Developing a "native" Barcode Scanner in Android

As you can read at my previous, I had presented a simple Barcode reader application. It's principle is user must download and install Zxing application from Google Play first, my app will call Zxing scanner screen as a sub-Activity and get the result (Barcode or QR code information) from it after scanning process finished!

The fact that we always would like to developing an application which be able to "embedding" this scanner in it, not warning that our device has not installed Barcode Reader application. Fortunately, there is a library developed by Dushyanth Maguluru which based on ZXing and ZBar, which be able to Barcode Scanner views, help us to develop a simple application which can scan Barcode/QR code itself.

Adding Barcode reader library to Android Studio Project

By reading it's source code on Github, we can find out that the author has combined ZXing and ZBar, each library to a dependency module in this project! In this tutorial, I will use Zxing, ZBar guide is absolutely similar!
In order to use this library, the simplest way is adding it's dependency to your application level build.gradle:

dependencies {
    compile 'me.dm7.barcodescanner:zxing:1.9' //barcode reader dependency
    compile 'com.android.support:appcompat-v7:24.1.1'
}

Project main activity

This main activity has 2 important works:

Start the scanning barcode activity as a sub-Activity by Intent.
Retrieve scanning results: barcode format and content by overriding onActivityResult().

It's source code simple like this:

MainActivity.java

package info.devexchanges.barcodescanner;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    private final static int REQUEST_SCANNER = 1;
    public final static String FORMAT = "format";
    public final static String CONTENT = "content";

    private TextView content;
    private TextView format;

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

        Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
        View btnScan = findViewById(R.id.btn_scan);
        format = (TextView) findViewById(R.id.format);
        content = (TextView) findViewById(R.id.content);

        setSupportActionBar(toolbar);

        btnScan.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this, ScannerActivity.class);
                startActivityForResult(intent, REQUEST_SCANNER);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == Activity.RESULT_OK) {
            content.setText(data.getStringExtra(CONTENT));
            format.setText(data.getStringExtra(FORMAT));
        }
    }
}

And it's layout:

activity_main.xml

<?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_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="info.devexchanges.barcodescanner.MainActivity">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_gravity="top"
        android:minHeight="?attr/actionBarSize"
        android:background="@color/colorPrimary"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

    <Button
        android:id="@+id/btn_scan"
        android:text="Scan Barcode"
        android:layout_margin="@dimen/activity_horizontal_margin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/format"
        android:gravity="center"
        android:padding="@dimen/activity_horizontal_margin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

    <TextView
        android:id="@+id/content"
        android:gravity="center"
        android:padding="@dimen/activity_horizontal_margin"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

Scanning Barcode/QR code Activity

As you can see at the MainActivity code above, when Button pressed, ScannerActivity will be launch as a sub-Activity.
The Barcode scanner view is initialized by a ZXingScannerView object. In onCreate(), declaring it like this:

ViewGroup contentFrame = (ViewGroup) findViewById(R.id.content_frame);

scannerView = new ZXingScannerView(this);
contentFrame.addView(scannerView);

The most important work is retrieving scanning result, so your ScannerActivity must implements ResultHandler interface and override handleResult(Result result) method. Moreover, start scanning by invoke this code:

scannerView.startCamera();

And if you want to stop this scanning, call closing camera method:

scannerView.stopCamera();

This is full code for this activity:

ScannerActivity.java

package info.devexchanges.barcodescanner;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.ViewGroup;

import com.google.zxing.Result;

import me.dm7.barcodescanner.zxing.ZXingScannerView;

public class ScannerActivity extends AppCompatActivity implements ZXingScannerView.ResultHandler {

    private ZXingScannerView scannerView;

    @Override
    public void onCreate(Bundle state) {
        super.onCreate(state);
        setContentView(R.layout.activity_scanner);
        ViewGroup contentFrame = (ViewGroup) findViewById(R.id.content_frame);

        scannerView = new ZXingScannerView(this);
        contentFrame.addView(scannerView);
    }

    @Override
    public void onResume() {
        super.onResume();
        scannerView.setResultHandler(this);
        scannerView.startCamera();
    }

    @Override
    public void onPause() {
        super.onPause();
        scannerView.stopCamera();
    }

    @Override
    public void handleResult(Result rawResult) {
        //Call back data to main activity
        Intent intent = new Intent();
        intent.putExtra(MainActivity.FORMAT, rawResult.getBarcodeFormat().toString());
        intent.putExtra(MainActivity.CONTENT, rawResult.getText());

        setResult(Activity.RESULT_OK, intent);
        finish();
    }
}

And it's layout:

activity_scanner.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/content_frame"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

</FrameLayout>

Running this application, we'll have this screen:

Clicking button, we'll start scanning:

Scanning Barcode

After scanning, we have this result:

An example after scanning a QR code:

Conclusions

Now, the simple "native" scanning Barcode/QR code app has been done! In this tutorial, we've run through the process of facilitating barcode/QR code scanning within Android app using the a third-party library based on ZXing. In your own apps, you might want to carry out further processing on the retrieved scan results, such as loading URLs or looking the data up in a third party data source. Moreover, by reading this library ZBar guide, you also can find out the way to use this module to your project - absolutely analogous!

View source code on Github