如何使用uiimageview rect遮罩圖像？

Question

我想掩蓋的圖像像這樣的代碼：

CGFloat plx = inputImage.size.width/_imageView.frame.size.width; 
CGFloat ply = inputImage.size.height/_imageView.frame.size.height; 

CGFloat radius = MIN(_postionView.frame.size.width * plx, _postionView.frame.size.height * ply)/1.5; 

CIVector *cen = [CIVector vectorWithX:_postionView.center.x * plx Y:_postionView.center.y * ply]; 

CIFilter *radialGradient = [CIFilter filterWithName:@"CIRadialGradient" keysAndValues: 
          @"inputRadius0", [NSNumber numberWithFloat:radius], 
          @"inputRadius1", [NSNumber numberWithFloat:radius + 1.0f], 
          @"inputColor0", [CIColor colorWithRed:0.0 green:1.0 blue:0.0 alpha:1.0], 
          @"inputColor1", [CIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:1.0], 
          @"inputCenter", cen, 
          nil]; 

CIImage *circleImage = [radialGradient valueForKey:kCIOutputImageKey]; 

_postionView是我的UIImageView。它沒有得到正確的位置。我猜這是因爲uikit座標系和石英不同的座標系。有任何想法嗎？

Answer 1

已經解決了，下面是解決代碼：

CGPoint touchPoint = [touch locationInView:self.view]; 
ScaleX = _imageView.image.size.width/self.view.frame.size.width; 
ScaleY = _imageView.image.size.height/self.view.frame.size.height; 

CGFloat imgX; 
CGFloat imgY; 

imgX = touchPoint.x * ScaleX; 
imgY = _imageView.image.size.height - touchPoint.y * ScaleY; 

VICPoint = CGPointMake(imgX, imgY); 

CIImage *maskImage = nil; 
CIVector *cen; 

cen = [CIVector vectorWithX:VICPoint.x Y:VICPoint.y]; 
CGFloat radius = MIN(80 * ScaleX, 80 * ScaleY)/1.5; 

CIFilter *radialGradient = [CIFilter filterWithName:@"CIRadialGradient" keysAndValues: 
          @"inputRadius0", [NSNumber numberWithFloat:radius], 
          @"inputRadius1", [NSNumber numberWithFloat:radius + 1.0f], 
          @"inputColor0", [CIColor colorWithRed:0.0 green:1.0 blue:0.0 alpha:1.0], 
          @"inputColor1", [CIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:1.0], 
          @"inputCenter", cen, 
          nil]; 

CIImage *circleImage = [radialGradient valueForKey:kCIOutputImageKey];