macOS: Trigger expose on screen param change for windows that opt into EDR

When the active EDR headroom of a display is updated, due to its brightness
setting changing e.g., the system sends us a screen parameter change.

We don't have a specific signal for these kinds of changes on a screen
or window level, so for now we do the next best thing, which is to trigger
an expose even for any relevant windows that might need to re-render to
reflect the updated EDR headroom.

Change-Id: I1edd8ff6b9714b558a9ae92d45aaee56a838af7c
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@qt.io>

src/plugins/platforms/cocoa/qcocoascreen.h

@@ -66,6 +66,8 @@ private:
     static void updateScreens();
     static void cleanupScreens();
 
+    static void updateHdrWindows();
+
     static QMacNotificationObserver s_screenParameterObserver;
     static CGDisplayReconfigurationCallBack s_displayReconfigurationCallBack;
 

src/plugins/platforms/cocoa/qcocoascreen.mm

@@ -64,6 +64,10 @@ void QCocoaScreen::initializeScreens()
         NSApplicationDidChangeScreenParametersNotification, [&]() {
             qCDebug(lcQpaScreen) << "Received screen parameter change notification";
             updateScreens();
+
+            // The notification is posted when the EDR headroom of a display changes,
+            // which might affect the rendering of windows that opt in to EDR.
+            updateHdrWindows();
         });
 }
 
@@ -500,6 +504,27 @@ void QCocoaScreen::maybeStopDisplayLink()
     CVDisplayLinkStop(m_displayLink);
 }
 
+
+// -----------------------------------------------------------
+
+void QCocoaScreen::updateHdrWindows()
+{
+    if (@available(macOS 14, *)) {
+        for (auto *window : QGuiApplication::allWindows()) {
+            auto *platformWindow = static_cast<QCocoaWindow*>(window->handle());
+            if (!platformWindow)
+                continue;
+
+            NSView *view = platformWindow->view();
+
+            if (!view.layer.wantsExtendedDynamicRangeContent)
+                continue;
+
+            [view setNeedsDisplay:YES];
+        }
+    }
+}
+
 // -----------------------------------------------------------
 
 QPlatformScreen::SubpixelAntialiasingType QCocoaScreen::subpixelAntialiasingTypeHint() const