使用UIImagePickerControllerCropRect裁剪UIImagePickerControllerOriginalImage会返回不正确的图像

Question

我正在尝试编辑捕获的图像并将其保存到图库.我做了

UIImagePickerController *picker=[[UIImagePickerController alloc] init];
picker.allowsEditting=YES;

我想将图像保存在可编辑的方形部分并将其保存到图库.我知道我可以利用它[info objectForKey:@"UIImagePickerControllerEditedImage"]来保存编辑过的图像.但这总是让我看到尺寸为320x320(iPad Mini)的图像,图像质量很差.所以我打算[info objectForKey:@"UIImagePickerControllerOriginalImage"]使用以下代码裁剪原始图像:

CGRect rect = [[info objectForKey:@"UIImagePickerControllerCropRect"]CGRectValue];
UIImage *originalImage=[info objectForKey:@"UIImagePickerControllerOriginalImage"];
CGImageRef imageRef = CGImageCreateWithImageInRect([originalImage CGImage], rect);
UIImage *result = [UIImage imageWithCGImage:imageRef
                                      scale:originalImage.scale
                                orientation:originalImage.imageOrientation];
CGImageRelease(imageRef);

然后我保存了结果图像和编辑图像([info objectForKey:@"UIImagePickerControllerEditedImage"]).当比较两个图像时,它们匹配.我附加了编辑和裁剪的图像.我的最终目标是将原始图像裁剪为可编辑方形部分中的图像,并将其保存到具有良好图像质量的图库中.谁能告诉我这里到底出了什么问题并帮我解决这个问题？

提前致谢.

Answer 1

我在这里找到了裁剪出错的原因。UIImagePickerControllerOriginalImage 返回的图像旋转到-90 度。因此，在旋转图像上进行裁剪后，我返回了错误的裁剪图像。所以我将图像旋转90度，然后裁剪它。最后我得到了预期的质量好的裁剪图像。下面的代码解决了我的问题。

 UIImage *originalImage = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
    CGRect rect=[[info objectForKey:@"UIImagePickerControllerCropRect"]CGRectValue];
    UIImage *rotatedOriginalImage=[originalImage imageRotatedByDegrees:90.0];
    CGImageRef imageRef = CGImageCreateWithImageInRect([rotatedOriginalImage CGImage], rect) ;
    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];

旋转图像的代码：

- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees{
// calculate the size of the rotated view's containing box for our drawing space
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.height, self.size.width)];
CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;


// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();

// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);

//   // Rotate the image context
CGContextRotateCTM(bitmap, DegreesToRadians(degrees));

// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-self.size.height / 2, -self.size.width / 2, self.size.height, self.size.width), [self CGImage]);

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}