macOS: Invalidate backingstore and trigger expose on color space changes

Fixes: QTBUG-77749
Change-Id: I677a71152e4a218c08d8863d4f886d158a79e809
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

1 files changed, 22 insertions, 0 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoabackingstore.mm b/src/plugins/platforms/cocoa/qcocoabackingstore.mm
index 02f56b4516..5d5e406d8a 100644
--- a/src/plugins/platforms/cocoa/qcocoabackingstore.mm
+++ b/src/plugins/platforms/cocoa/qcocoabackingstore.mm
@@ -51,6 +51,17 @@ QT_BEGIN_NAMESPACE
 QCocoaBackingStore::QCocoaBackingStore(QWindow *window)
     : QRasterBackingStore(window)
 {
+    // Ideally this would be plumbed from the platform layer to QtGui, and
+    // the QBackingStore would be recreated, but we don't have that code yet,
+    // so at least make sure we invalidate our backingstore when the backing
+    // properties (color space e.g.) are changed.
+    NSView *view = static_cast<QCocoaWindow *>(window->handle())->view();
+    m_backingPropertiesObserver = QMacNotificationObserver(view.window,
+        NSWindowDidChangeBackingPropertiesNotification, [this]() {
+            qCDebug(lcQpaBackingStore) << "Backing properties for"
+                << this->window() << "did change";
+            backingPropertiesChanged();
+        });
 }
 
 QCFType<CGColorSpaceRef> QCocoaBackingStore::colorSpace() const
@@ -299,6 +310,11 @@ void QNSWindowBackingStore::redrawRoundedBottomCorners(CGRect windowRect) const
 #endif
 }
 
+void QNSWindowBackingStore::backingPropertiesChanged()
+{
+    m_image = QImage();
+}
+
 // ----------------------------------------------------------------------------
 
 // https://stackoverflow.com/a/52722575/2761869
@@ -574,6 +590,12 @@ QImage QCALayerBackingStore::toImage() const
     return imageCopy;
 }
 
+void QCALayerBackingStore::backingPropertiesChanged()
+{
+    m_buffers.clear();
+    m_buffers.resize(1);
+}
+
 QPlatformGraphicsBuffer *QCALayerBackingStore::graphicsBuffer() const
 {
     return m_buffers.back().get();