On Feb 1, 2009, at 3:07 AM, Graham Cox wrote:

As others have mentioned, there is potentially a huge difference. If you invalidate a lot of small rectangles, the update region might be quite complex in shape; the <rect> passed in -drawRect: is only the bounds of this complex area.

Which is why the docs confused me. I knew there were subrectangles, but the weird thing was this line in the docs: "It is optimized to efficiently reject any rectangle that lies outside the bounding box of the area the receiver is being asked to draw in drawRect:."

So it's not optimized to reject anything outside of the sub- rectangles? This sentence really threw me off. In retrospect and I can see that it simply means that it's doing a simple check up front like below, but it's a rather poorly worded description as it doesn't mention the sub-rectangles at all. Documentation fail. ;-)

- (BOOL)needsDisplayInRect:(NSRect)rect;
{
        if (!NSIntersectsRect(rect, theBigBoundingRect)) {
                return NO;
        }

        ... other checks
}





But there is also a difference in intent between....
This is probably more than you need or care to know at this point but I thought it might be worth mentioning ;-)

Actually, it is very relevant to what I am doing. :-)




Thanks all,

--
Seth Willits



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