Does drawRect: automatically check whether something is within the bounds of the CGRect passed to it?

Question

I'm wondering whether I need to check if something is within the bounds of the CGRect passed to drawRect:, or if drawRect: automatically handles that for me.

For example, assume that I have 10 UIBezierPaths on the screen. Each curve is in an NSMutableArray named curves. Every time drawRect: is called, it loops through this array and draws the curves it finds there. If the use moves one curve, I find its containing CGRect and call [self setNeedsDisplayInRect:containingRect]. In my drawRect: implementation, do I need to personally check whether each of the UIBezierPaths falls within the CGRect passed to drawRect: (using CGRectIntersectsRect), or is that handled automatically?

Mat - yes, it works. But that could be because it's simply redrawing the entire screen, rather than just the dirty rect passed to drawRect: — maxedison, Jul 23 '11 at 13:46

score 0 · Accepted Answer · answered Aug 18 '11 at 08:58

0

This falls into a class of optimizations you'll have to make yourself if you think it's necessary after profiling.

UIKit isn't that smart unfortunately. Though it would probably be too slow if it was!

answered Aug 18 '11 at 08:58

David Hodge

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Does drawRect: automatically check whether something is within the bounds of the CGRect passed to it?

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