Android の Camera2 API と Mobile Vision API を使って バーコードを検出する

    <!-- 顔検出のとき -->
        <meta-data
            android:name="com.google.android.gms.vision.DEPENDENCIES"
            android:value="face" />

    <!-- バーコード検出のとき -->
        <meta-data
            android:name="com.google.android.gms.vision.DEPENDENCIES"
            android:value="barcode" />

  MultiProcessor<Barcode> processor

  BarcodeDetector barcodeDetector = new BarcodeDetector.Builder(this).build();

  barcodeDetector.setProcessor( processor );

    Barcode best = null;
    float bestDistance = Float.MAX_VALUE;
     for (BarcodeGraphic graphic : graphicOverlay.getGraphics()) {
            Barcode barcode = graphic.getBarcode();
            if (barcode.getBoundingBox().contains((int) x, (int) y)) {
                best = barcode;
                break;
            }
            float dx = x - barcode.getBoundingBox().centerX();
            float dy = y - barcode.getBoundingBox().centerY();
            float distance = (dx * dx) + (dy * dy);  
            if (distance < bestDistance) {
                best = barcode;
                bestDistance = distance;
            }
    }