[英]Camera image changes orientation
我一直试图将相机图像从iPhone上传到我的网络服务器,但有些图像是如何在病房后改变它的方向。 这只发生在相机图像上,而不是从我的机器上传到设备的简单图像。
以下是代码:
NSData *imgdataRepresentation = UIImageJPEGRepresentation(imgTemp, 0.5);
///////**********************************************
// setting up the URL to post to
NSString *addPhotoURL = [NSString stringWithFormat:@"%@%@%@",HTTP_HOST,ADD_PHOTO_URL,[userInfo.userDetail objectForKey:@"id"]];
// setting up the request object now
NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
[request setURL:[NSURL URLWithString:addPhotoURL]];
[request setHTTPMethod:@"POST"];
/*
add some header info now
we always need a boundary when we post a file
also we need to set the content type
You might want to generate a random boundary.. this is just the same
as my output from wireshark on a valid html post
*/
NSString *boundary = [NSString stringWithString:@"---------------------------14737809831466499882746641449"];
NSString *contentType = [NSString stringWithFormat:@"multipart/form-data; boundary=%@",boundary];
[request addValue:contentType forHTTPHeaderField: @"Content-Type"];
/*
now lets create the body of the post
*/
NSMutableData *body = [NSMutableData data];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithString:@"Content-Disposition: form-data; name=\"Album\"; filename=\"ipodfile.jpg\"\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[[NSString stringWithString:@"Content-Type: application/octet-stream\r\n\r\n"] dataUsingEncoding:NSUTF8StringEncoding]];
[body appendData:[NSData dataWithData:imgdataRepresentation ]];
[body appendData:[[NSString stringWithFormat:@"\r\n--%@--\r\n",boundary] dataUsingEncoding:NSUTF8StringEncoding]];
// setting the body of the post to the reqeust
[request setHTTPBody:body];
// now lets make the connection to the web
NSData *returnData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
NSString *returnString = [[NSString alloc] initWithData:returnData encoding:NSUTF8StringEncoding];
无论手机如何保存,iPhone图像始终以相同的方式存储,但EXIF数据中设置了一个标记,指定图像应该位于哪个方向。几乎所有本机OSX应用程序(如iPhoto和Preview)都可以读取此EXIF方向正确标记并自动旋转图像,但几乎所有Windows应用程序和Web浏览器都不考虑方向EXIF标记。 在保存之前,您必须手动旋转Web服务器上的图像。 我不知道您使用哪种Web服务器技术,但执行此操作的C#代码是:
public static void FixOrientation(this Image image)
{
// 0x0112 is the EXIF byte address for the orientation tag
if (!image.PropertyIdList.Contains(0x0112))
{
return;
}
// get the first byte from the orientation tag and convert it to an integer
var orientationNumber = image.GetPropertyItem(0x0112).Value[0];
switch (orientationNumber)
{
// up is pointing to the right
case 8:
image.RotateFlip(RotateFlipType.Rotate270FlipNone);
break;
// up is pointing to the bottom (image is upside-down)
case 3:
image.RotateFlip(RotateFlipType.Rotate180FlipNone);
break;
// up is pointing to the left
case 6:
image.RotateFlip(RotateFlipType.Rotate90FlipNone);
break;
// up is pointing up (correct orientation)
case 1:
break;
}
}
您可以使用imageOrientation方法获取UIImage的图像方向。 因此,例如,您想要保存从相机中拍摄的图像:
UIImage *image = [info objectForKey:UIImagePickerControllerOriginalImage];
if (image) {
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeImageToSavedPhotosAlbum:[image CGImage]
orientation:[image imageOrientation]
completionBlock:^(NSURL *assetURL, NSError *error){ /* error handling */ }];
[library autorelease];
}
然后当你想从库中获取UIImage时,可以通过执行以下操作来检索方向:
UIImage *image = [UIImage imageWithCGImage:[[asset defaultRepresentation] fullResolutionImage] scale:1.0 orientation:[asset orientation]];
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