Optimizing drawing by caching
Optimizing drawing by caching
- Subject: Optimizing drawing by caching
- From: Drew McCormack <email@hidden>
- Date: Sun, 29 Sep 2002 17:18:49 +0200
I have some drawing which is expensive to perform, but only needs to be
performed occasionally. If I use it in a scrollview as is, resizing and
scrolling performance is worse than it was under Mac OS X public beta
;-) In other words, it isn't good enough.
Since what is drawn changes infrequently, I thought I should cache the
drawing in an NSImage or something like that. Rather than draw to
screen, I would draw to the image, and then draw the image on the
screen whenever needed. I thought the best place to do the caching
would be the "display" method: this could rebuild the image if
necessary, and then call the super's display, which in turn would call
"drawRect:" where the image would actually be drawn on the screen.
Is this approach a good idea, or am I missing something? Are there any
pitfalls? Does anyone know any sample code for this? Can anyone give me
any idea what NSImage or NSBitmapImageRep classes I should use for this
purpose?
One more thing: All my drawn makes use of Quartz, so a postscript
format may be my best bet. Could I/Should I use a PDF image rep for
this caching, or a bitmap image rep?
Drew
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Dr. Drew McCormack
Trade Strategist (www.trade-strategist.com)
Trading simulation software for Mac OS X
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