ios - 将 CIFilter 应用于 CALayer

Question

CI Filters现在在 iOS 5 中可用，我正在尝试将一个应用到 CALayer，the way you'd do it on Mac .这是我的代码:

CALayer *myCircle = [CALayer layer];
myCircle.bounds = CGRectMake(0,0,30,30);
myCircle.position = CGPointMake(100,100);
myCircle.cornerRadius = 15;
myCircle.borderColor = [UIColor whiteColor].CGColor;
myCircle.borderWidth = 2;
myCircle.backgroundColor = [UIColor whiteColor].CGColor;

CIFilter *blurFilter = [CIFilter filterWithName:@"CIDiscBlur"];
[blurFilter setDefaults];
[blurFilter setValue:[NSNumber numberWithFloat:5.0f] forKey:@"inputRadius"];
[myCircle setFilters:[NSArray arrayWithObjects:blurFilter, nil]];

[self.view.layer addSublayer:myCircle];

我的白色圆圈画得很好，但没有应用滤镜。

Answer 1

除了 CIDiskBlur 不可用(自 iOS SDK 5.1 起)和 setFilters: 似乎不可用之外，您还可以执行以下操作:

从图层的内容创建输入 CIImage:

CIImage *inputImage = [CIImage imageWithCGImage:(CGImageRef)(myCircle.contents)];`

应用过滤器并在 CGImageRef 中获取结果:

CIFilter *filter = [CIFilter filterWith...];// A filter that is available in iOS or a custom one :)
...
CIImage *outputImage = [filter outputImage];
CIContext *context = [CIContext contextWithOptions:nil];
CGImageRef cgimg = [context createCGImage:outputImage fromRect:[outputImage extent]];

最后将 CGImageRef 设置为图层:

[myCircle setContents:(id)cgimg];

这应该有效:)