Re: Problem ... very slow scrolling.

[Adam Fedor]

Richard Frith-Macdonald wrote:

> Looking at the code for NSCopyBits(), it uses DPScomposite, which (in 
> the xgps backend)
> grabs an image from the source, manipulates it (alpha support etc), puts 
> the result in
> another image and writes that to the destination.  This means that, far 
> from NSCopyBits()
> being a fast function to shift parts of a view around, it's actually 
> rather slow.


Actually it already does this. When the operation is NSCompositeCopy, it 
calls the copyBits:fromRect:toPoint: method. The slow scrolling (in this 
case) is caused in GWorkspace iteself by an unecessary(*) call to 
setNeedsDisplay:

GWorkspace/Viewers/IconsViewer/IconsPanel.m:712 
(gwscrollView:scrollViewScrolled:hitPart:)

(*) I say unecessarily warily as taking this line out exposes some odd 
scrolling bug which causes the display to get messed up when scrolling 
continuously (but gets cleaned up if you just click outside the scroller 
knob).




--
Adam Fedor, Digital Optics            | I'm glad I hate spinach, because
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