img标签加载src图片，图片逆时针旋转了90度，解决方案
问题描述：
手机头像上传，遇到一个怪现象，就是拍照上传时，手机端显示头像正常，但在web端查看会有一个左旋90度的问题。
并且照片竖怕才会有此问题，横拍不存在。
原因分析：
手机拍照时，用相机拍摄出来的照片是含有EXIF信息的，在我们得到 UIImage时，可以查看此Image的imageOrientation属性，其实就是指的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上传等操作，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，保证返回的imageOrientaion为0。
//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];
原文：https://blog.csdn.net/hitwhylz/article/details/39518463
解决方法：
Swift版：
/**
照片竖拍 web显示旋转解决:图片大于2M会自动旋转90度
- parameter aImage: <#aImage description#>
- returns: <#return value description#>
*/
class func fixOrientation(aImage:UIImage)->UIImage {
if aImage.imageOrientation == UIImageOrientation.Up{
return aImage
}
var transform = CGAffineTransformIdentity
switch (aImage.imageOrientation) {
case .Down,.DownMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, aImage.size.height)
transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
break;
case .Left,.LeftMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, 0)
transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
break;
case .Right,.RightMirrored:
transform = CGAffineTransformTranslate(transform, 0, aImage.size.height)
transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
break;
default:
break;
}
switch (aImage.imageOrientation) {
case .UpMirrored,.DownMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.width, 0)
transform = CGAffineTransformScale(transform, -1, 1)
break;
case .LeftMirrored,.RightMirrored:
transform = CGAffineTransformTranslate(transform, aImage.size.height, 0)
transform = CGAffineTransformScale(transform, -1, 1)
break;
default:
break;
}
let ctx:CGContextRef = CGBitmapContextCreate(nil, Int(aImage.size.width), Int(aImage.size.height),
CGImageGetBitsPerComponent(aImage.CGImage), 0,
CGImageGetColorSpace(aImage.CGImage),
1)!
CGContextConcatCTM(ctx, transform)
switch (aImage.imageOrientation) {
case .Left,.LeftMirrored,.Right,.RightMirrored:
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;
}
let cgimg:CGImageRef = CGBitmapContextCreateImage(ctx)!
let img:UIImage = UIImage(CGImage: cgimg)
return img;
}OC版：
- (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;
}
在完成拍照代理里，获取到图片后，用此方法处理后，再上传服务器，可解决该问题。
//若是图片
var img:UIImage = info[UIImagePickerControllerOriginalImage] as! UIImage
//保存相册
UIImageWriteToSavedPhotosAlbum(img, self, nil, nil)
img = PublicMethod.fixOrientation(img)
//压缩图片
let imgData:NSData = UIImageJPEGRepresentation(img, 0.2)!
//上传服务器
self.uploadHeadImg(imgData, headImage: img)