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  • iOS 解决图片方向不正常的问题

    + (UIImage *)fixOrientation:(UIImage *)aImage {

    // 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;

    switch (aImage.imageOrientation) {
    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;
    default:
    break;
    }

    switch (aImage.imageOrientation) {
    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;
    default:
    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/yu0806/p/5049107.html
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