Re: selectionIndexesForProposedSelection on mouse Up or mouse Down
Re: selectionIndexesForProposedSelection on mouse Up or mouse Down
- Subject: Re: selectionIndexesForProposedSelection on mouse Up or mouse Down
- From: Brad Stone <email@hidden>
- Date: Thu, 12 May 2011 16:42:19 -0400
I'm thinking about the perception of the user. When I'm in Mail.app, for example, clicking in the outlineView (organized by thread) and I click on a row it feels less responsive because there's a pause before the row highlights (a pause until I release the mouse button). When I'm in iTunes and the row highlights as soon as the mouse button is down is just feels more responsive.
I put in NSLog calls to show me when "proposed" and "didChange" get called. NSTableView's delegate gets called on mouseDown while NSOutlineView on mouseUp.
On May 12, 2011, at 2:06 PM, Quincey Morris wrote:
> On May 12, 2011, at 10:05, Brad Stone wrote:
>
>> For my NSTableView (NSIndexSet *)tableView:(NSTableView *)tableView selectionIndexesForProposedSelection:(NSIndexSet *)proposedSelectionIndexes fires on mouseDown and (void)tableViewSelectionDidChange:(NSNotification *)aNotification fires on mouseUp.
>>
>> For my NSOutlineView (NSIndexSet *)outlineView:(NSOutlineView *)outlineView selectionIndexesForProposedSelection:(NSIndexSet *)proposedSelectionIndexes and (void)outlineViewSelectionDidChange:(NSNotification *)notification fire only on mouseUp.
>
> This can't be true.
>
> For a start, thinking of the delegate methods as "firing" on mouse events seems like a way to lead yourself astray. There are *various* ways to change a selection, only some of which start at a mouse down event, and the delegate methods are invoked at *various* points in the procedure depending on circumstances, no matter how it starts. (Well, ...DidChange presumably gets invoked only at the end, but what constitutes the end may vary.)
>
> Specifically, if NSOutlineView's 'selectionIndexesForProposedSelection:...' method wasn't ever called until a mouse up event (after an initial mouse down, I mean), it wouldn't be possible to prevent rows from getting selected while the mouse is being dragged, and it *is* possible to do so.
>
> There may be specific scenarios where the view decides not to invoke the delegate until mouse up, but that fact just demonstrates the pointlessness of trying to parse the mouse event behavior.
>
>
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