A simplest OCR in android JUnit

• Implement com.rmtheis:tess-two

androidTestImplementation 'com.rmtheis:tess-two:6.0.4'

• Take Bitmap screenshot

# In this case, I only need the top left corner of the screen
// private static UiAutomation uiAutomation = InstrumentationRegistry.getInstrumentation().getUiAutomation();
Bitmap takeBmpScreenshot() {
  Bitmap bmp = uiAutomation.takeScreenshot();
  return Bitmap.createBitmap(bmp, 0, 0, bmp.getWidth() / 2, bmp.getHeight() / 2);
}

• Download language data

In my case, I'm working on English text recognition

Please refer to English related OCR file.

• Push related file to the target device:

Note

1. File location MUST contains a tessdata subfolder.

// public class TessBaseAPI
File tessdata = new File(datapath + "tessdata");
if (!tessdata.exists() || !tessdata.isDirectory()) {
  throw new IllegalArgumentException("Data path must contain subfolder tessdata!");
}

2. If the file is in the external storage, remember to request the permission.

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

/sdcard/Temp/tessdata/eng.traineddata

• Generate a method to return the recognized string from the bitmap

String getOCRResult(Bitmap bmp) {
  TessBaseAPI mTess = new TessBaseAPI();
  String data = "/sdcard/Temp/";
  mTess.init(data, "eng");
  mTess.setImage(bmp);
  return mTess.getUTF8Text();
}

Pay attention to mTess.init(data, "eng");.

1. If you want to put the related file to /sdcard/Temp/, make a folder tessdata under /sdcard/Temp/, /sdcard/Temp/tessdata/.
   At last, put the file in that folder, /sdcard/Temp/tessdata/eng.traineddata.
   And the first parameter is /sdcard/Temp/.
2. If targeted at English, the second parameter is eng.

• Apply the method

Bitmap bmp = takeBmpScreenshot();
String recognition = getOCRResult(bmp);