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  • 旋转图片

    #pragma mark 转换图片的方向
    + (UIImage *)fixOrientation:(UIImage *)aImage {
        if (aImage==nil || !aImage) {
            return nil;
        }
        // No-op if the orientation is already correct
        if (aImage.imageOrientation == UIImageOrientationUp) return aImage;
        
        // 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;
        UIImageOrientation orientation=aImage.imageOrientation;
        int orientation_=orientation;
        switch (orientation_) {
            case UIImageOrientationDown:
            case UIImageOrientationDownMirrored:
                transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height);
                transform = CGAffineTransformRotate(transform, M_PI);
                break;
                
            case UIImageOrientationLeft:
            case UIImageOrientationLeftMirrored:
                transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
                transform = CGAffineTransformRotate(transform, M_PI_2);
                break;
                
            case UIImageOrientationRight:
            case UIImageOrientationRightMirrored:
                transform = CGAffineTransformTranslate(transform, 0, aImage.size.height);
                transform = CGAffineTransformRotate(transform, -M_PI_2);
                break;
        }
        
        switch (orientation_) {
            case UIImageOrientationUpMirrored:{
                
            }
            case UIImageOrientationDownMirrored:
                transform = CGAffineTransformTranslate(transform, aImage.size.width, 0);
                transform = CGAffineTransformScale(transform, -1, 1);
                break;
                
            case UIImageOrientationLeftMirrored:
            case UIImageOrientationRightMirrored:
                transform = CGAffineTransformTranslate(transform, aImage.size.height, 0);
                transform = CGAffineTransformScale(transform, -1, 1);
                break;
        }
        
        // Now we draw the underlying CGImage into a new context, applying the transform
        // calculated above.
        CGContextRef ctx = CGBitmapContextCreate(NULL, aImage.size.width, aImage.size.height,
                                                 CGImageGetBitsPerComponent(aImage.CGImage), 0,
                                                 CGImageGetColorSpace(aImage.CGImage),
                                                 CGImageGetBitmapInfo(aImage.CGImage));
        CGContextConcatCTM(ctx, transform);
        switch (aImage.imageOrientation) {
            case UIImageOrientationLeft:
            case UIImageOrientationLeftMirrored:
            case UIImageOrientationRight:
            case UIImageOrientationRightMirrored:
                // Grr...
                CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.height,aImage.size.width), aImage.CGImage);
                break;
                
            default:
                CGContextDrawImage(ctx, CGRectMake(0,0,aImage.size.width,aImage.size.height), aImage.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;
    }
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  • 原文地址:https://www.cnblogs.com/mkai/p/7519764.html
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