动画“变换”时抗锯齿CALayer 上的属性？
我有一个 CALayer，其中以最终大小绘制了一个圆圈。我想要为圆设置动画，使其以 1% 比例开始并以 100% 结束。现在动画不是很平滑，因为缩放时边缘会闪烁。在最终尺寸下，圆圈看起来是正确的。我想知道是否有办法在动画本身期间进行抗锯齿。
CATransform3D fromTransform = CATransform3DMakeScale(0.01, 0.01, 1.0);
CATransform3D toTransform = CATransform3DMakeScale(1.0, 1.0, 1.0);
CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
theAnimation.duration = 1.5;
theAnimation.fromValue = [NSValue valueWithCATransform3D:fromTransform];
theAnimation.toValue = [NSValue valueWithCATransform3D:toTransform];
[myLayer addAnimation:theAnimation forKey:@"animateScale"];
I have a CALayer with a circle drawn to it at its final size. I want to animate the circle in, such that it starts at 1% scale and finishes at 100%. Right now the animation is not very smooth because the edges flicker while it's scaling. At the final size the circle looks right. I'm wondering if there's a way to have anti-aliasing during the animation itself.
CATransform3D fromTransform = CATransform3DMakeScale(0.01, 0.01, 1.0);
CATransform3D toTransform = CATransform3DMakeScale(1.0, 1.0, 1.0);
CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
theAnimation.duration = 1.5;
theAnimation.fromValue = [NSValue valueWithCATransform3D:fromTransform];
theAnimation.toValue = [NSValue valueWithCATransform3D:toTransform];
[myLayer addAnimation:theAnimation forKey:@"animateScale"];
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我认为没有办法改变图层缩放的方式。但是，您可以通过以下方式获得更好的结果：将多种分辨率的圆渲染到不同大小的图层中，并同时对它们进行动画处理 - 逐渐缩放和淡入/淡出更大的图层，直到到达最终的全尺寸图层。
您还可以尝试直接逐帧绘制圆圈，而不是对图层大小进行动画处理 - 如果绘制速度足够快，您将保持良好的帧速率，并且不会出现任何缩放伪影。如果选择此路径，通常最好在专用于该动画的单独线程上执行此操作，而不是使用主线程。
在类似的情况下，我通常只是柔化绘图上的边缘 - 精心选择的阴影或光晕对于减少锯齿伪影确实有奇效，而且它比任何其他解决方案都简单得多。 （另请注意，圆圈的描边宽度随图层缩放：如果您使用全尺寸 1 像素的线宽在黑色背景上绘制白色圆圈，则在 1% 时，该线将只有 0.01 像素宽！）
I don't think there is a way to change the way layers scale. However, you may be able to achieve better results by rendering your circle at several resolutions into different-sized layers, and by animating them simultaneously — scaling and fading in/out progressively larger layers until you get to the final, full-sized layer.
You may also try drawing the circle directly frame by frame instead of animating the layer size — if the drawing is fast enough, you'll keep good framerates, and you'll have no scaling artifacts whatsoever. If you choose this path, it's usually best to do this on a separate thread that is dedicated to this animation rather than using the main thread.
In similar situations, I usually just end up softening the edges on my drawing — a well-chosen shadow or bloom does wonders for reducing aliasing artifacts, and it's much simpler to do than any other solution. (Note also that the stroke width of the circle scales with the layer: if you draw a white circle on black backround using a line width of 1 pixel at full size, then at 1% the line will be only 0.01 pixels wide!)
方法：使用
layer.shouldRasterizesuperlayer/superview，其在所有4个方向上都大1像素superlayer上进行变换/superviewlayer/view上启用layer.shouldRasterize方法：绘制到< code>UIImage
参考：http://darknoon.com/2012/05/18/the-transparent-border-trick/
Method: Using
layer.shouldRasterizesuperlayer/superviewwhich is 1 pixel bigger in all 4 directionssuperlayer/superviewlayer.shouldRasterizeon the originallayer/viewMethod: Drawing to a
UIImageReference: http://darknoon.com/2012/05/18/the-transparent-border-trick/