Android Studio - QR code scanning

• Ander Liu

tags: Android Studio

• Android Studio - QR code scanning
  • Zxing
  • Adding dependency with Gradle
  • Hardware Acceleration
  • Usage with IntentIntegrator
    • Customize options
    • Changing the orientation
  • Button and Text display
  • Reference
  • Future feature
  • Homepage

Zxing

• ZXing ("zebra crossing") is an open-source, multi-format 1D/2D barcode image processing library implemented in Java, with ports to other languages.
• 這堂課，我們打算使用 Zxing 這個 library to implement QR code scanning
• The Supported Formats of Zxing

1D product	1D industrial	2D
UPC-A	Code 39	QR Code
EAN-8	Code 128	Aztec (beta)
EAN-13	Codabar	PDF 417 (beta)
	ITF	MaxiCode
	RSS-14
	RSS-Expanded

• Official APP on Google Play
• 我們基本上是根據此網站來設置
  https://github.com/journeyapps/zxing-android-embedded

Adding dependency with Gradle

Android SDK 需要 19 以上

• 我們先把 library 加進來
• 開啟 build.gradle，在適當的位置加入以下 dependency

dependencies {
    implementation 'com.journeyapps:zxing-android-embedded:3.6.0'
    implementation 'com.android.support:appcompat-v7:25.3.1'   // Minimum 23+ is required
}

Hardware Acceleration

• Hardware accelation is required since TextureView is used
• 開啟 AndroidManifest.xml，在適當的位置 enable hardwareAccelerated 屬性

<application android:hardwareAccelerated="true" ... >

Usage with IntentIntegrator

• 此為 the source code of the IntentIntegrator
  https://github.com/journeyapps/zxing-android-embedded/blob/master/zxing-android-embedded/src/com/google/zxing/integration/android/IntentIntegrator.java
• IntentIntegrator顧名思義，就是 intent的integrate版。可以call一些method來設定要開啟的掃描acticity的屬性，最後 call initiateScan()來開啟掃描acticity

有關 intent，之後會再介紹

• 以下為可能會用到的 method
  • 第 98 行 IntentIntegrator(Activity activity) the Constructor
  • 第 146 行 IntentIntegrator forFragment(Fragment fragment)
  • 第 167 行 IntentIntegrator setPrompt(String prompt) Set a prompt to display on the capture screen, instead of using the default.
  • 第 179 行 IntentIntegrator setOrientationLocked(boolean locked) By default, the orientation is locked. Set to false to not lock.
  • 第 189 行 IntentIntegrator setCameraId(int cameraId) Use the specified camera ID.
  • 第 214 行 IntentIntegrator setBeepEnabled(boolean enabled) Set to false to disable beep on scan.
  • 第 225 行 IntentIntegrator setBarcodeImageEnabled(boolean enabled) Set to true to enable saving the barcode image and sending its path in the result Intent.
  • 第 247 行 IntentIntegrator setDesiredBarcodeFormats(String… desiredBarcodeFormats) Set the desired barcode formats to scan.
  • 第 258 行 void initiateScan() Initiates a scan for all known barcode types with the default camera.

new IntentIntegrator(this).initiateScan(); // \`this\` is the current Activity

// Get the results:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);
    if(result != null) {
        if(result.getContents() == null) {
            Toast.makeText(this, "Cancelled", Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(this, "Scanned: " + result.getContents(), Toast.LENGTH_LONG).show();
        }
    } else {
        super.onActivityResult(requestCode, resultCode, data);
    }
}

• 第 1 行，initiateScan()，用來啟動掃描Activity，可以寫在 onClick() 或是 onCreate() 等等method裡面
• 第 3-16行，onActictyResult()，目的是取得掃描Activity傳回來的結果，不需要動這部分，直接貼到 MainActivity.java 即可

有關啟動 Activity 以取得結果，之後會再介紹

• result.getContents() 為結果，如果打算顯示掃描結果，複製結果，開啟URL，便需要利用此結果

Customize options

• 此為其他客製化功能，和 initiateScan()一樣，寫在 onClick() 或是 onCreate() 等等method裡面

IntentIntegrator integrator = new IntentIntegrator(this);
integrator.setDesiredBarcodeFormats(IntentIntegrator.QR_CODE);
integrator.setPrompt("Scan a QR code");
integrator.setCameraId(0);  // Use a specific camera of the device
integrator.setBeepEnabled(false);
integrator.setBarcodeImageEnabled(true);
integrator.initiateScan();

Changing the orientation

1. 開啟 AndroidManifest.xml，加入以下code

<activity
        android:name="com.journeyapps.barcodescanner.CaptureActivity"
        android:screenOrientation="fullSensor"
        tools:replace="screenOrientation" />

2. setOrientationLocked() set false to not lock，和 initiateScan()寫在一起

IntentIntegrator integrator = new IntentIntegrator(this);
integrator.setOrientationLocked(false);
integrator.initiateScan();

Button and Text display

1. layout 如下所示
   

2. 在 MainActivity.java 寫一個 onClick() method，裡面放剛剛的那些code

public void onClick(View view){   
    IntentIntegrator integrator = new IntentIntegrator(this);  
    integrator.setOrientationLocked(false);  
    integrator.setDesiredBarcodeFormats(IntentIntegrator.QR_CODE);  
    integrator.setPrompt("Scan a QR code");  
    integrator.setCameraId(0); // Use a specific camera of the device  
    integrator.setBeepEnabled(false);  
    integrator.setBarcodeImageEnabled(true);  
    integrator.initiateScan();
}

3. 在 onActictyResult()裡面加入第 4 行和第 12 行，用 TextView顯示結果

// Get the results:  
@Override  
protected void onActivityResult(int requestCode, int resultCode, Intent data) {  
    TextView textView = findViewById(R.id.textView);
  
    IntentResult result = IntentIntegrator.parseActivityResult(requestCode, resultCode, data);  
    if(result != null) {  
        if(result.getContents() == null) {  
            Toast.makeText(this, "Cancelled", Toast.LENGTH_LONG).show();  
        } else {  
            Toast.makeText(this, "Scanned: " \+ result.getContents(), Toast.LENGTH_LONG).show();  
            textView.setText(result.getContents());  
        }  
    } else {  
        super.onActivityResult(requestCode, resultCode, data);  
    }  
}

4. 把 onClick() 設置到 button 上

Done!!!

Reference

• Github | Zxing
• Github | IntentIntegrator.java
• Useful Reference

Future feature

• Scan a photo
• Copy to clipboard
• Open the URL link

Homepage

• Homepage