Re: again with paths and images
Re: again with paths and images
- Subject: Re: again with paths and images
- From: Robert Clair <email@hidden>
- Date: Thu, 21 Dec 2006 08:59:29 -0500
I tried to calculate the path rects using formulas but with no
exciting
results (do you know where to find the formulas used in bezier
paths?).
This would be a very ugly calculation. I'm not privy to the low level
Quartz source code, but this is generally done by tessellating the
curve so that the maximum chordal deviation (maximum distance from a
segment of the tessellated approximation to the "real" curve) is
less than a pixel and then stroking the result. You'd need to go to a
textbook on computer graphics and read up on tessellation (actually
Quartz will do this for you, see [NSBezierPath
bezierPathByFlatteningPath:] and the methods for extracting dat from
an NSBezierPath) and Bresenham's algorithm. It's would be even uglier
taking account of anti-aliasing.
That's why I thought to draw it all in one image and then draw it in a
bigger rect (after all the final result will be a single image...). Of
course it' not a great solution, and it's expensive in terms of
time and
memory.
What's wrong with this ? It sounds like a perfectly reasonable
solution to what you're trying to achieve. Do you have really huge
images ? Do you know from trying it that it is too slow or does it
just seem that way ? The
Quartz compositor is very fast.
...Bob Clair
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