Re: NSTableView NSTrackingArea and mouse clicks

FROM : kvictor@pobox.com
DATE : Fri Jul 25 23:14:01 2008

hi corbin,
i understand ur explanation and it makes sense. and i see that the
fix works in PhotoSearch. unfortunately, it doesn't solve all my
problems. but at this point, i believe i may have a draw problem as
i'm seeing the highlight being drawn twice.

thanx,
ken

ps. i used the term toolbox because i wasn't sure if this was
foundation or appkit, and just used an old term wrongly. sorry.



At 1:42 PM -0700 7/25/08, Corbin Dunn wrote:
>Hi ken,
>
>It took me a minute to realize it, but what you describe below makes
>sense. Let me clarify what preparedCellAtColumn:row: does; this is
>the main funnel point that NSTableView uses to get a cell to do any
>operations (ie: drawing, type selection, etc). NSTableView's
>implementation gives you a cell set up with the correct state (ie:
>selected, etc).
>
>Now, what does the TrackableOutlineView app do? It *copies* this
>cell (and any state it had), and returns that copy in
>preparedCellAtColumn:row:. So, you mouse in, it copies the cell and
>starts returning that cell. If you click down, well, NSTableView
>never gets a chance to set the state, since you override
>preparedCellAtColumn:row:.
>
>Make sense? It is working correctly; it's not a bug in PhotoSearch
>or the framework (also -- we use the term AppKit or framework, but
>"toolbox" refers to another framework).
>
>Of course, you want it to not work that way. You want it to reflect
>the state that NSTableView sets. So, a quick hack:
>
>- (NSCell *)preparedCellAtColumn:(NSInteger)column row:(NSInteger)row {
>    // We check if the selectedCell is nil or not -- the
>selectedCell is a cell that is currently being edited or tracked. We
>don't want to return our override if we are in that state.
>    if ([self selectedCell] == nil && (row == iMouseRow) && (column
>== iMouseCol)) {
>        NSCell *superCell = [super preparedCellAtColumn:column row:row];
>        [iMouseCell setHighlighted:[superCell isHighlighted]];
>        return iMouseCell;
>    } else {
>        return [super preparedCellAtColumn:column row:row];
>    }
>}
>
>.corbin
>

>>thanx for the reply. i was pretty sure it wasn't my drawing code
>>and after some more "playing around" i'm convinced of that.
>>
>>i've narrowed down my problem (and i can reproduce it in the
>>PhotoSearch demo -- see below).
>>
>>the -[NSCell setHighlighted:] message does NOT get sent to a cell
>>if a click occurs inside an NSTrackingArea for the cell/view.
>>
>>to see this problem in the PhotoSearch demo app, add the following
>>3 lines to the bottom of -[ImagePreviewCell
>>addTrackingAreasForView:inRect:withUserInfo:mouseLocation:] :
>>
>>    cellFrame.size.width /=  2;
>>    NSTrackingArea *area2 = [[NSTrackingArea alloc]
>>initWithRect:cellFrame options:options owner:controlView
>>userInfo:userInfo];
>>    [controlView addTrackingArea:area2];
>>    [area2 release];
>>
>>also add an override of setHighlighted as follows:
>>
>>- (void) setHighlighted: (BOOL) value
>>{
>>NSLog(@"%s:  %d", __func__, value);
>>
>>    [super setHighlighted: value];
>>}
>>
>>you can verify that the new tracking area is working because if you
>>move the mouse into it, the info button changes. but if u click in
>>this second tracking area, your override of setHighlighted does NOT
>>get called.
>>
>>offhand, i would say that this doesn't sound like a bug in
>>PhotoSearch, but rather a bug in the toolbox. would you agree? if
>>you think this is a bug in PhotoSearch, can you suggest a solution?
>>if this is in fact a toolbox bug, let me know and i'll report in
>>radar; and also, could you suggest a work-around?
>>
>>thanx,
>>ken
>>
>>
>>
>>
>>At 7:44 AM -0700 7/25/08, Corbin Dunn wrote:

>>>On Jul 24, 2008, at 6:16 PM, <email_removed> wrote:
>>>

>>>>i have an NSTableView that uses a data source (no bindings, but i
>>>>don't think this is relevant). one column uses a custom cell that
>>>>is actually a subclass of NSTokenFieldCell (but i don't think
>>>>this is relevant either). i draw this cell differently depending
>>>>on whether or not the row it is in is the table's selected row.
>>>>(and i only allow one row at a time to be selected.)
>>>>
>>>>if i don't use any NSTrackingAreas, everything works as i want/expect.
>>>>
>>>>however, if i set up some tracking rects for my custom cell, then
>>>>things don't work properly. i am using the techniques from the
>>>>sample PhotoSearch app. by "don't work properly," what i mean is
>>>>that if i select a row by clicking in one of the NSTrackingAreas,
>>>>the cell draws as if the row isn't selected. if i don't click
>>>>inside one of the tracking rects, but click elsewhere in the row,
>>>>then my custom cell draws properly, ie in its highlighted state.
>>>>
>>>>since this is my first use of NSTrackingArea, i wouldn't be
>>>>surprised if its something i'm doing. are there known
>>>>interactions between NSTrackingArea a clicks in the tracking
>>>>area? can anyone suggest how i can proceed?

>>>
>>>No; none --- it is probably something wrong with your cell drawing
>>>code. Can you post it here? I'll take a look at it.
>>>
>>>corbin (I wrote that demo -- note, I think there are a few bugs in
>>>the tracking area code of the demo that I need to fix up, but this
>>>isn't one of them)