fast bitmap image scaling
fast bitmap image scaling
- Subject: fast bitmap image scaling
- From: Ben Zotto <email@hidden>
- Date: Wed, 10 Jan 2007 13:03:52 -0800 (PST)
Hi all,
I'm relatively new to the graphics end of the Mac platform, and I'm looking for pointers for optimizing some drawing I'm doing. I am working an NSImage composited into a custom view. I am user a timer to animate the image to grow from relatively small to relatively large in the view. It works, but the resizing is "chunky" at best. The image I'm using is of a pretty low resolution-- with its size set to the pixel size of the underlying bitmap-- and interpolation is set to None in the graphics context while this is happening. I'm drawing using NSImage's drawInRect: method, supplying larger and larger target rectangles. Shark doesn't tell me much that I can work with except that I'm spending a lot of time in CGContextDrawImage and its callees.
The quality of the scaling while it's animating is absolutely immaterial-- it can look terrible as long as it looks smooth. Now, I know that modern graphics hardware can do wickedly fast bitmap scaling (witness Expose's F9 function). So is anyone kind enough to toss out any collected wisdom about this subject, and possible subtle roadblocks that could be slowing me down? I don't know anything about colorspaces, should I learn more about them? I'm certainly willing to drop directly to Quartz calls if it might help, or even manipulate pixels/texels directly, if what I'm trying to do just isn't easy at the Cocoa level, but I don't want to go off on a wild goose chase if there's something else fundamentally off.
Thanks for any thoughts, techniques, pointers, etc.
Cheers
Ben
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