Examples: GLFW: rework examples main loop to handle minimization with…

…out burning CPU or GPU by running unthrottled code. (#7844)

Backends: GLFW: added ImGui_ImplGlfw_Sleep() helper.

backends/imgui_impl_glfw.cpp

@@ -20,6 +20,7 @@
 
 // CHANGELOG
 // (minor and older changes stripped away, please see git history for details)
+//  2024-07-31: Added ImGui_ImplGlfw_Sleep() helper function for usage by our examples app, since GLFW doesn't provide one.
 //  2024-07-08: *BREAKING* Renamed ImGui_ImplGlfw_InstallEmscriptenCanvasResizeCallback to ImGui_ImplGlfw_InstallEmscriptenCallbacks(), added GLFWWindow* parameter.
 //  2024-07-08: Emscripten: Added support for GLFW3 contrib port (GLFW 3.4.0 features + bug fixes): to enable, replace -sUSE_GLFW=3 with --use-port=contrib.glfw3 (requires emscripten 3.1.59+) (https://github.com/pongasoft/emscripten-glfw)
 //  2024-07-02: Emscripten: Added io.PlatformOpenInShellFn() handler for Emscripten versions.
@@ -99,6 +100,9 @@
 #endif
 #include <GLFW/glfw3native.h>   // for glfwGetCocoaWindow()
 #endif
+#ifndef _WIN32
+#include <unistd.h>             // for usleep()
+#endif
 
 #ifdef __EMSCRIPTEN__
 #include <emscripten.h>
@@ -825,6 +829,16 @@ void ImGui_ImplGlfw_NewFrame()
     ImGui_ImplGlfw_UpdateGamepads();
 }
 
+// GLFW doesn't provide a portable sleep function
+void ImGui_ImplGlfw_Sleep(int milliseconds)
+{
+#ifdef _WIN32
+    ::Sleep(milliseconds);
+#else
+    usleep(milliseconds * 1000);
+#endif
+}
+
 #ifdef EMSCRIPTEN_USE_EMBEDDED_GLFW3
 static EM_BOOL ImGui_ImplGlfw_OnCanvasSizeChange(int event_type, const EmscriptenUiEvent* event, void* user_data)
 {

backends/imgui_impl_glfw.h

@@ -57,4 +57,7 @@ IMGUI_IMPL_API void     ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key,
 IMGUI_IMPL_API void     ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c);
 IMGUI_IMPL_API void     ImGui_ImplGlfw_MonitorCallback(GLFWmonitor* monitor, int event);
 
+// GLFW helpers
+IMGUI_IMPL_API void     ImGui_ImplGlfw_Sleep(int milliseconds);
+
 #endif // #ifndef IMGUI_DISABLE

docs/CHANGELOG.txt

@@ -43,8 +43,10 @@ Breaking changes:
 
 Other changes:
 
-- Examples: SDL2 (all), SDL3 (all), Win32+OpenGL3: rework examples main loop to handle
-  minimization without burning CPU or GPU by running unthrottled code. (#7844)
+- Backends: GLFW: added ImGui_ImplGlfw_Sleep() helper function because GLFW does not
+  provide a way to do a portable sleep. (#7844)
+- Examples: GLFW (all), SDL2 (all), SDL3 (all), Win32+OpenGL3: rework examples main loop
+  to handle minimization without burning CPU or GPU by running unthrottled code. (#7844)
 
 
 

examples/example_glfw_opengl2/main.cpp

@@ -91,6 +91,11 @@ int main(int, char**)
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
         glfwPollEvents();
+        if (glfwGetWindowAttrib(window, GLFW_ICONIFIED) != 0)
+        {
+            ImGui_ImplGlfw_Sleep(10);
+            continue;
+        }
 
         // Start the Dear ImGui frame
         ImGui_ImplOpenGL2_NewFrame();

examples/example_glfw_opengl3/main.cpp

@@ -127,6 +127,11 @@ int main(int, char**)
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application, or clear/overwrite your copy of the keyboard data.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
         glfwPollEvents();
+        if (glfwGetWindowAttrib(window, GLFW_ICONIFIED) != 0)
+        {
+            ImGui_ImplGlfw_Sleep(10);
+            continue;
+        }
 
         // Start the Dear ImGui frame
         ImGui_ImplOpenGL3_NewFrame();

examples/example_glfw_vulkan/main.cpp

@@ -494,6 +494,11 @@ int main(int, char**)
             g_MainWindowData.FrameIndex = 0;
             g_SwapChainRebuild = false;
         }
+        if (glfwGetWindowAttrib(window, GLFW_ICONIFIED) != 0)
+        {
+            ImGui_ImplGlfw_Sleep(10);
+            continue;
+        }
 
         // Start the Dear ImGui frame
         ImGui_ImplVulkan_NewFrame();