macOS: Restore fallback sizes when setting application or window icons

We removed this logic in 059c3ae66a under the assumption that the icon
would always provide a set of sizes, but for SVG icons this is not
the case.

Change-Id: Ib3cc5740bca32cf4068a71baf99b52fa536da2ca
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

1 files changed, 6 insertions, 3 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 2cbe1b8684..069e9ce845 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -904,10 +904,13 @@ void QCocoaWindow::setWindowIcon(const QIcon &icon)
 
     QMacAutoReleasePool pool;
 
-    if (icon.isNull())
+    if (icon.isNull()) {
         iconButton.image = [NSWorkspace.sharedWorkspace iconForFile:m_view.window.representedFilename];
-    else
-        iconButton.image = [NSImage imageFromQIcon:icon];
+    } else {
+        // Fall back to a size that looks good on the highest resolution screen available
+        auto fallbackSize = iconButton.frame.size.height * qGuiApp->devicePixelRatio();
+        iconButton.image = [NSImage imageFromQIcon:icon withSize:fallbackSize];
+    }
 }
 
 void QCocoaWindow::setAlertState(bool enabled)