问题描述

剪裁图片导致图片向左旋转

做了一个剪裁图片的程序，调用剪裁：

UIImage* croppedImage = [self imageCrop:imageView toRect:CGRectMake(10.0 50.0 320 100)];

方法：

{    //create a context to do our clipping in    CGRect newRect = CGRectApplyAffineTransform(rect imageViewToCrop.transform);    UIImage *imageToCrop = imageViewToCrop.image;    UIGraphicsBeginImageContext(newRect.size);    CGContextRef currentContext = UIGraphicsGetCurrentContext();    //create a rect with the size we want to crop the image to    //the X and Y here are zero so we start at the beginning of our    //newly created context    CGRect clippedRect = CGRectMake(0 0 rect.size.width rect.size.height);    CGContextClipToRect( currentContext clippedRect);    //draw the image to our clipped context using our offset rect    CGContextDrawImage(currentContext newRect imageToCrop.CGImage);    //pull the image from our cropped context    UIImage *cropped = UIGraphicsGetImageFromCurrentImageContext();    //pop the context to get back to the default    UIGraphicsEndImageContext();    return cropped;}

设置图片到UIImageview的时候，图片向左旋转了。而且我也没办法让他向上旋转，怎么办？

解决方案

如楼上所说的可能是imageOrientation属性的问题。并且你也没有正确保存scale。这样创建剪裁的图片：

CGImageRef croppedRef = CGBitmapContextCreateImage(currentContext);UIImage* cropped = [UIImage imageWithCGImage:croppedRef scale:imageToCrop.scale orientation:imageToCrop.imageOrientation];CGImageRelease(croppedRef);

解决方案二：
UIImage有一个imageOrientation 属性，在某些情况下指示系统应该显示图片的方法，记录一下这个值。如果我猜的正确，应该调整剪裁算法，先创建一个CGImage，然后使用UIImage方法来进行方向参数的相关实现。