IOS图片旋转问题处理

@interface UIImage (fixOrientation)- (UIImage *)fixOrientation;@end

@implementation UIImage (fixOrientation)- (UIImage *)fixOrientation { // No-op if the orientation is already correct if (self.imageOrientation == UIImageOrientationUp) return self; // We need to calculate the proper transformation to make the image upright. // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored. CGAffineTransform transform = CGAffineTransformIdentity; switch (self.imageOrientation) { case UIImageOrientationDown: case UIImageOrientationDownMirrored: transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height); transform = CGAffineTransformRotate(transform, M_PI); break; case UIImageOrientationLeft: case UIImageOrientationLeftMirrored: transform = CGAffineTransformTranslate(transform, self.size.width, 0); transform = CGAffineTransformRotate(transform, M_PI_2); break; case UIImageOrientationRight: case UIImageOrientationRightMirrored: transform = CGAffineTransformTranslate(transform, 0, self.size.height); transform = CGAffineTransformRotate(transform, -M_PI_2); break; case UIImageOrientationUp: case UIImageOrientationUpMirrored: break; } switch (self.imageOrientation) { case UIImageOrientationUpMirrored: case UIImageOrientationDownMirrored: transform = CGAffineTransformTranslate(transform, self.size.width, 0); transform = CGAffineTransformScale(transform, -1, 1); break; case UIImageOrientationLeftMirrored: case UIImageOrientationRightMirrored: transform = CGAffineTransformTranslate(transform, self.size.height, 0); transform = CGAffineTransformScale(transform, -1, 1); break; case UIImageOrientationUp: case UIImageOrientationDown: case UIImageOrientationLeft: case UIImageOrientationRight: break; } // Now we draw the underlying CGImage into a new context, applying the transform // calculated above. CGContextRef ctx = CGBitmapContextCreate(NULL, self.size.width, self.size.height, CGImageGetBitsPerComponent(self.CGImage), 0, CGImageGetColorSpace(self.CGImage), CGImageGetBitmapInfo(self.CGImage)); CGContextConcatCTM(ctx, transform); switch (self.imageOrientation) { case UIImageOrientationLeft: case UIImageOrientationLeftMirrored: case UIImageOrientationRight: case UIImageOrientationRightMirrored: // Grr... CGContextDrawImage(ctx, CGRectMake(0,0,self.size.height,self.size.width), self.CGImage); break; default: CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.CGImage); break; } // And now we just create a new UIImage from the drawing context CGImageRef cgimg = CGBitmapContextCreateImage(ctx); UIImage *img = [UIImage imageWithCGImage:cgimg]; CGContextRelease(ctx); CGImageRelease(cgimg); return img;}@end