Android Light Weight QR Scanner

Introduction

In recent years, the use of mobile devices has become an increasingly important part of our daily lives. With the advanced technology available in smartphones today, we can perform an array of tasks, which were previously limited to large computers or specialized devices, such as scanning QR Codes. A QR Code Scanner is a simple and elegant way to quickly and reliably capture data from a real-world environment, such as printed labels, signs, bills, or even a camera's image.

Android, for instance, has a standard QR Code Scanner app packaged with most devices, using the built-in camera; however, this app seems to have some limitations – it might not work ideally in certain lighting conditions. Moreover, you might need dedicated QR code scanning apps capable of recognizing QR codes fast and accurately.

In an effort to provide a highly effective QR code scanning user experience, we will develop a light-weight QR CODE Scanner on Android. While the code is quite powerful, this tutorial will present a straightforward and easy understanding of the Android Light Weigh QR Scanner.

Light-Weight QR Scanner using Android Studio

In your Android Studio, create an empty activity project. By default, the project we have is a basic configuration. This project includes different files, such as, activity_main.xml, Fragment.java, and Fragment_host.xml.

Step - 1: Add JAR Library

First add the necessary JAR Libary, ZXing-MultiPlatform-1.7-jar-with-dependencies.jar to your project. To add the JAR library follow these steps −

• Right-click Project > Properties > Libraries module > "+" > Jars or directories > Select lib directory
• Add dependency in the build.gradle project level (app level ) −

  dependency
  implementation ' com.google.zxing:guava:28.6-jre'
  implementatio n 'com/google/zxing/library: library:3.3+'
  implementation 'kotlinx:kotlinx-coroutines-core:2.1.1’

**Step – 2: Create qr_code_scanner Activity

Create a new activity namely qr_code_scanner/activity_main.xml. Add one Button, one ImageViewand one EditText to this

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_margin="10dp"
     android:orientation="horizontal"
     android:baselineAligned="false"
xmlns:tools="http://schemas.android.com/tools/XMLSchema"

     android:orientation="vertical"
    tools:context=".qrCodeScanner"
     android:textSize="20sp"/>

        <Button

            android:id="@+id/button"
            style="@style/Widget.Mdp.FontIcon.Button"

            android:layout_below="@id/scanLayout"
            android:ems="10"
            android:hint="Scan to read"
            android.inputType="text"
</LinearLayout>

qr_code_scanner/ ScannerActivity.kt

Use the CameraManager to interact with the camera hardware

import androidhardware.camera2.CameraManager.close
import androidhardware.CaptureSession
import camerax_preview_usecase_camerax_preview_use-case

lateinit var

**Step–3: Implement QR reader logic in ScannerActivity

Use ZXing library library to implement QR reader functionalities

/**
 * Starts the camera manager.
 */
private fun takePicture() {
    imageCapture?.takePicture(setupPictureCallback())

    val qrCodeContents = findViewById<TextView>(findViewById(R.id.qr_results).text.toString()

    qrCodeContents?: return

    val newFragment = QRCode.decodeContents(qrCodeContents)

    if(QRCode.isQRInputValid(newFragment))            QRCode.showQRText(newFragment)

end
}

Using this Light-WeightQR Scanner app, you shall be able to scan easily QR Codes and display scanning results instantly.