Xamarin iOS相机和照片 [英] Xamarin iOS camera and photos
问题描述
我正在使用iOS相机拍照,并尝试从图像中提取元数据.这是我的代码:-
I am taking a picture with the iOS camera and trying to extract metadata from the image. This is my code:-
partial void BtnCamera_TouchUpInside(UIButton sender)
{
UIImagePickerController imagePicker = new UIImagePickerController();
imagePicker.PrefersStatusBarHidden();
imagePicker.SourceType = UIImagePickerControllerSourceType.Camera;
// handle saving picture and extracting meta-data from picture //
imagePicker.FinishedPickingMedia += Handle_FinishedPickingMedia;
// present //
PresentViewController(imagePicker, true, () => { });
}
protected void Handle_FinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs e)
{
try
{
// determine what was selected, video or image
bool isImage = false;
switch (e.Info[UIImagePickerController.MediaType].ToString())
{
case "public.image":
isImage = true;
break;
}
// get common info
NSUrl referenceURL = e.Info[new NSString("UIImagePickerControllerReferenceURL")] as NSUrl;
if (referenceURL != null)
Console.WriteLine("Url:" + referenceURL.ToString());
我可以启动相机,拍照,然后单击使用照片" ... referenceURL返回为NULL ...如何获取URL,以便提取GPS的坐标照片和其他这样的属性?
I am able to initiate the camera, take the picture and then however when I click 'use photo'... The referenceURL comes back as NULL... How can I get the url, such that to extract GPS coordinates of the photo and such other attributes ?
推荐答案
您可以从参考URL请求PHAsset
,其中将包含一些元数据.您可以请求图像数据以获得更多.
You can request a PHAsset
from the reference Url and that will contain some metadata. You can request the image data to obtain more.
注意:如果需要完整的EXIF,则需要检查以确保设备上的图像(可能是基于iCloud的图像),如果需要,请下载它,然后使用ImageIO
框架(很多)加载图像数据. SO帖子数量涵盖了这一点.)
Note: If you need full EXIF, you need to check to ensure the image on on the device (could be iCloud-based), download it if needed, and then load the image data with the ImageIO
framework (lots of SO postings cover this).
public void ImagePicker_FinishedPickingMedia(object sender, UIImagePickerMediaPickedEventArgs e)
{
void ImageData(PHAsset asset)
{
if (asset == null) throw new Exception("PHAsset is null");
PHImageManager.DefaultManager.RequestImageData(asset, null, (data, dataUti, orientation, info) =>
{
Console.WriteLine(data);
Console.WriteLine(info);
});
}
PHAsset phAsset;
if (e.ReferenceUrl == null)
{
e.OriginalImage?.SaveToPhotosAlbum((image, error) =>
{
if (error == null)
{
var options = new PHFetchOptions
{
FetchLimit = 1,
SortDescriptors = new[] { new NSSortDescriptor("creationDate", true) }
};
phAsset = PHAsset.FetchAssets(options).FirstOrDefault() as PHAsset;
ImageData(phAsset);
}
});
}
else
{
phAsset = PHAsset.FetchAssets(new[] { e.ReferenceUrl }, null).FirstOrDefault() as PHAsset;
ImageData(phAsset);
}
}
注意:请确保您已请求运行时照片库授权PHPhotoLibrary.RequestAuthorization
),并已在info.plist中设置了Privacy - Photo Library Usage Description
字符串,以避免造成严重的隐私崩溃
Note: Make sure you have request runtime photo library authorization PHPhotoLibrary.RequestAuthorization
) and have set the Privacy - Photo Library Usage Description
string in your info.plist to avoid a nasty privacy crash
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