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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "win32_window.h"
#include <dwmapi.h>
#include <flutter_windows.h>
#include "resource.h"
namespace {
/// Window attribute that enables dark mode window decorations.
///
/// Redefined in case the developer's machine has a Windows SDK older than
/// version 10.0.22000.0.
/// See: https://docs.microsoft.com/windows/win32/api/dwmapi/ne-dwmapi-dwmwindowattribute
#ifndef DWMWA_USE_IMMERSIVE_DARK_MODE
#define DWMWA_USE_IMMERSIVE_DARK_MODE 20
#endif
constexpr const wchar_t kWindowClassName[] = L"FLUTTER_RUNNER_WIN32_WINDOW";
/// Registry key for app theme preference.
///
/// A value of 0 indicates apps should use dark mode. A non-zero or missing
/// value indicates apps should use light mode.
constexpr const wchar_t kGetPreferredBrightnessRegKey[] =
L"Software\\Microsoft\\Windows\\CurrentVersion\\Themes\\Personalize";
constexpr const wchar_t kGetPreferredBrightnessRegValue[] = L"AppsUseLightTheme";
// The number of Win32Window objects that currently exist.
static int g_active_window_count = 0;
using EnableNonClientDpiScaling = BOOL __stdcall(HWND hwnd);
// Scale helper to convert logical scaler values to physical using passed in
// scale factor
int Scale(int source, double scale_factor) {
return static_cast<int>(source * scale_factor);
}
// Dynamically loads the |EnableNonClientDpiScaling| from the User32 module.
// This API is only needed for PerMonitor V1 awareness mode.
void EnableFullDpiSupportIfAvailable(HWND hwnd) {
HMODULE user32_module = LoadLibraryA("User32.dll");
if (!user32_module) {
return;
}
auto enable_non_client_dpi_scaling =
reinterpret_cast<EnableNonClientDpiScaling*>(
GetProcAddress(user32_module, "EnableNonClientDpiScaling"));
if (enable_non_client_dpi_scaling != nullptr) {
enable_non_client_dpi_scaling(hwnd);
FreeLibrary(user32_module);
}
}
} // namespace
// Manages the Win32Window's window class registration.
class WindowClassRegistrar {
public:
~WindowClassRegistrar() = default;
// Returns the singleton registrar instance.
static WindowClassRegistrar* GetInstance() {
if (!instance_) {
instance_ = new WindowClassRegistrar();
}
return instance_;
}
// Returns the name of the window class, registering the class if it hasn't
// previously been registered.
const wchar_t* GetWindowClass();
// Unregisters the window class. Should only be called if there are no
// instances of the window.
void UnregisterWindowClass();
private:
WindowClassRegistrar() = default;
static WindowClassRegistrar* instance_;
bool class_registered_ = false;
};
WindowClassRegistrar* WindowClassRegistrar::instance_ = nullptr;
const wchar_t* WindowClassRegistrar::GetWindowClass() {
if (!class_registered_) {
WNDCLASS window_class{};
window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
window_class.lpszClassName = kWindowClassName;
window_class.style = CS_HREDRAW | CS_VREDRAW;
window_class.cbClsExtra = 0;
window_class.cbWndExtra = 0;
window_class.hInstance = GetModuleHandle(nullptr);
window_class.hIcon =
LoadIcon(window_class.hInstance, MAKEINTRESOURCE(IDI_APP_ICON));
window_class.hbrBackground = 0;
window_class.lpszMenuName = nullptr;
window_class.lpfnWndProc = Win32Window::WndProc;
RegisterClass(&window_class);
class_registered_ = true;
}
return kWindowClassName;
}
void WindowClassRegistrar::UnregisterWindowClass() {
UnregisterClass(kWindowClassName, nullptr);
class_registered_ = false;
}
Win32Window::Win32Window() {
++g_active_window_count;
}
Win32Window::~Win32Window() {
--g_active_window_count;
Destroy();
}
bool Win32Window::Create(const std::wstring& title,
const Point& origin,
const Size& size) {
Destroy();
const wchar_t* window_class =
WindowClassRegistrar::GetInstance()->GetWindowClass();
const POINT target_point = {static_cast<LONG>(origin.x),
static_cast<LONG>(origin.y)};
HMONITOR monitor = MonitorFromPoint(target_point, MONITOR_DEFAULTTONEAREST);
UINT dpi = FlutterDesktopGetDpiForMonitor(monitor);
double scale_factor = dpi / 96.0;
HWND window = CreateWindow(
window_class, title.c_str(), WS_OVERLAPPEDWINDOW,
Scale(origin.x, scale_factor), Scale(origin.y, scale_factor),
Scale(size.width, scale_factor), Scale(size.height, scale_factor),
nullptr, nullptr, GetModuleHandle(nullptr), this);
if (!window) {
return false;
}
UpdateTheme(window);
return OnCreate();
}
bool Win32Window::Show() {
return ShowWindow(window_handle_, SW_SHOWNORMAL);
}
// static
LRESULT CALLBACK Win32Window::WndProc(HWND const window,
UINT const message,
WPARAM const wparam,
LPARAM const lparam) noexcept {
if (message == WM_NCCREATE) {
auto window_struct = reinterpret_cast<CREATESTRUCT*>(lparam);
SetWindowLongPtr(window, GWLP_USERDATA,
reinterpret_cast<LONG_PTR>(window_struct->lpCreateParams));
auto that = static_cast<Win32Window*>(window_struct->lpCreateParams);
EnableFullDpiSupportIfAvailable(window);
that->window_handle_ = window;
} else if (Win32Window* that = GetThisFromHandle(window)) {
return that->MessageHandler(window, message, wparam, lparam);
}
return DefWindowProc(window, message, wparam, lparam);
}
LRESULT
Win32Window::MessageHandler(HWND hwnd,
UINT const message,
WPARAM const wparam,
LPARAM const lparam) noexcept {
switch (message) {
case WM_DESTROY:
window_handle_ = nullptr;
Destroy();
if (quit_on_close_) {
PostQuitMessage(0);
}
return 0;
case WM_DPICHANGED: {
auto newRectSize = reinterpret_cast<RECT*>(lparam);
LONG newWidth = newRectSize->right - newRectSize->left;
LONG newHeight = newRectSize->bottom - newRectSize->top;
SetWindowPos(hwnd, nullptr, newRectSize->left, newRectSize->top, newWidth,
newHeight, SWP_NOZORDER | SWP_NOACTIVATE);
return 0;
}
case WM_SIZE: {
RECT rect = GetClientArea();
if (child_content_ != nullptr) {
// Size and position the child window.
MoveWindow(child_content_, rect.left, rect.top, rect.right - rect.left,
rect.bottom - rect.top, TRUE);
}
return 0;
}
case WM_ACTIVATE:
if (child_content_ != nullptr) {
SetFocus(child_content_);
}
return 0;
case WM_DWMCOLORIZATIONCOLORCHANGED:
UpdateTheme(hwnd);
return 0;
}
return DefWindowProc(window_handle_, message, wparam, lparam);
}
void Win32Window::Destroy() {
OnDestroy();
if (window_handle_) {
DestroyWindow(window_handle_);
window_handle_ = nullptr;
}
if (g_active_window_count == 0) {
WindowClassRegistrar::GetInstance()->UnregisterWindowClass();
}
}
Win32Window* Win32Window::GetThisFromHandle(HWND const window) noexcept {
return reinterpret_cast<Win32Window*>(
GetWindowLongPtr(window, GWLP_USERDATA));
}
void Win32Window::SetChildContent(HWND content) {
child_content_ = content;
SetParent(content, window_handle_);
RECT frame = GetClientArea();
MoveWindow(content, frame.left, frame.top, frame.right - frame.left,
frame.bottom - frame.top, true);
SetFocus(child_content_);
}
RECT Win32Window::GetClientArea() {
RECT frame;
GetClientRect(window_handle_, &frame);
return frame;
}
HWND Win32Window::GetHandle() {
return window_handle_;
}
void Win32Window::SetQuitOnClose(bool quit_on_close) {
quit_on_close_ = quit_on_close;
}
bool Win32Window::OnCreate() {
// No-op; provided for subclasses.
return true;
}
void Win32Window::OnDestroy() {
// No-op; provided for subclasses.
}
void Win32Window::UpdateTheme(HWND const window) {
DWORD light_mode;
DWORD light_mode_size = sizeof(light_mode);
LSTATUS result = RegGetValue(HKEY_CURRENT_USER, kGetPreferredBrightnessRegKey,
kGetPreferredBrightnessRegValue,
RRF_RT_REG_DWORD, nullptr, &light_mode,
&light_mode_size);
if (result == ERROR_SUCCESS) {
BOOL enable_dark_mode = light_mode == 0;
DwmSetWindowAttribute(window, DWMWA_USE_IMMERSIVE_DARK_MODE,
&enable_dark_mode, sizeof(enable_dark_mode));
}
}