Viewport, Platform: Added ImGuiViewportFlags_TopMost that will be used by tooltip window (without it, clicking and holding the window emitting the tooltip would move the tooltip to the back) + GLFW backend fixes for non-win32 platforms. (#1542)

examples/imgui_impl_glfw.cpp

@@ -41,8 +41,10 @@
 #define GLFW_HAS_GLFW_HOVERED   0
 #endif
 #define GLFW_HAS_WINDOW_ALPHA   (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3300) // 3.3+
+#define GLFW_HAS_WINDOW_TOPMOST (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3200) // 3.2+
 #define GLFW_HAS_VULKAN         (GLFW_VERSION_MAJOR * 1000 + GLFW_VERSION_MINOR * 100 >= 3200) // 3.2+
 
+
 // Data
 enum GlfwClientApi
 {
@@ -357,6 +359,9 @@ static void ImGui_ImplGlfw_CreateWindow(ImGuiViewport* viewport)
     glfwWindowHint(GLFW_VISIBLE, false);
     glfwWindowHint(GLFW_FOCUSED, false);
     glfwWindowHint(GLFW_DECORATED, (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? false : true);
+#if GLFW_HAS_WINDOW_TOPMOST
+    glfwWindowHint(GLFW_FLOATING, (viewport->Flags & imGuiViewportFlags_TopMost) ? true : false);
+#endif
     GLFWwindow* share_window = (g_ClientApi == GlfwClientApi_OpenGL) ? g_Window : NULL;
     data->Window = glfwCreateWindow((int)viewport->Size.x, (int)viewport->Size.y, "No Title Yet", NULL, share_window);
     data->WindowOwned = true;
@@ -373,7 +378,7 @@ static void ImGui_ImplGlfw_DestroyWindow(ImGuiViewport* viewport)
     {
         if (data->WindowOwned)
         {
-#if GLFW_HAS_GLFW_HOVERED
+#if GLFW_HAS_GLFW_HOVERED && defined(_WIN32)
             HWND hwnd = glfwGetWin32Window(data->Window);
             ::RemovePropA(hwnd, "IMGUI_VIEWPORT");
 #endif
@@ -419,7 +424,7 @@ static void ImGui_ImplGlfw_ShowWindow(ImGuiViewport* viewport)
     }
 
     // GLFW hack: install hook for WM_NCHITTEST message handler
-#if GLFW_HAS_GLFW_HOVERED
+#if GLFW_HAS_GLFW_HOVERED && defined(_WIN32)
     ::SetPropA(hwnd, "IMGUI_VIEWPORT", viewport);
     if (g_GlfwWndProc == NULL)
         g_GlfwWndProc = (WNDPROC)::GetWindowLongPtr(hwnd, GWLP_WNDPROC);

examples/imgui_impl_sdl2.cpp

@@ -34,6 +34,7 @@
 #include <SDL_syswm.h>
 #define SDL_HAS_CAPTURE_MOUSE   SDL_VERSION_ATLEAST(2,0,4)
 #define SDL_HAS_WINDOW_OPACITY  SDL_VERSION_ATLEAST(2,0,5)
+#define SDL_HAS_ALWAYS_ON_TOP   SDL_VERSION_ATLEAST(2,0,5)
 #define SDL_HAS_VULKAN          SDL_VERSION_ATLEAST(2,0,6)
 #if !SDL_HAS_VULKAN
 static const Uint32 SDL_WINDOW_VULKAN = 0x10000000;
@@ -317,6 +318,9 @@ static void ImGui_ImplSDL2_CreateWindow(ImGuiViewport* viewport)
     sdl_flags |= SDL_WINDOW_HIDDEN;
     sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? SDL_WINDOW_BORDERLESS : 0;
     sdl_flags |= (viewport->Flags & ImGuiViewportFlags_NoDecoration) ? 0 : SDL_WINDOW_RESIZABLE;
+#if SDL_HAS_ALWAYS_ON_TOP
+    sdl_flags |= (viewport->Flags & imGuiViewportFlags_TopMost) ? SDL_WINDOW_ALWAYS_ON_TOP : 0;
+#endif
     data->Window = SDL_CreateWindow("No Title Yet", (int)viewport->PlatformPos.x, (int)viewport->PlatformPos.y, (int)viewport->Size.x, (int)viewport->Size.y, sdl_flags);
     data->WindowOwned = true; 
     if (use_opengl)

examples/imgui_impl_win32.cpp

@@ -389,6 +389,8 @@ static void ImGui_ImplWin32_CreateWindow(ImGuiViewport* viewport)
         data->DwStyle = WS_OVERLAPPEDWINDOW;
         data->DwExStyle = no_task_bar_icon ? WS_EX_TOOLWINDOW : WS_EX_APPWINDOW;
     }
+    if (viewport->Flags & imGuiViewportFlags_TopMost)
+        data->DwExStyle |= WS_EX_TOPMOST;
 
     // Create window
     RECT rect = { (LONG)viewport->PlatformPos.x, (LONG)viewport->PlatformPos.y, (LONG)(viewport->PlatformPos.x + viewport->Size.x), (LONG)(viewport->PlatformPos.y + viewport->Size.y) };

imgui.cpp

@@ -434,7 +434,7 @@
      perfectly fine, as the bool toggle fairly rarely. If you have on a touch device, you might find use for an early call to NewFrameUpdateHoveredWindowAndCaptureFlags().
     Note: Text input widget releases focus on "Return KeyDown", so the subsequent "Return KeyUp" event that your application receive will typically 
      have 'io.WantCaptureKeyboard=false'. Depending on your application logic it may or not be inconvenient. You might want to track which key-downs
-     were targetted for Dear ImGui, e.g. with an array of bool, and filter out the corresponding key-ups.)
+     were targeted for Dear ImGui, e.g. with an array of bool, and filter out the corresponding key-ups.)
 
  Q: How can I display an image? What is ImTextureID, how does it works?
  A: ImTextureID is a void* used to pass renderer-agnostic texture references around until it hits your render function.
@@ -766,7 +766,7 @@ const ImGuiID           IMGUI_VIEWPORT_DEFAULT_ID = 0x11111111; // Using an arbi
 static inline ImRect    GetViewportRect(ImGuiWindow* window) { return window->Viewport->GetRect(); }
 static inline ImVec2    ConvertViewportPosToPlatformPos(const ImVec2& imgui_pos, ImGuiViewport* viewport)    { return imgui_pos - viewport->Pos + viewport->PlatformPos; }
 static inline ImVec2    ConvertPlatformPosToViewportPos(const ImVec2& platform_pos, ImGuiViewport* viewport) { return platform_pos - viewport->PlatformPos + viewport->Pos; }
-static ImGuiViewportP*  Viewport(ImGuiWindow* window, ImGuiID id, ImGuiViewportFlags flags, const ImVec2& platform_pos, const ImVec2& size);
+static ImGuiViewportP*  AddViewport(ImGuiWindow* window, ImGuiID id, ImGuiViewportFlags flags, const ImVec2& platform_pos, const ImVec2& size);
 static void             UpdateViewports();
 static void             UpdateSelectWindowViewport(ImGuiWindow* window);
 static void             SetCurrentViewport(ImGuiViewportP* viewport);
@@ -3330,7 +3330,7 @@ static void ImGui::NewFrameUpdateMovingWindowDropViewport(ImGuiWindow* window)
     {
         // Create/persist new viewport
         ImVec2 platform_pos = ConvertViewportPosToPlatformPos(window->Pos, window->Viewport);
-        ImGuiViewportP* viewport = Viewport(window, window->ID, 0, platform_pos, window->Size);
+        ImGuiViewportP* viewport = AddViewport(window, window->ID, 0, platform_pos, window->Size);
         SetWindowViewportTranslateToPreservePlatformPos(window, window->Viewport, viewport);
     }
 }
@@ -3475,7 +3475,7 @@ static void ImGui::UpdateViewports()
     ImVec2 main_viewport_platform_pos = ImVec2(0.0f, 0.0f);
     if ((g.IO.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
         main_viewport_platform_pos = g.PlatformIO.Platform_GetWindowPos(main_viewport);
-    Viewport(NULL, IMGUI_VIEWPORT_DEFAULT_ID, ImGuiViewportFlags_CanHostOtherWindows, main_viewport_platform_pos, g.IO.DisplaySize);
+    AddViewport(NULL, IMGUI_VIEWPORT_DEFAULT_ID, ImGuiViewportFlags_CanHostOtherWindows, main_viewport_platform_pos, g.IO.DisplaySize);
 
     if (!(g.IO.ConfigFlags & ImGuiConfigFlags_ViewportsEnable))
     {
@@ -3560,10 +3560,16 @@ void ImGui::UpdatePlatformWindows()
             continue;
         }
 
-        // Update ImGuiViewportFlags_NoTaskBarIcon flag
+        // New windows that appears directly in a new viewport won't always have a size on their frame
+        if (viewport->Size.x <= 0 || viewport->Size.y <= 0)
+            continue;
+
+        // Update viewport flags
         if (viewport->Window != NULL)
         {
+            bool topmost = (viewport->Window->Flags & ImGuiWindowFlags_Tooltip) != 0;
             bool no_task_bar_icon = (g.IO.ConfigFlags & ImGuiConfigFlags_ViewportsNoTaskBarIcons) != 0 || (viewport->Window->Flags & (ImGuiWindowFlags_ChildMenu | ImGuiWindowFlags_Tooltip | ImGuiWindowFlags_Popup)) != 0;
+            viewport->Flags = topmost ? (viewport->Flags | imGuiViewportFlags_TopMost) : (viewport->Flags & ~imGuiViewportFlags_TopMost);
             viewport->Flags = no_task_bar_icon ? (viewport->Flags | ImGuiViewportFlags_NoTaskBarIcon) : (viewport->Flags & ~ImGuiViewportFlags_NoTaskBarIcon);
         }
 
@@ -4506,7 +4512,7 @@ void ImGui::EndFrame()
     for (int i = 0; i < g.Viewports.Size; i++)
     {
         ImGuiViewportP* viewport = g.Viewports[i];
-        if (viewport->LastFrameActive < g.FrameCount)
+        if (viewport->LastFrameActive < g.FrameCount || viewport->Size.x <= 0.0f || viewport->Size.y <= 0.0f)
             continue;
         if (i > 0)
             IM_ASSERT(viewport->Window != NULL);
@@ -4679,7 +4685,7 @@ void ImGui::SetCurrentViewport(ImGuiViewportP* viewport)
         g.PlatformIO.Platform_OnChangedViewport(g.CurrentViewport);
 }
 
-ImGuiViewportP* ImGui::Viewport(ImGuiWindow* window, ImGuiID id, ImGuiViewportFlags flags, const ImVec2& platform_pos, const ImVec2& size)
+ImGuiViewportP* ImGui::AddViewport(ImGuiWindow* window, ImGuiID id, ImGuiViewportFlags flags, const ImVec2& platform_pos, const ImVec2& size)
 {
     ImGuiContext& g = *GImGui;
     IM_ASSERT(id != 0);
@@ -6164,7 +6170,7 @@ static void ImGui::UpdateSelectWindowViewport(ImGuiWindow* window)
         window->Viewport = FindViewportByID(window->ViewportId);
         if (window->Viewport == NULL && window->ViewportPlatformPos.x != FLT_MAX && window->ViewportPlatformPos.y != FLT_MAX)
         {
-            ImGuiViewportP* viewport = Viewport(window, window->ID, ImGuiViewportFlags_NoDecoration, window->ViewportPlatformPos, window->Size);
+            ImGuiViewportP* viewport = AddViewport(window, window->ID, ImGuiViewportFlags_NoDecoration, window->ViewportPlatformPos, window->Size);
             window->Flags |= ImGuiWindowFlags_FullViewport;
             window->Viewport = viewport;
             created_viewport = true;
@@ -6189,7 +6195,7 @@ static void ImGui::UpdateSelectWindowViewport(ImGuiWindow* window)
             // Calculate mouse position in OS/platform coordinates, create a Viewport at this position.
             ImVec2 platform_pos = ConvertViewportPosToPlatformPos(g.IO.MousePos - g.ActiveIdClickOffset, g.MousePosViewport);
             ImGuiViewportFlags viewport_flags = ImGuiViewportFlags_NoDecoration | ImGuiViewportFlags_NoFocusOnAppearing | ImGuiViewportFlags_NoInputs;
-            ImGuiViewportP* viewport = Viewport(window, window->ID, viewport_flags, platform_pos, window->Size);
+            ImGuiViewportP* viewport = AddViewport(window, window->ID, viewport_flags, platform_pos, window->Size);
             window->Flags |= ImGuiWindowFlags_FullViewport;
             window->Viewport = viewport;
             created_viewport = true;

imgui.h

@@ -1937,7 +1937,8 @@ enum ImGuiViewportFlags_
     ImGuiViewportFlags_NoFocusOnAppearing       = 1 << 1,   // Platform Window: Don't take focus when created.
     ImGuiViewportFlags_NoInputs                 = 1 << 2,   // Platform Window: Make mouse pass through so we can drag this window while peaking behind it.
     ImGuiViewportFlags_NoTaskBarIcon            = 1 << 3,   // Platform Window: Disable platform task bar icon (for popups, menus, or all windows if ImGuiConfigFlags_ViewportsNoTaskBarIcons if set)
-    ImGuiViewportFlags_NoRendererClear          = 1 << 4    // Platform Window: Renderer doesn't need to clear the framebuffer ahead.
+    ImGuiViewportFlags_NoRendererClear          = 1 << 4,   // Platform Window: Renderer doesn't need to clear the framebuffer ahead.
+    imGuiViewportFlags_TopMost                  = 1 << 5    // Platform Window: Display on top (for tooltips only)
 };
 
 // The viewports created and managed by imgui. The role of the platform back-end is to create the platform/OS windows corresponding to each viewport.