text: // dear imgui: Renderer + Platform Backend for Allegro 5
  // (Info: Allegro 5 is a cross-platform general purpose library for handling windows, inputs, graphics, etc.)
  
  // Implemented features:
  //  [X] Renderer: User texture binding. Use 'ALLEGRO_BITMAP*' as ImTextureID. Read the FAQ about ImTextureID!
  //  [X] Platform: Clipboard support (from Allegro 5.1.12)
  //  [X] Platform: Mouse cursor shape and visibility. Disable with 'io.ConfigFlags |= ImGuiConfigFlags_NoMouseCursorChange'.
  // Issues:
  //  [ ] Renderer: The renderer is suboptimal as we need to unindex our buffers and convert vertices manually.
  //  [ ] Platform: Missing gamepad support.
  
  // You can copy and use unmodified imgui_impl_* files in your project. See examples/ folder for examples of using this.
  // If you are new to Dear ImGui, read documentation from the docs/ folder + read the top of imgui.cpp.
  // Read online: https://github.com/ocornut/imgui/tree/master/docs
  
  // CHANGELOG
  // (minor and older changes stripped away, please see git history for details)
  //  2021-02-18: Change blending equation to preserve alpha in output buffer.
  //  2020-08-10: Inputs: Fixed horizontal mouse wheel direction.
  //  2019-12-05: Inputs: Added support for ImGuiMouseCursor_NotAllowed mouse cursor.
  //  2019-07-21: Inputs: Added mapping for ImGuiKey_KeyPadEnter.
  //  2019-05-11: Inputs: Don't filter character value from ALLEGRO_EVENT_KEY_CHAR before calling AddInputCharacter().
  //  2019-04-30: Renderer: Added support for special ImDrawCallback_ResetRenderState callback to reset render state.
  //  2018-11-30: Platform: Added touchscreen support.
  //  2018-11-30: Misc: Setting up io.BackendPlatformName/io.BackendRendererName so they can be displayed in the About Window.
  //  2018-06-13: Platform: Added clipboard support (from Allegro 5.1.12).
  //  2018-06-13: Renderer: Use draw_data->DisplayPos and draw_data->DisplaySize to setup projection matrix and clipping rectangle.
  //  2018-06-13: Renderer: Backup/restore transform and clipping rectangle.
  //  2018-06-11: Misc: Setup io.BackendFlags ImGuiBackendFlags_HasMouseCursors flag + honor ImGuiConfigFlags_NoMouseCursorChange flag.
  //  2018-04-18: Misc: Renamed file from imgui_impl_a5.cpp to imgui_impl_allegro5.cpp.
  //  2018-04-18: Misc: Added support for 32-bit vertex indices to avoid conversion at runtime. Added imconfig_allegro5.h to enforce 32-bit indices when included from imgui.h.
  //  2018-02-16: Misc: Obsoleted the io.RenderDrawListsFn callback and exposed ImGui_ImplAllegro5_RenderDrawData() in the .h file so you can call it yourself.
  //  2018-02-06: Misc: Removed call to ImGui::Shutdown() which is not available from 1.60 WIP, user needs to call CreateContext/DestroyContext themselves.
  //  2018-02-06: Inputs: Added mapping for ImGuiKey_Space.
  
  #include <stdint.h>     // uint64_t
  #include <cstring>      // memcpy
  #include <math.h>       // isinf
  #include "imgui.h"
  #include "imgui_impl_allegro5.h"
  
  // Allegro
  #include <allegro5/allegro.h>
  #include <allegro5/allegro_primitives.h>
  #ifdef _WIN32
  #include <allegro5/allegro_windows.h>
  #endif
  #define ALLEGRO_HAS_CLIPBOARD   (ALLEGRO_VERSION_INT >= ((5 << 24) | (1 << 16) | (12 << 8)))    // Clipboard only supported from Allegro 5.1.12
  
  // Visual Studio warnings
  #ifdef _MSC_VER
  #pragma warning (disable: 4127) // condition expression is constant
  #endif
  
  // Data
  static ALLEGRO_DISPLAY*         g_Display = NULL;
  static ALLEGRO_BITMAP*          g_Texture = NULL;
  static double                   g_Time = 0.0;
  static ALLEGRO_MOUSE_CURSOR*    g_MouseCursorInvisible = NULL;
  static ALLEGRO_VERTEX_DECL*     g_VertexDecl = NULL;
  static char*                    g_ClipboardTextData = NULL;
  
  struct ImDrawVertAllegro
  {
      ImVec2 pos;
      ImVec2 uv;
      ALLEGRO_COLOR col;
  };
  
  static void ImGui_ImplAllegro5_SetupRenderState(ImDrawData* draw_data)
  {
      // Setup blending
      al_set_separate_blender(ALLEGRO_ADD, ALLEGRO_ALPHA, ALLEGRO_INVERSE_ALPHA, ALLEGRO_ADD, ALLEGRO_ONE, ALLEGRO_INVERSE_ALPHA);
  
      // Setup orthographic projection matrix
      // Our visible imgui space lies from draw_data->DisplayPos (top left) to draw_data->DisplayPos+data_data->DisplaySize (bottom right).
      {
          float L = draw_data->DisplayPos.x;
          float R = draw_data->DisplayPos.x + draw_data->DisplaySize.x;
          float T = draw_data->DisplayPos.y;
          float B = draw_data->DisplayPos.y + draw_data->DisplaySize.y;
          ALLEGRO_TRANSFORM transform;
          al_identity_transform(&transform);
          al_use_transform(&transform);
          al_orthographic_transform(&transform, L, T, 1.0f, R, B, -1.0f);
          al_use_projection_transform(&transform);
      }
  }
  
  // Render function.
  void ImGui_ImplAllegro5_RenderDrawData(ImDrawData* draw_data)
  {
      // Avoid rendering when minimized
      if (draw_data->DisplaySize.x <= 0.0f || draw_data->DisplaySize.y <= 0.0f)
          return;
  
      // Backup Allegro state that will be modified
      ALLEGRO_TRANSFORM last_transform = *al_get_current_transform();
      ALLEGRO_TRANSFORM last_projection_transform = *al_get_current_projection_transform();
      int last_clip_x, last_clip_y, last_clip_w, last_clip_h;
      al_get_clipping_rectangle(&last_clip_x, &last_clip_y, &last_clip_w, &last_clip_h);
      int last_blender_op, last_blender_src, last_blender_dst;
      al_get_blender(&last_blender_op, &last_blender_src, &last_blender_dst);
  
      // Setup desired render state
      ImGui_ImplAllegro5_SetupRenderState(draw_data);
  
      // Render command lists
      for (int n = 0; n < draw_data->CmdListsCount; n++)
      {
          const ImDrawList* cmd_list = draw_data->CmdLists[n];
  
          // Allegro's implementation of al_draw_indexed_prim() for DX9 is completely broken. Unindex our buffers ourselves.
          // FIXME-OPT: Unfortunately Allegro doesn't support 32-bit packed colors so we have to convert them to 4 float as well..
          static ImVector<ImDrawVertAllegro> vertices;
          vertices.resize(cmd_list->IdxBuffer.Size);
          for (int i = 0; i < cmd_list->IdxBuffer.Size; i++)
          {
              const ImDrawVert* src_v = &cmd_list->VtxBuffer[cmd_list->IdxBuffer[i]];
              ImDrawVertAllegro* dst_v = &vertices[i];
              dst_v->pos = src_v->pos;
              dst_v->uv = src_v->uv;
              unsigned char* c = (unsigned char*)&src_v->col;
              dst_v->col = al_map_rgba(c[0], c[1], c[2], c[3]);
          }
  
          const int* indices = NULL;
          if (sizeof(ImDrawIdx) == 2)
          {
              // FIXME-OPT: Unfortunately Allegro doesn't support 16-bit indices.. You can '#define ImDrawIdx int' in imconfig.h to request Dear ImGui to output 32-bit indices.
              // Otherwise, we convert them from 16-bit to 32-bit at runtime here, which works perfectly but is a little wasteful.
              static ImVector<int> indices_converted;
              indices_converted.resize(cmd_list->IdxBuffer.Size);
              for (int i = 0; i < cmd_list->IdxBuffer.Size; ++i)
                  indices_converted[i] = (int)cmd_list->IdxBuffer.Data[i];
              indices = indices_converted.Data;
          }
          else if (sizeof(ImDrawIdx) == 4)
          {
              indices = (const int*)cmd_list->IdxBuffer.Data;
          }
  
          // Render command lists
          int idx_offset = 0;
          ImVec2 clip_off = draw_data->DisplayPos;
          for (int cmd_i = 0; cmd_i < cmd_list->CmdBuffer.Size; cmd_i++)
          {
              const ImDrawCmd* pcmd = &cmd_list->CmdBuffer[cmd_i];
              if (pcmd->UserCallback)
              {
                  // User callback, registered via ImDrawList::AddCallback()
                  // (ImDrawCallback_ResetRenderState is a special callback value used by the user to request the renderer to reset render state.)
                  if (pcmd->UserCallback == ImDrawCallback_ResetRenderState)
                      ImGui_ImplAllegro5_SetupRenderState(draw_data);
                  else
                      pcmd->UserCallback(cmd_list, pcmd);
              }
              else
              {
                  // Draw
                  ALLEGRO_BITMAP* texture = (ALLEGRO_BITMAP*)pcmd->TextureId;
                  al_set_clipping_rectangle(pcmd->ClipRect.x - clip_off.x, pcmd->ClipRect.y - clip_off.y, pcmd->ClipRect.z - pcmd->ClipRect.x, pcmd->ClipRect.w - pcmd->ClipRect.y);
                  al_draw_prim(&vertices[0], g_VertexDecl, texture, idx_offset, idx_offset + pcmd->ElemCount, ALLEGRO_PRIM_TRIANGLE_LIST);
              }
              idx_offset += pcmd->ElemCount;
          }
      }
  
      // Restore modified Allegro state
      al_set_blender(last_blender_op, last_blender_src, last_blender_dst);
      al_set_clipping_rectangle(last_clip_x, last_clip_y, last_clip_w, last_clip_h);
      al_use_transform(&last_transform);
      al_use_projection_transform(&last_projection_transform);
  }
  
  bool ImGui_ImplAllegro5_CreateDeviceObjects()
  {
      // Build texture atlas
      ImGuiIO& io = ImGui::GetIO();
      unsigned char* pixels;
      int width, height;
      io.Fonts->GetTexDataAsRGBA32(&pixels, &width, &height);
  
      // Create texture
      int flags = al_get_new_bitmap_flags();
      int fmt = al_get_new_bitmap_format();
      al_set_new_bitmap_flags(ALLEGRO_MEMORY_BITMAP | ALLEGRO_MIN_LINEAR | ALLEGRO_MAG_LINEAR);
      al_set_new_bitmap_format(ALLEGRO_PIXEL_FORMAT_ABGR_8888_LE);
      ALLEGRO_BITMAP* img = al_create_bitmap(width, height);
      al_set_new_bitmap_flags(flags);
      al_set_new_bitmap_format(fmt);
      if (!img)
          return false;
  
      ALLEGRO_LOCKED_REGION* locked_img = al_lock_bitmap(img, al_get_bitmap_format(img), ALLEGRO_LOCK_WRITEONLY);
      if (!locked_img)
      {
          al_destroy_bitmap(img);
          return false;
      }
      memcpy(locked_img->data, pixels, sizeof(int) * width * height);
      al_unlock_bitmap(img);
  
      // Convert software texture to hardware texture.
      ALLEGRO_BITMAP* cloned_img = al_clone_bitmap(img);
      al_destroy_bitmap(img);
      if (!cloned_img)
          return false;
  
      // Store our identifier
      io.Fonts->SetTexID((void*)cloned_img);
      g_Texture = cloned_img;
  
      // Create an invisible mouse cursor
      // Because al_hide_mouse_cursor() seems to mess up with the actual inputs..
      ALLEGRO_BITMAP* mouse_cursor = al_create_bitmap(8, 8);
      g_MouseCursorInvisible = al_create_mouse_cursor(mouse_cursor, 0, 0);
      al_destroy_bitmap(mouse_cursor);
  
      return true;
  }
  
  void ImGui_ImplAllegro5_InvalidateDeviceObjects()
  {
      if (g_Texture)
      {
          ImGuiIO& io = ImGui::GetIO();
          io.Fonts->SetTexID(NULL);
          al_destroy_bitmap(g_Texture);
          g_Texture = NULL;
      }
      if (g_MouseCursorInvisible)
      {
          al_destroy_mouse_cursor(g_MouseCursorInvisible);
          g_MouseCursorInvisible = NULL;
      }
  }
  
  #if ALLEGRO_HAS_CLIPBOARD
  static const char* ImGui_ImplAllegro5_GetClipboardText(void*)
  {
      if (g_ClipboardTextData)
          al_free(g_ClipboardTextData);
      g_ClipboardTextData = al_get_clipboard_text(g_Display);
      return g_ClipboardTextData;
  }
  
  static void ImGui_ImplAllegro5_SetClipboardText(void*, const char* text)
  {
      al_set_clipboard_text(g_Display, text);
  }
  #endif
  
  bool ImGui_ImplAllegro5_Init(ALLEGRO_DISPLAY* display)
  {
      g_Display = display;
  
      // Setup backend capabilities flags
      ImGuiIO& io = ImGui::GetIO();
      io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;       // We can honor GetMouseCursor() values (optional)
      io.BackendPlatformName = io.BackendRendererName = "imgui_impl_allegro5";
  
      // Create custom vertex declaration.
      // Unfortunately Allegro doesn't support 32-bit packed colors so we have to convert them to 4 floats.
      // We still use a custom declaration to use 'ALLEGRO_PRIM_TEX_COORD' instead of 'ALLEGRO_PRIM_TEX_COORD_PIXEL' else we can't do a reliable conversion.
      ALLEGRO_VERTEX_ELEMENT elems[] =
      {
          { ALLEGRO_PRIM_POSITION, ALLEGRO_PRIM_FLOAT_2, IM_OFFSETOF(ImDrawVertAllegro, pos) },
          { ALLEGRO_PRIM_TEX_COORD, ALLEGRO_PRIM_FLOAT_2, IM_OFFSETOF(ImDrawVertAllegro, uv) },
          { ALLEGRO_PRIM_COLOR_ATTR, 0, IM_OFFSETOF(ImDrawVertAllegro, col) },
          { 0, 0, 0 }
      };
      g_VertexDecl = al_create_vertex_decl(elems, sizeof(ImDrawVertAllegro));
  
      io.KeyMap[ImGuiKey_Tab] = ALLEGRO_KEY_TAB;
      io.KeyMap[ImGuiKey_LeftArrow] = ALLEGRO_KEY_LEFT;
      io.KeyMap[ImGuiKey_RightArrow] = ALLEGRO_KEY_RIGHT;
      io.KeyMap[ImGuiKey_UpArrow] = ALLEGRO_KEY_UP;
      io.KeyMap[ImGuiKey_DownArrow] = ALLEGRO_KEY_DOWN;
      io.KeyMap[ImGuiKey_PageUp] = ALLEGRO_KEY_PGUP;
      io.KeyMap[ImGuiKey_PageDown] = ALLEGRO_KEY_PGDN;
      io.KeyMap[ImGuiKey_Home] = ALLEGRO_KEY_HOME;
      io.KeyMap[ImGuiKey_End] = ALLEGRO_KEY_END;
      io.KeyMap[ImGuiKey_Insert] = ALLEGRO_KEY_INSERT;
      io.KeyMap[ImGuiKey_Delete] = ALLEGRO_KEY_DELETE;
      io.KeyMap[ImGuiKey_Backspace] = ALLEGRO_KEY_BACKSPACE;
      io.KeyMap[ImGuiKey_Space] = ALLEGRO_KEY_SPACE;
      io.KeyMap[ImGuiKey_Enter] = ALLEGRO_KEY_ENTER;
      io.KeyMap[ImGuiKey_Escape] = ALLEGRO_KEY_ESCAPE;
      io.KeyMap[ImGuiKey_KeyPadEnter] = ALLEGRO_KEY_PAD_ENTER;
      io.KeyMap[ImGuiKey_A] = ALLEGRO_KEY_A;
      io.KeyMap[ImGuiKey_C] = ALLEGRO_KEY_C;
      io.KeyMap[ImGuiKey_V] = ALLEGRO_KEY_V;
      io.KeyMap[ImGuiKey_X] = ALLEGRO_KEY_X;
      io.KeyMap[ImGuiKey_Y] = ALLEGRO_KEY_Y;
      io.KeyMap[ImGuiKey_Z] = ALLEGRO_KEY_Z;
      io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
  
  #if ALLEGRO_HAS_CLIPBOARD
      io.SetClipboardTextFn = ImGui_ImplAllegro5_SetClipboardText;
      io.GetClipboardTextFn = ImGui_ImplAllegro5_GetClipboardText;
      io.ClipboardUserData = NULL;
  #endif
  
      return true;
  }
  
  void ImGui_ImplAllegro5_Shutdown()
  {
      ImGui_ImplAllegro5_InvalidateDeviceObjects();
  
      g_Display = NULL;
      g_Time = 0.0;
  
      if (g_VertexDecl)
          al_destroy_vertex_decl(g_VertexDecl);
      g_VertexDecl = NULL;
  
      if (g_ClipboardTextData)
          al_free(g_ClipboardTextData);
      g_ClipboardTextData = NULL;
  }
  
  void ImGui_ImplAllegro5_WaitForEvent(ALLEGRO_EVENT_QUEUE* queue)
  {
      if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
          return;
  
      int display_flags = al_get_display_flags(g_Display);
      bool window_is_hidden = display_flags & ALLEGRO_MINIMIZED;
      double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
      if (waiting_time > 0.0)
      {
          if (isinf(waiting_time))
              al_wait_for_event(queue, NULL);
          else
              al_wait_for_event_timed(queue, NULL, waiting_time);
      }
  }
  
  
  // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
  // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
  // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
  // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
  bool ImGui_ImplAllegro5_ProcessEvent(ALLEGRO_EVENT* ev)
  {
      ImGuiIO& io = ImGui::GetIO();
  
      io.FrameCountSinceLastInput = 0;
  
      switch (ev->type)
      {
      case ALLEGRO_EVENT_MOUSE_AXES:
          if (ev->mouse.display == g_Display)
          {
              io.MouseWheel += ev->mouse.dz;
              io.MouseWheelH -= ev->mouse.dw;
              io.MousePos = ImVec2(ev->mouse.x, ev->mouse.y);
          }
          return true;
      case ALLEGRO_EVENT_MOUSE_BUTTON_DOWN:
      case ALLEGRO_EVENT_MOUSE_BUTTON_UP:
          if (ev->mouse.display == g_Display && ev->mouse.button <= 5)
              io.MouseDown[ev->mouse.button - 1] = (ev->type == ALLEGRO_EVENT_MOUSE_BUTTON_DOWN);
          return true;
      case ALLEGRO_EVENT_TOUCH_MOVE:
          if (ev->touch.display == g_Display)
              io.MousePos = ImVec2(ev->touch.x, ev->touch.y);
          return true;
      case ALLEGRO_EVENT_TOUCH_BEGIN:
      case ALLEGRO_EVENT_TOUCH_END:
      case ALLEGRO_EVENT_TOUCH_CANCEL:
          if (ev->touch.display == g_Display && ev->touch.primary)
              io.MouseDown[0] = (ev->type == ALLEGRO_EVENT_TOUCH_BEGIN);
          return true;
      case ALLEGRO_EVENT_MOUSE_LEAVE_DISPLAY:
          if (ev->mouse.display == g_Display)
              io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
          return true;
      case ALLEGRO_EVENT_KEY_CHAR:
          if (ev->keyboard.display == g_Display)
              if (ev->keyboard.unichar != 0)
                  io.AddInputCharacter((unsigned int)ev->keyboard.unichar);
          return true;
      case ALLEGRO_EVENT_KEY_DOWN:
      case ALLEGRO_EVENT_KEY_UP:
          if (ev->keyboard.display == g_Display)
              io.KeysDown[ev->keyboard.keycode] = (ev->type == ALLEGRO_EVENT_KEY_DOWN);
          return true;
      }
      return false;
  }
  
  static void ImGui_ImplAllegro5_UpdateMouseCursor()
  {
      ImGuiIO& io = ImGui::GetIO();
      if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)
          return;
  
      ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
      if (io.MouseDrawCursor || imgui_cursor == ImGuiMouseCursor_None)
      {
          // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
          al_set_mouse_cursor(g_Display, g_MouseCursorInvisible);
      }
      else
      {
          ALLEGRO_SYSTEM_MOUSE_CURSOR cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_DEFAULT;
          switch (imgui_cursor)
          {
          case ImGuiMouseCursor_TextInput:    cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_EDIT; break;
          case ImGuiMouseCursor_ResizeAll:    cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_MOVE; break;
          case ImGuiMouseCursor_ResizeNS:     cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_RESIZE_N; break;
          case ImGuiMouseCursor_ResizeEW:     cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_RESIZE_E; break;
          case ImGuiMouseCursor_ResizeNESW:   cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_RESIZE_NE; break;
          case ImGuiMouseCursor_ResizeNWSE:   cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_RESIZE_NW; break;
          case ImGuiMouseCursor_NotAllowed:   cursor_id = ALLEGRO_SYSTEM_MOUSE_CURSOR_UNAVAILABLE; break;
          }
          al_set_system_mouse_cursor(g_Display, cursor_id);
      }
  }
  
  void ImGui_ImplAllegro5_NewFrame()
  {
      if (!g_Texture)
          ImGui_ImplAllegro5_CreateDeviceObjects();
  
      ImGuiIO& io = ImGui::GetIO();
  
      // Setup display size (every frame to accommodate for window resizing)
      int w, h;
      w = al_get_display_width(g_Display);
      h = al_get_display_height(g_Display);
      io.DisplaySize = ImVec2((float)w, (float)h);
  
      // Setup time step
      double current_time = al_get_time();
      io.DeltaTime = g_Time > 0.0 ? (float)(current_time - g_Time) : (float)(1.0f / 60.0f);
      g_Time = current_time;
  
      // Setup inputs
      ALLEGRO_KEYBOARD_STATE keys;
      al_get_keyboard_state(&keys);
      io.KeyCtrl = al_key_down(&keys, ALLEGRO_KEY_LCTRL) || al_key_down(&keys, ALLEGRO_KEY_RCTRL);
      io.KeyShift = al_key_down(&keys, ALLEGRO_KEY_LSHIFT) || al_key_down(&keys, ALLEGRO_KEY_RSHIFT);
      io.KeyAlt = al_key_down(&keys, ALLEGRO_KEY_ALT) || al_key_down(&keys, ALLEGRO_KEY_ALTGR);
      io.KeySuper = al_key_down(&keys, ALLEGRO_KEY_LWIN) || al_key_down(&keys, ALLEGRO_KEY_RWIN);
  
      ImGui_ImplAllegro5_UpdateMouseCursor();
  }
  