Re: drawing/masking one image with the alpha value from another
Re: drawing/masking one image with the alpha value from another
- Subject: Re: drawing/masking one image with the alpha value from another
- From: David Duncan <email@hidden>
- Date: Wed, 23 Sep 2009 09:22:43 -0700
On Sep 23, 2009, at 6:25 AM, Roland King wrote:
One question about Transparency Layers, the docs say that when you
start one the global alpha is set to 1, shadows are turned off and
blend mode is set normal (actually only the Quartz 2D guide says
that the blend mode changes, the actual API docs don't mention it).
When the layer is ended it's composited back to the original
context, what blending mode is used to do that, I assume the
original blend mode at the point the Transparency Layer was started
right?
You can think of a transparency layer as creating a bitmap context,
drawing to it, then creating an image and drawing it to the original
context. Its not quite the same, but as far as final results are
concerned, it is similar (more to the point, yes the original blend
mode should be used for compositing).
--
David Duncan
Apple DTS Animation and Printing
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