macOS: Add categorized logging of event and notification forwarding

Useful for debugging issues in this area.

Change-Id: Ic343ef790e20b66371028265efe2ec1816c954bd
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>

src/plugins/platforms/cocoa/qcocoawindow.mm

@@ -79,6 +79,8 @@ static void qt_closePopups()
     }
 }
 
+Q_LOGGING_CATEGORY(lcCocoaNotifications, "qt.qpa.cocoa.notifications");
+
 static void qRegisterNotificationCallbacks()
 {
     static const QLatin1String notificationHandlerPrefix(Q_NOTIFICATION_PREFIX);
@@ -110,11 +112,24 @@ static void qRegisterNotificationCallbacks()
                 if (QNSView *qnsView = qnsview_cast(notification.object))
                     cocoaWindows += qnsView.platformWindow;
             } else {
-                qCWarning(lcQpaCocoaWindow) << "Unhandled notifcation"
+                qCWarning(lcCocoaNotifications) << "Unhandled notifcation"
                     << notification.name << "for" << notification.object;
                 return;
             }
 
+            if (lcCocoaNotifications().isDebugEnabled()) {
+                if (cocoaWindows.isEmpty()) {
+                    qCDebug(lcCocoaNotifications) << "Could not find forwarding target for" <<
+                        qPrintable(notificationName) << "from" << notification.object;
+                } else {
+                    QVector<QCocoaWindow *> debugWindows;
+                    for (QCocoaWindow *cocoaWindow : cocoaWindows)
+                        debugWindows += cocoaWindow;
+                    qCDebug(lcCocoaNotifications) << "Forwarding" << qPrintable(notificationName) <<
+                        "to" << debugWindows;
+                }
+            }
+
             // FIXME: Could be a foreign window, look up by iterating top level QWindows
 
             for (QCocoaWindow *cocoaWindow : cocoaWindows) {

src/plugins/platforms/cocoa/qnswindow.mm

@@ -46,6 +46,8 @@
 #include <qpa/qwindowsysteminterface.h>
 #include <qoperatingsystemversion.h>
 
+Q_LOGGING_CATEGORY(lcCocoaEvents, "qt.qpa.cocoa.events");
+
 static bool isMouseEvent(NSEvent *ev)
 {
     switch ([ev type]) {
@@ -116,6 +118,22 @@ static bool isMouseEvent(NSEvent *ev)
     return qnsview_cast(self.contentView).platformWindow;
 }
 
+- (NSString *)description
+{
+    NSMutableString *description = [NSMutableString stringWithString:qt_objcDynamicSuper()];
+
+#ifndef QT_NO_DEBUG_STREAM
+    QString contentViewDescription;
+    QDebug debug(&contentViewDescription);
+    debug.nospace() << "; contentView=" << qnsview_cast(self.contentView) << ">";
+
+    NSRange lastCharacter = [description rangeOfComposedCharacterSequenceAtIndex:description.length - 1];
+    [description replaceCharactersInRange:lastCharacter withString:contentViewDescription.toNSString()];
+#endif
+
+    return description;
+}
+
 - (BOOL)canBecomeKeyWindow
 {
     QCocoaWindow *pw = self.platformWindow;
@@ -177,6 +195,8 @@ static bool isMouseEvent(NSEvent *ev)
 
 - (void)sendEvent:(NSEvent*)theEvent
 {
+    qCDebug(lcCocoaEvents) << "Sending" << theEvent << "to" << self;
+
     // We might get events for a NSWindow after the corresponding platform
     // window has been deleted, as the NSWindow can outlive the QCocoaWindow
     // e.g. if being retained by other parts of AppKit, or in an auto-release