call the render callback on window size and move.

examples/core/core_basic_window.c

@@ -27,16 +27,20 @@
 ********************************************************************************************/
 
 #include "raylib.h"
+#include <math.h>
 
 bool RunFrame(void)
 {
     if (WindowShouldClose())
         return false;
 
-    ClearBackground(RAYWHITE);
+    ClearBackground(BLACK);
 
-    DrawText("Congrats! You created your first window!", 190, 200, 20, LIGHTGRAY);
+    float offset = cosf(GetTime() * 2.0f) *60.0f;
+    DrawTextEx(GetFontDefault(), "Congrats! You created your first window!", (Vector2) { 190, 200 + offset}, 20, 2, LIGHTGRAY);
 
+    DrawFPS(10, 10);
+    DrawText(TextFormat("FrameTime %0.3f", GetFrameTime()), 10, 30, 20, GRAY);
     return true;
 }
 
@@ -50,6 +54,7 @@ int main(void)
     const int screenWidth = 800;
     const int screenHeight = 450;
 
+    SetConfigFlags(FLAG_WINDOW_RESIZABLE);
     InitWindow(screenWidth, screenHeight, "raylib [core] example - basic window");
 
     SetTargetFPS(60);               // Set our game to run at 60 frames-per-second

src/platforms/rcore_desktop_glfw.c

@@ -144,6 +144,7 @@ static void WindowIconifyCallback(GLFWwindow *window, int iconified);
 static void WindowMaximizeCallback(GLFWwindow *window, int maximized);                  // GLFW3 Window Maximize Callback, runs when window is maximized
 static void WindowFocusCallback(GLFWwindow *window, int focused);                       // GLFW3 WindowFocus Callback, runs when window get/lose focus
 static void WindowDropCallback(GLFWwindow *window, int count, const char **paths);      // GLFW3 Window Drop Callback, runs when drop files into window
+static void WindowRefreshCallback(GLFWwindow* window);                                  // GLFW3 Window Refresh Callback, runs when window content needs to be refreshed
 
 // Input callbacks events
 static void KeyCallback(GLFWwindow *window, int key, int scancode, int action, int mods); // GLFW3 Keyboard Callback, runs on key pressed
@@ -1438,17 +1439,23 @@ void WindowRefreshCallback(GLFWwindow* window)
     {
         return;
     }
+
+    CORE.Time.current = GetTime();      // Number of elapsed seconds since InitTimer()
+    CORE.Time.update = CORE.Time.current - CORE.Time.previous;
+    CORE.Time.previous = CORE.Time.current;
+
+    rlLoadIdentity();                   // Reset current matrix (modelview)
+    rlMultMatrixf(MatrixToFloat(CORE.Window.screenScale)); // Apply screen scaling
     
     CORE.Window.updateCallback();
 
     rlDrawRenderBatchActive();
+
     SwapScreenBuffer();
     CORE.Time.current = GetTime();
     CORE.Time.draw = CORE.Time.current - CORE.Time.previous;
     CORE.Time.previous = CORE.Time.current;
 
-    SwapScreenBuffer();                  // Copy back buffer to front buffer (screen)
-
     // Frame time control system
     CORE.Time.current = GetTime();
     CORE.Time.draw = CORE.Time.current - CORE.Time.previous;
@@ -1457,6 +1464,8 @@ void WindowRefreshCallback(GLFWwindow* window)
     CORE.Time.frame = CORE.Time.update + CORE.Time.draw;
 
     CORE.Time.frameCounter++;
+
+    CORE.Window.wasDirtyThisFrame = true;
 }
 
 // Initialize platform: graphics, inputs and more
@@ -2026,6 +2035,7 @@ static void WindowPosCallback(GLFWwindow *window, int x, int y)
     // Set current window position
     CORE.Window.position.x = x;
     CORE.Window.position.y = y;
+    WindowRefreshCallback(window);  // Force window refresh on position change
 }
 
 // GLFW3: Window iconify callback, runs when window is minimized/restored

src/rcore.c

@@ -319,7 +319,7 @@ typedef struct CoreData {
         unsigned int dropFileCount;         // Count dropped files strings
 
         bool(*updateCallback)(void);        // Optional user defined callback to draw a frame
-
+        bool wasDirtyThisFrame;
     } Window;
     struct {
         const char *basePath;               // Base path for data storage
@@ -743,12 +743,19 @@ static bool RunLoop = false;
 
 void ProcessSingleFrame(void)
 {
+    // if the dirty callback rendered this frame, don't double render, skip it until the next frame
+    if (CORE.Window.wasDirtyThisFrame)
+    {
+        CORE.Window.wasDirtyThisFrame = false;
+        return;
+    }
+
     BeginDrawing();
     RunLoop = CORE.Window.updateCallback();
     EndDrawing();
 
-#if defined(SUPPORT_CUSTOM_FRAME_CONTROL)
-    SwapBuffers();
+#if SUPPORT_CUSTOM_FRAME_CONTROL
+    SwapScreenBuffer();
     PollInputEvents();
 #endif
 }