图像裁剪问题

Question

我写了以下用于裁剪椭圆形图像的代码。但没有得到预期的结果。原始图像大小为382x453。并在CGRectMake（50,100,100,150）进行日食。但是图像始终从原始图像的0,0位置进行裁剪。我在这段代码中做了一些事情。请帮帮我，我错了。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clippedRect的rect make中。

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

变为

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