图像裁剪问题

Question

我已经编写了下面的代码来裁剪椭圆形图像。但没有得到预期的结果。原始图像大小是382x453。并在CGRectMake（50,100,100,150）上进行日食。但图像总是从原始图像的0,0位置裁剪。我在这段代码中做了许多事情。请帮我解决我错在哪里。非常感谢，Ghufran

CGSize croppedSize = CGSizeMake(100, 150); 
CGRect clippedRect = CGRectMake(0, 0, croppedSize.width, croppedSize.height); 
UIGraphicsBeginImageContext(croppedSize); 
CGContextBeginPath(UIGraphicsGetCurrentContext()); 
CGContextAddEllipseInRect(UIGraphicsGetCurrentContext(), clippedRect); 
CGContextClosePath(UIGraphicsGetCurrentContext()); 
CGContextClip(UIGraphicsGetCurrentContext()); 
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), 0, croppedSize.height); 
CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0); 
CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(clippedRect.origin.x * -1, clippedRect.origin.y * -1, mImage.size.width, mImage.size.height), mImage.CGImage); 
//pull the image from our cropped context 
UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext(); 

Answer 1

我认为原点（50,100）需要反映在resedRect的矩形中。

CGRect clippedRect = CGRectMake(0, 0, croppedSize.width, croppedSize.height); 

成为

CGRect clippedRect = CGRectMake(50, 100, croppedSize.width, croppedSize.height);