Android Text Recognizer Using Camera and Firebase ML Kit

In this blog, we will learn about implementing a Text Recognizer Using Camera and Firebase ML Kit.

With the updated firebase release, the developers have released new powers to image processing in a very easy and resource-friendly way.

Now, If you want you can use image processing and machine learning techniques in your application very easily using Firebase ML kit.

ML Kit is a mobile SDK that brings Google’s machine learning expertise to Android and iOS apps in a powerful yet easy-to-use package. Whether you’re new or experienced in machine learning, you can implement the functionality you need in just a few lines of code. There’s no need to have deep knowledge of neural networks or model optimization to get started. On the other hand, if you are an experienced ML developer, ML Kit provides convenient APIs that help you use your custom TensorFlow Lite models in your mobile apps.

— Firebase Developer Guide

Well, the firebase ML kit contains 5 options currently, which are :

Recognize Text
Face Detection
Barcode Scanning
Label images
Recognize Landmarks

We will currently focus on how we can recognize the text using the camera of an Android device.

Just a precap of what you will be able to do after reading this blog :

Things you need to get started :

Android Studio 3.1(or a newer version).
Google Account to link firebase.

With these, you are good to go.

Before you start coding :

Open build.gradle of your root android project and check these lines

 dependencies {
        // ...
        classpath 'com.android.tools.build:gradle:3.1.2'
        classpath 'com.google.gms:google-services:3.2.0'
    }

dependencies {

// ...

classpath 'com.android.tools.build:gradle:3.1.2'

classpath 'com.google.gms:google-services:3.2.0'

}

These versions are the minimum value required for the ML kit to function smoothly.

Open build.gradle of your module and add these dependencies

dependencies { // ... implementation 'com.google.firebase:firebase-ml-vision:16.0.0' }

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dependencies {
// ...
implementation 'com.google.firebase:firebase-ml-vision:16.0.0'
}

Open your Manifest File and Add These lines

//...
 <uses-feature android:name="android.hardware.camera" />
 <uses-feature android:name="android.hardware.camera.autofocus" />

//...
<application ...>
  ...
  <meta-data
      android:name="com.google.firebase.ml.vision.DEPENDENCIES"
      android:value="text" />
  <!-- To use multiple models: android:value="label,text" -->
</application>

//...

<uses-feature android:name="android.hardware.camera" />

<uses-feature android:name="android.hardware.camera.autofocus" />

//...

...

<meta-data

android:name="com.google.firebase.ml.vision.DEPENDENCIES"

android:value="text" />

</application>

After these initial steps, you are good to start writing code for the text recognizer.

APPROACH

You need to create custom view classes CameraSourcePreview, GraphicOverlay to interact with the camera hardware and manage the content on the device screen.
For quicker integration, you can check the official sample project and use their classes from here
Classes you will need to include in your project: CameraSource.java, CameraSourcePreview.java, FrameMetadata.java, GraphicOverlay.java, VisionImageProcessor.java, VisionProcessorBase.java, TextRecognitionProcessor.java
After you have successfully added these classes to your project, now you just need to create an activity/ fragment and manage these classes and results from firebase.
The results will be received as an object of FirebaseVisionText class and you will need to parse them as per your use case.

CODE

I have named my Activity as LauncherActivity.

Xml File :->

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

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/fireTopLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000"
    android:keepScreenOn="true"
    android:orientation="vertical">

    <com.webkul.mobikul.mlkitdemo.customviews.CameraSourcePreview
        android:id="@+id/Preview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_alignParentTop="true">

        <com.webkul.mobikul.mlkitdemo.customviews.GraphicOverlay
            android:id="@+id/Overlay"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_alignParentTop="true" />
    </com.webkul.mobikul.mlkitdemo.customviews.CameraSourcePreview>>

    <RelativeLayout
        android:id="@+id/control"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_toEndOf="@id/Preview"
        android:layout_toRightOf="@id/Preview"
        >

        <TextView
            android:id="@+id/resultsMessageTv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_centerHorizontal="true"
            android:layout_centerVertical="true"
            android:drawableTint="@android:color/white"
            android:padding="6dp"
            android:text="@string/results_found"
            android:textColor="@android:color/white" />


    </RelativeLayout>

    <LinearLayout
        android:id="@+id/resultsContainer"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="bottom"
        android:layout_above="@id/control"
        >
        <android.support.v7.widget.RecyclerView
            android:id="@+id/results_spinner"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:listitem="@layout/camera_simple_spinner_item"
            />
    </LinearLayout>

</RelativeLayout>

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

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/fireTopLayout"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:background="#000"

android:keepScreenOn="true"

android:orientation="vertical">

<com.webkul.mobikul.mlkitdemo.customviews.CameraSourcePreview

android:id="@+id/Preview"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layout_alignParentLeft="true"

android:layout_alignParentStart="true"

android:layout_alignParentTop="true">

<com.webkul.mobikul.mlkitdemo.customviews.GraphicOverlay

android:id="@+id/Overlay"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:layout_alignParentBottom="true"

android:layout_alignParentLeft="true"

android:layout_alignParentStart="true"

android:layout_alignParentTop="true" />

</com.webkul.mobikul.mlkitdemo.customviews.CameraSourcePreview>>

<RelativeLayout

android:id="@+id/control"

android:layout_width="match_parent"

android:layout_height="60dp"

android:layout_alignParentBottom="true"

android:layout_alignParentLeft="true"

android:layout_alignParentStart="true"

android:layout_toEndOf="@id/Preview"

android:layout_toRightOf="@id/Preview"

<TextView

android:id="@+id/resultsMessageTv"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_centerHorizontal="true"

android:layout_centerVertical="true"

android:drawableTint="@android:color/white"

android:padding="6dp"

android:text="@string/results_found"

android:textColor="@android:color/white" />

</RelativeLayout>

<LinearLayout

android:id="@+id/resultsContainer"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:gravity="bottom"

android:layout_above="@id/control"

<android.support.v7.widget.RecyclerView

android:id="@+id/results_spinner"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:listitem="@layout/camera_simple_spinner_item"

</LinearLayout>

</RelativeLayout>

Java Class File( LauncherActivity ) : ->

public class LauncherActivity extends AppCompatActivity {
    private static final String TAG = "LauncherActivity";
    private CameraSourcePreview preview; // To handle the camera
    private GraphicOverlay graphicOverlay; // To draw over the camera screen
    private CameraSource cameraSource = null; //To handle the camera
    private RecyclerView resultSpinner;// To display the results recieved from Firebase MLKit
    private static final int PERMISSION_REQUESTS = 1; // to handle the runtime permissions
    private List<String> displayList; // to manage the adapter of the results recieved
    private ResultAdapter displayAdapter; // adapter bound with the result recycler view ---> Contains a simple textview with background
    private TextView resultNumberTv;// to display the number of results
    private LinearLayout resultContainer;// just another layout to maintain the symmetry

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


        // getting views from the xml
        resultNumberTv = (TextView) findViewById(R.id.resultsMessageTv);
        resultContainer = (LinearLayout) findViewById(R.id.resultsContainer);
        resultSpinner = (RecyclerView) findViewById(R.id.results_spinner);
        preview = (CameraSourcePreview) findViewById(R.id.Preview);
        graphicOverlay = (GraphicOverlay) findViewById(R.id.Overlay);


        // intializing views
        displayList = new ArrayList<>();
        resultSpinner.setLayoutManager(new LinearLayoutManager(LauncherActivity.this, LinearLayoutManager.VERTICAL, false));
        displayAdapter = new ResultAdapter(LauncherActivity.this, displayList);
        resultSpinner.setAdapter(displayAdapter);
        resultContainer.getLayoutParams().height = (int) (Resources.getSystem().getDisplayMetrics().heightPixels * 0.65);
        resultNumberTv.setText(getString(R.string.x_results_found, displayList.size()));

        if (preview == null) {
            Log.d(TAG, " Preview is null ");
        }

        if (graphicOverlay == null) {
            Log.d(TAG, "graphicOverlay is null ");
        }
        if (allPermissionsGranted()) {
            createCameraSource();
        } else {
            getRuntimePermissions();
        }
    }

    @Override
    protected void onResume() {
        super.onResume();
        startCameraSource();
    }
    @Override
    protected void onPause() {
        super.onPause();
        preview.stop();
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        if (cameraSource != null) {
            cameraSource.release();
        }
    }

    // Actual code to start the camera
    private void startCameraSource() {
        if (cameraSource != null) {
            try {
                if (preview == null) {
                    Log.d(TAG, "startCameraSource resume: Preview is null ");
                }
                if (graphicOverlay == null) {
                    Log.d(TAG, "startCameraSource resume: graphOverlay is null ");
                }
                preview.start(cameraSource, graphicOverlay);
            } catch (IOException e) {
                Log.d(TAG, "startCameraSource : Unable to start camera source." + e.getMessage());
                cameraSource.release();
                cameraSource = null;
            }
        }
    }

    // Function to check if all permissions given by the user
    private boolean allPermissionsGranted() {
        for (String permission : getRequiredPermissions()) {
            if (!isPermissionGranted(this, permission)) {
                return false;
            }
        }
        return true;
    }

    // List of permissions required by the application to run.
    private String[] getRequiredPermissions() {
        return new String[]{android.Manifest.permission.CAMERA, android.Manifest.permission.INTERNET, Manifest.permission.WRITE_EXTERNAL_STORAGE};
    }

    // Checking a Runtime permission value
    private static boolean isPermissionGranted(Context context, String permission) {
        if (ContextCompat.checkSelfPermission(context, permission)
                == PackageManager.PERMISSION_GRANTED) {
            Log.d(TAG, "isPermissionGranted Permission granted : " + permission);
            return true;
        }
        Log.d(TAG, "isPermissionGranted: Permission NOT granted -->" + permission);
        return false;
    }

    // getting runtime permissions
    private void getRuntimePermissions() {
        List<String> allNeededPermissions = new ArrayList<>();
        for (String permission : getRequiredPermissions()) {
            if (!isPermissionGranted(this, permission)) {
                allNeededPermissions.add(permission);
            }
        }

        if (!allNeededPermissions.isEmpty()) {
            ActivityCompat.requestPermissions(
                    this, allNeededPermissions.toArray(new String[0]), PERMISSION_REQUESTS);
        }
    }

    // Function to create a camera source and retain it.
    private void createCameraSource() {
        // If there's no existing cameraSource, create one.
        if (cameraSource == null) {
            cameraSource = new CameraSource(this, graphicOverlay);
        }

        try {

            cameraSource.setMachineLearningFrameProcessor(new TextRecognitionProcessor(this));

        } catch (Exception e) {
            Log.d(TAG, "createCameraSource can not create camera source: " + e.getCause());
            e.printStackTrace();
        }
    }


    //  updating and displaying the results recieved from Firebase Text Processor Api
    public void updateSpinnerFromTextResults(FirebaseVisionText textresults) {
        List<FirebaseVisionText.Block> blocks = textresults.getBlocks();
        for (FirebaseVisionText.Block eachBlock : blocks) {
            for (FirebaseVisionText.Line eachLine : eachBlock.getLines()) {
                for (FirebaseVisionText.Element eachElement : eachLine.getElements()) {
                    if (!displayList.contains(eachElement.getText()) && displayList.size() <= 9) {
                        displayList.add(eachElement.getText());
                    }
                }
            }
        }
        resultNumberTv.setText(getString(R.string.x_results_found, displayList.size()));
        displayAdapter.notifyDataSetChanged();
    }
}

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public class LauncherActivity extends AppCompatActivity {

private static final String TAG = "LauncherActivity";

private CameraSourcePreview preview; // To handle the camera

private GraphicOverlay graphicOverlay; // To draw over the camera screen

private CameraSource cameraSource = null; //To handle the camera

private RecyclerView resultSpinner;// To display the results recieved from Firebase MLKit

private static final int PERMISSION_REQUESTS = 1; // to handle the runtime permissions

private List<String> displayList; // to manage the adapter of the results recieved

private ResultAdapter displayAdapter; // adapter bound with the result recycler view ---> Contains a simple textview with background

private TextView resultNumberTv;// to display the number of results

private LinearLayout resultContainer;// just another layout to maintain the symmetry

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_launcher);

// getting views from the xml

resultNumberTv = (TextView) findViewById(R.id.resultsMessageTv);

resultContainer = (LinearLayout) findViewById(R.id.resultsContainer);

resultSpinner = (RecyclerView) findViewById(R.id.results_spinner);

preview = (CameraSourcePreview) findViewById(R.id.Preview);

graphicOverlay = (GraphicOverlay) findViewById(R.id.Overlay);

// intializing views

displayList = new ArrayList<>();

resultSpinner.setLayoutManager(new LinearLayoutManager(LauncherActivity.this, LinearLayoutManager.VERTICAL, false));

displayAdapter = new ResultAdapter(LauncherActivity.this, displayList);

resultSpinner.setAdapter(displayAdapter);

resultContainer.getLayoutParams().height = (int) (Resources.getSystem().getDisplayMetrics().heightPixels * 0.65);

resultNumberTv.setText(getString(R.string.x_results_found, displayList.size()));

if (preview == null) {

Log.d(TAG, " Preview is null ");

}

if (graphicOverlay == null) {

Log.d(TAG, "graphicOverlay is null ");

}

if (allPermissionsGranted()) {

createCameraSource();

} else {

getRuntimePermissions();

}

@Override

protected void onResume() {

super.onResume();

startCameraSource();

}

@Override

protected void onPause() {

super.onPause();

preview.stop();

}

@Override

public void onDestroy() {

super.onDestroy();

if (cameraSource != null) {

cameraSource.release();

}

// Actual code to start the camera

private void startCameraSource() {

if (cameraSource != null) {

try {

if (preview == null) {

Log.d(TAG, "startCameraSource resume: Preview is null ");

}

if (graphicOverlay == null) {

Log.d(TAG, "startCameraSource resume: graphOverlay is null ");

}

preview.start(cameraSource, graphicOverlay);

} catch (IOException e) {

Log.d(TAG, "startCameraSource : Unable to start camera source." + e.getMessage());

cameraSource.release();

cameraSource = null;

}

// Function to check if all permissions given by the user

private boolean allPermissionsGranted() {

for (String permission : getRequiredPermissions()) {

if (!isPermissionGranted(this, permission)) {

return false;

}

return true;

}

// List of permissions required by the application to run.

private String[] getRequiredPermissions() {

return new String[]{android.Manifest.permission.CAMERA, android.Manifest.permission.INTERNET, Manifest.permission.WRITE_EXTERNAL_STORAGE};

}

// Checking a Runtime permission value

private static boolean isPermissionGranted(Context context, String permission) {

if (ContextCompat.checkSelfPermission(context, permission)

== PackageManager.PERMISSION_GRANTED) {

Log.d(TAG, "isPermissionGranted Permission granted : " + permission);

return true;

}

Log.d(TAG, "isPermissionGranted: Permission NOT granted -->" + permission);

return false;

}

// getting runtime permissions

private void getRuntimePermissions() {

List<String> allNeededPermissions = new ArrayList<>();

for (String permission : getRequiredPermissions()) {

if (!isPermissionGranted(this, permission)) {

allNeededPermissions.add(permission);

}

if (!allNeededPermissions.isEmpty()) {

ActivityCompat.requestPermissions(

this, allNeededPermissions.toArray(new String[0]), PERMISSION_REQUESTS);

}

// Function to create a camera source and retain it.

private void createCameraSource() {

// If there's no existing cameraSource, create one.

if (cameraSource == null) {

cameraSource = new CameraSource(this, graphicOverlay);

}

try {

cameraSource.setMachineLearningFrameProcessor(new TextRecognitionProcessor(this));

} catch (Exception e) {

Log.d(TAG, "createCameraSource can not create camera source: " + e.getCause());

e.printStackTrace();

}

// updating and displaying the results recieved from Firebase Text Processor Api

public void updateSpinnerFromTextResults(FirebaseVisionText textresults) {

List<FirebaseVisionText.Block> blocks = textresults.getBlocks();

for (FirebaseVisionText.Block eachBlock : blocks) {

for (FirebaseVisionText.Line eachLine : eachBlock.getLines()) {

for (FirebaseVisionText.Element eachElement : eachLine.getElements()) {

if (!displayList.contains(eachElement.getText()) && displayList.size() <= 9) {

displayList.add(eachElement.getText());

}

resultNumberTv.setText(getString(R.string.x_results_found, displayList.size()));

displayAdapter.notifyDataSetChanged();

}

TextRecognitionProcessor : –>

public class TextRecognitionProcessor extends VisionProcessorBase<FirebaseVisionText> {

    private static final String TAG = "TextRecognitionProcessr";

    private final FirebaseVisionTextDetector detector;
    private final LauncherActivity activityInstance;

    public TextRecognitionProcessor(LauncherActivity activity) {
        detector = FirebaseVision.getInstance().getVisionTextDetector();
        activityInstance = activity;
    }

    @Override
    public void stop() {
        try {
            detector.close();
        } catch (IOException e) {
            Log.e(TAG, "Exception thrown while trying to close Text Detector: " + e);
        }
    }

    @Override
    protected Task<FirebaseVisionText> detectInImage(FirebaseVisionImage image) {
        return detector.detectInImage(image);
    }

    @Override
    protected void onSuccess(
            @NonNull FirebaseVisionText results,
            @NonNull FrameMetadata frameMetadata,
            @NonNull GraphicOverlay graphicOverlay) {
        graphicOverlay.clear();
        activityInstance.updateSpinnerFromTextResults(results);
    }

    @Override
    protected void onFailure(@NonNull Exception e) {
        Log.w(TAG, "Text detection failed." + e);
    }
}

public class TextRecognitionProcessor extends VisionProcessorBase<FirebaseVisionText> {

private static final String TAG = "TextRecognitionProcessr";

private final FirebaseVisionTextDetector detector;

private final LauncherActivity activityInstance;

public TextRecognitionProcessor(LauncherActivity activity) {

detector = FirebaseVision.getInstance().getVisionTextDetector();

activityInstance = activity;

}

@Override

public void stop() {

try {

detector.close();

} catch (IOException e) {

Log.e(TAG, "Exception thrown while trying to close Text Detector: " + e);

}

@Override

protected Task<FirebaseVisionText> detectInImage(FirebaseVisionImage image) {

return detector.detectInImage(image);

}

@Override

protected void onSuccess(

@NonNull FirebaseVisionText results,

@NonNull FrameMetadata frameMetadata,

@NonNull GraphicOverlay graphicOverlay) {

graphicOverlay.clear();

activityInstance.updateSpinnerFromTextResults(results);

}

@Override

protected void onFailure(@NonNull Exception e) {

Log.w(TAG, "Text detection failed." + e);

}

ResultAdapter :–>

public class ResultAdapter extends RecyclerView.Adapter<ResultAdapter.ViewHolder> {
    private Context context;
    private List<String> labelList;

    public ResultAdapter(Context context, List<String> labelList) {
        this.context = context;
        this.labelList = labelList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.camera_result_item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, final int position) {
        ((TextView) holder.itemView.findViewById(R.id.label_tv)).setText(labelList.get(position));
    }

    @Override
    public int getItemCount() {
        return labelList.size();
    }


    public class ViewHolder extends RecyclerView.ViewHolder {
        public ViewHolder(View itemView) {
            super(itemView);
        }
    }
}

public class ResultAdapter extends RecyclerView.Adapter<ResultAdapter.ViewHolder> {

private Context context;

private List<String> labelList;

public ResultAdapter(Context context, List<String> labelList) {

this.context = context;

this.labelList = labelList;

}

@NonNull

@Override

public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

View view = LayoutInflater.from(context).inflate(R.layout.camera_result_item, parent, false);

return new ViewHolder(view);

}

@Override

public void onBindViewHolder(@NonNull ViewHolder holder, final int position) {

((TextView) holder.itemView.findViewById(R.id.label_tv)).setText(labelList.get(position));

}

@Override

public int getItemCount() {

return labelList.size();

}

public class ViewHolder extends RecyclerView.ViewHolder {

public ViewHolder(View itemView) {

super(itemView);

}

camera_result_item (Xml File) : –>

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_height="wrap_content"
    android:layout_width="match_parent"
    android:orientation="vertical"
    >
    <TextView
        android:id="@+id/label_tv"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:minHeight="48dp"
        tools:text="label"/>
    <View
        android:layout_width="match_parent"
        android:layout_height="1dp"
        android:background="#a8ffffff"
        />

</LinearLayout>

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

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:layout_height="wrap_content"

android:layout_width="match_parent"

android:orientation="vertical"

<TextView

android:id="@+id/label_tv"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:minHeight="48dp"

tools:text="label"/>

<View

android:layout_width="match_parent"

android:layout_height="1dp"

android:background="#a8ffffff"

</LinearLayout>

Some other demos :

Sources :

https://firebase.google.com/docs/ml-kit/android/recognize-text

https://github.com/firebase/quickstart-android/tree/master/mlkit/

Keep coding and Keep Sharing 🙂

anchit

A dynamic developer specializing in Flutter, Dart, and React Native. Delivers high-performance Android and iOS apps with intuitive designs, scalability, and seamless cross-platform integration.

1 Jul, 2023
Updated by - anchit
29 Oct, 2021
Updated by - Mobikul

. . .

29 comments

Khalis Ramni 6 years ago

Hi Anchit,

Can you share the ResultAdapter code here?

anchit (Moderator) 6 years ago
Ok,

I have added the same in the last section of the Blog.

Please do have a look.

Reply

Vinod Gaur 7 years ago

Hi Anchit,

Can you share me the code as i need it as very urgent basis and the MLKIT library is outdated.

anchit (Moderator) 7 years ago
Hello Vinod,

Yes, the MLKIT library dependency mentioned in the blog is outdated, but then this is quite a common thing for firebase dependencies. You can still use this version if you want or even update, it is completely up to you and your use case.

Secondly, the blog in here is a complete reference to tell you how you can use this functionality.
I do not have any code other than the files shared in the blog.

Still, If you want you can share your code and I will try to help you out

Reply
- Josh 6 years ago
  i got error in resultadapter, how can i resolve that?
  
  Reply
  - anchit (Moderator) 6 years ago
    Hello josh,
    
    What exactly is the error you are facing?
    
    Please do share some insight about the error so that I can look into it & help you.
    
    Reply
    - Richard 6 years ago
      Same problem. ResultAdapter is not defined.
      
      Reply
      - anchit (Moderator) 6 years ago
        Hello Richard,
        
        ResultAdapter is just a simple recycler view Adapter class in which I have just inflated a text view and a background(just to make the views presentable).
        I have also mentioned the same in the comment along with the declaration of the ResultAdapter object.
        
        Still, if you face any issue, then do let me know.
        
        Reply
        
        Khalis Ramni 6 years ago
        Hi Anchit,
        
        Can you share the ResultAdapter code here?
        
        Reply
        
        anchit (Moderator) 6 years ago
        I have added the same in the last section of the Blog.
        
        Please do have a look.

Mattia 7 years ago

I receive ‘fail to connect to camera service’. How can i fix this?

anchit (Moderator) 7 years ago
Hi there,

Please do check first if you have added the camera permission in your manifest file and are also checking for it as per the android api level.

Reply

Ahmed Ibrahim 7 years ago

App is showing a black screen in camera preview even though I have added the permissions in manifest file. can you help please ?

anchit (Moderator) 7 years ago
Well without seeing code it is hard to tell what exactly is the reason for your problem.

But the problem you are stating is most probably due to improper use of CameraSourcePreview Object.

Please cross check that before you access the camera have you initialized the camera source and then started it in on resume of your activity.

Reply

Kingsley 7 years ago

Hi anchit, thanks for the tutorial,
Can you post the code snippets on how you did this?

“I personally modified the constructor of TextRecognitionProcessor.java and passed the instance of Launcher activity in the constructor.”

including the call back to the Launcher method. thanks heaps

anchit (Moderator) 7 years ago
Hi Kingsley,

The constructor of TextRecognitionProcessor.java will be like :
public TextRecognitionProcessor(LauncherActivity activity) {
detector = FirebaseVision.getInstance().getVisionTextDetector();
activityInstance = activity;
}

Now in this your onSuccess method will be something like this :

@Override
protected void onSuccess(
@NonNull FirebaseVisionText results,
@NonNull FrameMetadata frameMetadata,
@NonNull GraphicOverlay graphicOverlay) {
graphicOverlay.clear();
activityInstance.updateSpinnerFromTextResults(results);
}

I am also adding this file in the article as well, so that you can refer it completely.

If still you have any confusions, please feel free to ask.

Reply
- Kingsley 7 years ago
  Thankyou so much anchit, that was the hint I needed,
  appreciate the quick update too.
  
  Reply
  - anchit (Moderator) 7 years ago
    Well, Thanks to you for making this article better.
    
    Reply

Sultan 7 years ago

Hi, Thanks for the tutorial its really helping one.I have an issue. in LauncherActivity.java how did you call updateSpinnerFromTextResults(FirebaseVisionText textresults) method.help appreciated.

anchit (Moderator) 7 years ago
For calling method “updateSpinnerFromTextResults(FirebaseVisionText textresults) ” of the Launcher Activity, you will need to look where exactly you have recieved the results from Firebase.

For Example, i have recieved the results in the method “onSuccess” of TextRecognitionProcessor.java which is a child of VisionProcessorBase

I personally modified the constructor of TextRecognitionProcessor.java and passed the instance of Launcher activity in the constructor.

You can also implement the same using interface as well.

If you still have any doubts, do let me know, i will help you as much as i can.

Reply
- Sultan 7 years ago
  Thanks anchit. I have already did it using interface.
  
  Reply
  - anchit (Moderator) 7 years ago
    That Sound’s Great.
    
    Reply
- Kingsley 7 years ago
  Thanks anchit, appreciate the work on this, I have the official example working,
  
  Can you post the code on how to do this (including the call back to the Launcher.
  “I personally modified the constructor of TextRecognitionProcessor.java and passed the instance of Launcher activity in the constructor.”
  thanks heaps
  Kingsley
  
  Reply

Lucas 7 years ago

Hi, I tried to apply the tutorial above but I could not. Could you just make the above demo code available in a github repository? Thanks!

anchit (Moderator) 7 years ago
Hi Lucas,
Thanks for your comment, but currently i cannot put this code on Github repository.

You can ask me over here the issue you are facing and I will try to reply as soon as possible for me.

Reply

Farooq Arshed 7 years ago

Your code is incomplete. Can you provide a link to final version?

anchit 7 years ago
Dear Farooq,
The code in the blog is a complete reference.
Please do let me know which part in the blog you think is incomplete or you are unable to link with.
I will try to improvise that part of the blog so that it helps all the readers.

Reply
- Irjavan 6 years ago
  camera_simple_spinner_item layout is absent, also I see the black screen instead of camera
  
  Reply
  - anchit (Moderator) 6 years ago
    Dear Irjavan,
    the camera_simple_spinner_item layout missing is something used in the namespace tools, you can easily remove that line or replace that layout with the camera_result_item whose code is shared in the blog itself.
    
    Regarding the black screen on the camera, for this the issue is that the CameraSourcePreview class is not initiating correctly in your code. Please do debug that code or share your code with us and we will help you with the same.
    
    Hope this helps you.
    
    Reply

Android Text Recognizer Using Camera and Firebase ML Kit

Things you need to get started :

Before you start coding :

APPROACH

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