Re: Threaded drawing
Re: Threaded drawing
- Subject: Re: Threaded drawing
- From: Roland King <email@hidden>
- Date: Fri, 06 Dec 2013 21:42:08 +0800
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>> That might be another way, by the way, render to your own tiled small bitmaps on background threads then blit them into the real context.
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> Yep, that was also on my list to try, but for top performance it would make sense not to do that if it can be avoided.
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My WAG would be that works well enough. Heavy lifting on the threads, then toss a bitmap/CGImage copy to the main thread where I'd hope it was just a bitblt into the context. I've seen similar recommended for iOS but only with a fullsize bitmap, not with bits and pieces. In most of those cases the view was an image and the contents was constructed on a background thread and then set into the image outside the drawrect call.
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>> Perhaps that code is fine on OSX, I'd certainly be happier if there was a create context from context call you could use to relate your small contexts to the draw rect one.
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> That was what I looked for at first as well, but there doesn’t appear to be such a call, such as CGContextCreateCopy. Pity, hence the veering into hackery territory. But there may be a cleaner way, I just haven’t discovered it yet.
You and I looked for the same API point. If it existed it would probably require the contexts would be used on the same thread and thus be useless.
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