Examples: GLFW: rework examples main loop to handle minimization without 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