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Suppose I have image canvas or previously loaded image which supports transparency (gif/png). What are the steps to implement changing transparency for the image, but not for the whole image, but only a part of it? I undestand I should use CGContext, but i'm lacking the details.

rattkin
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1 Answers1

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1) create a memory buffer

2) cast it into a CGContext with alpha by using CGBitmapContextCreate

3) draw your image into it with CGContextDrawImage

4) modify the mask via the buffer you created in step 1.

5) $$$

Rhythmic Fistman
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