public async void GetEXIFAsync(string photoId)
{
if (IsGettingEXIFInfo(photoId))
return;
exifQueue.Add(photoId);
string timestamp = DateTimeUtils.GetTimestamp();
string nonce = Guid.NewGuid().ToString().Replace("-", null);
Dictionary<string, string> paramDict = new Dictionary<string, string>();
paramDict["method"] = "flickr.photos.getExif";
paramDict["format"] = "json";
paramDict["nojsoncallback"] = "1";
paramDict["oauth_consumer_key"] = consumerKey;
paramDict["oauth_nonce"] = nonce;
paramDict["oauth_signature_method"] = "HMAC-SHA1";
paramDict["oauth_timestamp"] = timestamp;
paramDict["oauth_token"] = AccessToken;
paramDict["oauth_version"] = "1.0";
paramDict["photo_id"] = photoId;
paramDict["extras"] = UrlHelper.Encode(commonExtraParameters);
string paramString = GenerateParamString(paramDict);
string signature = GenerateSignature("GET", AccessTokenSecret, "https://api.flickr.com/services/rest", paramString);
string requestUrl = "https://api.flickr.com/services/rest?" + paramString + "&oauth_signature=" + signature;
HttpWebResponse response = await DispatchRequest("GET", requestUrl, null).ConfigureAwait(false);
using (StreamReader reader = new StreamReader(response.GetResponseStream()))
{
if(exifQueue.Contains(photoId))
exifQueue.Remove(photoId);
GetEXIFExceptionEventArgs exceptionArgs = null;
if (response.StatusCode != HttpStatusCode.OK)
{
exceptionArgs = new GetEXIFExceptionEventArgs();
exceptionArgs.PhotoId = photoId;
EXIFException.DispatchEvent(this, exceptionArgs);
return;
}
string jsonString = await reader.ReadToEndAsync().ConfigureAwait(false);
if (!IsResponseSuccess(jsonString))
{
exceptionArgs = new GetEXIFExceptionEventArgs();
exceptionArgs.PhotoId = photoId;
EXIFException.DispatchEvent(this, exceptionArgs);
return;
}
GetEXIFEventArgs args = new GetEXIFEventArgs();
args.PhotoId = photoId;
args.Response = jsonString;
EXIFReturned.DispatchEvent(this, args);
}
}
private void OnEXIFException(object sender, GetEXIFExceptionEventArgs e)
{
Dispatcher.BeginInvoke(() =>
{
if (e.PhotoId != PhotoSource.ResourceId)
return;
LoadingView.Visibility = Visibility.Collapsed;
DescriptionLabel.Visibility = Visibility.Visible;
DescriptionLabel.Text = AppResources.DetailPageLoadEXIFErrorText;
});
}