Preventing a drag in draggingSourceOperationMaskForLocal: not working
Preventing a drag in draggingSourceOperationMaskForLocal: not working
- Subject: Preventing a drag in draggingSourceOperationMaskForLocal: not working
- From: "Jeremy Higgs" <email@hidden>
- Date: Fri, 22 Sep 2006 15:34:28 +1000
Hi everyone,
I'm trying to implement horizontal dragging in an NSTableView cell (the same
sort of functionality iTunes provides when setting song ratings), but am
having some problems. I have overridden the
draggingSourceOperationMaskForLocal: method in an NSTableView subclass
(which has been set as the custom class in the nib) to do the following:
- (NSDragOperation)draggingSourceOperationMaskForLocal:(BOOL)isLocal;
{
// If we're in one of the "no-drag" columns (set in mouseDown:) don't
allow a drag to occur
if (!_horizontalMotionCanBeginDrag)
{
return NSDragOperationNone;
}
return [super draggingSourceOperationMaskForLocal:isLocal];
}
The value for _horizontalMotionCanBeginDrag is set in mouseDown:, by
checking if the mouse cursor is in one of the table columns we want to
disable drags in:
- (void)mouseDown:(NSEvent *)event
{
BOOL mouseInNoDragColumns = ([[[self mouseTableColumnForEvent:event]
identifier] isEqualToString:@"columnA"] ||
[[[self mouseTableColumnForEvent:event]
identifier] isEqualToString:@"columnB"]);
// If we're in a "no-drag" column, flag it
_horizontalMotionCanBeginDrag = !mouseInNoDragColumns;
[super mouseDown:event];
}
---
When I try and perform a "horizontal" drag in those particular cells, I can
see NSDragOperationNone being returned from the
draggingSourceOperationMaskForLocal: method. Despite this, a drag image is
still produced (and a drag occurs, as writeRows: in the delegate is called).
According to the docs, this is what I should be doing to prevent a drag from
this row.
Has anyone successfully prevented drags from occurring in this manner? I
thought about doing it in the delegate, but AFAIK it's a bit harder to get
what column the mouse is in (and it's not event-driven).
Any tips would be greatly appreciated!
Thanks,
Jeremy
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