Thanks again.
It seems tracking area is not suited for this application. And I
revert to cursor rect finally. Wish a better tracking area from Apple.
On Mon, Apr 28, 2008 at 1:30 AM, Quincey Morris
<[EMAIL PROTECTED]> wrote:
> I think the problem is that you are not properly handling *responsibility*
> for the cursor. You should only change the cursor when you are responsible
> for it, and when you are responsible for it you should make sure that you
> set it. So, for example:
>
>
> On Apr 27, 2008, at 02:35, an0 wrote:
> - (IBAction)setItemPropertiesToDefault:(id)sender
> {
> [self setLocation:NSMakePoint(0.0,0.0)];
>
> NSTrackingAreaOptions options = NSTrackingCursorUpdate |
> NSTrackingActiveInActiveApp;
>
> NSPoint localPoint = [self convertPoint:[[self window]
> mouseLocationOutsideOfEventStream]
> fromView:nil];
>
> if ([self isPointInItem:localPoint]) {
> inTrackingRect = YES;
> options |= NSTrackingAssumeInside;
> [[NSCursor openHandCursor] set];
> } else {
> inTrackingRect = NO;
> }
>
> if (trackingRect) {
> [self removeTrackingArea:trackingRect];
> }
>
> self.trackingRect = [[[NSTrackingArea alloc] initWithRect:[self
> calculatedItemBounds]
> options:options
> owner:self
> userInfo:nil]
> autorelease];
> [self addTrackingArea:trackingRect];
> }
>
> This method is called from awakeFromNib, but at that time you don't know
> that you are responsible for the cursor -- the mouse pointer could be
> anywhere. You can set up the tracking area, yes, but you should defer
> setting the cursor until you're told that you are responsible for setting
> it, which is what the cursorUpdate event is for:
>
> -(void)cursorUpdate:(NSEvent *)event
> {
> if (dragging) {
> return;
> }
>
> if (!inTrackingRect) {
> [[NSCursor openHandCursor] set];
> } else {
> [[NSCursor arrowCursor] set];
> }
> inTrackingRect = !inTrackingRect;
> }
>
> This has the opposite problem. You should set the cursor before returning
> while dragging, since getting to this method means that you are currently
> responsible for the cursor.
>
> Also, you haven't taken responsibility for setting the cursor when the mouse
> pointer is in the view containing these draggable items but outside all of
> the items. If the mouse pointer is outside all of the tracking areas you've
> created, your cursorUpdate is not going to be called, and the cursor will
> default to an arrow. This is OK when you're not dragging, but means the
> cursor won't "stick" as the closed hand when you are dragging.
>
> To fix that, you really need to add a tracking area to the superview (with
> the NSTrackingInVisibleRect option in this case). Then you would also have
> to add a cursorUpdate to the superview, which knows to set the cursor to the
> closed hand or the arrow depending on the dragging state. (So, the superview
> needs to be a custom view too.)
>
> There's another source of complexity here, too. Tracking areas really deal
> with the concept of the mouse entering or exiting a rectangle, not the
> concept of the mouse *being* in the rectangle. So, when you create or
> recreate a tracking area, you don't get any related events immediately. You
> might not get an event until the mouse actually crosses into or out of the
> rectangle. Using NSTrackingAssumeInside helps, but even with it you won't
> get an event until the mouse actually moves (well, that's true for
> mouseEntered/mouseExited events -- I'm not certain about cursorUpdate).
>
> This means that every time you create or recreate a tracking area, there can
> be a temporary loss of synchronization between your code's idea of the mouse
> state and the actual state. There's no complete solution to this defect in
> tracking area, afaik.
>
>
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