iPhone: CALayer + rotate in 3D + antialias?-优快云博客

本文介绍了解决iOS设备上图像旋转时出现锯齿的方法。通过为图像增加透明像素边距或调整CALayer绘制内容的方式实现抗锯齿效果。文章提供了具体的代码示例和技术细节。

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You could try adding some transparent pixels around the edge of the image, either by putting the UIImageView in a slightly larger empty view that you apply rotation to, or by changing the source images.

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By "I've heard people mention," I assume you mean the discussion on this question . What was suggested there was to actually draw the content in your CALayer so that it has a one-pixel transparent border outside of the core content, using the code

CGContextSetAllowsAntialiasing
(
theContext
,
 
true
);



CGContextSetShouldAntialias
(
theContext
,
 
true
);

within your Quartz drawing for that layer.

There's also the edgeAntialiasingMask property on CALayer, but I've seen no impact when using code like the following:

layer
.
edgeAntialiasingMask 
=
 kCALayerLeftEdge 
|
 kCALayerRightEdge 
|
 kCALayerBottomEdge 
|
 kCALayerTopEdge
;

on the antialiasing of transformed layer edges. See also this question for discussion of this, as well as how they solved their problem using one-pixel transparent borders around their images.

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The best result that I could come up with was by doing what I suggested in my comment: I grew each (transparent) graphic by 1 pixel on each side. With that little bit of margin, the cards composited much better with the background.

So, not exactly an iPhone code answer, but one that nonetheless works on the iPhone.

Here's an "after" shot that you can compare to the "before", above: alt text

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http://stackoverflow.com/questions/2686027/iphone-calayer-rotate-in-3d-antialias

http://stackoverflow.com/questions/1136110/any-quick-and-dirty-anti-aliasing-techniques-for-a-rotated-uiimageview

http://stackoverflow.com/questions/2465645/how-to-anti-alias-layers-in-iphoneos