cursorUpdate called, but cursor not updated

Question

I have been working on this for hours, have no idea what went wrong. I want a custom cursor for a button which is a subview of NSTextView, I add a tracking area and send the cursorUpdate message when mouse entered button.

The cursorUpdate method is indeed called every time the mouse entered the tracking area. But the cursor stays the IBeamCursor.

Any ideas?

Reference of the Apple Docs: managing cursor-update event

- (void)cursorUpdate:(NSEvent *)event {
    [[NSCursor arrowCursor] set];
}

- (void)myAddTrackingArea {
    [self myRemoveTrackingArea];

    NSTrackingAreaOptions trackingOptions = NSTrackingCursorUpdate | NSTrackingMouseEnteredAndExited | NSTrackingActiveInKeyWindow;
    _trackingArea = [[NSTrackingArea alloc] initWithRect: [self bounds] options: trackingOptions owner: self userInfo: nil];
    [self addTrackingArea: _trackingArea];
}

- (void)myRemoveTrackingArea {
    if (_trackingArea)
    {
        [self removeTrackingArea: _trackingArea];
        _trackingArea = nil;
    }
}

Answer 1

I ran into the same problem.

The issue is, that NSTextView updates its cursor every time it receives a mouseMoved: event. The event is triggered by a self updating NSTrackingArea of the NSTextView, which always tracks the visible part of the NSTextView inside the NSScrollView. So there are maybe 2 solutions I can think of.

1. Override updateTrackingAreas remove the tracking area that is provided by Cocoa and make sure you always create a new one instead that excludes the button. (I would not do this!)

2. Override mouseMoved: and make sure it doesn't call super when the cursor is over the button.

   - (void)mouseMoved:(NSEvent *)theEvent {
       NSPoint windowPt = [theEvent locationInWindow];
       NSPoint superViewPt = [[self superview]
             convertPoint: windowPt  fromView: nil];
       if ([self hitTest: superViewPt] == self) {
           [super mouseMoved:theEvent];
       }
   }
   

Answer 2

I had the same issue but using a simple NSView subclass that was a child of the window's contentView and did not reside within an NScrollView.

The documentation for the cursorUpdate flag of NSTrackingArea makes it sound like you only need to handle the mouse entering the tracking area rect. However, I had to manually check the mouse location as the cursorUpdate(event:) method is called both when the mouse enters the tracking area's rect and when it leaves the tracking rect. So if the cursorUpdate(event:) implementation only sets the cursor without checking whether it lies within the tracking area rect, it is set both when it enters and leaves the rect.

The documentation for cursorUpdate(event:) states:

Override this method to set the cursor image. The default implementation uses cursor rectangles, if cursor rectangles are currently valid. If they are not, it calls super to send the message up the responder chain.

If the responder implements this method, but decides not to handle a particular event, it should invoke the superclass implementation of this method.

override func cursorUpdate(with event: NSEvent) {
    // Convert mouse location to the view coordinates
    let mouseLocation = convert(event.locationInWindow, from: nil)

    // Check if the mouse location lies within the rect being tracked
    if trackingRect.contains(mouseLocation) {
        // Set the custom cursor
        NSCursor.openHand.set()
    } else {
        // Reset the cursor
        super.cursorUpdate(with: event)
    }
}

Answer 3

I just ran across this through a Google search, so I thought I'd post my solution.

1. Subclass the NSTextView/NSTextField.

2. Follow the steps in the docs to create an NSTrackingArea. Should look something like the following. Put this code in the subclass's init method (also add the updateTrackingAreas method):

   NSTrackingArea *trackingArea = [[NSTrackingArea alloc] initWithRect:self.bounds options:(NSTrackingMouseMoved | NSTrackingActiveInKeyWindow) owner:self userInfo:nil];
   [self addTrackingArea:trackingArea];
   self.trackingArea = trackingArea;
   

3. Now you need to add the mouseMoved: method to the subclass:

   - (void)mouseMoved:(NSEvent *)theEvent {
       NSPoint point = [self convertPoint:theEvent.locationInWindow fromView:nil];
       if (NSPointInRect(point, self.popUpButton.frame)) {
           [[NSCursor arrowCursor] set];
       } else {
           [[NSCursor IBeamCursor] set];
       }
   }
   

Note: the self.popUpButton is the button that is a subview of the NSTextView/NSTextField.

That's it! Not too hard it ends up--just had to used mouseMoved: instead of cursorUpdate:. Took me a few hours to figure this out, hopefully someone can use it.