REVIEWED: HighDPI support on macOS (when requested by app)

Tested on two monitors with different DPI configuration, for HigDPI enabled and not, including window resizing (with framebuffer resizing if required). Verified mouse coordinates follow the requested screen size.

src/platforms/rcore_desktop_glfw.c

@@ -135,12 +135,12 @@ static void ErrorCallback(int error, const char *description);
 // Window callbacks events
 static void WindowSizeCallback(GLFWwindow *window, int width, int height);              // GLFW3 WindowSize Callback, runs when window is resized
 static void FramebufferSizeCallback(GLFWwindow *window, int width, int height);         // GLFW3 FramebufferSize Callback, runs when window is resized
+static void WindowContentScaleCallback(GLFWwindow *window, float scalex, float scaley); // GLFW3 Window Content Scale Callback, runs when window changes scale
 static void WindowPosCallback(GLFWwindow *window, int x, int y);                        // GLFW3 WindowPos Callback, runs when window is moved
 static void WindowIconifyCallback(GLFWwindow *window, int iconified);                   // GLFW3 WindowIconify Callback, runs when window is minimized/restored
 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 WindowContentScaleCallback(GLFWwindow *window, float scalex, float scaley); // GLFW3 Window Content Scale Callback, runs when window changes scale
 
 // Input callbacks events
 static void KeyCallback(GLFWwindow *window, int key, int scancode, int action, int mods); // GLFW3 Keyboard Callback, runs on key pressed
@@ -1024,8 +1024,8 @@ Vector2 GetWindowPosition(void)
 // Get window scale DPI factor for current monitor
 Vector2 GetWindowScaleDPI(void)
 {
-    Vector2 scale = { 0 };
+    Vector2 scale = { 1.0f, 1.0f };
-    glfwGetWindowContentScale(platform.handle, &scale.x, &scale.y);
+    if (FLAG_IS_SET(CORE.Window.flags, FLAG_WINDOW_HIGHDPI)) glfwGetWindowContentScale(platform.handle, &scale.x, &scale.y);
     return scale;
 }
 
@@ -1452,12 +1452,18 @@ int InitPlatform(void)
         // NOTE: This hint only has an effect on platforms where screen coordinates and 
         // pixels always map 1:1 such as Windows and X11
         // On platforms like macOS the resolution of the framebuffer is changed independently of the window size
-        glfwWindowHint(GLFW_SCALE_TO_MONITOR, GLFW_TRUE); // Scale content area based on the monitor content scale where window is placed on
+        glfwWindowHint(GLFW_SCALE_TO_MONITOR, GLFW_TRUE);
 #if defined(__APPLE__)
         glfwWindowHint(GLFW_SCALE_FRAMEBUFFER, GLFW_TRUE);
 #endif
     }
-    else glfwWindowHint(GLFW_SCALE_TO_MONITOR, GLFW_FALSE);
+    else 
+    {
+        glfwWindowHint(GLFW_SCALE_TO_MONITOR, GLFW_FALSE);
+#if defined(__APPLE__)
+        glfwWindowHint(GLFW_SCALE_FRAMEBUFFER, GLFW_FALSE);
+#endif
+    }
 
     // Mouse passthrough
     if (FLAG_IS_SET(CORE.Window.flags, FLAG_WINDOW_MOUSE_PASSTHROUGH)) glfwWindowHint(GLFW_MOUSE_PASSTHROUGH, GLFW_TRUE);
@@ -1527,9 +1533,7 @@ int InitPlatform(void)
     GLFWmonitor *monitor = NULL;
     if (CORE.Window.fullscreen)
     {
-        // According to glfwCreateWindow(), if the user does not have a choice, fullscreen applications
+        // NOTE: Fullscreen applications default to the primary monitor
-        // should default to the primary monitor
-
         monitor = glfwGetPrimaryMonitor();
         if (!monitor)
         {
@@ -1538,7 +1542,7 @@ int InitPlatform(void)
         }
 
         // Set dimensions from monitor
-        GLFWvidmode *mode = glfwGetVideoMode(monitor);
+        const GLFWvidmode *mode = glfwGetVideoMode(monitor);
 
         // Default display resolution to that of the current mode
         CORE.Window.display.width = mode->width;
@@ -1635,7 +1639,7 @@ int InitPlatform(void)
         if (monitorIndex < monitorCount)
         {
             monitor = monitors[monitorIndex];
-            GLFWvidmode *mode = glfwGetVideoMode(monitor);
+            const GLFWvidmode *mode = glfwGetVideoMode(monitor);
 
             // Default display resolution to that of the current mode
             CORE.Window.display.width = mode->width;
@@ -1846,6 +1850,7 @@ static void WindowSizeCallback(GLFWwindow *window, int width, int height)
 }
 
 // GLFW3: Framebuffer size change callback, runs when framebuffer is resized
+// WARNING: If FLAG_WINDOW_HIGHDPI is set, WindowContentScaleCallback() is called before this function
 static void FramebufferSizeCallback(GLFWwindow *window, int width, int height)
 {
     //TRACELOG(LOG_INFO, "GLFW3: Window framebuffer size callback called [%i,%i]", width, height);
@@ -1863,32 +1868,26 @@ static void FramebufferSizeCallback(GLFWwindow *window, int width, int height)
     CORE.Window.currentFbo.height = height;
     CORE.Window.resizedLastFrame = true;
 
-    if (IsWindowFullscreen()) return;
-
     // Check if render size was actually scaled for high-dpi
     if (FLAG_IS_SET(CORE.Window.flags, FLAG_WINDOW_HIGHDPI))
     {
+        // Set screen size to logical pixel size, considering content scaling
         Vector2 scaleDpi = GetWindowScaleDPI();
-        width = (int)((float)width/scaleDpi.x);
+        CORE.Window.screen.width = (int)((float)width/scaleDpi.x);
-        height = (int)((float)height/scaleDpi.y);
+        CORE.Window.screen.height = (int)((float)height/scaleDpi.y);
+    }
+    else
+    {
+        // Set screen size to render size (physical pixel size)
+        CORE.Window.screen.width = width;
+        CORE.Window.screen.height = height;
     }
-
-    // Set current screen size
-    CORE.Window.screen.width = width;
-    CORE.Window.screen.height = height;
 
     // WARNING: If using a render texture, it is not scaled to new size
 }
 
-// GLFW3: Window position callback, runs when window position changes
-static void WindowPosCallback(GLFWwindow *window, int x, int y)
-{
-    // Set current window position
-    CORE.Window.position.x = x;
-    CORE.Window.position.y = y;
-}
-
 // GLFW3: Window content scale callback, runs on monitor content scale change detected
+// WARNING: If FLAG_WINDOW_HIGHDPI is not set, this function is not called
 static void WindowContentScaleCallback(GLFWwindow *window, float scalex, float scaley)
 {
     TRACELOG(LOG_INFO, "GLFW3: Window content scale changed, scale: [%.2f,%.2f]", scalex, scaley);
@@ -1896,13 +1895,13 @@ static void WindowContentScaleCallback(GLFWwindow *window, float scalex, float s
     float fbWidth = (float)CORE.Window.screen.width*scalex;
     float fbHeight = (float)CORE.Window.screen.height*scaley;
 
-#if !defined(__APPLE__)
     // NOTE: On APPLE platforms system should manage window/input scaling and also framebuffer scaling
     // Framebuffer scaling is activated with: glfwWindowHint(GLFW_SCALE_FRAMEBUFFER, GLFW_TRUE);
     CORE.Window.screenScale = MatrixScale(scalex, scaley, 1.0f);
 
+#if !defined(__APPLE__)
     // Mouse input scaling for the new screen size
-    SetMouseScale(1.0f/scalex, 1.0f/scaley);
+    SetMouseScale((float)CORE.Window.screen.width/fbWidth, (float)CORE.Window.screen.height/fbHeight);
 #endif
 
     CORE.Window.render.width = (int)fbWidth;
@@ -1911,6 +1910,16 @@ static void WindowContentScaleCallback(GLFWwindow *window, float scalex, float s
     CORE.Window.currentFbo.height = (int)fbHeight;
 }
 
+// GLFW3: Window position callback, runs when window position changes
+static void WindowPosCallback(GLFWwindow *window, int x, int y)
+{
+    TRACELOG(LOG_INFO, "GLFW3: Window position changed");
+
+    // Set current window position
+    CORE.Window.position.x = x;
+    CORE.Window.position.y = y;
+}
+
 // GLFW3: Window iconify callback, runs when window is minimized/restored
 static void WindowIconifyCallback(GLFWwindow *window, int iconified)
 {