Xsseract

This is a Xamarin based implmentation of an OCR app. I'm using the Tesseract engine for the actual OCR task (https://code.google.com/p/tesseract-ocr/).

The app has been published on the Google Play store at
https://play.google.com/store/apps/details?id=ro.onos.xsseract

The special bit about this implementation is that you can interact with it from other apps via the ro.onos.xsseract.ResolveImage intent. Because of what I think is a bug in either the Xamarin platform or in Android itself, when using the above intent you also need to specify a boolean extra, named PipeResult with a value of true (I'll investigate this later on).

When the user accepts the OCR result, the parsed text will be returned via the Result extra.

Example

To invoke the app:

Intent ocrIntent = new Intent(XsseractResolveImageIntent);
ocrIntent.PutExtra("PipeResult", true);
StartActivityForResult(ocrIntent, 2);

And to retrieve the result:

protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
  base.OnActivityResult(requestCode, resultCode, data);
  switch (requestCode)
  {
    ...
    case 2:
      if(resultCode == Result.Ok)
      {
        var result = data.GetStringExtra("Result");
        ...
      }
      break;
  }
}

Tested on

I'll add more to this list as soon as Insights data becomes available or people report their configurations.
https://github.com/marono/Xsseract/blob/master/TestedDevices.md

To contribute

The solution is currently missing two files for obvious reasons:

src\Xsseract.Droid\Assets\Settings.DEBUG.json

src\Xsseract.Droid\Assets\Settings.RELEASE.json

After downloading the files, you'll need to add them yourselves. The structure is as follows:

{
  "InsightsKey": "<value or empty to disable Xamarin Insights analytics>",
  "TessDataFiles": [
    { "culture": "en", "url": "file:///android_asset/tesseract-ocr-3.02.eng.tar.gz" }
  ],
  "TessOsdUrl": "file:///android_asset/tesseract-ocr-3.01.osd.tar.gz",
  "FeedbackEmailAddress": "<fill in only if using the feedback action>",
  "SuccessCountForRatingPrompt": 1
}

The SuccessCountForRatingPrompt value indicates how many successful parses the application will perform before asking the user to rate the app.

That's it!
Good luck cracking!