今天开发一个拍照获取照片的功能的时候, 发现上传之后图片会自动旋转90.
测试发现, 只要是图片大于2M, 系统就会自动翻转照片
相机拍照后直接取出来的UIimage（用UIImagePickerControllerOriginalImage取出），它本身的imageOrientation属性是3，即UIImageOrientationRight。如果这个图片直接使用则没事，但是如果对它进行裁剪、缩放等操作后，它的这个imageOrientation属性会变成0。此时这张图片用在别的地方就会发生旋转。imageOrientation是只读的，不能直接修改其值。
解决方法如下:
1. 设置相机的一个属性allowsEditing为YES，设了这个值，你拍完照片后会在照片上出现一个框框，这就是对照片的裁剪编辑。在相机的代理方法中取照片的时候就别用UIImagePickerControllerOriginalImage来取了，要用UIImagePickerControllerEditedImage。用这个key取出来的照片，它的imageOrientation是0，所以之后的任何裁剪、缩放操作都不会造成旋转。这是第一种方法。
2. 第一种解决方法基本没用, 开发中基本都会对图片进行裁剪和压缩. 这里有一个专门针对这个事的很好的category
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+ (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) { caseUIImageOrientationDown: caseUIImageOrientationDownMirrored: transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height); transform = CGAffineTransformRotate(transform, M_PI); break; caseUIImageOrientationLeft: caseUIImageOrientationLeftMirrored: transform = CGAffineTransformTranslate(transform, aImage.size.width,0); transform = CGAffineTransformRotate(transform, M_PI_2); break; caseUIImageOrientationRight: caseUIImageOrientationRightMirrored: transform = CGAffineTransformTranslate(transform, 0, aImage.size.height); transform = CGAffineTransformRotate(transform, -M_PI_2); break; default: break; } switch (aImage.imageOrientation) { caseUIImageOrientationUpMirrored: caseUIImageOrientationDownMirrored: transform = CGAffineTransformTranslate(transform, aImage.size.width,0); transform = CGAffineTransformScale(transform, -1, 1); break; caseUIImageOrientationLeftMirrored: caseUIImageOrientationRightMirrored: 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) { caseUIImageOrientationLeft: caseUIImageOrientationLeftMirrored: caseUIImageOrientationRight: caseUIImageOrientationRightMirrored: // 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 = [UIImageimageWithCGImage:cgimg]; CGContextRelease(ctx); CGImageRelease(cgimg); return img;} |
以上所述是小编给大家介绍的iOS拍照后图片自动旋转90度的完美解决方法，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：http://blog.csdn.net/sharpyl/article/details/53855948
