Android 二维码相关(三)

本篇文章主要讲下二维码扫描相关.

1: 权限相关

由于文中需要使用Camera以及surfaceview,所以我们需要提前申请相机权限:

<uses-permission android:name="android.permission.CAMERA" />

2: 添加SurfaceView预览

<?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=".ScanActivity"><SurfaceViewandroid:layout_width="match_parent"android:layout_height="match_parent"app:layout_constraintStart_toStartOf="parent"app:layout_constraintTop_toTopOf="parent"android:id="@+id/surface"/>
</androidx.constraintlayout.widget.ConstraintLayout>

3: 初始化相机

通过SurfaceView我们获取SurfaceHolder:

surfaceView = findViewById(R.id.surface);
SurfaceHolder holder = surfaceView.getHolder();
holder.addCallback(new SurfaceHolder.Callback() {@Overridepublic void surfaceCreated(SurfaceHolder holder) {}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {}
});

1. surfaceCreated中我们初始化相机配置
2. surfaceDestroyed 中我们重置参数

3.1 startCamera()

private void startCamera() {Camera open = Camera.open();Camera.Parameters parameters = open.getParameters();parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);open.setParameters(parameters);open.setDisplayOrientation(90);open.setPreviewCallback(new Camera.PreviewCallback() {@Overridepublic void onPreviewFrame(byte[] data, Camera camera) {}});try {open.setPreviewDisplay(surfaceView.getHolder());open.startPreview();} catch (IOException e) {e.printStackTrace();}
}

3.2 stopCamera()

private void stopCamera() {if (open != null) {open.stopPreview();open.setPreviewCallback(null);open.release();open = null;}
}

3.3 Camera.PreviewCallback

具体的解析方法,以及数据来源根据Camera.PreviewCallback 的回调来实现:

1. 获取数据的宽高

   Camera.Size previewSize = camera.getParameters().getPreviewSize();
   int width = previewSize.width;
   int height = previewSize.height;
   

2. 将预览数据转换为二进制位图

    PlanarYUVLuminanceSource planarYUVLuminanceSource = new PlanarYUVLuminanceSource(data, width, height, 0, 0, width, height, false);BinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(planarYUVLuminanceSource));
   

3. 设置解码参数

   EnumMap<DecodeHintType, Object> decodeHintTypeObjectEnumMap = new EnumMap<>(DecodeHintType.class);
   Collection<BarcodeFormat> list = new ArrayList<>();
   list.addAll(EnumSet.of(BarcodeFormat.QR_CODE));
   decodeHintTypeObjectEnumMap.put(DecodeHintType.POSSIBLE_FORMATS, list);
   

4. 解码

   创建MultiFormatReader对象,用于解码.并通过setHints方法设置解码格式

   MultiFormatReader multiFormatReader = new MultiFormatReader();
   multiFormatReader.setHints(decodeHintTypeObjectEnumMap);
   try {Result decode = multiFormatReader.decode(binaryBitmap);String text = decode.getText();Log.i("xxxxx", "onPreviewFrame: " + text);
   } catch (Throwable e) {Log.e("xxxxx", "onPreviewFrame: ", e);
   }
   

注: onPreviewFrame是Android相机预览帧回调函数，它会在每一帧预览数据可用时被调用.

完整的代码如下:

public class ScanActivity extends AppCompatActivity implements SurfaceHolder.Callback, Camera.PreviewCallback {private SurfaceView surfaceView;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_scan);surfaceView = findViewById(R.id.surface);SurfaceHolder holder = surfaceView.getHolder();holder.addCallback(this);}Camera open;private void startCamera() {Camera open = Camera.open();Camera.Parameters parameters = open.getParameters();parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);open.setParameters(parameters);open.setDisplayOrientation(90);open.setPreviewCallback(this);try {open.setPreviewDisplay(surfaceView.getHolder());open.startPreview();} catch (IOException e) {e.printStackTrace();}}private void stopCamera() {if (open != null) {open.stopPreview();open.setPreviewCallback(null);open.release();open = null;}}@Overridepublic void surfaceCreated(SurfaceHolder holder) {startCamera();}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {stopCamera();}@Overridepublic void onPreviewFrame(byte[] data, Camera camera) {if (camera == null || camera.getParameters() == null) return;Camera.Size previewSize = camera.getParameters().getPreviewSize();int width = previewSize.width;int height = previewSize.height;//预览数据转二进制位图PlanarYUVLuminanceSource planarYUVLuminanceSource = new PlanarYUVLuminanceSource(data, width, height, 0, 0, width, height, false);BinaryBitmap binaryBitmap = new BinaryBitmap(new HybridBinarizer(planarYUVLuminanceSource));// 设置解码参数EnumMap<DecodeHintType, Object> decodeHintTypeObjectEnumMap = new EnumMap<>(DecodeHintType.class);Collection<BarcodeFormat> list = new ArrayList<>();list.addAll(EnumSet.of(BarcodeFormat.QR_CODE));decodeHintTypeObjectEnumMap.put(DecodeHintType.POSSIBLE_FORMATS, list);MultiFormatReader multiFormatReader = new MultiFormatReader();multiFormatReader.setHints(decodeHintTypeObjectEnumMap);try {Result decode = multiFormatReader.decode(binaryBitmap);String text = decode.getText();Log.i("xxxxx", "onPreviewFrame: " + text);} catch (Throwable e) {Log.e("xxxxx", "onPreviewFrame: ", e);}}
}