Removed IMGUI_ONCE_UPON_A_FRAME in favor of ImGuiOnceUponAFrame which is supported by all compilers

imgui.cpp

@@ -142,7 +142,7 @@
       e.g. "##Foobar" display an empty label and uses "##Foobar" as ID
    - read articles about the imgui principles (see web links) to understand the requirement and use of ID.
 
- - tip: the construct 'if (IMGUI_ONCE_UPON_A_FRAME)' will evaluate to true only once a frame, you can use it to add custom UI in the middle of a deep nested inner loop in your code.
+ - tip: the construct 'static ImGuiOnceUponAFrame once; if (once)' will evaluate to 'true' only once a frame, you can use it to quickly add custom UI in the middle of a deep nested inner loop in your code.
  - tip: you can call Render() multiple times (e.g for VR renders), up to you to communicate the extra state to your RenderDrawListFn function.
  - tip: you can create widgets without a Begin()/End() block, they will go in an implicit window called "Debug"
  - tip: read the ShowTestWindow() code for more example of how to use ImGui!
@@ -6674,6 +6674,10 @@ void ImGui::ShowTestWindow(bool* open)
             ImGui::EndTooltip();
         }
 
+		//static ImGuiOnceUponAFrame oaf;
+		//if (oaf) ImGui::Text("This will be displayed.");
+		//if (oaf) ImGui::Text("This won't be displayed!");
+
         ImGui::Separator();
         ImGui::Text("^ Horizontal separator");
 

imgui.h

@@ -123,7 +123,7 @@ public:
 #endif // #ifndef ImVector
 
 // Helpers at bottom of the file:
-// - if (IMGUI_ONCE_UPON_A_FRAME)       // Execute a block of code once per frame only
+// - struct ImGuiOnceUponAFrame         // Execute a block of code once per frame only (convenient for creating UI within deep-nested code that runs multiple times)
 // - struct ImGuiTextFilter             // Parse and apply text filters. In format "aaaaa[,bbbb][,ccccc]"
 // - struct ImGuiTextBuffer             // Text buffer for logging/accumulating text
 // - struct ImGuiStorage                // Custom key value storage (if you need to alter open/close states manually)
@@ -529,15 +529,15 @@ struct ImGuiIO
 //-----------------------------------------------------------------------------
 
 // Helper: execute a block of code once a frame only
-// Usage: if (IMGUI_ONCE_UPON_A_FRAME) {/*do something once a frame*/)
+// Convenient if you want to quickly create an UI within deep-nested code that runs multiple times every frame.
-#define IMGUI_ONCE_UPON_A_FRAME         static ImGuiOncePerFrame im = ImGuiOncePerFrame()
+// Usage: 
-struct ImGuiOncePerFrame
+//   static ImGuiOnceUponAFrame once;
+//   if (once) { ... }
+struct ImGuiOnceUponAFrame
 {
-    ImGuiOncePerFrame() : LastFrame(-1) {}
+    ImGuiOnceUponAFrame() { RefFrame = -1; }
-    operator bool() const { return TryIsNewFrame(); }
+    mutable int RefFrame;
-private:
+    operator bool() const {	const int current_frame = ImGui::GetFrameCount(); if (RefFrame == current_frame) return false; RefFrame = current_frame; return true; }
-    mutable int LastFrame;
-    bool        TryIsNewFrame() const   { const int current_frame = ImGui::GetFrameCount(); if (LastFrame == current_frame) return false; LastFrame = current_frame; return true; }
 };
 
 // Helper: Parse and apply text filters. In format "aaaaa[,bbbb][,ccccc]"