Extract text from images

This post describes how to extract text from images using MLKIT.

In app level build.gradle add the mlkit dependency.

plugins {
    id 'com.android.application'
}

android {
    compileSdkVersion 30
    buildToolsVersion "30.0.3"

    defaultConfig {
        applicationId "com.example.pickfile"
        minSdkVersion 21
        targetSdkVersion 30
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
}

dependencies {
    implementation 'androidx.appcompat:appcompat:1.3.1'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.1'
    implementation 'com.google.android.gms:play-services-mlkit-text-recognition:17.0.0'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

In AndroidManifest.xml add metadata for MLKIT.

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.pickfile">
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:usesCleartextTraffic="true"
        android:theme="@style/Theme.PickFile">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".ResultActivity"
            android:hardwareAccelerated="true"/>
        <meta-data
            android:name="com.google.mlkit.vision.DEPENDENCIES"
            android:value="ocr" />
    </application>

</manifest>

Create your layout in activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        android:text="PICK FILE"
        android:textSize="20sp"
        app:layout_constraintEnd_toStartOf="@id/button2"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button1"
        tools:srcCompat="@tools:sample/avatars" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Extract text"
        android:layout_margin="10dp"
        android:textSize="20sp"
        app:layout_constraintStart_toEndOf="@id/button1"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

In MainActivity.java use following codes.

package com.example.pickfile;

import android.content.Intent;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import androidx.activity.result.ActivityResultCallback;
import androidx.activity.result.ActivityResultLauncher;
import androidx.activity.result.contract.ActivityResultContracts;
import androidx.appcompat.app.AppCompatActivity;

public class MainActivity extends AppCompatActivity {

    ImageView imageview1;
    String uriString = "";

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

        Button button1 = findViewById(R.id.button1);
        Button button2 = findViewById(R.id.button2);
        imageview1 = findViewById(R.id.imageView);

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mGetContent.launch("image/*");
            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(MainActivity.this, ResultActivity.class);
                intent.putExtra("uri", uriString);
                startActivity(intent);
            }
        });

    }

    ActivityResultLauncher<String> mGetContent = registerForActivityResult(
            new ActivityResultContracts.GetContent(),
            new ActivityResultCallback<Uri>() {
                @Override
                public void onActivityResult(Uri uri) {
                    imageview1.setImageURI(uri);
                    uriString = uri.toString();
                }
            });

}

Add a layout file result.xml with an EditText.

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <EditText
        android:id="@+id/edittext1"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_margin="10dp"
        android:gravity="start"
        android:hint="EditText"
        android:textSize="20sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

In ResultActivity.java use following codes.

package com.example.pickfile;

import android.content.Context;
import android.net.Uri;
import android.os.Bundle;
import android.widget.EditText;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;

import com.google.android.gms.tasks.OnFailureListener;
import com.google.android.gms.tasks.OnSuccessListener;
import com.google.android.gms.tasks.Task;
import com.google.mlkit.vision.common.InputImage;
import com.google.mlkit.vision.text.Text;
import com.google.mlkit.vision.text.TextRecognition;
import com.google.mlkit.vision.text.TextRecognizer;
import com.google.mlkit.vision.text.latin.TextRecognizerOptions;
import java.io.IOException;

public class ResultActivity extends AppCompatActivity {

    EditText edittext1;

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

        edittext1 = findViewById(R.id.edittext1);

        String uriString = getIntent().getStringExtra("uri");
        Uri uri = Uri.parse(uriString);
        _extractTextFromUri(getApplicationContext(), uri);
    }

    public void  _extractTextFromUri(Context context, Uri _uri) {
        TextRecognizer recognizer = TextRecognition.getClient(TextRecognizerOptions.DEFAULT_OPTIONS);
        try {
            InputImage image = InputImage.fromFilePath(context, _uri);
            Task<Text> result =
                    recognizer.process(image)
                            .addOnSuccessListener(new OnSuccessListener<Text>() {
                                @Override
                                public void onSuccess(Text visionText) {
                                    // Task completed successfully
                                   edittext1.setText(visionText.getText());
                                }
                            })
                            .addOnFailureListener(
                                    new OnFailureListener() {
                                        @Override
                                        public void onFailure(@NonNull Exception e) {
                                            // Task failed with an exception
                                        }
                                    });
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

}

Now run the app.

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