Does iPhone support per pixel alpha?

I am f开发者_如何转开发inding a way to draw image with per pixel alpha using UIView on iphone, any one have tried that?

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This is possible. I'm assuming you are using a UIImageView to display the image? Just make sure that the background colour of your view is set to clear and that Opaque is set to false.

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Yes.

You can back an UIView with an RGBA bitmap of the same size where every pixel has it's own 8 bits of alpha channel.

Unless you specify otherwise (by scaling or using a transform, etc.), a generic UIView uses a CALayer backed by such a bitmap.