macOS: Use shared NSWindowDelegate instead of one per window

All the delegate callbacks give us the relevant NSWindow, so we don't
need one delegate per window just to be able to resolve the correct
platform window.

Change-Id: I8e44186da63bf01f029bb0b1fefcd8880f49dda6
Fixes: QTBUG-65693
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

4 files changed, 27 insertions, 25 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoawindow.mm b/src/plugins/platforms/cocoa/qcocoawindow.mm
index 1ce671941d..4dc3ea4bd6 100644
--- a/src/plugins/platforms/cocoa/qcocoawindow.mm
+++ b/src/plugins/platforms/cocoa/qcocoawindow.mm
@@ -1548,7 +1548,9 @@ QCocoaNSWindow *QCocoaWindow::createNSWindow(bool shouldBePanel)
             QWindowSystemInterface::SynchronousDelivery>(window(), targetScreen);
     }
 
-    nsWindow.delegate = [[QNSWindowDelegate alloc] initWithQCocoaWindow:this];
+    static QSharedPointer<QNSWindowDelegate> sharedDelegate([[QNSWindowDelegate alloc] init],
+        [](QNSWindowDelegate *delegate) { [delegate release]; });
+    nsWindow.delegate = sharedDelegate.get();
 
     // Prevent Cocoa from releasing the window on close. Qt
     // handles the close event asynchronously and we want to
diff --git a/src/plugins/platforms/cocoa/qnswindow.mm b/src/plugins/platforms/cocoa/qnswindow.mm
index b3cd3c1d8c..dd6ee3058a 100644
--- a/src/plugins/platforms/cocoa/qnswindow.mm
+++ b/src/plugins/platforms/cocoa/qnswindow.mm
@@ -248,7 +248,6 @@ static bool isMouseEvent(NSEvent *ev)
 - (void)dealloc
 {
     qCDebug(lcQpaWindow) << "dealloc" << self;
-    [self.delegate release];
     self.delegate = nil;
 
     qt_objcDynamicSuper();
diff --git a/src/plugins/platforms/cocoa/qnswindowdelegate.h b/src/plugins/platforms/cocoa/qnswindowdelegate.h
index e71afcbb2a..be870deb3a 100644
--- a/src/plugins/platforms/cocoa/qnswindowdelegate.h
+++ b/src/plugins/platforms/cocoa/qnswindowdelegate.h
@@ -48,9 +48,6 @@ class QCocoaWindow;
 QT_END_NAMESPACE
 
 @interface QT_MANGLE_NAMESPACE(QNSWindowDelegate) : NSObject <NSWindowDelegate>
-
-- (instancetype)initWithQCocoaWindow:(QT_PREPEND_NAMESPACE(QCocoaWindow) *)cocoaWindow;
-
 @end
 
 QT_NAMESPACE_ALIAS_OBJC_CLASS(QNSWindowDelegate);
diff --git a/src/plugins/platforms/cocoa/qnswindowdelegate.mm b/src/plugins/platforms/cocoa/qnswindowdelegate.mm
index 97309ea990..14f1ca0114 100644
--- a/src/plugins/platforms/cocoa/qnswindowdelegate.mm
+++ b/src/plugins/platforms/cocoa/qnswindowdelegate.mm
@@ -49,23 +49,17 @@
 
 static QRegExp whitespaceRegex = QRegExp(QStringLiteral("\\s*"));
 
-@implementation QNSWindowDelegate {
-    QCocoaWindow *m_cocoaWindow;
-}
-
-- (instancetype)initWithQCocoaWindow:(QCocoaWindow *)cocoaWindow
+static QCocoaWindow *toPlatformWindow(NSWindow *window)
 {
-    if ((self = [self init]))
-        m_cocoaWindow = cocoaWindow;
-    return self;
+    return qnsview_cast(window.contentView).platformWindow;
 }
 
-- (BOOL)windowShouldClose:(NSNotification *)notification
+@implementation QNSWindowDelegate
+
+- (BOOL)windowShouldClose:(NSWindow *)window
 {
-    Q_UNUSED(notification);
-    if (m_cocoaWindow) {
-        return m_cocoaWindow->windowShouldClose();
-    }
+    if (QCocoaWindow *platformWindow = toPlatformWindow(window))
+        return platformWindow->windowShouldClose();
 
     return YES;
 }
@@ -79,14 +73,16 @@ static QRegExp whitespaceRegex = QRegExp(QStringLiteral("\\s*"));
 - (NSRect)windowWillUseStandardFrame:(NSWindow *)window defaultFrame:(NSRect)proposedFrame
 {
     Q_UNUSED(proposedFrame);
-    Q_ASSERT(window == m_cocoaWindow->nativeWindow());
-    const QWindow *w = m_cocoaWindow->window();
+
+    QCocoaWindow *platformWindow = toPlatformWindow(window);
+    Q_ASSERT(platformWindow);
+    const QWindow *w = platformWindow->window();
 
     // maximumSize() refers to the client size, but AppKit expects the full frame size
     QSizeF maximumSize = w->maximumSize() + QSize(0, w->frameMargins().top());
 
     // The window should never be larger than the current screen geometry
-    const QRectF screenGeometry = m_cocoaWindow->screen()->geometry();
+    const QRectF screenGeometry = platformWindow->screen()->geometry();
     maximumSize = maximumSize.boundedTo(screenGeometry.size());
 
     // Use the current frame position for the initial maximized frame,
@@ -113,6 +109,8 @@ static QRegExp whitespaceRegex = QRegExp(QStringLiteral("\\s*"));
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 - (NSSize)windowWillResize:(NSWindow *)window toSize:(NSSize)frameSize
 {
+    Q_ASSERT(toPlatformWindow(window));
+
     qCDebug(lcQpaWindow) << window << "will resize to" << QSizeF::fromCGSize(frameSize)
         << "- disabling screen updates temporarily";
 
@@ -131,6 +129,8 @@ static QRegExp whitespaceRegex = QRegExp(QStringLiteral("\\s*"));
 - (void)windowDidResize:(NSNotification *)notification
 {
     NSWindow *window = notification.object;
+    Q_ASSERT(toPlatformWindow(window));
+
     qCDebug(lcQpaWindow) << window << "was resized - re-enabling screen updates";
     NSEnableScreenUpdates();
 }
@@ -138,23 +138,27 @@ static QRegExp whitespaceRegex = QRegExp(QStringLiteral("\\s*"));
 
 - (BOOL)window:(NSWindow *)window shouldPopUpDocumentPathMenu:(NSMenu *)menu
 {
-    Q_UNUSED(window);
     Q_UNUSED(menu);
 
+    QCocoaWindow *platformWindow = toPlatformWindow(window);
+    Q_ASSERT(platformWindow);
+
     // Only pop up document path if the filename is non-empty. We allow whitespace, to
     // allow faking a window icon by setting the file path to a single space character.
-    return !whitespaceRegex.exactMatch(m_cocoaWindow->window()->filePath());
+    return !whitespaceRegex.exactMatch(platformWindow->window()->filePath());
 }
 
 - (BOOL)window:(NSWindow *)window shouldDragDocumentWithEvent:(NSEvent *)event from:(NSPoint)dragImageLocation withPasteboard:(NSPasteboard *)pasteboard
 {
-    Q_UNUSED(window);
     Q_UNUSED(event);
     Q_UNUSED(dragImageLocation);
     Q_UNUSED(pasteboard);
 
+    QCocoaWindow *platformWindow = toPlatformWindow(window);
+    Q_ASSERT(platformWindow);
+
     // Only allow drag if the filename is non-empty. We allow whitespace, to
     // allow faking a window icon by setting the file path to a single space.
-    return !whitespaceRegex.exactMatch(m_cocoaWindow->window()->filePath());
+    return !whitespaceRegex.exactMatch(platformWindow->window()->filePath());
 }
 @end