputs            = 1 << 18,  // No gamepad/keyboard navigation within the window
    ImGuiWindowFlags_NoNavFocus             = 1 << 19,  // No focusing toward this window with gamepad/keyboard navigation (e.g. skipped by CTRL+TAB)
    ImGuiWindowFlags_NoNav                  = ImGuiWindowFlags_NoNavInputs | ImGuiWindowFlags_NoNavFocus,

    // [Internal]
    ImGuiWindowFlags_NavFlattened           = 1 << 23,  // (WIP) Allow gamepad/keyboard navigation to cross over parent border to this child (only use on child that have no scrolling!)
    ImGuiWindowFlags_ChildWindow            = 1 << 24,  // Don't use! For internal use by BeginChild()
    ImGuiWindowFlags_Tooltip                = 1 << 25,  // Don't use! For internal use by BeginTooltip()
    ImGuiWindowFlags_Popup                  = 1 << 26,  // Don't use! For internal use by BeginPopup()
    ImGuiWindowFlags_Modal                  = 1 << 27,  // Don't use! For internal use by BeginPopupModal()
    ImGuiWindowFlags_ChildMenu              = 1 << 28   // Don't use! For internal use by BeginMenu()
};

// Flags for ImGui::InputText()
enum ImGuiInputTextFlags_
{
    ImGuiInputTextFlags_CharsDecimal        = 1 << 0,   // Allow 0123456789.+-*/
    ImGuiInputTextFlags_CharsHexadecimal    = 1 << 1,   // Allow 0123456789ABCDEFabcdef
    ImGuiInputTextFlags_CharsUppercase      = 1 << 2,   // Turn a..z into A..Z
    ImGuiInputTextFlags_CharsNoBlank        = 1 << 3,   // Filter out spaces, tabs
    ImGuiInputTextFlags_AutoSelectAll       = 1 << 4,   // Select entire text when first taking mouse focus
    ImGuiInputTextFlags_EnterReturnsTrue    = 1 << 5,   // Return 'true' when Enter is pressed (as opposed to when the value was modified)
    ImGuiInputTextFlags_CallbackCompletion  = 1 << 6,   // Call user function on pressing TAB (for completion handling)
    ImGuiInputTextFlags_CallbackHistory     = 1 << 7,   // Call user function on pressing Up/Down arrows (for history handling)
    ImGuiInputTextFlags_CallbackAlways      = 1 << 8,   // Call user function every time. User code may query cursor position, modify text buffer.
    ImGuiInputTextFlags_CallbackCharFilter  = 1 << 9,   // Call user function to filter character. Modify data->EventChar to replace/filter input, or return 1 to discard character.
    ImGuiInputTextFlags_AllowTabInput       = 1 << 10,  // Pressing TAB input a '\t' character into the text field
    ImGuiInputTextFlags_CtrlEnterForNewLine = 1 << 11,  // In multi-line mode, unfocus with Enter, add new line with Ctrl+Enter (default is opposite: unfocus with Ctrl+Enter, add line with Enter).
    ImGuiInputTextFlags_NoHorizontalScroll  = 1 << 12,  // Disable following the cursor horizontally
    ImGuiInputTextFlags_AlwaysInsertMode    = 1 << 13,  // Insert mode
    ImGuiInputTextFlags_ReadOnly            = 1 << 14,  // Read-only mode
    ImGuiInputTextFlags_Password            = 1 << 15,  // Password mode, display all characters as '*'
    ImGuiInputTextFlags_NoUndoRedo          = 1 << 16,  // Disable undo/redo. Note that input text owns the text data while active, if you want to provide your own undo/redo stack you need e.g. to call ClearActiveID().
    // [Internal]
    ImGuiInputTextFlags_Multiline           = 1 << 20   // For internal use by InputTextMultiline()
};

// Flags for ImGui::TreeNodeEx(), ImGui::CollapsingHeader*()
enum ImGuiTreeNodeFlags_
{
    ImGuiTreeNodeFlags_Selected             = 1 << 0,   // Draw as selected
    ImGuiTreeNodeFlags_Framed               = 1 << 1,   // Full colored frame (e.g. for CollapsingHeader)
    ImGuiTreeNodeFlags_AllowItemOverlap     = 1 << 2,   // Hit testing to allow subsequent widgets to overlap this one
    ImGuiTreeNodeFlags_NoTreePushOnOpen     = 1 << 3,   // Don't do a TreePush() when open (e.g. for CollapsingHeader) = no extra indent nor pushing on ID stack
    ImGuiTreeNodeFlags_NoAutoOpenOnLog      = 1 << 4,   // Don't automatically and temporarily open node when Logging is active (by default logging will automatically open tree nodes)
    ImGuiTreeNodeFlags_DefaultOpen          = 1 << 5,   // Default node to be open
    ImGuiTreeNodeFlags_OpenOnDoubleClick    = 1 << 6,   // Need double-click to open node
    ImGuiTreeNodeFlags_OpenOnArrow          = 1 << 7,   // Only open when clicking on the arrow part. If ImGuiTreeNodeFlags_OpenOnDoubleClick is also set, single-click arrow or double-click all box to open.
    ImGuiTreeNodeFlags_Leaf                 = 1 << 8,   // No collapsing, no arrow (use as a convenience for leaf nodes). 
    ImGuiTreeNodeFlags_Bullet               = 1 << 9,   // Display a bullet instead of arrow
    ImGuiTreeNodeFlags_FramePadding         = 1 << 10,  // Use FramePadding (even for an unframed text node) to vertically align text baseline to regular widget height. Equivalent to calling AlignTextToFramePadding().
    //ImGuITreeNodeFlags_SpanAllAvailWidth  = 1 << 11,  // FIXME: TODO: Extend hit box horizontally even if not framed
    //ImGuiTreeNodeFlags_NoScrollOnOpen     = 1 << 12,  // FIXME: TODO: Disable automatic scroll on TreePop() if node got just open and contents is not visible
    ImGuiTreeNodeFlags_NavLeftJumpsBackHere = 1 << 13,  // (WIP) Nav: left direction may move to this TreeNode() from any of its child (items submitted between TreeNode and TreePop)
    ImGuiTreeNodeFlags_CollapsingHeader     = ImGuiTreeNodeFlags_Framed | ImGuiTreeNodeFlags_NoAutoOpenOnLog

    // Obsolete names (will be removed)
#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    , ImGuiTreeNodeFlags_AllowOverlapMode = ImGuiTreeNodeFlags_AllowItemOverlap
#endif
};

// Flags for ImGui::Selectable()
enum ImGuiSelectableFlags_
{
    ImGuiSelectableFlags_DontClosePopups    = 1 << 0,   // Clicking this don't close parent popup window
    ImGuiSelectableFlags_SpanAllColumns     = 1 << 1,   // Selectable frame can span all columns (text will still fit in current column)
    ImGuiSelectableFlags_AllowDoubleClick   = 1 << 2    // Generate press events on double clicks too
};

// Flags for ImGui::BeginCombo()
enum ImGuiComboFlags_
{
    ImGuiComboFlags_PopupAlignLeft          = 1 << 0,   // Align the popup toward the left by default
    ImGuiComboFlags_HeightSmall             = 1 << 1,   // Max ~4 items visible. Tip: If you want your combo popup to be a specific size you can use SetNextWindowSizeConstraints() prior to calling BeginCombo()
    ImGuiComboFlags_HeightRegular           = 1 << 2,   // Max ~8 items visible (default)
    ImGuiComboFlags_HeightLarge             = 1 << 3,   // Max ~20 items visible
    ImGuiComboFlags_HeightLargest           = 1 << 4,   // As many fitting items as possible
    ImGuiComboFlags_HeightMask_             = ImGuiComboFlags_HeightSmall | ImGuiComboFlags_HeightRegular | ImGuiComboFlags_HeightLarge | ImGuiComboFlags_HeightLargest
};

// Flags for ImGui::IsWindowFocused()
enum ImGuiFocusedFlags_
{
    ImGuiFocusedFlags_ChildWindows                  = 1 << 0,   // IsWindowFocused(): Return true if any children of the window is focused
    ImGuiFocusedFlags_RootWindow                    = 1 << 1,   // IsWindowFocused(): Test from root window (top most parent of the current hierarchy)
    ImGuiFocusedFlags_AnyWindow                     = 1 << 2,   // IsWindowFocused(): Return true if any window is focused
    ImGuiFocusedFlags_RootAndChildWindows           = ImGuiFocusedFlags_RootWindow | ImGuiFocusedFlags_ChildWindows
};

// Flags for ImGui::IsItemHovered(), ImGui::IsWindowHovered()
enum ImGuiHoveredFlags_
{
    ImGuiHoveredFlags_Default                       = 0,        // Return true if directly over the item/window, not obstructed by another window, not obstructed by an active popup or modal blocking inputs under them.
    ImGuiHoveredFlags_ChildWindows                  = 1 << 0,   // IsWindowHovered() only: Return true if any children of the window is hovered
    ImGuiHoveredFlags_RootWindow                    = 1 << 1,   // IsWindowHovered() only: Test from root window (top most parent of the current hierarchy)
    ImGuiHoveredFlags_AnyWindow                     = 1 << 2,   // IsWindowHovered() only: Return true if any window is hovered
    ImGuiHoveredFlags_AllowWhenBlockedByPopup       = 1 << 3,   // Return true even if a popup window is normally blocking access to this item/window
    //ImGuiHoveredFlags_AllowWhenBlockedByModal     = 1 << 4,   // Return true even if a modal popup window is normally blocking access to this item/window. FIXME-TODO: Unavailable yet.
    ImGuiHoveredFlags_AllowWhenBlockedByActiveItem  = 1 << 5,   // Return true even if an active item is blocking access to this item/window. Useful for Drag and Drop patterns.
    ImGuiHoveredFlags_AllowWhenOverlapped           = 1 << 6,   // Return true even if the position is overlapped by another window
    ImGuiHoveredFlags_RectOnly                      = ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem | ImGuiHoveredFlags_AllowWhenOverlapped,
    ImGuiHoveredFlags_RootAndChildWindows           = ImGuiHoveredFlags_RootWindow | ImGuiHoveredFlags_ChildWindows
};

// Flags for ImGui::BeginDragDropSource(), ImGui::AcceptDragDropPayload()
enum ImGuiDragDropFlags_
{
    // BeginDragDropSource() flags
    ImGuiDragDropFlags_SourceNoPreviewTooltip       = 1 << 0,       // By default, a successful call to BeginDragDropSource opens a tooltip so you can display a preview or description of the source contents. This flag disable this behavior.
    ImGuiDragDropFlags_SourceNoDisableHover         = 1 << 1,       // By default, when dragging we clear data so that IsItemHovered() will return true, to avoid subsequent user code submitting tooltips. This flag disable this behavior so you can still call IsItemHovered() on the source item.
    ImGuiDragDropFlags_SourceNoHoldToOpenOthers     = 1 << 2,       // Disable the behavior that allows to open tree nodes and collapsing header by holding over them while dragging a source item.
    ImGuiDragDropFlags_SourceAllowNullID            = 1 << 3,       // Allow items such as Text(), Image() that have no unique identifier to be used as drag source, by manufacturing a temporary identifier based on their window-relative position. This is extremely unusual within the dear imgui ecosystem and so we made it explicit.
    ImGuiDragDropFlags_SourceExtern                 = 1 << 4,       // External source (from outside of imgui), won't attempt to read current item/window info. Will always return true. Only one Extern source can be active simultaneously.
    // AcceptDragDropPayload() flags
    ImGuiDragDropFlags_AcceptBeforeDelivery         = 1 << 10,      // AcceptDragDropPayload() will returns true even before the mouse button is released. You can then call IsDelivery() to test if the payload needs to be delivered.
    ImGuiDragDropFlags_AcceptNoDrawDefaultRect      = 1 << 11,      // Do not draw the default highlight rectangle when hovering over target.
    ImGuiDragDropFlags_AcceptPeekOnly               = ImGuiDragDropFlags_AcceptBeforeDelivery | ImGuiDragDropFlags_AcceptNoDrawDefaultRect  // For peeking ahead and inspecting the payload before delivery.
};

// Standard Drag and Drop payload types. You can define you own payload types using 12-characters long strings. Types starting with '_' are defined by Dear ImGui.
#define IMGUI_PAYLOAD_TYPE_COLOR_3F     "_COL3F"    // float[3]     // Standard type for colors, without alpha. User code may use this type. 
#define IMGUI_PAYLOAD_TYPE_COLOR_4F     "_COL4F"    // float[4]     // Standard type for colors. User code may use this type.

// User fill ImGuiIO.KeyMap[] array with indices into the ImGuiIO.KeysDown[512] array
enum ImGuiKey_
{
    ImGuiKey_Tab,
    ImGuiKey_LeftArrow,
    ImGuiKey_RightArrow,
    ImGuiKey_UpArrow,
    ImGuiKey_DownArrow,
    ImGuiKey_PageUp,
    ImGuiKey_PageDown,
    ImGuiKey_Home,
    ImGuiKey_End,
    ImGuiKey_Insert,
    ImGuiKey_Delete,
    ImGuiKey_Backspace,
    ImGuiKey_Space,
    ImGuiKey_Enter,
    ImGuiKey_Escape,
    ImGuiKey_A,         // for text edit CTRL+A: select all
    ImGuiKey_C,         // for text edit CTRL+C: copy
    ImGuiKey_V,         // for text edit CTRL+V: paste
    ImGuiKey_X,         // for text edit CTRL+X: cut
    ImGuiKey_Y,         // for text edit CTRL+Y: redo
    ImGuiKey_Z,         // for text edit CTRL+Z: undo
    ImGuiKey_COUNT
};

// [BETA] Gamepad/Keyboard directional navigation
// Keyboard: Set io.NavFlags |= ImGuiNavFlags_EnableKeyboard to enable. NewFrame() will automatically fill io.NavInputs[] based on your io.KeyDown[] + io.KeyMap[] arrays.
// Gamepad:  Set io.NavFlags |= ImGuiNavFlags_EnableGamepad to enable. Fill the io.NavInputs[] fields before calling NewFrame(). Note that io.NavInputs[] is cleared by EndFrame().
// Read instructions in imgui.cpp for more details.
enum ImGuiNavInput_
{
    // Gamepad Mapping
    ImGuiNavInput_Activate,      // activate / open / toggle / tweak value       // e.g. Circle (PS4), A (Xbox), B (Switch), Space (Keyboard)
    ImGuiNavInput_Cancel,        // cancel / close / exit                        // e.g. Cross  (PS4), B (Xbox), A (Switch), Escape (Keyboard)
    ImGuiNavInput_Input,         // text input / on-screen keyboard              // e.g. Triang.(PS4), Y (Xbox), X (Switch), Return (Keyboard)
    ImGuiNavInput_Menu,          // tap: toggle menu / hold: focus, move, resize // e.g. Square (PS4), X (Xbox), Y (Switch), Alt (Keyboard)
    ImGuiNavInput_DpadLeft,      // move / tweak / resize window (w/ PadMenu)    // e.g. D-pad Left/Right/Up/Down (Gamepads), Arrow keys (Keyboard)
    ImGuiNavInput_DpadRight,     // 
    ImGuiNavInput_DpadUp,        // 
    ImGuiNavInput_DpadDown,      // 
    ImGuiNavInput_LStickLeft,    // scroll / move window (w/ PadMenu)            // e.g. Left Analog Stick Left/Right/Up/Down
    ImGuiNavInput_LStickRight,   // 
    ImGuiNavInput_LStickUp,      // 
    ImGuiNavInput_LStickDown,    // 
    ImGuiNavInput_FocusPrev,     // next window (w/ PadMenu)                     // e.g. L1 or L2 (PS4), LB or LT (Xbox), L or ZL (Switch)
    ImGuiNavInput_FocusNext,     // prev window (w/ PadMenu)                     // e.g. R1 or R2 (PS4), RB or RT (Xbox), R or ZL (Switch) 
    ImGuiNavInput_TweakSlow,     // slower tweaks                                // e.g. L1 or L2 (PS4), LB or LT (Xbox), L or ZL (Switch)
    ImGuiNavInput_TweakFast,     // faster tweaks                                // e.g. R1 or R2 (PS4), RB or RT (Xbox), R or ZL (Switch)

    // [Internal] Don't use directly! This is used internally to differentiate keyboard from gamepad inputs for behaviors that require to differentiate them.
    // Keyboard behavior that have no corresponding gamepad mapping (e.g. CTRL+TAB) may be directly reading from io.KeyDown[] instead of io.NavInputs[].
    ImGuiNavInput_KeyMenu_,      // toggle menu                                  // = io.KeyAlt
    ImGuiNavInput_KeyLeft_,      // move left                                    // = Arrow keys
    ImGuiNavInput_KeyRight_,     // move right
    ImGuiNavInput_KeyUp_,        // move up
    ImGuiNavInput_KeyDown_,      // move down
    ImGuiNavInput_COUNT,
    ImGuiNavInput_InternalStart_ = ImGuiNavInput_KeyMenu_
};

// [BETA] Gamepad/Keyboard directional navigation flags, stored in io.NavFlags
enum ImGuiNavFlags_
{
    ImGuiNavFlags_EnableKeyboard    = 1 << 0,   // Master keyboard navigation enable flag. NewFrame() will automatically fill io.NavInputs[] based on io.KeyDown[].
    ImGuiNavFlags_EnableGamepad     = 1 << 1,   // Master gamepad navigation enable flag. This is mostly to instruct your imgui back-end to fill io.NavInputs[].
    ImGuiNavFlags_MoveMouse         = 1 << 2,   // Request navigation to allow moving the mouse cursor. May be useful on TV/console systems where moving a virtual mouse is awkward. Will update io.MousePos and set io.WantMoveMouse=true. If enabled you MUST honor io.WantMoveMouse requests in your binding, otherwise ImGui will react as if the mouse is jumping around back and forth.
    ImGuiNavFlags_NoCaptureKeyboard = 1 << 3    // Do not set the io.WantCaptureKeyboard flag with io.NavActive is set. 
};

// Enumeration for PushStyleColor() / PopStyleColor()
enum ImGuiCol_
{
    ImGuiCol_Text,
    ImGuiCol_TextDisabled,
    ImGuiCol_WindowBg,              // Background of normal windows
    ImGuiCol_ChildBg,               // Background of child windows
    ImGuiCol_PopupBg,               // Background of popups, menus, tooltips windows
    ImGuiCol_Border,
    ImGuiCol_BorderShadow,
    ImGuiCol_FrameBg,               // Background of checkbox, radio button, plot, slider, text input
    ImGuiCol_FrameBgHovered,
    ImGuiCol_FrameBgActive,
    ImGuiCol_TitleBg,
    ImGuiCol_TitleBgActive,
    ImGuiCol_TitleBgCollapsed,
    ImGuiCol_MenuBarBg,
    ImGuiCol_ScrollbarBg,
    ImGuiCol_ScrollbarGrab,
    ImGuiCol_ScrollbarGrabHovered,
    ImGuiCol_ScrollbarGrabActive,
    ImGuiCol_CheckMark,
    ImGuiCol_SliderGrab,
    ImGuiCol_SliderGrabActive,
    ImGuiCol_Button,
    ImGuiCol_ButtonHovered,
    ImGuiCol_ButtonActive,
    ImGuiCol_Header,
    ImGuiCol_HeaderHovered,
    ImGuiCol_HeaderActive,
    ImGuiCol_Separator,
    ImGuiCol_SeparatorHovered,
    ImGuiCol_SeparatorActive,
    ImGuiCol_ResizeGrip,
    ImGuiCol_ResizeGripHovered,
    ImGuiCol_ResizeGripActive,
    ImGuiCol_CloseButton,
    ImGuiCol_CloseButtonHovered,
    ImGuiCol_CloseButtonActive,
    ImGuiCol_PlotLines,
    ImGuiCol_PlotLinesHovered,
    ImGuiCol_PlotHistogram,
    ImGuiCol_PlotHistogramHovered,
    ImGuiCol_TextSelectedBg,
    ImGuiCol_ModalWindowDarkening,  // darken entire screen when a modal window is active
    ImGuiCol_DragDropTarget,
    ImGuiCol_NavHighlight,          // gamepad/keyboard: current highlighted item 
    ImGuiCol_NavWindowingHighlight, // gamepad/keyboard: when holding NavMenu to focus/move/resize windows
    ImGuiCol_COUNT

    // Obsolete names (will be removed)
#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    //, ImGuiCol_ComboBg = ImGuiCol_PopupBg     // ComboBg has been merged with PopupBg, so a redirect isn't accurate.
    , ImGuiCol_ChildWindowBg = ImGuiCol_ChildBg, ImGuiCol_Column = ImGuiCol_Separator, ImGuiCol_ColumnHovered = ImGuiCol_SeparatorHovered, ImGuiCol_ColumnActive = ImGuiCol_SeparatorActive
#endif
};

// Enumeration for PushStyleVar() / PopStyleVar() to temporarily modify the ImGuiStyle structure.
// NB: the enum only refers to fields of ImGuiStyle which makes sense to be pushed/popped inside UI code. During initialization, feel free to just poke into ImGuiStyle directly.
// NB: if changing this enum, you need to update the associated internal table GStyleVarInfo[] accordingly. This is where we link enum values to members offset/type.
enum ImGuiStyleVar_
{
    // Enum name ......................// Member in ImGuiStyle structure (see ImGuiStyle for descriptions)
    ImGuiStyleVar_Alpha,               // float     Alpha
    ImGuiStyleVar_WindowPadding,       // ImVec2    WindowPadding
    ImGuiStyleVar_WindowRounding,      // float     WindowRounding
    ImGuiStyleVar_WindowBorderSize,    // float     WindowBorderSize
    ImGuiStyleVar_WindowMinSize,       // ImVec2    WindowMinSize
    ImGuiStyleVar_WindowTitleAlign,    // ImVec2    WindowTitleAlign
    ImGuiStyleVar_ChildRounding,       // float     ChildRounding
    ImGuiStyleVar_ChildBorderSize,     // float     ChildBorderSize
    ImGuiStyleVar_PopupRounding,       // float     PopupRounding
    ImGuiStyleVar_PopupBorderSize,     // float     PopupBorderSize
    ImGuiStyleVar_FramePadding,        // ImVec2    FramePadding
    ImGuiStyleVar_FrameRounding,       // float     FrameRounding
    ImGuiStyleVar_FrameBorderSize,     // float     FrameBorderSize
    ImGuiStyleVar_ItemSpacing,         // ImVec2    ItemSpacing
    ImGuiStyleVar_ItemInnerSpacing,    // ImVec2    ItemInnerSpacing
    ImGuiStyleVar_IndentSpacing,       // float     IndentSpacing
    ImGuiStyleVar_ScrollbarSize,       // float     ScrollbarSize
    ImGuiStyleVar_ScrollbarRounding,   // float     ScrollbarRounding
    ImGuiStyleVar_GrabMinSize,         // float     GrabMinSize
    ImGuiStyleVar_GrabRounding,        // float     GrabRounding
    ImGuiStyleVar_ButtonTextAlign,     // ImVec2    ButtonTextAlign
    ImGuiStyleVar_Count_

    // Obsolete names (will be removed)
#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    , ImGuiStyleVar_ChildWindowRounding = ImGuiStyleVar_ChildRounding
#endif
};

// Enumeration for ColorEdit3() / ColorEdit4() / ColorPicker3() / ColorPicker4() / ColorButton()
enum ImGuiColorEditFlags_
{
    ImGuiColorEditFlags_NoAlpha         = 1 << 1,   //              // ColorEdit, ColorPicker, ColorButton: ignore Alpha component (read 3 components from the input pointer).
    ImGuiColorEditFlags_NoPicker        = 1 << 2,   //              // ColorEdit: disable picker when clicking on colored square.
    ImGuiColorEditFlags_NoOptions       = 1 << 3,   //              // ColorEdit: disable toggling options menu when right-clicking on inputs/small preview.
    ImGuiColorEditFlags_NoSmallPreview  = 1 << 4,   //              // ColorEdit, ColorPicker: disable colored square preview next to the inputs. (e.g. to show only the inputs)
    ImGuiColorEditFlags_NoInputs        = 1 << 5,   //              // ColorEdit, ColorPicker: disable inputs sliders/text widgets (e.g. to show only the small preview colored square).
    ImGuiColorEditFlags_NoTooltip       = 1 << 6,   //              // ColorEdit, ColorPicker, ColorButton: disable tooltip when hovering the preview.
    ImGuiColorEditFlags_NoLabel         = 1 << 7,   //              // ColorEdit, ColorPicker: disable display of inline text label (the label is still forwarded to the tooltip and picker).
    ImGuiColorEditFlags_NoSidePreview   = 1 << 8,   //              // ColorPicker: disable bigger color preview on right side of the picker, use small colored square preview instead.
    // User Options (right-click on widget to change some of them). You can set application defaults using SetColorEditOptions(). The idea is that you probably don't want to override them in most of your calls, let the user choose and/or call SetColorEditOptions() during startup.
    ImGuiColorEditFlags_AlphaBar        = 1 << 9,   //              // ColorEdit, ColorPicker: show vertical alpha bar/gradient in picker.
    ImGuiColorEditFlags_AlphaPreview    = 1 << 10,  //              // ColorEdit, ColorPicker, ColorButton: display preview as a transparent color over a checkerboard, instead of opaque.
    ImGuiColorEditFlags_AlphaPreviewHalf= 1 << 11,  //              // ColorEdit, ColorPicker, ColorButton: display half opaque / half checkerboard, instead of opaque.
    ImGuiColorEditFlags_HDR             = 1 << 12,  //              // (WIP) ColorEdit: Currently only disable 0.0f..1.0f limits in RGBA edition (note: you probably want to use ImGuiColorEditFlags_Float flag as well).
    ImGuiColorEditFlags_RGB             = 1 << 13,  // [Inputs]     // ColorEdit: choose one among RGB/HSV/HEX. ColorPicker: choose any combination using RGB/HSV/HEX.
    ImGuiColorEditFlags_HSV             = 1 << 14,  // [Inputs]     // "
    ImGuiColorEditFlags_HEX             = 1 << 15,  // [Inputs]     // "
    ImGuiColorEditFlags_Uint8           = 1 << 16,  // [DataType]   // ColorEdit, ColorPicker, ColorButton: _display_ values formatted as 0..255. 
    ImGuiColorEditFlags_Float           = 1 << 17,  // [DataType]   // ColorEdit, ColorPicker, ColorButton: _display_ values formatted as 0.0f..1.0f floats instead of 0..255 integers. No round-trip of value via integers.
    ImGuiColorEditFlags_PickerHueBar    = 1 << 18,  // [PickerMode] // ColorPicker: bar for Hue, rectangle for Sat/Value.
    ImGuiColorEditFlags_PickerHueWheel  = 1 << 19,  // [PickerMode] // ColorPicker: wheel for Hue, triangle for Sat/Value.
    // Internals/Masks
    ImGuiColorEditFlags__InputsMask     = ImGuiColorEditFlags_RGB|ImGuiColorEditFlags_HSV|ImGuiColorEditFlags_HEX,
    ImGuiColorEditFlags__DataTypeMask   = ImGuiColorEditFlags_Uint8|ImGuiColorEditFlags_Float,
    ImGuiColorEditFlags__PickerMask     = ImGuiColorEditFlags_PickerHueWheel|ImGuiColorEditFlags_PickerHueBar,
    ImGuiColorEditFlags__OptionsDefault = ImGuiColorEditFlags_Uint8|ImGuiColorEditFlags_RGB|ImGuiColorEditFlags_PickerHueBar    // Change application default using SetColorEditOptions()
};

// Enumeration for GetMouseCursor()
enum ImGuiMouseCursor_
{
    ImGuiMouseCursor_None = -1,
    ImGuiMouseCursor_Arrow = 0,
    ImGuiMouseCursor_TextInput,         // When hovering over InputText, etc.
    ImGuiMouseCursor_ResizeAll,         // Unused
    ImGuiMouseCursor_ResizeNS,          // When hovering over an horizontal border
    ImGuiMouseCursor_ResizeEW,          // When hovering over a vertical border or a column
    ImGuiMouseCursor_ResizeNESW,        // When hovering over the bottom-left corner of a window
    ImGuiMouseCursor_ResizeNWSE,        // When hovering over the bottom-right corner of a window
    ImGuiMouseCursor_Count_
};

// Condition for ImGui::SetWindow***(), SetNextWindow***(), SetNextTreeNode***() functions
// All those functions treat 0 as a shortcut to ImGuiCond_Always. From the point of view of the user use this as an enum (don't combine multiple values into flags).
enum ImGuiCond_
{
    ImGuiCond_Always        = 1 << 0,   // Set the variable
    ImGuiCond_Once          = 1 << 1,   // Set the variable once per runtime session (only the first call with succeed)
    ImGuiCond_FirstUseEver  = 1 << 2,   // Set the variable if the window has no saved data (if doesn't exist in the .ini file)
    ImGuiCond_Appearing     = 1 << 3    // Set the variable if the window is appearing after being hidden/inactive (or the first time)

    // Obsolete names (will be removed)
#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    , ImGuiSetCond_Always = ImGuiCond_Always, ImGuiSetCond_Once = ImGuiCond_Once, ImGuiSetCond_FirstUseEver = ImGuiCond_FirstUseEver, ImGuiSetCond_Appearing = ImGuiCond_Appearing
#endif
};

// You may modify the ImGui::GetStyle() main instance during initialization and before NewFrame().
// During the frame, prefer using ImGui::PushStyleVar(ImGuiStyleVar_XXXX)/PopStyleVar() to alter the main style values, and ImGui::PushStyleColor(ImGuiCol_XXX)/PopStyleColor() for colors.
struct ImGuiStyle
{
    float       Alpha;                      // Global alpha applies to everything in ImGui.
    ImVec2      WindowPadding;              // Padding within a window.
    float       WindowRounding;             // Radius of window corners rounding. Set to 0.0f to have rectangular windows.
    float       WindowBorderSize;           // Thickness of border around windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
    ImVec2      WindowMinSize;              // Minimum window size. This is a global setting. If you want to constraint individual windows, use SetNextWindowSizeConstraints().
    ImVec2      WindowTitleAlign;           // Alignment for title bar text. Defaults to (0.0f,0.5f) for left-aligned,vertically centered.
    float       ChildRounding;              // Radius of child window corners rounding. Set to 0.0f to have rectangular windows.
    float       ChildBorderSize;            // Thickness of border around child windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
    float       PopupRounding;              // Radius of popup window corners rounding.
    float       PopupBorderSize;            // Thickness of border around popup windows. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
    ImVec2      FramePadding;               // Padding within a framed rectangle (used by most widgets).
    float       FrameRounding;              // Radius of frame corners rounding. Set to 0.0f to have rectangular frame (used by most widgets).
    float       FrameBorderSize;            // Thickness of border around frames. Generally set to 0.0f or 1.0f. (Other values are not well tested and more CPU/GPU costly).
    ImVec2      ItemSpacing;                // Horizontal and vertical spacing between widgets/lines.
    ImVec2      ItemInnerSpacing;           // Horizontal and vertical spacing between within elements of a composed widget (e.g. a slider and its label).
    ImVec2      TouchExtraPadding;          // Expand reactive bounding box for touch-based system where touch position is not accurate enough. Unfortunately we don't sort widgets so priority on overlap will always be given to the first widget. So don't grow this too much!
    float       IndentSpacing;              // Horizontal indentation when e.g. entering a tree node. Generally == (FontSize + FramePadding.x*2).
    float       ColumnsMinSpacing;          // Minimum horizontal spacing between two columns.
    float       ScrollbarSize;              // Width of the vertical scrollbar, Height of the horizontal scrollbar.
    float       ScrollbarRounding;          // Radius of grab corners for scrollbar.
    float       GrabMinSize;                // Minimum width/height of a grab box for slider/scrollbar.
    float       GrabRounding;               // Radius of grabs corners rounding. Set to 0.0f to have rectangular slider grabs.
    ImVec2      ButtonTextAlign;            // Alignment of button text when button is larger than text. Defaults to (0.5f,0.5f) for horizontally+vertically centered.
    ImVec2      DisplayWindowPadding;       // Window positions are clamped to be visible within the display area by at least this amount. Only covers regular windows.
    ImVec2      DisplaySafeAreaPadding;     // If you cannot see the edge of your screen (e.g. on a TV) increase the safe area padding. Covers popups/tooltips as well regular windows.
    float       MouseCursorScale;           // Scale software rendered mouse cursor (when io.MouseDrawCursor is enabled). May be removed later.
    bool        AntiAliasedLines;           // Enable anti-aliasing on lines/borders. Disable if you are really tight on CPU/GPU.
    bool        AntiAliasedFill;            // Enable anti-aliasing on filled shapes (rounded rectangles, circles, etc.)
    float       CurveTessellationTol;       // Tessellation tolerance when using PathBezierCurveTo() without a specific number of segments. Decrease for highly tessellated curves (higher quality, more polygons), increase to reduce quality.
    ImVec4      Colors[ImGuiCol_COUNT];

    IMGUI_API ImGuiStyle();
    IMGUI_API void ScaleAllSizes(float scale_factor);
};

// This is where your app communicate with ImGui. Access via ImGui::GetIO().
// Read 'Programmer guide' section in .cpp file for general usage.
struct ImGuiIO
{
    //------------------------------------------------------------------
    // Settings (fill once)                 // Default value:
    //------------------------------------------------------------------

    ImVec2        DisplaySize;              // <unset>              // Display size, in pixels. For clamping windows positions.
    float         DeltaTime;                // = 1.0f/60.0f         // Time elapsed since last frame, in seconds.
    ImGuiNavFlags NavFlags;                 // = 0x00               // See ImGuiNavFlags_. Gamepad/keyboard navigation options.
    float         IniSavingRate;            // = 5.0f               // Maximum time between saving positions/sizes to .ini file, in seconds.
    const char*   IniFilename;              // = "imgui.ini"        // Path to .ini file. NULL to disable .ini saving.
    const char*   LogFilename;              // = "imgui_log.txt"    // Path to .log file (default parameter to ImGui::LogToFile when no file is specified).
    float         MouseDoubleClickTime;     // = 0.30f              // Time for a double-click, in seconds.
    float         MouseDoubleClickMaxDist;  // = 6.0f               // Distance threshold to stay in to validate a double-click, in pixels.
    float         MouseDragThreshold;       // = 6.0f               // Distance threshold before considering we are dragging.
    int           KeyMap[ImGuiKey_COUNT];   // <unset>              // Map of indices into the KeysDown[512] entries array which represent your "native" keyboard state.
    float         KeyRepeatDelay;           // = 0.250f             // When holding a key/button, time before it starts repeating, in seconds (for buttons in Repeat mode, etc.).
    float         KeyRepeatRate;            // = 0.050f             // When holding a key/button, rate at which it repeats, in seconds.
    void*         UserData;                 // = NULL               // Store your own data for retrieval by callbacks.

    ImFontAtlas*  Fonts;                    // <auto>               // Load and assemble one or more fonts into a single tightly packed texture. Output to Fonts array.
    float         FontGlobalScale;          // = 1.0f               // Global scale all fonts
    bool          FontAllowUserScaling;     // = false              // Allow user scaling text of individual window with CTRL+Wheel.
    ImFont*       FontDefault;              // = NULL               // Font to use on NewFrame(). Use NULL to uses Fonts->Fonts[0].
    ImVec2        DisplayFramebufferScale;  // = (1.0f,1.0f)        // For retina display or other situations where window coordinates are different from framebuffer coordinates. User storage only, presently not used by ImGui.
    ImVec2        DisplayVisibleMin;        // <unset> (0.0f,0.0f)  // If you use DisplaySize as a virtual space larger than your screen, set DisplayVisibleMin/Max to the visible area.
    ImVec2        DisplayVisibleMax;        // <unset> (0.0f,0.0f)  // If the values are the same, we defaults to Min=(0.0f) and Max=DisplaySize

    // Advanced/subtle behaviors
    bool          OptMacOSXBehaviors;       // = defined(__APPLE__) // OS X style: Text editing cursor movement using Alt instead of Ctrl, Shortcuts using Cmd/Super instead of Ctrl, Line/Text Start and End using Cmd+Arrows instead of Home/End, Double click selects by word instead of selecting whole text, Multi-selection in lists uses Cmd/Super instead of Ctrl
    bool          OptCursorBlink;           // = true               // Enable blinking cursor, for users who consider it annoying.

    //------------------------------------------------------------------
    // Settings (User Functions)
    //------------------------------------------------------------------

    // Optional: access OS clipboard
    // (default to use native Win32 clipboard on Windows, otherwise uses a private clipboard. Override to access OS clipboard on other architectures)
    const char* (*GetClipboardTextFn)(void* user_data);
    void        (*SetClipboardTextFn)(void* user_data, const char* text);
    void*       ClipboardUserData;

    // Optional: notify OS Input Method Editor of the screen position of your cursor for text input position (e.g. when using Japanese/Chinese IME in Windows)
    // (default to use native imm32 api on Windows)
    void        (*ImeSetInputScreenPosFn)(int x, int y);
    void*       ImeWindowHandle;            // (Windows) Set this to your HWND to get automatic IME cursor positioning.

#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    // [OBSOLETE] Rendering function, will be automatically called in Render(). Please call your rendering function yourself now! You can obtain the ImDrawData* by calling ImGui::GetDrawData() after Render().
    // See example applications if you are unsure of how to implement this.
    void        (*RenderDrawListsFn)(ImDrawData* data);
#endif

    //------------------------------------------------------------------
    // Input - Fill before calling NewFrame()
    //------------------------------------------------------------------

    ImVec2      MousePos;                       // Mouse position, in pixels. Set to ImVec2(-FLT_MAX,-FLT_MAX) if mouse is unavailable (on another screen, etc.)
    bool        MouseDown[5];                   // Mouse buttons: left, right, middle + extras. ImGui itself mostly only uses left button (BeginPopupContext** are using right button). Others buttons allows us to track if the mouse is being used by your application + available to user as a convenience via IsMouse** API.
    float       MouseWheel;                     // Mouse wheel: 1 unit scrolls about 5 lines text. 
    float       MouseWheelH;                    // Mouse wheel (Horizontal). Most users don't have a mouse with an horizontal wheel, may not be filled by all back-ends.
    bool        MouseDrawCursor;                // Request ImGui to draw a mouse cursor for you (if you are on a platform without a mouse cursor).
    bool        KeyCtrl;                        // Keyboard modifier pressed: Control
    bool        KeyShift;                       // Keyboard modifier pressed: Shift
    bool        KeyAlt;                         // Keyboard modifier pressed: Alt
    bool        KeySuper;                       // Keyboard modifier pressed: Cmd/Super/Windows
    bool        KeysDown[512];                  // Keyboard keys that are pressed (ideally left in the "native" order your engine has access to keyboard keys, so you can use your own defines/enums for keys).
    ImWchar     InputCharacters[16+1];          // List of characters input (translated by user from keypress+keyboard state). Fill using AddInputCharacter() helper.
    float       NavInputs[ImGuiNavInput_COUNT]; // Gamepad inputs (keyboard keys will be auto-mapped and be written here by ImGui::NewFrame)

    // Functions
    IMGUI_API void AddInputCharacter(ImWchar c);                        // Add new character into InputCharacters[]
    IMGUI_API void AddInputCharactersUTF8(const char* utf8_chars);      // Add new characters into InputCharacters[] from an UTF-8 string
    inline void    ClearInputCharacters() { InputCharacters[0] = 0; }   // Clear the text input buffer manually

    //------------------------------------------------------------------
    // Output - Retrieve after calling NewFrame()
    //------------------------------------------------------------------

    bool        WantCaptureMouse;           // When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application. This is set by ImGui when it wants to use your mouse (e.g. unclicked mouse is hovering a window, or a widget is active). 
    bool        WantCaptureKeyboard;        // When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application. This is set by ImGui when it wants to use your keyboard inputs.
    bool        WantTextInput;              // Mobile/console: when io.WantTextInput is true, you may display an on-screen keyboard. This is set by ImGui when it wants textual keyboard input to happen (e.g. when a InputText widget is active).
    bool        WantMoveMouse;              // MousePos has been altered, back-end should reposition mouse on next frame. Set only when ImGuiNavFlags_MoveMouse flag is enabled in io.NavFlags.
    bool        NavActive;                  // Directional navigation is currently allowed (will handle ImGuiKey_NavXXX events) = a window is focused and it doesn't use the ImGuiWindowFlags_NoNavInputs flag.
    bool        NavVisible;                 // Directional navigation is visible and allowed (will handle ImGuiKey_NavXXX events).
    float       Framerate;                  // Application framerate estimation, in frame per second. Solely for convenience. Rolling average estimation based on IO.DeltaTime over 120 frames
    int         MetricsRenderVertices;      // Vertices output during last call to Render()
    int         MetricsRenderIndices;       // Indices output during last call to Render() = number of triangles * 3
    int         MetricsActiveWindows;       // Number of visible root windows (exclude child windows)
    ImVec2      MouseDelta;                 // Mouse delta. Note that this is zero if either current or previous position are invalid (-FLT_MAX,-FLT_MAX), so a disappearing/reappearing mouse won't have a huge delta.

    //------------------------------------------------------------------
    // [Internal] ImGui will maintain those fields. Forward compatibility not guaranteed!
    //------------------------------------------------------------------

    ImVec2      MousePosPrev;               // Previous mouse position temporary storage (nb: not for public use, set to MousePos in NewFrame())
    ImVec2      MouseClickedPos[5];         // Position at time of clicking
    float       MouseClickedTime[5];        // Time of last click (used to figure out double-click)
    bool        MouseClicked[5];            // Mouse button went from !Down to Down
    bool        MouseDoubleClicked[5];      // Has mouse button been double-clicked?
    bool        MouseReleased[5];           // Mouse button went from Down to !Down
    bool        MouseDownOwned[5];          // Track if button was clicked inside a window. We don't request mouse capture from the application if click started outside ImGui bounds.
    float       MouseDownDuration[5];       // Duration the mouse button has been down (0.0f == just clicked)
    float       MouseDownDurationPrev[5];   // Previous time the mouse button has been down
    ImVec2      MouseDragMaxDistanceAbs[5]; // Maximum distance, absolute, on each axis, of how much mouse has traveled from the clicking point
    float       MouseDragMaxDistanceSqr[5]; // Squared maximum distance of how much mouse has traveled from the clicking point
    float       KeysDownDuration[512];      // Duration the keyboard key has been down (0.0f == just pressed)
    float       KeysDownDurationPrev[512];  // Previous duration the key has been down
    float       NavInputsDownDuration[ImGuiNavInput_COUNT];
    float       NavInputsDownDurationPrev[ImGuiNavInput_COUNT];

    IMGUI_API   ImGuiIO();
};

//-----------------------------------------------------------------------------
// Obsolete functions (Will be removed! Read 'API BREAKING CHANGES' section in imgui.cpp for details)
//-----------------------------------------------------------------------------

#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
namespace ImGui
{
    // OBSOLETED in 1.60 (from Dec 2017)
    static inline bool  IsAnyWindowFocused()                  { return IsWindowFocused(ImGuiFocusedFlags_AnyWindow); }
    static inline bool  IsAnyWindowHovered()                  { return IsWindowHovered(ImGuiHoveredFlags_AnyWindow); }
    static inline ImVec2 CalcItemRectClosestPoint(const ImVec2& pos, bool on_edge = false, float outward = 0.f) { (void)on_edge; (void)outward; IM_ASSERT(0); return pos; }
    // OBSOLETED in 1.53 (between Oct 2017 and Dec 2017)
    static inline void  ShowTestWindow()                      { return ShowDemoWindow(); }
    static inline bool  IsRootWindowFocused()                 { return IsWindowFocused(ImGuiFocusedFlags_RootWindow); }
    static inline bool  IsRootWindowOrAnyChildFocused()       { return IsWindowFocused(ImGuiFocusedFlags_RootAndChildWindows); }
    static inline void  SetNextWindowContentWidth(float w)    { SetNextWindowContentSize(ImVec2(w, 0.0f)); }
    static inline float GetItemsLineHeightWithSpacing()       { return GetFrameHeightWithSpacing(); }
    // OBSOLETED in 1.52 (between Aug 2017 and Oct 2017)
    bool                Begin(const char* name, bool* p_open, const ImVec2& size_on_first_use, float bg_alpha_override = -1.0f, ImGuiWindowFlags flags = 0); // Use SetNextWindowSize(size, ImGuiCond_FirstUseEver) + SetNextWindowBgAlpha() instead.
    static inline bool  IsRootWindowOrAnyChildHovered()       { return IsWindowHovered(ImGuiHoveredFlags_RootAndChildWindows); }
    static inline void  AlignFirstTextHeightToWidgets()       { AlignTextToFramePadding(); }
    static inline void  SetNextWindowPosCenter(ImGuiCond c=0) { ImGuiIO& io = GetIO(); SetNextWindowPos(ImVec2(io.DisplaySize.x * 0.5f, io.DisplaySize.y * 0.5f), c, ImVec2(0.5f, 0.5f)); }
    // OBSOLETED in 1.51 (between Jun 2017 and Aug 2017)
    static inline bool  IsItemHoveredRect()                   { return IsItemHovered(ImGuiHoveredFlags_RectOnly); }
    static inline bool  IsPosHoveringAnyWindow(const ImVec2&) { IM_ASSERT(0); return false; } // This was misleading and partly broken. You probably want to use the ImGui::GetIO().WantCaptureMouse flag instead.
    static inline bool  IsMouseHoveringAnyWindow()            { return IsWindowHovered(ImGuiHoveredFlags_AnyWindow); }
    static inline bool  IsMouseHoveringWindow()               { return IsWindowHovered(ImGuiHoveredFlags_AllowWhenBlockedByPopup | ImGuiHoveredFlags_AllowWhenBlockedByActiveItem); }
    // OBSOLETED IN 1.49 (between Apr 2016 and May 2016)
    static inline bool  CollapsingHeader(const char* label, const char* str_id, bool framed = true, bool default_open = false) { (void)str_id; (void)framed; ImGuiTreeNodeFlags default_open_flags = 1 << 5; return CollapsingHeader(label, (default_open ? default_open_flags : 0)); }
}
#endif

//-----------------------------------------------------------------------------
// Helpers
//-----------------------------------------------------------------------------

// Lightweight std::vector<> like class to avoid dragging dependencies (also: windows implementation of STL with debug enabled is absurdly slow, so let's bypass it so our code runs fast in debug).
// Our implementation does NOT call C++ constructors/destructors. This is intentional and we do not require it. Do not use this class as a straight std::vector replacement in your code!
template<typename T>
class ImVector
{
public:
    int                         Size;
    int                         Capacity;
    T*                          Data;

    typedef T                   value_type;
    typedef value_type*         iterator;
    typedef const value_type*   const_iterator;

    inline ImVector()           { Size = Capacity = 0; Data = NULL; }
    inline ~ImVector()          { if (Data) ImGui::MemFree(Data); }

    inline bool                 empty() const                   { return Size == 0; }
    inline int                  size() const                    { return Size; }
    inline int                  capacity() const                { return Capacity; }

    inline value_type&          operator[](int i)               { IM_ASSERT(i < Size); return Data[i]; }
    inline const value_type&    operator[](int i) const         { IM_ASSERT(i < Size); return Data[i]; }

    inline void                 clear()                         { if (Data) { Size = Capacity = 0; ImGui::MemFree(Data); Data = NULL; } }
    inline iterator             begin()                         { return Data; }
    inline const_iterator       begin() const                   { return Data; }
    inline iterator             end()                           { return Data + Size; }
    inline const_iterator       end() const                     { return Data + Size; }
    inline value_type&          front()                         { IM_ASSERT(Size > 0); return Data[0]; }
    inline const value_type&    front() const                   { IM_ASSERT(Size > 0); return Data[0]; }
    inline value_type&          back()                          { IM_ASSERT(Size > 0); return Data[Size - 1]; }
    inline const value_type&    back() const                    { IM_ASSERT(Size > 0); return Data[Size - 1]; }
    inline void                 swap(ImVector<T>& rhs)          { int rhs_size = rhs.Size; rhs.Size = Size; Size = rhs_size; int rhs_cap = rhs.Capacity; rhs.Capacity = Capacity; Capacity = rhs_cap; value_type* rhs_data = rhs.Data; rhs.Data = Data; Data = rhs_data; }

    inline int                  _grow_capacity(int sz) const    { int new_capacity = Capacity ? (Capacity + Capacity/2) : 8; return new_capacity > sz ? new_capacity : sz; }

    inline void                 resize(int new_size)            { if (new_size > Capacity) reserve(_grow_capacity(new_size)); Size = new_size; }
    inline void                 resize(int new_size, const T& v){ if (new_size > Capacity) reserve(_grow_capacity(new_size)); if (new_size > Size) for (int n = Size; n < new_size; n++) Data[n] = v; Size = new_size; }
    inline void                 reserve(int new_capacity)
    {
        if (new_capacity <= Capacity) 
            return;
        T* new_data = (value_type*)ImGui::MemAlloc((size_t)new_capacity * sizeof(T));
        if (Data)
            memcpy(new_data, Data, (size_t)Size * sizeof(T));
        ImGui::MemFree(Data);
        Data = new_data;
        Capacity = new_capacity;
    }

    // NB: &v cannot be pointing inside the ImVector Data itself! e.g. v.push_back(v[10]) is forbidden.
    inline void                 push_back(const value_type& v)  { if (Size == Capacity) reserve(_grow_capacity(Size + 1)); Data[Size++] = v; }
    inline void                 pop_back()                      { IM_ASSERT(Size > 0); Size--; }
    inline void                 push_front(const value_type& v) { if (Size == 0) push_back(v); else insert(Data, v); }

    inline iterator             erase(const_iterator it)                        { IM_ASSERT(it >= Data && it < Data+Size); const ptrdiff_t off = it - Data; memmove(Data + off, Data + off + 1, ((size_t)Size - (size_t)off - 1) * sizeof(value_type)); Size--; return Data + off; }
    inline iterator             insert(const_iterator it, const value_type& v)  { IM_ASSERT(it >= Data && it <= Data+Size); const ptrdiff_t off = it - Data; if (Size == Capacity) reserve(_grow_capacity(Size + 1)); if (off < (int)Size) memmove(Data + off + 1, Data + off, ((size_t)Size - (size_t)off) * sizeof(value_type)); Data[off] = v; Size++; return Data + off; }
    inline bool                 contains(const value_type& v) const             { const T* data = Data;  const T* data_end = Data + Size; while (data < data_end) if (*data++ == v) return true; return false; }
};

// Helper: execute a block of code at maximum once a frame. Convenient if you want to quickly create an UI within deep-nested code that runs multiple times every frame.
// Usage:
//   static ImGuiOnceUponAFrame oaf;
//   if (oaf)
//       ImGui::Text("This will be called only once per frame");
struct ImGuiOnceUponAFrame
{
    ImGuiOnceUponAFrame() { RefFrame = -1; }
    mutable int RefFrame;
    operator bool() const { int current_frame = ImGui::GetFrameCount(); if (RefFrame == current_frame) return false; RefFrame = current_frame; return true; }
};

// Helper macro for ImGuiOnceUponAFrame. Attention: The macro expands into 2 statement so make sure you don't use it within e.g. an if() statement without curly braces.
#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS    // Will obsolete
#define IMGUI_ONCE_UPON_A_FRAME     static ImGuiOnceUponAFrame imgui_oaf; if (imgui_oaf)
#endif

// Helper: Parse and apply text filters. In format "aaaaa[,bbbb][,ccccc]"
struct ImGuiTextFilter
{
    struct TextRange
    {
        const char* b;
        const char* e;

        TextRange() { b = e = NULL; }
        TextRange(const char* _b, const char* _e) { b = _b; e = _e; }
        const char* begin() const { return b; }
        const char* end() const { return e; }
        bool empty() const { return b == e; }
        char front() const { return *b; }
        static bool is_blank(char c) { return c == ' ' || c == '\t'; }
        void trim_blanks() { while (b < e && is_blank(*b)) b++; while (e > b && is_blank(*(e-1))) e--; }
        IMGUI_API void split(char separator, ImVector<TextRange>& out);
    };

    char                InputBuf[256];
    ImVector<TextRange> Filters;
    int                 CountGrep;

    IMGUI_API           ImGuiTextFilter(const char* default_filter = "");
    IMGUI_API bool      Draw(const char* label = "Filter (inc,-exc)", float width = 0.0f);    // Helper calling InputText+Build
    IMGUI_API bool      PassFilter(const char* text, const char* text_end = NULL) const;
    IMGUI_API void      Build();
    void                Clear() { InputBuf[0] = 0; Build(); }
    bool                IsActive() const { return !Filters.empty(); }
};

// Helper: Text buffer for logging/accumulating text
struct ImGuiTextBuffer
{
    ImVector<char>      Buf;

    ImGuiTextBuffer()   { Buf.push_back(0); }
    inline char         operator[](int i) { return Buf.Data[i]; }
    const char*         begin() const { return &Buf.front(); }
    const char*         end() const { return &Buf.back(); }      // Buf is zero-terminated, so end() will point on the zero-terminator
    int                 size() const { return Buf.Size - 1; }
    bool                empty() { return Buf.Size <= 1; }
    void                clear() { Buf.clear(); Buf.push_back(0); }
    void                reserve(int capacity) { Buf.reserve(capacity); }
    const char*         c_str() const { return Buf.Data; }
    IMGUI_API void      appendf(const char* fmt, ...) IM_FMTARGS(2);
    IMGUI_API void      appendfv(const char* fmt, va_list args) IM_FMTLIST(2);
};

// Helper: Simple Key->value storage
// Typically you don't have to worry about this since a storage is held within each Window.
// We use it to e.g. store collapse state for a tree (Int 0/1), store color edit options. 
// This is optimized for efficient reading (dichotomy into a contiguous buffer), rare writing (typically tied to user interactions)
// You can use it as custom user storage for temporary values. Declare your own storage if, for example:
// - You want to manipulate the open/close state of a particular sub-tree in your interface (tree node uses Int 0/1 to store their state).
// - You want to store custom debug data easily without adding or editing structures in your code (probably not efficient, but convenient)
// Types are NOT stored, so it is up to you to make sure your Key don't collide with different types.
struct ImGuiStorage
{
    struct Pair
    {
        ImGuiID key;
        union { int val_i; float val_f; void* val_p; };
        Pair(ImGuiID _key, int _val_i)   { key = _key; val_i = _val_i; }
        Pair(ImGuiID _key, float _val_f) { key = _key; val_f = _val_f; }
        Pair(ImGuiID _key, void* _val_p) { key = _key; val_p = _val_p; }
    };
    ImVector<Pair>      Data;

    // - Get***() functions find pair, never add/allocate. Pairs are sorted so a query is O(log N)
    // - Set***() functions find pair, insertion on demand if missing.
    // - Sorted insertion is costly, paid once. A typical frame shouldn't need to insert any new pair.
    void                Clear() { Data.clear(); }
    IMGUI_API int       GetInt(ImGuiID key, int default_val = 0) const;
    IMGUI_API void      SetInt(ImGuiID key, int val);
    IMGUI_API bool      GetBool(ImGuiID key, bool default_val = false) const;
    IMGUI_API void      SetBool(ImGuiID key, bool val);
    IMGUI_API float     GetFloat(ImGuiID key, float default_val = 0.0f) const;
    IMGUI_API void      SetFloat(ImGuiID key, float val);
    IMGUI_API void*     GetVoidPtr(ImGuiID key) const; // default_val is NULL
    IMGUI_API void      SetVoidPtr(ImGuiID key, void* val);

    // - Get***Ref() functions finds pair, insert on demand if missing, return pointer. Useful if you intend to do Get+Set.
    // - References are only valid until a new value is added to the storage. Calling a Set***() function or a Get***Ref() function invalidates the pointer.
    // - A typical use case where this is convenient for quick hacking (e.g. add storage during a live Edit&Continue session if you can't modify existing struct)
    //      float* pvar = ImGui::GetFloatRef(key); ImGui::SliderFloat("var", pvar, 0, 100.0f); some_var += *pvar;
    IMGUI_API int*      GetIntRef(ImGuiID key, int default_val = 0);
    IMGUI_API bool*     GetBoolRef(ImGuiID key, bool default_val = false);
    IMGUI_API float*    GetFloatRef(ImGuiID key, float default_val = 0.0f);
    IMGUI_API void**    GetVoidPtrRef(ImGuiID key, void* default_val = NULL);

    // Use on your own storage if you know only integer are being stored (open/close all tree nodes)
    IMGUI_API void      SetAllInt(int val);

    // For quicker full rebuild of a storage (instead of an incremental one), you may add all your contents and then sort once.
    IMGUI_API void      BuildSortByKey();
};

// Shared state of InputText(), passed to callback when a ImGuiInputTextFlags_Callback* flag is used and the corresponding callback is triggered.
struct ImGuiTextEditCallbackData
{
    ImGuiInputTextFlags EventFlag;      // One of ImGuiInputTextFlags_Callback* // Read-only
    ImGuiInputTextFlags Flags;          // What user passed to InputText()      // Read-only
    void*               UserData;       // What user passed to InputText()      // Read-only
    bool                ReadOnly;       // Read-only mode                       // Read-only

    // CharFilter event:
    ImWchar             EventChar;      // Character input                      // Read-write (replace character or set to zero)

    // Completion,History,Always events:
    // If you modify the buffer contents make sure you update 'BufTextLen' and set 'BufDirty' to true.
    ImGuiKey            EventKey;       // Key pressed (Up/Down/TAB)            // Read-only
    char*               Buf;            // Current text buffer                  // Read-write (pointed data only, can't replace the actual pointer)
    int                 BufTextLen;     // Current text length in bytes         // Read-write
    int                 BufSize;        // Maximum text length in bytes         // Read-only
    bool                BufDirty;       // Set if you modify Buf/BufTextLen!!   // Write
    int                 CursorPos;      //                                      // Read-write
    int                 SelectionStart; //                                      // Read-write (== to SelectionEnd when no selection)
    int                 SelectionEnd;   //                                      // Read-write

    // NB: Helper functions for text manipulation. Calling those function loses selection.
    IMGUI_API void    DeleteChars(int pos, int bytes_count);
    IMGUI_API void    InsertChars(int pos, const char* text, const char* text_end = NULL);
    bool              HasSelection() const { return SelectionStart != SelectionEnd; }
};

// Resizing callback data to apply custom constraint. As enabled by SetNextWindowSizeConstraints(). Callback is called during the next Begin().
// NB: For basic min/max size constraint on each axis you don't need to use the callback! The SetNextWindowSizeConstraints() parameters are enough.
struct ImGuiSizeCallbackData
{
    void*   UserData;       // Read-only.   What user passed to SetNextWindowSizeConstraints()
    ImVec2  Pos;            // Read-only.   Window position, for reference.
    ImVec2  CurrentSize;    // Read-only.   Current window size.
    ImVec2  DesiredSize;    // Read-write.  Desired size, based on user's mouse position. Write to this field to restrain resizing.
};

// Data payload for Drag and Drop operations
struct ImGuiPayload
{
    // Members
    const void*     Data;               // Data (copied and owned by dear imgui)
    int             DataSize;           // Data size

    // [Internal]
    ImGuiID         SourceId;           // Source item id
    ImGuiID         SourceParentId;     // Source parent id (if available)
    int             DataFrameCount;     // Data timestamp
    char            DataType[12 + 1];   // Data type tag (short user-supplied string, 12 characters max)
    bool            Preview;            // Set when AcceptDragDropPayload() was called and mouse has been hovering the target item (nb: handle overlapping drag targets)
    bool            Delivery;           // Set when AcceptDragDropPayload() was called and mouse button is released over the target item.

    ImGuiPayload()  { Clear(); }
    void Clear()    { SourceId = SourceParentId = 0; Data = NULL; DataSize = 0; memset(DataType, 0, sizeof(DataType)); DataFrameCount = -1; Preview = Delivery = false; }
    bool IsDataType(const char* type) const { return DataFrameCount != -1 && strcmp(type, DataType) == 0; }
    bool IsPreview() const                  { return Preview; }
    bool IsDelivery() const                 { return Delivery; }
};

// Helpers macros to generate 32-bits encoded colors
#ifdef IMGUI_USE_BGRA_PACKED_COLOR
#define IM_COL32_R_SHIFT    16
#define IM_COL32_G_SHIFT    8
#define IM_COL32_B_SHIFT    0
#define IM_COL32_A_SHIFT    24
#define IM_COL32_A_MASK     0xFF000000
#else
#define IM_COL32_R_SHIFT    0
#define IM_COL32_G_SHIFT    8
#define IM_COL32_B_SHIFT    16
#define IM_COL32_A_SHIFT    24
#define IM_COL32_A_MASK     0xFF000000
#endif
#define IM_COL32(R,G,B,A)    (((ImU32)(A)<<IM_COL32_A_SHIFT) | ((ImU32)(B)<<IM_COL32_B_SHIFT) | ((ImU32)(G)<<IM_COL32_G_SHIFT) | ((ImU32)(R)<<IM_COL32_R_SHIFT))
#define IM_COL32_WHITE       IM_COL32(255,255,255,255)  // Opaque white = 0xFFFFFFFF
#define IM_COL32_BLACK       IM_COL32(0,0,0,255)        // Opaque black
#define IM_COL32_BLACK_TRANS IM_COL32(0,0,0,0)          // Transparent black = 0x00000000

// ImColor() helper to implicity converts colors to either ImU32 (packed 4x1 byte) or ImVec4 (4x1 float)
// Prefer using IM_COL32() macros if you want a guaranteed compile-time ImU32 for usage with ImDrawList API.
// **Avoid storing ImColor! Store either u32 of ImVec4. This is not a full-featured color class. MAY OBSOLETE.
// **None of the ImGui API are using ImColor directly but you can use it as a convenience to pass colors in either ImU32 or ImVec4 formats. Explicitly cast to ImU32 or ImVec4 if needed.
struct ImColor
{
    ImVec4              Value;

    ImColor()                                                       { Value.x = Value.y = Value.z = Value.w = 0.0f; }
    ImColor(int r, int g, int b, int a = 255)                       { float sc = 1.0f/255.0f; Value.x = (float)r * sc; Value.y = (float)g * sc; Value.z = (float)b * sc; Value.w = (float)a * sc; }
    ImColor(ImU32 rgba)                                             { float sc = 1.0f/255.0f; Value.x = (float)((rgba>>IM_COL32_R_SHIFT)&0xFF) * sc; Value.y = (float)((rgba>>IM_COL32_G_SHIFT)&0xFF) * sc; Value.z = (float)((rgba>>IM_COL32_B_SHIFT)&0xFF) * sc; Value.w = (float)((rgba>>IM_COL32_A_SHIFT)&0xFF) * sc; }
    ImColor(float r, float g, float b, float a = 1.0f)              { Value.x = r; Value.y = g; Value.z = b; Value.w = a; }
    ImColor(const ImVec4& col)                                      { Value = col; }
    inline operator ImU32() const                                   { return ImGui::ColorConvertFloat4ToU32(Value); }
    inline operator ImVec4() const                                  { return Value; }

    // FIXME-OBSOLETE: May need to obsolete/cleanup those helpers.
    inline void    SetHSV(float h, float s, float v, float a = 1.0f){ ImGui::ColorConvertHSVtoRGB(h, s, v, Value.x, Value.y, Value.z); Value.w = a; }
    static ImColor HSV(float h, float s, float v, float a = 1.0f)   { float r,g,b; ImGui::ColorConvertHSVtoRGB(h, s, v, r, g, b); return ImColor(r,g,b,a); }
};

// Helper: Manually clip large list of items.
// If you are submitting lots of evenly spaced items and you have a random access to the list, you can perform coarse clipping based on visibility to save yourself from processing those items at all.
// The clipper calculates the range of visible items and advance the cursor to compensate for the non-visible items we have skipped. 
// ImGui already clip items based on their bounds but it needs to measure text size to do so. Coarse clipping before submission makes this cost and your own data fetching/submission cost null.
// Usage:
//     ImGuiListClipper clipper(1000);  // we have 1000 elements, evenly spaced.
//     while (clipper.Step())
//         for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++)
//             ImGui::Text("line number %d", i);
// - Step 0: the clipper let you process the first element, regardless of it being visible or not, so we can measure the element height (step skipped if we passed a known height as second arg to constructor).
// - Step 1: the clipper infer height from first element, calculate the actual range of elements to display, and position the cursor before the first element.
// - (Step 2: dummy step only required if an explicit items_height was passed to constructor or Begin() and user call Step(). Does nothing and switch to Step 3.)
// - Step 3: the clipper validate that we have reached the expected Y position (corresponding to element DisplayEnd), advance the cursor to the end of the list and then returns 'false' to end the loop.
struct ImGuiListClipper
{
    float   StartPosY;
    float   ItemsHeight;
    int     ItemsCount, StepNo, DisplayStart, DisplayEnd;

    // items_count:  Use -1 to ignore (you can call Begin later). Use INT_MAX if you don't know how many items you have (in which case the cursor won't be advanced in the final step).
    // items_height: Use -1.0f to be calculated automatically on first step. Otherwise pass in the distance between your items, typically GetTextLineHeightWithSpacing() or GetFrameHeightWithSpacing().
    // If you don't specify an items_height, you NEED to call Step(). If you specify items_height you may call the old Begin()/End() api directly, but prefer calling Step().
    ImGuiListClipper(int items_count = -1, float items_height = -1.0f)  { Begin(items_count, items_height); } // NB: Begin() initialize every fields (as we allow user to call Begin/End multiple times on a same instance if they want).
    ~ImGuiListClipper()                                                 { IM_ASSERT(ItemsCount == -1); }      // Assert if user forgot to call End() or Step() until false.

    IMGUI_API bool Step();                                              // Call until it returns false. The DisplayStart/DisplayEnd fields will be set and you can process/draw those items.
    IMGUI_API void Begin(int items_count, float items_height = -1.0f);  // Automatically called by constructor if you passed 'items_count' or by Step() in Step 1.
    IMGUI_API void End();                                               // Automatically called on the last call of Step() that returns false.
};

//-----------------------------------------------------------------------------
// Draw List
// Hold a series of drawing commands. The user provides a renderer for ImDrawData which essentially contains an array of ImDrawList.
//-----------------------------------------------------------------------------

// Draw callbacks for advanced uses.
// NB- You most likely do NOT need to use draw callbacks just to create your own widget or customized UI rendering (you can poke into the draw list for that)
// Draw callback may be useful for example, A) Change your GPU render state, B) render a complex 3D scene inside a UI element (without an intermediate texture/render target), etc.
// The expected behavior from your rendering function is 'if (cmd.UserCallback != NULL) cmd.UserCallback(parent_list, cmd); else RenderTriangles()'
typedef void (*ImDrawCallback)(const ImDrawList* parent_list, const ImDrawCmd* cmd);

// Typically, 1 command = 1 GPU draw call (unless command is a callback)
struct ImDrawCmd
{
    unsigned int    ElemCount;              // Number of indices (multiple of 3) to be rendered as triangles. Vertices are stored in the callee ImDrawList's vtx_buffer[] array, indices in idx_buffer[].
    ImVec4          ClipRect;               // Clipping rectangle (x1, y1, x2, y2)
    ImTextureID     TextureId;              // User-provided texture ID. Set by user in ImfontAtlas::SetTexID() for fonts or passed to Image*() functions. Ignore if never using images or multiple fonts atlas.
    ImDrawCallback  UserCallback;           // If != NULL, call the function instead of rendering the vertices. clip_rect and texture_id will be set normally.
    void*           UserCallbackData;       // The draw callback code can access this.

    ImDrawCmd() { ElemCount = 0; ClipRect.x = ClipRect.y = ClipRect.z = ClipRect.w = 0.0f; TextureId = NULL; UserCallback = NULL; UserCallbackData = NULL; }
};

// Vertex index (override with '#define ImDrawIdx unsigned int' inside in imconfig.h)
#ifndef ImDrawIdx
typedef unsigned short ImDrawIdx;
#endif

// Vertex layout
#ifndef IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT
struct ImDrawVert
{
    ImVec2  pos;
    ImVec2  uv;
    ImU32   col;
};
#else
// You can override the vertex format layout by defining IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT in imconfig.h
// The code expect ImVec2 pos (8 bytes), ImVec2 uv (8 bytes), ImU32 col (4 bytes), but you can re-order them or add other fields as needed to simplify integration in your engine.
// The type has to be described within the macro (you can either declare the struct or use a typedef)
// NOTE: IMGUI DOESN'T CLEAR THE STRUCTURE AND DOESN'T CALL A CONSTRUCTOR SO ANY CUSTOM FIELD WILL BE UNINITIALIZED. IF YOU ADD EXTRA FIELDS (SUCH AS A 'Z' COORDINATES) YOU WILL NEED TO CLEAR THEM DURING RENDER OR TO IGNORE THEM. 
IMGUI_OVERRIDE_DRAWVERT_STRUCT_LAYOUT;
#endif

// Draw channels are used by the Columns API to "split" the render list into different channels while building, so items of each column can be batched together.
// You can also use them to simulate drawing layers and submit primitives in a different order than how they will be rendered.
struct ImDrawChannel
{
    ImVector<ImDrawCmd>     CmdBuffer;
    ImVector<ImDrawIdx>     IdxBuffer;
};

enum ImDrawCornerFlags_
{
    ImDrawCornerFlags_TopLeft   = 1 << 0, // 0x1
    ImDrawCornerFlags_TopRight  = 1 << 1, // 0x2
    ImDrawCornerFlags_BotLeft   = 1 << 2, // 0x4
    ImDrawCornerFlags_BotRight  = 1 << 3, // 0x8
    ImDrawCornerFlags_Top       = ImDrawCornerFlags_TopLeft | ImDrawCornerFlags_TopRight,   // 0x3
    ImDrawCornerFlags_Bot       = ImDrawCornerFlags_BotLeft | ImDrawCornerFlags_BotRight,   // 0xC
    ImDrawCornerFlags_Left      = ImDrawCornerFlags_TopLeft | ImDrawCornerFlags_BotLeft,    // 0x5
    ImDrawCornerFlags_Right     = ImDrawCornerFlags_TopRight | ImDrawCornerFlags_BotRight,  // 0xA
    ImDrawCornerFlags_All       = 0xF     // In your function calls you may use ~0 (= all bits sets) instead of ImDrawCornerFlags_All, as a convenience
};

enum ImDrawListFlags_
{
    ImDrawListFlags_AntiAliasedLines = 1 << 0,
    ImDrawListFlags_AntiAliasedFill  = 1 << 1
};

// Draw command list
// This is the low-level list of polygons that ImGui functions are filling. At the end of the frame, all command lists are passed to your ImGuiIO::RenderDrawListFn function for rendering.
// Each ImGui window contains its own ImDrawList. You can use ImGui::GetWindowDrawList() to access the current window draw list and draw custom primitives.
// You can interleave normal ImGui:: calls and adding primitives to the current draw list.
// All positions are generally in pixel coordinates (top-left at (0,0), bottom-right at io.DisplaySize), however you are totally free to apply whatever transformation matrix to want to the data (if you apply such transformation you'll want to apply it to ClipRect as well)
// Important: Primitives are always added to the list and not culled (culling is done at higher-level by ImGui:: functions), if you use this API a lot consider coarse culling your drawn objects.
struct ImDrawList
{
    // This is what you have to render
    ImVector<ImDrawCmd>     CmdBuffer;          // Draw commands. Typically 1 command = 1 GPU draw call, unless the command is a callback.
    ImVector<ImDrawIdx>     IdxBuffer;          // Index buffer. Each command consume ImDrawCmd::ElemCount of those
    ImVector<ImDrawVert>    VtxBuffer;          // Vertex buffer.

    // [Internal, used while building lists]
    ImDrawListFlags         Flags;              // Flags, you may poke into these to adjust anti-aliasing settings per-primitive.
    const ImDrawListSharedData* _Data;          // Pointer to shared draw data (you can use ImGui::GetDrawListSharedData() to get the one from current ImGui context)
    const char*             _OwnerName;         // Pointer to owner window's name for debugging
    unsigned int            _VtxCurrentIdx;     // [Internal] == VtxBuffer.Size
    ImDrawVert*             _VtxWritePtr;       // [Internal] point within VtxBuffer.Data after each add command (to avoid using the ImVector<> operators too much)
    ImDrawIdx*              _IdxWritePtr;       // [Internal] point within IdxBuffer.Data after each add command (to avoid using the ImVector<> operators too much)
    ImVector<ImVec4>        _ClipRectStack;     // [Internal]
    ImVector<ImTextureID>   _TextureIdStack;    // [Internal]
    ImVector<ImVec2>        _Path;              // [Internal] current path building
    int                     _ChannelsCurrent;   // [Internal] current channel number (0)
    int                     _ChannelsCount;     // [Internal] number of active channels (1+)
    ImVector<ImDrawChannel> _Channels;          // [Internal] draw channels for columns API (not resized down so _ChannelsCount may be smaller than _Channels.Size)

    // If you want to create ImDrawList instances, pass them ImGui::GetDrawListSharedData() or create and use your own ImDrawListSharedData (so you can use ImDrawList without ImGui)
    ImDrawList(const ImDrawListSharedData* shared_data) { _Data = shared_data; _OwnerName = NULL; Clear(); }
    ~ImDrawList() { ClearFreeMemory(); }
    IMGUI_API void  PushClipRect(ImVec2 clip_rect_min, ImVec2 clip_rect_max, bool intersect_with_current_clip_rect = false);  // Render-level scissoring. This is passed down to your render function but not used for CPU-side coarse clipping. Prefer using higher-level ImGui::PushClipRect() to affect logic (hit-testing and widget culling)
    IMGUI_API void  PushClipRectFullScreen();
    IMGUI_API void  PopClipRect();
    IMGUI_API void  PushTextureID(ImTextureID texture_id);
    IMGUI_API void  PopTextureID();
    inline ImVec2   GetClipRectMin() const { const ImVec4& cr = _ClipRectStack.back(); return ImVec2(cr.x, cr.y); }
    inline ImVec2   GetClipRectMax() const { const ImVec4& cr = _ClipRectStack.back(); return ImVec2(cr.z, cr.w); }

    // Primitives
    IMGUI_API void  AddLine(const ImVec2& a, const ImVec2& b, ImU32 col, float thickness = 1.0f);
    IMGUI_API void  AddRect(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners_flags = ImDrawCornerFlags_All, float thickness = 1.0f);   // a: upper-left, b: lower-right, rounding_corners_flags: 4-bits corresponding to which corner to round
    IMGUI_API void  AddRectFilled(const ImVec2& a, const ImVec2& b, ImU32 col, float rounding = 0.0f, int rounding_corners_flags = ImDrawCornerFlags_All);                     // a: upper-left, b: lower-right
    IMGUI_API void  AddRectFilledMultiColor(const ImVec2& a, const ImVec2& b, ImU32 col_upr_left, ImU32 col_upr_right, ImU32 col_bot_right, ImU32 col_bot_left);
    IMGUI_API void  AddQuad(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, ImU32 col, float thickness = 1.0f);
    IMGUI_API void  AddQuadFilled(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, ImU32 col);
    IMGUI_API void  AddTriangle(const ImVec2& a, const ImVec2& b, const ImVec2& c, ImU32 col, float thickness = 1.0f);
    IMGUI_API void  AddTriangleFilled(const ImVec2& a, const ImVec2& b, const ImVec2& c, ImU32 col);
    IMGUI_API void  AddCircle(const ImVec2& centre, float radius, ImU32 col, int num_segments = 12, float thickness = 1.0f);
    IMGUI_API void  AddCircleFilled(const ImVec2& centre, float radius, ImU32 col, int num_segments = 12);
    IMGUI_API void  AddText(const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end = NULL);
    IMGUI_API void  AddText(const ImFont* font, float font_size, const ImVec2& pos, ImU32 col, const char* text_begin, const char* text_end = NULL, float wrap_width = 0.0f, const ImVec4* cpu_fine_clip_rect = NULL);
    IMGUI_API void  AddImage(ImTextureID user_texture_id, const ImVec2& a, const ImVec2& b, const ImVec2& uv_a = ImVec2(0,0), const ImVec2& uv_b = ImVec2(1,1), ImU32 col = 0xFFFFFFFF);
    IMGUI_API void  AddImageQuad(ImTextureID user_texture_id, const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, const ImVec2& uv_a = ImVec2(0,0), const ImVec2& uv_b = ImVec2(1,0), const ImVec2& uv_c = ImVec2(1,1), const ImVec2& uv_d = ImVec2(0,1), ImU32 col = 0xFFFFFFFF);
    IMGUI_API void  AddImageRounded(ImTextureID user_texture_id, const ImVec2& a, const ImVec2& b, const ImVec2& uv_a, const ImVec2& uv_b, ImU32 col, float rounding, int rounding_corners = ImDrawCornerFlags_All);
    IMGUI_API void  AddPolyline(const ImVec2* points, const int num_points, ImU32 col, bool closed, float thickness);
    IMGUI_API void  AddConvexPolyFilled(const ImVec2* points, const int num_points, ImU32 col);
    IMGUI_API void  AddBezierCurve(const ImVec2& pos0, const ImVec2& cp0, const ImVec2& cp1, const ImVec2& pos1, ImU32 col, float thickness, int num_segments = 0);

    // Stateful path API, add points then finish with PathFill() or PathStroke()
    inline    void  PathClear()                                                 { _Path.resize(0); }
    inline    void  PathLineTo(const ImVec2& pos)                               { _Path.push_back(pos); }
    inline    void  PathLineToMergeDuplicate(const ImVec2& pos)                 { if (_Path.Size == 0 || memcmp(&_Path[_Path.Size-1], &pos, 8) != 0) _Path.push_back(pos); }
    inline    void  PathFillConvex(ImU32 col)                                   { AddConvexPolyFilled(_Path.Data, _Path.Size, col); PathClear(); }
    inline    void  PathStroke(ImU32 col, bool closed, float thickness = 1.0f)  { AddPolyline(_Path.Data, _Path.Size, col, closed, thickness); PathClear(); }
    IMGUI_API void  PathArcTo(const ImVec2& centre, float radius, float a_min, float a_max, int num_segments = 10);
    IMGUI_API void  PathArcToFast(const ImVec2& centre, float radius, int a_min_of_12, int a_max_of_12);                                // Use precomputed angles for a 12 steps circle
    IMGUI_API void  PathBezierCurveTo(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, int num_segments = 0);
    IMGUI_API void  PathRect(const ImVec2& rect_min, const ImVec2& rect_max, float rounding = 0.0f, int rounding_corners_flags = ImDrawCornerFlags_All);

    // Channels
    // - Use to simulate layers. By switching channels to can render out-of-order (e.g. submit foreground primitives before background primitives)
    // - Use to minimize draw calls (e.g. if going back-and-forth between multiple non-overlapping clipping rectangles, prefer to append into separate channels then merge at the end)
    IMGUI_API void  ChannelsSplit(int channels_count);
    IMGUI_API void  ChannelsMerge();
    IMGUI_API void  ChannelsSetCurrent(int channel_index);

    // Advanced
    IMGUI_API void  AddCallback(ImDrawCallback callback, void* callback_data);  // Your rendering function must check for 'UserCallback' in ImDrawCmd and call the function instead of rendering triangles.
    IMGUI_API void  AddDrawCmd();                                               // This is useful if you need to forcefully create a new draw call (to allow for dependent rendering / blending). Otherwise primitives are merged into the same draw-call as much as possible

    // Internal helpers
    // NB: all primitives needs to be reserved via PrimReserve() beforehand!
    IMGUI_API void  Clear();
    IMGUI_API void  ClearFreeMemory();
    IMGUI_API void  PrimReserve(int idx_count, int vtx_count);
    IMGUI_API void  PrimRect(const ImVec2& a, const ImVec2& b, ImU32 col);      // Axis aligned rectangle (composed of two triangles)
    IMGUI_API void  PrimRectUV(const ImVec2& a, const ImVec2& b, const ImVec2& uv_a, const ImVec2& uv_b, ImU32 col);
    IMGUI_API void  PrimQuadUV(const ImVec2& a, const ImVec2& b, const ImVec2& c, const ImVec2& d, const ImVec2& uv_a, const ImVec2& uv_b, const ImVec2& uv_c, const ImVec2& uv_d, ImU32 col);
    inline    void  PrimWriteVtx(const ImVec2& pos, const ImVec2& uv, ImU32 col){ _VtxWritePtr->pos = pos; _VtxWritePtr->uv = uv; _VtxWritePtr->col = col; _VtxWritePtr++; _VtxCurrentIdx++; }
    inline    void  PrimWriteIdx(ImDrawIdx idx)                                 { *_IdxWritePtr = idx; _IdxWritePtr++; }
    inline    void  PrimVtx(const ImVec2& pos, const ImVec2& uv, ImU32 col)     { PrimWriteIdx((ImDrawIdx)_VtxCurrentIdx); PrimWriteVtx(pos, uv, col); }
    IMGUI_API void  UpdateClipRect();
    IMGUI_API void  UpdateTextureID();
};

// All draw data to render an ImGui frame
struct ImDrawData
{
    bool            Valid;                  // Only valid after Render() is called and before the next NewFrame() is called.
    ImDrawList**    CmdLists;
    int             CmdListsCount;
    int             TotalVtxCount;          // For convenience, sum of all cmd_lists vtx_buffer.Size
    int             TotalIdxCount;          // For convenience, sum of all cmd_lists idx_buffer.Size

    // Functions
    ImDrawData() { Clear(); }
    void Clear() { Valid = false; CmdLists = NULL; CmdListsCount = TotalVtxCount = TotalIdxCount = 0; } // Draw lists are owned by the ImGuiContext and only pointed to here.
    IMGUI_API void DeIndexAllBuffers();               // For backward compatibility or convenience: convert all buffers from indexed to de-indexed, in case you cannot render indexed. Note: this is slow and most likely a waste of resources. Always prefer indexed rendering!
    IMGUI_API void ScaleClipRects(const ImVec2& sc);  // Helper to scale the ClipRect field of each ImDrawCmd. Use if your final output buffer is at a different scale than ImGui expects, or if there is a difference between your window resolution and framebuffer resolution.
};

struct ImFontConfig
{
    void*           FontData;                   //          // TTF/OTF data
    int             FontDataSize;               //          // TTF/OTF data size
    bool            FontDataOwnedByAtlas;       // true     // TTF/OTF data ownership taken by the container ImFontAtlas (will delete memory itself).
    int             FontNo;                     // 0        // Index of font within TTF/OTF file
    float           SizePixels;                 //          // Size in pixels for rasterizer.
    int             OversampleH, OversampleV;   // 3, 1     // Rasterize at higher quality for sub-pixel positioning. We don't use sub-pixel positions on the Y axis.
    bool            PixelSnapH;                 // false    // Align every glyph to pixel boundary. Useful e.g. if you are merging a non-pixel aligned font with the default font. If enabled, you can set OversampleH/V to 1.
    ImVec2          GlyphExtraSpacing;          // 0, 0     // Extra spacing (in pixels) between glyphs. Only X axis is supported for now.
    ImVec2          GlyphOffset;                // 0, 0     // Offset all glyphs from this font input.
    const ImWchar*  GlyphRanges;                // NULL     // Pointer to a user-provided list of Unicode range (2 value per range, values are inclusive, zero-terminated list). THE ARRAY DATA NEEDS TO PERSIST AS LONG AS THE FONT IS ALIVE.
    bool            MergeMode;                  // false    // Merge into previous ImFont, so you can combine multiple inputs font into one ImFont (e.g. ASCII font + icons + Japanese glyphs). You may want to use GlyphOffset.y when merge font of different heights.
    unsigned int    RasterizerFlags;            // 0x00     // Settings for custom font rasterizer (e.g. ImGuiFreeType). Leave as zero if you aren't using one.
    float           RasterizerMultiply;         // 1.0f     // Brighten (>1.0f) or darken (<1.0f) font output. Brightening small fonts may be a good workaround to make them more readable.

    // [Internal]
    char            Name[32];                               // Name (strictly to ease debugging)
    ImFont*         DstFont;

    IMGUI_API ImFontConfig();
};

struct ImFontGlyph
{
    ImWchar         Codepoint;          // 0x0000..0xFFFF
    float           AdvanceX;           // Distance to next character (= data from font + ImFontConfig::GlyphExtraSpacing.x baked in)
    float           X0, Y0, X1, Y1;     // Glyph corners
    float           U0, V0, U1, V1;     // Texture coordinates
};

enum ImFontAtlasFlags_
{
    ImFontAtlasFlags_NoPowerOfTwoHeight = 1 << 0,   // Don't round the height to next power of two
    ImFontAtlasFlags_NoMouseCursors     = 1 << 1    // Don't build software mouse cursors into the atlas
};

// Load and rasterize multiple TTF/OTF fonts into a same texture.
// Sharing a texture for multiple fonts allows us to reduce the number of draw calls during rendering.
// We also add custom graphic data into the texture that serves for ImGui.
//  1. (Optional) Call AddFont*** functions. If you don't call any, the default font will be loaded for you.
//  2. Call GetTexDataAsAlpha8() or GetTexDataAsRGBA32() to build and retrieve pixels data.
//  3. Upload the pixels data into a texture within your graphics system.
//  4. Call SetTexID(my_tex_id); and pass the pointer/identifier to your texture. This value will be passed back to you during rendering to identify the texture.
// IMPORTANT: If you pass a 'glyph_ranges' array to AddFont*** functions, you need to make sure that your array persist up until the ImFont is build (when calling GetTextData*** or Build()). We only copy the pointer, not the data.
struct ImFontAtlas
{
    IMGUI_API ImFontAtlas();
    IMGUI_API ~ImFontAtlas();
    IMGUI_API ImFont*           AddFont(const ImFontConfig* font_cfg);
    IMGUI_API ImFont*           AddFontDefault(const ImFontConfig* font_cfg = NULL);
    IMGUI_API ImFont*           AddFontFromFileTTF(const char* filename, float size_pixels, const ImFontConfig* font_cfg = NULL, const ImWchar* glyph_ranges = NULL);
    IMGUI_API ImFont*           AddFontFromMemoryTTF(void* font_data, int font_size, float size_pixels, const ImFontConfig* font_cfg = NULL, const ImWchar* glyph_ranges = NULL); // Note: Transfer ownership of 'ttf_data' to ImFontAtlas! Will be deleted after Build(). Set font_cfg->FontDataOwnedByAtlas to false to keep ownership.
    IMGUI_API ImFont*           AddFontFromMemoryCompressedTTF(const void* compressed_font_data, int compressed_font_size, float size_pixels, const ImFontConfig* font_cfg = NULL, const ImWchar* glyph_ranges = NULL); // 'compressed_font_data' still owned by caller. Compress with binary_to_compressed_c.cpp.
    IMGUI_API ImFont*           AddFontFromMemoryCompressedBase85TTF(const char* compressed_font_data_base85, float size_pixels, const ImFontConfig* font_cfg = NULL, const ImWchar* glyph_ranges = NULL);              // 'compressed_font_data_base85' still owned by caller. Compress with binary_to_compressed_c.cpp with -base85 parameter.
    IMGUI_API void              ClearTexData();             // Clear the CPU-side texture data. Saves RAM once the texture has been copied to graphics memory.
    IMGUI_API void              ClearInputData();           // Clear the input TTF data (inc sizes, glyph ranges)
    IMGUI_API void              ClearFonts();               // Clear the ImGui-side font data (glyphs storage, UV coordinates)
    IMGUI_API void              Clear();                    // Clear all

    // Build atlas, retrieve pixel data.
    // User is in charge of copying the pixels into graphics memory (e.g. create a texture with your engine). Then store your texture handle with SetTexID().
    // RGBA32 format is provided for convenience and compatibility, but note that unless you use CustomRect to draw color data, the RGB pixels emitted from Fonts will all be white (~75% of waste). 
    // Pitch = Width * BytesPerPixels
    IMGUI_API bool              Build();                    // Build pixels data. This is called automatically for you by the GetTexData*** functions.
    IMGUI_API void              GetTexDataAsAlpha8(unsigned char** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel = NULL);  // 1 byte per-pixel
    IMGUI_API void              GetTexDataAsRGBA32(unsigned char** out_pixels, int* out_width, int* out_height, int* out_bytes_per_pixel = NULL);  // 4 bytes-per-pixel
    void                        SetTexID(ImTextureID id)    { TexID = id; }

    //-------------------------------------------
    // Glyph Ranges
    //-------------------------------------------

    // Helpers to retrieve list of common Unicode ranges (2 value per range, values are inclusive, zero-terminated list)
    // NB: Make sure that your string are UTF-8 and NOT in your local code page. In C++11, you can create UTF-8 string literal using the u8"Hello world" syntax. See FAQ for details.
    IMGUI_API const ImWchar*    GetGlyphRangesDefault();    // Basic Latin, Extended Latin
    IMGUI_API const ImWchar*    GetGlyphRangesKorean();     // Default + Korean characters
    IMGUI_API const ImWchar*    GetGlyphRangesJapanese();   // Default + Hiragana, Katakana, Half-Width, Selection of 1946 Ideographs
    IMGUI_API const ImWchar*    GetGlyphRangesChinese();    // Default + Japanese + full set of about 21000 CJK Unified Ideographs
    IMGUI_API const ImWchar*    GetGlyphRangesCyrillic();   // Default + about 400 Cyrillic characters
    IMGUI_API const ImWchar*    GetGlyphRangesThai();       // Default + Thai characters

    // Helpers to build glyph ranges from text data. Feed your application strings/characters to it then call BuildRanges().
    struct GlyphRangesBuilder
    {
        ImVector<unsigned char> UsedChars;  // Store 1-bit per Unicode code point (0=unused, 1=used)
        GlyphRangesBuilder()                { UsedChars.resize(0x10000 / 8); memset(UsedChars.Data, 0, 0x10000 / 8); }
        bool           GetBit(int n)        { return (UsedChars[n >> 3] & (1 << (n & 7))) != 0; }
        void           SetBit(int n)        { UsedChars[n >> 3] |= 1 << (n & 7); }  // Set bit 'c' in the array
        void           AddChar(ImWchar c)   { SetBit(c); }                          // Add character
        IMGUI_API void AddText(const char* text, const char* text_end = NULL);      // Add string (each character of the UTF-8 string are added)
        IMGUI_API void AddRanges(const ImWchar* ranges);                            // Add ranges, e.g. builder.AddRanges(ImFontAtlas::GetGlyphRangesDefault) to force add all of ASCII/Latin+Ext
        IMGUI_API void BuildRanges(ImVector<ImWchar>* out_ranges);                  // Output new ranges
    };

    //-------------------------------------------
    // Custom Rectangles/Glyphs API
    //-------------------------------------------

    // You can request arbitrary rectangles to be packed into the atlas, for your own purposes. After calling Build(), you can query the rectangle position and render your pixels.
    // You can also request your rectangles to be mapped as font glyph (given a font + Unicode point), so you can render e.g. custom colorful icons and use them as regular glyphs.
    struct CustomRect
    {
        unsigned int    ID;             // Input    // User ID. Use <0x10000 to map into a font glyph, >=0x10000 for other/internal/custom texture data.
        unsigned short  Width, Height;  // Input    // Desired rectangle dimension
        unsigned short  X, Y;           // Output   // Packed position in Atlas
        float           GlyphAdvanceX;  // Input    // For custom font glyphs only (ID<0x10000): glyph xadvance
        ImVec2          GlyphOffset;    // Input    // For custom font glyphs only (ID<0x10000): glyph display offset
        ImFont*         Font;           // Input    // For custom font glyphs only (ID<0x10000): target font
        CustomRect()            { ID = 0xFFFFFFFF; Width = Height = 0; X = Y = 0xFFFF; GlyphAdvanceX = 0.0f; GlyphOffset = ImVec2(0,0); Font = NULL; }
        bool IsPacked() const   { return X != 0xFFFF; }
    };

    IMGUI_API int       AddCustomRectRegular(unsigned int id, int width, int height);                                                                   // Id needs to be >= 0x10000. Id >= 0x80000000 are reserved for ImGui and ImDrawList
    IMGUI_API int       AddCustomRectFontGlyph(ImFont* font, ImWchar id, int width, int height, float advance_x, const ImVec2& offset = ImVec2(0,0));   // Id needs to be < 0x10000 to register a rectangle to map into a specific font.
    const CustomRect*   GetCustomRectByIndex(int index) const { if (index < 0) return NULL; return &CustomRects[index]; }

    // Internals
    IMGUI_API void      CalcCustomRectUV(const CustomRect* rect, ImVec2* out_uv_min, ImVec2* out_uv_max);
    IMGUI_API bool      GetMouseCursorTexData(ImGuiMouseCursor cursor, ImVec2* out_offset, ImVec2* out_size, ImVec2 out_uv_border[2], ImVec2 out_uv_fill[2]);

    //-------------------------------------------
    // Members
    //-------------------------------------------

    ImFontAtlasFlags            Flags;              // Build flags (see ImFontAtlasFlags_)
    ImTextureID                 TexID;              // User data to refer to the texture once it has been uploaded to user's graphic systems. It is passed back to you during rendering via the ImDrawCmd structure.
    int                         TexDesiredWidth;    // Texture width desired by user before Build(). Must be a power-of-two. If have many glyphs your graphics API have texture size restrictions you may want to increase texture width to decrease height.
    int                         TexGlyphPadding;    // Padding between glyphs within texture in pixels. Defaults to 1.

    // [Internal]
    // NB: Access texture data via GetTexData*() calls! Which will setup a default font for you.
    unsigned char*              TexPixelsAlpha8;    // 1 component per pixel, each component is unsigned 8-bit. Total size = TexWidth * TexHeight
    unsigned int*               TexPixelsRGBA32;    // 4 component per pixel, each component is unsigned 8-bit. Total size = TexWidth * TexHeight * 4
    int                         TexWidth;           // Texture width calculated during Build().
    int                         TexHeight;          // Texture height calculated during Build().
    ImVec2                      TexUvScale;         // = (1.0f/TexWidth, 1.0f/TexHeight)
    ImVec2                      TexUvWhitePixel;    // Texture coordinates to a white pixel
    ImVector<ImFont*>           Fonts;              // Hold all the fonts returned by AddFont*. Fonts[0] is the default font upon calling ImGui::NewFrame(), use ImGui::PushFont()/PopFont() to change the current font.
    ImVector<CustomRect>        CustomRects;        // Rectangles for packing custom texture data into the atlas.
    ImVector<ImFontConfig>      ConfigData;         // Internal data
    int                         CustomRectIds[1];   // Identifiers of custom texture rectangle used by ImFontAtlas/ImDrawList
};

// Font runtime data and rendering
// ImFontAtlas automatically loads a default embedded font for you when you call GetTexDataAsAlpha8() or GetTexDataAsRGBA32().
struct ImFont
{
    // Members: Hot ~62/78 bytes
    float                       FontSize;           // <user set>   // Height of characters, set during loading (don't change after loading)
    float                       Scale;              // = 1.f        // Base font scale, multiplied by the per-window font scale which you can adjust with SetFontScale()
    ImVec2                      DisplayOffset;      // = (0.f,1.f)  // Offset font rendering by xx pixels
    ImVector<ImFontGlyph>       Glyphs;             //              // All glyphs.
    ImVector<float>             IndexAdvanceX;      //              // Sparse. Glyphs->AdvanceX in a directly indexable way (more cache-friendly, for CalcTextSize functions which are often bottleneck in large UI).
    ImVector<unsigned short>    IndexLookup;        //              // Sparse. Index glyphs by Unicode code-point.
    const ImFontGlyph*          FallbackGlyph;      // == FindGlyph(FontFallbackChar)
    float                       FallbackAdvanceX;   // == FallbackGlyph->AdvanceX
    ImWchar                     FallbackChar;       // = '?'        // Replacement glyph if one isn't found. Only set via SetFallbackChar()

    // Members: Cold ~18/26 bytes
    short                       ConfigDataCount;    // ~ 1          // Number of ImFontConfig involved in creating this font. Bigger than 1 when merging multiple font sources into one ImFont.
    ImFontConfig*               ConfigData;         //              // Pointer within ContainerAtlas->ConfigData
    ImFontAtlas*                ContainerAtlas;     //              // What we has been loaded into
    float                       Ascent, Descent;    //              // Ascent: distance from top to bottom of e.g. 'A' [0..FontSize]
    int                         MetricsTotalSurface;//              // Total surface in pixels to get an idea of the font rasterization/texture cost (not exact, we approximate the cost of padding between glyphs)

    // Methods
    IMGUI_API ImFont();
    IMGUI_API ~ImFont();
    IMGUI_API void              ClearOutputData();
    IMGUI_API void              BuildLookupTable();
    IMGUI_API const ImFontGlyph*FindGlyph(ImWchar c) const;
    IMGUI_API void              SetFallbackChar(ImWchar c);
    float                       GetCharAdvance(ImWchar c) const     { return ((int)c < IndexAdvanceX.Size) ? IndexAdvanceX[(int)c] : FallbackAdvanceX; }
    bool                        IsLoaded() const                    { return ContainerAtlas != NULL; }
    const char*                 GetDebugName() const                { return ConfigData ? ConfigData->Name : "<unknown>"; }

    // 'max_width' stops rendering after a certain width (could be turned into a 2d size). FLT_MAX to disable.
    // 'wrap_width' enable automatic word-wrapping across multiple lines to fit into given width. 0.0f to disable.
    IMGUI_API ImVec2            CalcTextSizeA(float size, float max_width, float wrap_width, const char* text_begin, const char* text_end = NULL, const char** remaining = NULL) const; // utf8
    IMGUI_API const char*       CalcWordWrapPositionA(float scale, const char* text, const char* text_end, float wrap_width) const;
    IMGUI_API void              RenderChar(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col, unsigned short c) const;
    IMGUI_API void              RenderText(ImDrawList* draw_list, float size, ImVec2 pos, ImU32 col, const ImVec4& clip_rect, const char* text_begin, const char* text_end, float wrap_width = 0.0f, bool cpu_fine_clip = false) const;

    // [Internal]
    IMGUI_API void              GrowIndex(int new_size);
    IMGUI_API void              AddGlyph(ImWchar c, float x0, float y0, float x1, float y1, float u0, float v0, float u1, float v1, float advance_x);
    IMGUI_API void              AddRemapChar(ImWchar dst, ImWchar src, bool overwrite_dst = true); // Makes 'dst' character/glyph points to 'src' character/glyph. Currently needs to be called AFTER fonts have been built.

#ifndef IMGUI_DISABLE_OBSOLETE_FUNCTIONS
    typedef ImFontGlyph Glyph; // OBSOLETE 1.52+
#endif
};

#if defined(__clang__)
#pragma clang diagnostic pop
#endif

// Include imgui_user.h at the end of imgui.h (convenient for user to only explicitly include vanilla imgui.h)
#ifdef IMGUI_INCLUDE_IMGUI_USER_H
#include "imgui_user.h"
#endif