update imgui-sdl2 binding code

fredakilla · fredakilla · commit afeaaed583db · 2018-10-26T15:34:59.000+02:00
diff --git a/src/core/PlatformSDL2.cpp b/src/core/PlatformSDL2.cpp
@@ -177,8 +177,12 @@ static bool ImGui_ImplSdlGL3_Init(SDL_Window* window)
     // Create bgfx imgui objects
     GPImGui::Get()->imguiInit();
 
-    // Keyboard mapping. ImGui will use those indices to peek into the io.KeyDown[] array.
+    // Setup back-end capabilities flags
     ImGuiIO& io = ImGui::GetIO();
+    io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;       // We can honor GetMouseCursor() values (optional)
+    io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;        // We can honor io.WantSetMousePos requests (optional, rarely used)
+
+    // Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array.
     io.KeyMap[ImGuiKey_Tab] = SDL_SCANCODE_TAB;
     io.KeyMap[ImGuiKey_LeftArrow] = SDL_SCANCODE_LEFT;
     io.KeyMap[ImGuiKey_RightArrow] = SDL_SCANCODE_RIGHT;
@@ -212,6 +216,7 @@ static bool ImGui_ImplSdlGL3_Init(SDL_Window* window)
     g_MouseCursors[ImGuiMouseCursor_ResizeEW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZEWE);
     g_MouseCursors[ImGuiMouseCursor_ResizeNESW] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENESW);
     g_MouseCursors[ImGuiMouseCursor_ResizeNWSE] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_SIZENWSE);
+    g_MouseCursors[ImGuiMouseCursor_Hand] = SDL_CreateSystemCursor(SDL_SYSTEM_CURSOR_HAND);
 
 #ifdef _WIN32
     SDL_SysWMinfo wmInfo;
@@ -225,66 +230,94 @@ static bool ImGui_ImplSdlGL3_Init(SDL_Window* window)
     return true;
 }
 
-static void ImGui_ImplSdlGL3_NewFrame(SDL_Window* window)
+static void ImGui_ImplSDL2_UpdateMousePosAndButtons()
 {
     ImGuiIO& io = ImGui::GetIO();
 
-    // Setup display size (every frame to accommodate for window resizing)
-    int w, h;
-    int display_w, display_h;
-    SDL_GetWindowSize(window, &w, &h);
-    SDL_GL_GetDrawableSize(window, &display_w, &display_h);
-    io.DisplaySize = ImVec2((float)w, (float)h);
-    io.DisplayFramebufferScale = ImVec2(w > 0 ? ((float)display_w / w) : 0, h > 0 ? ((float)display_h / h) : 0);
-
-    // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
-    /*static Uint64 frequency = SDL_GetPerformanceFrequency();
-    Uint64 current_time = SDL_GetPerformanceCounter();
-    io.DeltaTime = g_Time > 0 ? (float)((double)(current_time - g_Time) / frequency) : (float)(1.0f / 60.0f);
-    g_Time = current_time;*/
+    // Set OS mouse position if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
+    if (io.WantSetMousePos)
+        SDL_WarpMouseInWindow(__window, (int)io.MousePos.x, (int)io.MousePos.y);
+    else
+        io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
 
-    // Setup mouse inputs (we already got mouse wheel, keyboard keys & characters from our event handler)
     int mx, my;
     Uint32 mouse_buttons = SDL_GetMouseState(&mx, &my);
-    io.MousePos = ImVec2(-FLT_MAX, -FLT_MAX);
     io.MouseDown[0] = g_MousePressed[0] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_LEFT)) != 0;  // If a mouse press event came, always pass it as "mouse held this frame", so we don't miss click-release events that are shorter than 1 frame.
     io.MouseDown[1] = g_MousePressed[1] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_RIGHT)) != 0;
     io.MouseDown[2] = g_MousePressed[2] || (mouse_buttons & SDL_BUTTON(SDL_BUTTON_MIDDLE)) != 0;
     g_MousePressed[0] = g_MousePressed[1] = g_MousePressed[2] = false;
 
-    // We need to use SDL_CaptureMouse() to easily retrieve mouse coordinates outside of the client area. This is only supported from SDL 2.0.4 (released Jan 2016)
-#if (SDL_MAJOR_VERSION >= 2) && (SDL_MINOR_VERSION >= 0) && (SDL_PATCHLEVEL >= 4)
-    if ((SDL_GetWindowFlags(window) & (SDL_WINDOW_MOUSE_FOCUS | SDL_WINDOW_MOUSE_CAPTURE)) != 0)
+#if SDL_HAS_CAPTURE_MOUSE && !defined(__EMSCRIPTEN__)
+    SDL_Window* focused_window = SDL_GetKeyboardFocus();
+    if (g_Window == focused_window)
+    {
+        // SDL_GetMouseState() gives mouse position seemingly based on the last window entered/focused(?)
+        // The creation of a new windows at runtime and SDL_CaptureMouse both seems to severely mess up with that, so we retrieve that position globally.
+        int wx, wy;
+        SDL_GetWindowPosition(focused_window, &wx, &wy);
+        SDL_GetGlobalMouseState(&mx, &my);
+        mx -= wx;
+        my -= wy;
         io.MousePos = ImVec2((float)mx, (float)my);
-    bool any_mouse_button_down = false;
-    for (int n = 0; n < IM_ARRAYSIZE(io.MouseDown); n++)
-        any_mouse_button_down |= io.MouseDown[n];
-    if (any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) == 0)
-        SDL_CaptureMouse(SDL_TRUE);
-    if (!any_mouse_button_down && (SDL_GetWindowFlags(window) & SDL_WINDOW_MOUSE_CAPTURE) != 0)
-        SDL_CaptureMouse(SDL_FALSE);
+    }
+
+    // SDL_CaptureMouse() let the OS know e.g. that our imgui drag outside the SDL window boundaries shouldn't e.g. trigger the OS window resize cursor.
+    // The function is only supported from SDL 2.0.4 (released Jan 2016)
+    bool any_mouse_button_down = ImGui::IsAnyMouseDown();
+    SDL_CaptureMouse(any_mouse_button_down ? SDL_TRUE : SDL_FALSE);
 #else
-    if ((SDL_GetWindowFlags(window) & SDL_WINDOW_INPUT_FOCUS) != 0)
+    if (SDL_GetWindowFlags(__window) & SDL_WINDOW_INPUT_FOCUS)
         io.MousePos = ImVec2((float)mx, (float)my);
 #endif
+}
+
+static void ImGui_ImplSDL2_UpdateMouseCursor()
+{
+    ImGuiIO& io = ImGui::GetIO();
+    if (io.ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)
+        return;
 
-    // Update OS/hardware mouse cursor if imgui isn't drawing a software cursor
-    ImGuiMouseCursor cursor = ImGui::GetMouseCursor();
-    if (io.MouseDrawCursor || cursor == ImGuiMouseCursor_None)
+    ImGuiMouseCursor imgui_cursor = ImGui::GetMouseCursor();
+    if (io.MouseDrawCursor || imgui_cursor == ImGuiMouseCursor_None)
     {
-        SDL_ShowCursor(0);
+        // Hide OS mouse cursor if imgui is drawing it or if it wants no cursor
+        SDL_ShowCursor(SDL_FALSE);
     }
     else
     {
-        SDL_SetCursor(g_MouseCursors[cursor] ? g_MouseCursors[cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
-        SDL_ShowCursor(1);
+        // Show OS mouse cursor
+        SDL_SetCursor(g_MouseCursors[imgui_cursor] ? g_MouseCursors[imgui_cursor] : g_MouseCursors[ImGuiMouseCursor_Arrow]);
+        SDL_ShowCursor(SDL_TRUE);
     }
+}
 
-    // fix issue when debugging (mouse was still captured by sdl and we cannot use it in debugger)
-    SDL_CaptureMouse(SDL_FALSE);
+static void ImGui_ImplSdlGL3_NewFrame(SDL_Window* window)
+{
+    ImGuiIO& io = ImGui::GetIO();
+    IM_ASSERT(io.Fonts->IsBuilt());     // Font atlas needs to be built, call renderer _NewFrame() function e.g. ImGui_ImplOpenGL3_NewFrame()
+
+    // Setup display size (every frame to accommodate for window resizing)
+    int w, h;
+    int display_w, display_h;
+    SDL_GetWindowSize(window, &w, &h);
+    SDL_GL_GetDrawableSize(window, &display_w, &display_h);
+    io.DisplaySize = ImVec2((float)w, (float)h);
+    io.DisplayFramebufferScale = ImVec2(w > 0 ? ((float)display_w / w) : 0, h > 0 ? ((float)display_h / h) : 0);
+
+    // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
+    static Uint64 frequency = SDL_GetPerformanceFrequency();
+    Uint64 current_time = SDL_GetPerformanceCounter();
+    io.DeltaTime = g_Time > 0 ? (float)((double)(current_time - g_Time) / frequency) : (float)(1.0f / 60.0f);
+    g_Time = current_time;
+
+    ImGui_ImplSDL2_UpdateMousePosAndButtons();
+    ImGui_ImplSDL2_UpdateMouseCursor();
 
     // Start the frame. This call will update the io.WantCaptureMouse, io.WantCaptureKeyboard flag that you can use to dispatch inputs (or not) to your application.
     ImGui::NewFrame();
+
+    // fix issue when debugging (mouse was still captured by sdl and we cannot use it in debugger)
+    //SDL_CaptureMouse(SDL_FALSE);
 }
 
 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
