impeller/playground/widgets.h

// Copyright 2013 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.

#pragma once

#include <tuple>

#include "impeller/base/strings.h"
#include "impeller/geometry/color.h"
#include "impeller/geometry/point.h"
#include "third_party/imgui/imgui.h"

#define IMPELLER_PLAYGROUND_POINT(default_position, radius, color)             \
  ({                                                                           \
    static impeller::Point position = default_position;                        \
    static impeller::Point reset_position = default_position;                  \
    float radius_ = radius;                                                    \
    impeller::Color color_ = color;                                            \
                                                                               \
    static bool dragging = false;                                              \
    impeller::Point mouse_pos(ImGui::GetMousePos().x, ImGui::GetMousePos().y); \
    static impeller::Point prev_mouse_pos = mouse_pos;                         \
                                                                               \
    if (ImGui::IsKeyPressed('R')) {                                            \
      position = reset_position;                                               \
      dragging = false;                                                        \
    }                                                                          \
                                                                               \
    bool hovering = position.GetDistance(mouse_pos) < radius_ &&               \
                    position.GetDistance(prev_mouse_pos) < radius_;            \
    if (!ImGui::IsMouseDown(0)) {                                              \
      dragging = false;                                                        \
    } else if (hovering && ImGui::IsMouseClicked(0)) {                         \
      dragging = true;                                                         \
    }                                                                          \
    if (dragging) {                                                            \
      position += mouse_pos - prev_mouse_pos;                                  \
    }                                                                          \
    ImGui::GetBackgroundDrawList()->AddCircleFilled(                           \
        {position.x, position.y}, radius_,                                     \
        ImColor(color_.red, color_.green, color_.blue,                         \
                (hovering || dragging) ? 0.6f : 0.3f));                        \
    if (hovering || dragging) {                                                \
      ImGui::GetBackgroundDrawList()->AddText(                                 \
          {position.x - radius_, position.y + radius_ + 10},                   \
          ImColor(color_.red, color.green, color.blue, 1.0f),                  \
          impeller::SPrintF("x:%0.3f y:%0.3f", position.x, position.y)         \
              .c_str());                                                       \
    }                                                                          \
    prev_mouse_pos = mouse_pos;                                                \
    position;                                                                  \
  })

#define IMPELLER_PLAYGROUND_LINE(default_position_a, default_position_b, \
                                 radius, color_a, color_b)               \
  ({                                                                     \
    impeller::Point position_a = default_position_a;                     \
    impeller::Point position_b = default_position_b;                     \
    float r_ = radius;                                                   \
    impeller::Color color_a_ = color_a;                                  \
    impeller::Color color_b_ = color_b;                                  \
                                                                         \
    position_a = IMPELLER_PLAYGROUND_POINT(position_a, r_, color_a_);    \
    position_b = IMPELLER_PLAYGROUND_POINT(position_b, r_, color_b_);    \
                                                                         \
    auto dir = (position_b - position_a).Normalize() * r_;               \
    auto line_a = position_a + dir;                                      \
    auto line_b = position_b - dir;                                      \
    ImGui::GetBackgroundDrawList()->AddLine(                             \
        {line_a.x, line_a.y}, {line_b.x, line_b.y},                      \
        ImColor(color_b.red, color_b.green, color_b.blue, 0.3f));        \
                                                                         \
    std::make_tuple(position_a, position_b);                             \
  })