textRecognizer.detect(frame); it returns size as 0

Question

I am using google vision API and trying to get the text from the captured image. I have set the captured image in an image view and then I am trying to get the text from the image. but I am getting SparseArray of size 0. what can be the problem. Here is my java code.

    public class MainActivity extends AppCompatActivity {


    ImageView imgPic;
    TextView tvText;
    Button btnClick, btnCapture;
    private int REQUEST_IMAGE_CAPTURE = 1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imgPic = findViewById(R.id.img_pic);
        tvText = findViewById(R.id.tv_text);
        btnClick = findViewById(R.id.btn_click);
        btnCapture = findViewById(R.id.btn_capture);

        btnCapture.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
                if (takePictureIntent.resolveActivity(getPackageManager()) != null) {
                    startActivityForResult(takePictureIntent, REQUEST_IMAGE_CAPTURE);
                }


            }
        });


        btnClick.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

Bitmap bitmap;
 if (imgPic.getDrawable() != null && imgPic.getDrawable() instanceof BitmapDrawable) {
                bitmap = ((BitmapDrawable) imgPic.getDrawable()).getBitmap();
            }

                TextRecognizer textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();
                if (!textRecognizer.isOperational()) {

                    Toast.makeText(MainActivity.this, "could not get the text", Toast.LENGTH_SHORT).show();
                } else {
                    if (bitmap != null) {
                        Frame frame = new Frame.Builder().setBitmap(bitmap).build();
                        SparseArray<TextBlock> items = textRecognizer.detect(frame);
                        StringBuilder sb = new StringBuilder();
                        for (int i = 0; i < items.size(); i++) {
                            TextBlock myItem = items.valueAt(i);
                            Log.e("hello", (String) myItem.getValue());
                            sb.append(myItem.getValue());
                            sb.append("\n");

                        }

                        tvText.setText(sb.toString());
                    } else {
                        Toast.makeText(MainActivity.this, "returned null", Toast.LENGTH_SHORT).show();

                    }

                }
            }
        });


    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK) {
            Bundle extras = data.getExtras();
            Bitmap imageBitmap = (Bitmap) extras.get("data");
            imgPic.setImageBitmap(imageBitmap);


        }

    }
}

here is my main activity xml file.

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
    <Button
        android:id="@+id/btn_capture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="20dp"
        android:text="capture"
        />


    <ImageView
        android:id="@+id/img_pic"
        android:layout_width="370dp"
        android:layout_height="300dp" />

    <TextView
        android:textColor="@color/colorAccent"
        android:id="@+id/tv_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:textSize="25sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="click here"
        android:id="@+id/btn_click"/>
</LinearLayout>

The main thing is when i set image manually in an imageView it shows the result but when i capture the image by my self and then i try to get the text i am not getting the results i am always gets a 0 sized array.

Answer 1

Why don't you store the bitmap in a global variable? You can of course convert the drawable of an ImageView back to a bitmap but this requires extra ressources.

Anyway the answer to your question would be:

if(imgPic.getDrawable() != null && imgPic.getDrawable() instanceof BitmapDrawable) {
    Bitmap bitmap = ((BitmapDrawable)imgPic.getDrawable()).getBitmap();
}

You should check if the drawable is not null and if the bitmap stored inside the drawable is really of type BitmapDrawable.