Re: Preventing a drag in draggingSourceOperationMaskForLocal: not working
Re: Preventing a drag in draggingSourceOperationMaskForLocal: not working
- Subject: Re: Preventing a drag in draggingSourceOperationMaskForLocal: not working
- From: "Jeremy Higgs" <email@hidden>
- Date: Sun, 24 Sep 2006 16:34:38 +1000
On 9/23/06, Corbin Dunn <email@hidden> wrote:
>
> 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.
That's too late to do it. From a table, do this in your delegate:
- (BOOL)tableView:(NSYourTableView *)tableView writeRowsWithIndexes:
(NSIndexSet *)rowIndexes toPasteboard:(NSPasteboard*)pboard {
if ([tableView canDrag]) { ... stuff } else { return NO; }
}
set the "canDrag" in the subclass of your tableview (NSYourTableView)
with mouseDown: code similar to what you have.
I understand this is difficult to do and something like this will be
made easier to do in the future.
thanks,
--corbin
Hi Corbin,
Thanks a lot for that! Works a treat now.
Jeremy
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