Improving Finger Painting Performance

Question

Simple Painting:
Fingering the iPhone screen paints temporary graphics to a UIView. These temporary graphics are erased after a touch ends, and are then

Answer 1

Why not just draw everything onto a CGBitmapContextRef buffer so the drawing operations will accumulate, and then draw that to the screen in your drawRect:? You will be able to perform arbitrary graphics operations without slowing down as the total number of operations increases.

If undo support is necessary, one could always keep a copy for each change made and invalidate the oldest copies when a memory warning is received. (or for an even fancier solution, store the operations as you do now, but keep a cached copy every dozen user operations or so)