public async Task <GeneralOcrResult> MatchOnCloudAsync(
string cloudEndpoint,
string cloudApiKey,
DeviceOcrResult deviceOcrResult,
TimeSpan timeBetweenCalls,
TimeSpan timeout)
{
GeneralOcrResult ocrResult = new GeneralOcrResult()
{
ResultType = OcrMatchResult.CloudCallFailed
};
if (deviceOcrResult.ResultType != OcrMatchResult.TimedOutCloudCallAvailable)
{
throw new InvalidOperationException();
}
var resultLocation = await SubmitBitmapToCloudGetResultLocationAsync(
cloudEndpoint, cloudApiKey, deviceOcrResult);
if (!string.IsNullOrEmpty(resultLocation))
{
ocrResult = await PollCloudResultLocation(resultLocation, cloudApiKey, timeBetweenCalls, timeout);
}
return(ocrResult);
}
async Task <GeneralOcrResult> PollCloudResultLocation(
string operationLocationUri,
string cloudApiKey,
TimeSpan timeBetweenCalls,
TimeSpan timeout)
{
GeneralOcrResult result = new GeneralOcrResult()
{
ResultType = OcrMatchResult.CloudCallTimedOut
};
var delayTask = Task.Delay(timeout);
using (var httpClient = new HttpClient())
{
httpClient.DefaultRequestHeaders[API_SUBSCRIPTION_KEY_HEADER] = cloudApiKey;
bool continuePolling = true;
while (!delayTask.IsCompleted && continuePolling)
{
// Note - some sort of delay between polling calls might be nice? :-)
var response = await httpClient.GetAsync(new Uri(operationLocationUri));
// Note that this API can return 'too many requests' and ask you to re-call
// in a number of seconds. Not sure what to do on that front.
if (response.IsSuccessStatusCode)
{
var jsonResponse = await response.Content.ReadAsStringAsync();
var jsonObject = JsonObject.Parse(jsonResponse);
switch (jsonObject[JSON_STATUS_VALUE].GetString())
{
case RECOGNITION_API_SUCCEEDED:
continuePolling = false;
result.MatchedText = this.ParseRecognitionServiceResponseForMatch(jsonObject);
result.ResultType =
string.IsNullOrEmpty(result.MatchedText) ? OcrMatchResult.CloudCallProducedNoMatch : OcrMatchResult.Succeeded;
break;
case RECOGNITION_API_RUNNING:
case RECOGNITION_API_NOT_STARTED:
break;
case RECOGNITION_API_FAILED:
result.ResultType = OcrMatchResult.CloudCallFailed;
break;
default:
break;
}
}
await Task.Delay(timeBetweenCalls);
}
}
return(result);
}