Examples: GLFW, SDL: Preserve DisplayFramebufferScale when main viewport is minimized. (This is particularly useful for the viewport branch because we are not supporting per-viewport frame-buffer scale. It fixes windows not refreshing when main viewport is minimized.) (#2416)

docs/CHANGELOG.txt

@@ -89,6 +89,9 @@ Other Changes:
 - Misc: Asserting in NewFrame() if style.WindowMinSize is zero or smaller than (1.0f,1.0f).
 - Demo: Using GetBackgroundDrawList() and GetForegroundDrawList() in "Custom Rendering" demo.
 - Demo: InputText: Demonstrating use of ImGuiInputTextFlags_CallbackResize. (#2006, #1443, #1008).
+- Examples: GLFW, SDL: Preserve DisplayFramebufferScale when main viewport is minimized.
+  (This is particularly useful for the viewport branch because we are not supporting per-viewport
+  frame-buffer scale. It fixes windows not refreshing when main viewport is minimized.) (#2416)
 - Examples: OpenGL: Fix to be able to run on ES 2.0 / WebGL 1.0. [@rmitton, @gabrielcuvillier]
 - Examples: OpenGL: Fix for OSX not supporting OpenGL 4.5, we don't try to read GL_CLIP_ORIGIN
   even if the OpenGL headers/loader happens to define the value. (#2366, #2186)

examples/imgui_impl_glfw.cpp

@@ -15,6 +15,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2019-03-12: Misc: Preserve DisplayFramebufferScale when main window is minimized.
 //  2018-11-30: Misc: Setting up io.BackendPlatformName so it can be displayed in the About Window.
 //  2018-11-07: Inputs: When installing our GLFW callbacks, we save user's previously installed ones - if any - and chain call them.
 //  2018-08-01: Inputs: Workaround for Emscripten which doesn't seem to handle focus related calls.
@@ -313,7 +314,8 @@ void ImGui_ImplGlfw_NewFrame()
     glfwGetWindowSize(g_Window, &w, &h);
     glfwGetFramebufferSize(g_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);
+    if (w > 0 && h > 0)
+        io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);
 
     // Setup time step
     double current_time = glfwGetTime();

examples/imgui_impl_sdl.cpp

@@ -17,6 +17,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2019-03-12: Misc: Preserve DisplayFramebufferScale when main window is minimized.
 //  2018-12-21: Inputs: Workaround for Android/iOS which don't seem to handle focus related calls.
 //  2018-11-30: Misc: Setting up io.BackendPlatformName so it can be displayed in the About Window.
 //  2018-11-14: Changed the signature of ImGui_ImplSDL2_ProcessEvent() to take a 'const SDL_Event*'.
@@ -279,7 +280,8 @@ void ImGui_ImplSDL2_NewFrame(SDL_Window* window)
     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);
+    if (w > 0 && h > 0)
+        io.DisplayFramebufferScale = ImVec2((float)display_w / w, (float)display_h / h);
 
     // Setup time step (we don't use SDL_GetTicks() because it is using millisecond resolution)
     static Uint64 frequency = SDL_GetPerformanceFrequency();