winemac.drv: Use window drag notifications when available.

When running on macOS 10.12+, there are private notification center
messages we can use to reliably detect when a window is being
dragged by its titlebar. These are less finicky than the current
combination of an undocumented event subtype and a left mouse up.

Signed-off-by: Tim Clem <tclem@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>

dlls/winemac.drv/cocoa_app.h

@@ -131,6 +131,7 @@ @interface WineApplicationController : NSObject <NSApplicationDelegate>
     BOOL beenActive;
 
     NSMutableSet* windowsBeingDragged;
+    BOOL useDragNotifications;
 }
 
 @property (nonatomic) CGEventSourceKeyboardType keyboardType;

dlls/winemac.drv/cocoa_app.m

@@ -27,6 +27,12 @@
 
 static NSString* const WineAppWaitQueryResponseMode = @"WineAppWaitQueryResponseMode";
 
+// Private notifications that are reliably dispatched when a window is moved by dragging its titlebar.
+// The object of the notification is the window being dragged.
+// Available in macOS 10.12+
+static NSString* const NSWindowWillStartDraggingNotification = @"NSWindowWillStartDraggingNotification";
+static NSString* const NSWindowDidEndDraggingNotification = @"NSWindowDidEndDraggingNotification";
+
 
 int macdrv_err_on;
 
@@ -181,6 +187,15 @@ - (id) init
 
             windowsBeingDragged = [[NSMutableSet alloc] init];
 
+            // On macOS 10.12+, use notifications to more reliably detect when windows are being dragged.
+            if ([NSProcessInfo instancesRespondToSelector:@selector(isOperatingSystemAtLeastVersion:)])
+            {
+                NSOperatingSystemVersion requiredVersion = { 10, 12, 0 };
+                useDragNotifications = [[NSProcessInfo processInfo] isOperatingSystemAtLeastVersion:requiredVersion];
+            }
+            else
+                useDragNotifications = NO;
+
             if (!requests || !requestsManipQueue || !eventQueues || !eventQueuesLock ||
                 !keyWindows || !originalDisplayModes || !latentDisplayModes || !warpRecords)
             {
@@ -1554,10 +1569,7 @@ - (void) windowWillOrderOut:(WineWindow*)window
         }
     }
 
-    - (void) handleWindowDrag:(NSEvent*)anEvent begin:(BOOL)begin
+    - (void) handleWindowDrag:(WineWindow*)window begin:(BOOL)begin
-    {
-        WineWindow* window = (WineWindow*)[anEvent window];
-        if ([window isKindOfClass:[WineWindow class]])
     {
         macdrv_event* event;
         int eventType;
@@ -1580,7 +1592,6 @@ - (void) handleWindowDrag:(NSEvent*)anEvent begin:(BOOL)begin
         [window.queue postEvent:event];
         macdrv_release_event(event);
     }
-    }
 
     - (void) handleMouseMove:(NSEvent*)anEvent
     {
@@ -1736,8 +1747,13 @@ - (void) handleMouseButton:(NSEvent*)theEvent
         WineWindow* windowBroughtForward = nil;
         BOOL process = FALSE;
 
-        if (type == NSEventTypeLeftMouseUp && [windowsBeingDragged count])
+        if (!useDragNotifications &&
-            [self handleWindowDrag:theEvent begin:NO];
+            type == NSEventTypeLeftMouseUp &&
+            [windowsBeingDragged count] &&
+            [window isKindOfClass:[WineWindow class]])
+        {
+            [self handleWindowDrag:window begin:NO];
+        }
 
         if ([window isKindOfClass:[WineWindow class]] &&
             type == NSEventTypeLeftMouseDown &&
@@ -2085,15 +2101,16 @@ - (BOOL) handleEvent:(NSEvent*)anEvent
                     [window postKeyEvent:anEvent];
             }
         }
-        else if (type == NSEventTypeAppKitDefined)
+        else if (!useDragNotifications && type == NSEventTypeAppKitDefined)
         {
+            WineWindow *window = (WineWindow *)[anEvent window];
             short subtype = [anEvent subtype];
 
             // These subtypes are not documented but they appear to mean
             // "a window is being dragged" and "a window is no longer being
             // dragged", respectively.
-            if (subtype == 20 || subtype == 21)
+            if ((subtype == 20 || subtype == 21) && [window isKindOfClass:[WineWindow class]])
-                [self handleWindowDrag:anEvent begin:(subtype == 20)];
+                [self handleWindowDrag:window begin:(subtype == 20)];
         }
 
         return ret;
@@ -2155,6 +2172,26 @@ - (void) setupObservations
             [self updateCursorClippingState];
         }];
 
+        if (useDragNotifications) {
+            [nc addObserverForName:NSWindowWillStartDraggingNotification
+                            object:nil
+                             queue:[NSOperationQueue mainQueue]
+                        usingBlock:^(NSNotification *note){
+                NSWindow* window = [note object];
+                if ([window isKindOfClass:[WineWindow class]])
+                    [self handleWindowDrag:(WineWindow *)window begin:YES];
+            }];
+
+            [nc addObserverForName:NSWindowDidEndDraggingNotification
+                            object:nil
+                             queue:[NSOperationQueue mainQueue]
+                        usingBlock:^(NSNotification *note){
+                NSWindow* window = [note object];
+                if ([window isKindOfClass:[WineWindow class]])
+                    [self handleWindowDrag:(WineWindow *)window begin:NO];
+            }];
+        }
+
         [nc addObserver:self
                selector:@selector(keyboardSelectionDidChange)
                    name:NSTextInputContextKeyboardSelectionDidChangeNotification