Cocoa: Update window state when maximizing from the title bar

There's no NSWindow notification we can listen to, but we can override
behavior from its delegate.

Change-Id: I61cebf4119f83c770fe4e7f45ff0d4e8bf9d0df9
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>

src/plugins/platforms/cocoa/qnsview.h

@@ -82,6 +82,7 @@ QT_END_NAMESPACE
 - (void)drawRect:(NSRect)dirtyRect;
 - (void)updateGeometry;
 - (void)windowNotification : (NSNotification *) windowNotification;
+- (void)notifyWindowWillZoom:(BOOL)willZoom;
 - (void)viewDidHide;
 - (void)viewDidUnhide;
 

src/plugins/platforms/cocoa/qnsview.mm

@@ -306,6 +306,16 @@ static QTouchDevice *touchDevice = 0;
     }
 }
 
+- (void)notifyWindowWillZoom:(BOOL)willZoom
+{
+    Qt::WindowState newState = willZoom ? Qt::WindowMaximized : Qt::WindowNoState;
+    QWindowSystemInterface::handleWindowStateChanged(m_window, newState);
+    // We want to read the window state back from the window,
+    // but the event we just sent may be asynchronous.
+    QWindowSystemInterface::flushWindowSystemEvents();
+    m_platformWindow->setSynchedWindowStateFromWindow();
+}
+
 - (void)viewDidHide
 {
     m_platformWindow->obscureWindow();

src/plugins/platforms/cocoa/qnswindowdelegate.h

@@ -57,6 +57,7 @@
 - (void)windowDidMove:(NSNotification *)notification;
 - (void)windowWillMove:(NSNotification *)notification;
 - (BOOL)windowShouldClose:(NSNotification *)notification;
+- (BOOL)windowShouldZoom:(NSWindow *)window toFrame:(NSRect)newFrame;
 
 @end
 

src/plugins/platforms/cocoa/qnswindowdelegate.mm

@@ -90,4 +90,12 @@
     return YES;
 }
 
+- (BOOL)windowShouldZoom:(NSWindow *)window toFrame:(NSRect)newFrame
+{
+    Q_UNUSED(newFrame);
+    if (m_cocoaWindow && m_cocoaWindow->m_qtView)
+        [m_cocoaWindow->m_qtView notifyWindowWillZoom:![window isZoomed]];
+    return YES;
+}
+
 @end