我从画廊拍摄图像并使用CGAffineTransform应用缩放,旋转和反转变换。最后,我将图像保存到图库。但是保存的图像有白色矩形边界![带有白色背景的旋转UIImageView] [1]。
- (UIImage *)getTheTransformedOriginalImage:(UIImage *)aTransImage
{
CGAffineTransform transform = selImageView.transform;
CGPathRef rotatedImageRectPath = CGPathCreateWithRect(selImageView.frame, &transform);
CGRect boundingBox = CGPathGetBoundingBox(rotatedImageRectPath);
CGSize rotatedSize = boundingBox.size;
UIGraphicsBeginImageContext(rotatedSize);
UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, 0.0f);
// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(UIGraphicsGetCurrentContext(), rotatedSize.width/2, rotatedSize.height/2);
//Rotate the image context using tranform
CGContextConcatCTM(UIGraphicsGetCurrentContext(), selImageView.transform);
// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(UIGraphicsGetCurrentContext(), 1.0, -1.0);
CGContextDrawImage(UIGraphicsGetCurrentContext(), CGRectMake(-aTransImage.size.width / 2, -aTransImage.size.height / 2, aTransImage.size.width, aTransImage.size.height), [aTransImage CGImage]);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
- (IBAction)saveToGalleryClicked:(id)sender
{
UIImage *aTransImage = selImageView.image;
UIImage *shareImage = [self getTheTransformedOriginalImage:aTransImage]
UIImageWriteToSavedPhotosAlbum(shareImage, nil, nil, nil);
}
我在附件中添加了旋转的UIImage。
答案 0 :(得分:0)
为了不具有白色背景(即不透明图像),您需要使用不同的功能来开始图像上下文:
UIGraphicsBeginImageContextWithOptions(CGSize size, **BOOL opaque**, CGFloat scale)
所以,替换:
UIGraphicsBeginImageContext(rotatedSize);
使用:
UIGraphicsBeginImageContextWithOptions(rotatedSize, NO, [[UIScreen mainScreen]scale])
这将确保以透明度绘制上下文。