iOS开发- 相机摄像头获取到的图片自动旋转90度解决办法

╰+哭是因爲堅強的太久メ 2022-03-17 09:48 515阅读 0赞

分享一下我老师大神的人工智能教程。零基础！通俗易懂！风趣幽默！还带黄段子！希望你也加入到我们人工智能的队伍中来！[https://blog.csdn.net/jiangjunshow][https_blog.csdn.net_jiangjunshow]

今天写demo的时候发现, 如果把通过相机获取到的图片，直接进行操作, 比如裁剪, 缩放, 则会把原图片向又旋转90度。

刚开始觉得[莫名其妙][Link 1], [不知所措][Link 2]。 后来[百度][Link 3]了一下，找到了解决办法。

ps: 查找过程中, 碰到了一种说法:

//get original photo from iOS photos //如果该图片大于2M，会自动旋转90度；否则不旋转UIImage* originalImg=[dict objectForKey:UIImagePickerControllerOriginalImage];

至于是否正确, 还没确定。 先Mark。

下面的解决办法亲测可行。 原文:http://www.cnblogs.com/jiangyazhou/archive/2012/03/22/2412343.html

用相机拍摄出来的照片含有EXIF信息，UIImage的imageOrientation属性指的就是EXIF中的orientation信息。  
如果我们忽略orientation信息，而直接对照片进行像素处理或者drawInRect等操作，得到的结果是翻转或者旋转90之后的样子。这是因为我们执行像素处理或者drawInRect等操作之后，imageOrientaion信息被删除了，imageOrientaion被重设为0，造成照片内容和imageOrientaion不匹配。  
所以，在对照片进行处理之前，先将照片旋转到正确的方向，并且返回的imageOrientaion为0。  
下面这个方法就是一个UIImage category中的方法，用它可以达到以上目的。

- (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;}

[https_blog.csdn.net_jiangjunshow]: https://blog.csdn.net/jiangjunshow/article/details/77338485
[Link 1]: https://www.baidu.com/s?wd=%E8%8E%AB%E5%90%8D%E5%85%B6%E5%A6%99&tn=24004469_oem_dg&rsv_dl=gh_pl_sl_csd
[Link 2]: https://www.baidu.com/s?wd=%E4%B8%8D%E7%9F%A5%E6%89%80%E6%8E%AA&tn=24004469_oem_dg&rsv_dl=gh_pl_sl_csd
[Link 3]: https://www.baidu.com/s?wd=%E7%99%BE%E5%BA%A6&tn=24004469_oem_dg&rsv_dl=gh_pl_sl_csd