Android Paper Integration

1. Implement RecognizerCallback

RecognizerCallback delivers scan results and error events:

public interface RecognizerCallback {
    // Called when scanning is complete and results are ready.
    void onRecognizerDone(@NonNull ScanResults results, Media media);

    // Called if an exception occurs while processing a frame.
    void onRecognizerException(@NonNull Throwable e);

    // Called each time an intermediate result is produced during scanning.
    void onRecognizerResultsChanged(@NonNull RecognizerResult result);
}

Intermediate Result Types

onRecognizerResultsChanged fires throughout the scan session. Cast the RecognizerResult to the specific type you need:

Preliminary results — partial data before the scan ends:

@Override
public void onRecognizerResultsChanged(@NonNull RecognizerResult result) {
    if (result instanceof PreliminaryResult) {
        PreliminaryResult preliminary = (PreliminaryResult) result;
        // Use partial receipt data
    }
}

Raw OCR results:

@Override
public void onRecognizerResultsChanged(@NonNull RecognizerResult result) {
    if (result instanceof OcrRawResult) {
        OcrRawResult ocrRawResult = (OcrRawResult) result;
    }
}

Edge detection results — frame quality feedback:

@Override
public void onRecognizerResultsChanged(@NonNull RecognizerResult result) {
    if (result instanceof EdgeDetectionResult) {
        EdgeDetectionResult edges = (EdgeDetectionResult) result;
        // edges.contentPercent — how much of the frame the receipt fills
        // edges.state — ABOVE_THRESHOLD, BELOW_THRESHOLD, etc.
    }
}

Edge detection states:

State	Meaning
ABOVE_THRESHOLD	Receipt fills at least the configured minimum percentage of the frame
BELOW_THRESHOLD	Receipt is too small in the frame
CONSECUTIVE_ABOVE_THRESHOLD_LIMIT_REACHED	N consecutive frames above threshold — ready to capture
CONSECUTIVE_BELOW_THRESHOLD_LIMIT_REACHED	N consecutive frames below threshold

Camera Callback

If you are using RecognizerView (custom UI), also implement CameraRecognizerCallback:

public interface CameraRecognizerCallback {
    // Called when a captured frame is saved to disk.
    void onConfirmPicture(@NonNull File file);

    // Called when camera permission is denied.
    void onPermissionDenied();

    void onPreviewStarted();
    void onPreviewStopped();
    void onException(@NonNull Throwable throwable);
}

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2. RecognizerView (Custom Camera UI)

RecognizerView gives you a camera preview surface you can embed in any layout. It manages its own internal state, but you must forward activity lifecycle events to it:

@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    recognizerView.create();
}

@Override
public void onStart() {
    super.onStart();
    recognizerView.start();
}

@Override
public void onResume() {
    super.onResume();
    recognizerView.resume();
}

@Override
public void onPause() {
    super.onPause();
    recognizerView.pause();
}

@Override
public void onStop() {
    super.onStop();
    recognizerView.stop();
}

@Override
public void onDestroy() {
    super.onDestroy();
    recognizerView.destroy();
}

Initializing the View

Before use, call initialize(ScanOptions scanOptions) with your scan configuration.

Capturing Frames

recognizerView.takePicture(cameraCaptureListener);

The listener receives a BitmapResult. Once the user confirms the frame:

recognizerView.confirmPicture(bitmapResult);

Confirmed frames are written to disk and returned via the Media object in onRecognizerDone.

Finishing a Scan

recognizerView.finishedScanning();

This compiles and finalizes results, delivering them through onRecognizerDone(ScanResults results, Media media). All RecognizerCallback methods are invoked on the main thread.

To cancel mid-scan:

recognizerView.terminate();

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3. AndroidManifest Keys

Add optional service keys to AndroidManifest.xml inside the <application> element:

Product Intelligence — enriches receipt line items with product data:

<meta-data
    android:name="com.microblink.ProductIntelligence"
    android:value="YOUR_PRODUCT_INTELLIGENCE_KEY" />

Google Places — merchant location enrichment:

<meta-data
    android:name="com.microblink.GooglePlacesKey"
    android:value="YOUR_GOOGLE_PLACES_KEY" />

Yelp — merchant data enrichment:

<meta-data
    android:name="com.microblink.YelpKey"
    android:value="YOUR_YELP_KEY" />

Client User ID — associates scan sessions with your user identifiers:

<meta-data
    android:name="com.microblink.ClientUserId"
    android:value="YOUR_CLIENT_USER_ID" />