Step-by-Step tutorial to build an android application which reads text from an image like OCR, using Google Vision API

 

Step 1:- Create a new Project.

Step 2:- Add the following dependency in module-level build.gradle file:-

compile 'com.google.android.gms:play-services-vision:9.8.0'

Step 3:- Set the style in styles.xml present in values folder of res folder,

style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar"

Step 4:- Add meta-data to AndroidManifest.xml,

<meta-data
    android:name="com.google.android.gms.vision.DEPENDENCIES"
    android:value="orc"/>

Step 5:- Now Design the layout in activity_main.xml,

<?xml version="1.0" encoding="utf-8"?>
<ScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:android="http://schemas.android.com/apk/res/android" >
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.himalayabhagwani.textrecognitionimage.MainActivity">

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="400dp"
        android:id="@+id/image_view"
        android:scaleType="centerInside"
        android:layout_alignParentTop="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_below="@+id/image_view"
        android:layout_marginTop="15dp"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:id="@+id/btnProcess"
        android:scaleType="centerInside"
        android:text="PROCESS"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/txtResult"
        android:text="No Text"
        android:textSize="24sp"
        android:gravity="center"
        android:layout_below="@+id/btnProcess"
        android:layout_centerHorizontal="true" />


</RelativeLayout>
</ScrollView>

Step 6:- Now write the code in MainActivity.java,

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseArray;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.google.android.gms.vision.Frame;
import com.google.android.gms.vision.text.TextBlock;
import com.google.android.gms.vision.text.TextRecognizer;

public class MainActivity extends AppCompatActivity {

    ImageView imageView;
    Button btnProcess;
    TextView txtResult;

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

        imageView = (ImageView) findViewById(R.id.image_view);
        btnProcess = (Button) findViewById(R.id.btnProcess);
        txtResult = (TextView) findViewById(R.id.txtResult);

        final Bitmap bitmap = BitmapFactory.decodeResource(getApplicationContext().getResources(),R.drawable.imp);
        imageView.setImageBitmap(bitmap);

        btnProcess.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                TextRecognizer textRecognizer = new TextRecognizer.Builder(getApplicationContext()).build();
                if (!textRecognizer.isOperational())
                    Log.e("ERROR","Detector dependencies are not yet available");
                else {
                    Frame frame = new Frame.Builder().setBitmap(bitmap).build();
                    SparseArray<TextBlock> items = textRecognizer.detect(frame);
                    StringBuilder stringBuilder =  new StringBuilder();
                    for(int i=0;i<items.size();i++)
                    {
                        TextBlock item = items.valueAt(i);
                        stringBuilder.append(item.getValue());
                        stringBuilder.append("\n");
                    }
                    txtResult.setText(stringBuilder.toString());
                }
            }
        });

    }

}