Why does Adding Core Animation slow down drawing of my NSTableView?
- by Will Goring
I have a simple App that displays a list of items using NSTableView. There are usually about 15-25 items in the list, and the table has 10 columns, all but one of which are text (the other's an icon.) There are simple data transformers on a couple of the columns. So nothing taxing; you'd expect it to run just fine.
And as it stands, it is; the app is responsive and everything draws pretty much instantly. Scrolling, changing column sizes, resizing the window; whatever you do the redraws keep up with the mouse-pointer.
Tonight, I thought I'd try adding a little visual flair to the app with Core Animation (which I've never used before,) but I've found that if anything above the NSTableView in the hierarchy is set 'Wants Core Animation Layer,' then the NSTableView redraws go to hell. Scrolling is usually fine, but resizing columns or the window causes it to pick up an effect like texture tearing, where some of the rows have the new size, and some have the old one, and everything flickers horribly. It looks terrible. Basically it looks like what you'd expect if rendering the individual rows or columns was taking a long time.
I've put it through Shark and, sure enough, it looks like it's spending most of its time drawing the text in the cells; what I don't understand is why that should take longer when there's a Core Animation layer involved than when there isn't - and quite noticeably longer at that.
Has anyone got any ideas? Is there any Core Animation initialisation or config I've missed or something (I've literally just ticked the "Wants Core Animation Layer" box in IB)?
Cheers,
Will
