1

我正在开发一个裁剪图像的应用程序。我正在使用以下代码来调用裁剪方法:

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

这是该方法的代码:

{
    //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;
}

问题是当我将此图像设置为 UIImageView 时,我发现返回的图像向左旋转。我不能让它旋转起来。任何人都可以知道这个问题吗?

4

2 回答 2

2

Uiimage 有一个imageOrientation属性,在某些情况下指示系统应该显示图像位的方式。尝试记录该值并查看。如果它像我怀疑的那样,那么您可能需要调整您的裁剪算法,首先创建一个 CGImage,然后使用 UIImage 方法从中制作一个具有方向参数的 UIImage。

于 2013-04-21T12:30:36.837 回答
1

正如大卫所写,问题很可能是您没有保留imageOrientation属性。您的代码的问题还在于您不保留比例属性。尝试像这样创建裁剪的图像:

CGImageRef croppedRef = CGBitmapContextCreateImage(currentContext);
UIImage* cropped = [UIImage imageWithCGImage:croppedRef scale:imageToCrop.scale orientation:imageToCrop.imageOrientation];
CGImageRelease(croppedRef);
于 2013-04-21T12:42:16.490 回答