对CALayer应用CIFilter

Question

CI Filters现在在iOS 5中可用，我正在尝试将其中一个应用到CALayer the way you'd do it on Mac中。下面是我的代码：

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(从iOS SDK5.1开始)和setFilters:似乎不可用之外，您还可以执行以下操作：

从层的内容创建输入CIImage：

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

应用您的过滤器并在CGImageRef中获得结果：

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设置为层：

[myCircle setContents:(id)cgimg];

这应该是可行的:)