我想在同一个活动中停止后重新启动相机源

Question

我制作了一个条形码检测器应用程序，因此我使用 SurfaceView 来处理相机源。相机检测到条形码并返回其值后，我让它停止。没有任何函数可以在任何事件上重新启动相机源和表面视图，只有一个函数，即camersource.start()；

它启动了，但问题在后台运行，我看不到任何内容如何解决这个问题？并再次显示表面视图和相机源。

这是活动 onCreate 方法的完整代码

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

        surfaceView = (SurfaceView) findViewById(R.id.cameraPreview);
        txtShow = (TextView) findViewById(R.id.txtShow);

        startBarcode();

    }

    public void startBarcode() {
        barcodeDetector = new BarcodeDetector.Builder(this)
                .setBarcodeFormats(Barcode.ALL_FORMATS)
                .build();
        cameraSource = new CameraSource.Builder(this, barcodeDetector)
                .setRequestedPreviewSize(800, 600)
                .setAutoFocusEnabled(true)
                .build();

        //Events

        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                if (ActivityCompat.checkSelfPermission(getApplicationContext(), android.Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
                    //Make Request Runtime Permission
                    ActivityCompat.requestPermissions(MainActivity.this,
                            new String[]{Manifest.permission.CAMERA}, RequestCameraPermissionId);
                    return;
                }
                try {
                    cameraSource.start(surfaceView.getHolder());

                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                if (ActivityCompat.checkSelfPermission(MainActivity.this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {

                    //Make Request Runtime Permission
                    ActivityCompat.requestPermissions(MainActivity.this,
                            new String[]{Manifest.permission.CAMERA}, RequestCameraPermissionId);
                    return;
                }
                try {
                    cameraSource.start();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                cameraSource.stop();
            }
        });

        barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {

            @Override
            public void release() {

            }

            @Override
            public void receiveDetections(Detector.Detections<Barcode> detections) {
                final SparseArray<Barcode> qrCodes = detections.getDetectedItems();
                if (qrCodes.size() != 0) {
                    txtShow.post(new Runnable() {
                        @Override
                        public void run() {
                            //create vibrate
                            Vibrator vibrator = (Vibrator) getApplicationContext().getSystemService(Context.VIBRATOR_SERVICE);
                            vibrator.vibrate(500);


                            //set result for Text View
                            txtShow.setText(qrCodes.valueAt(0).displayValue);

                            // surfaceView.setTop(200);
                            cameraSource.stop();


                            final MediaPlayer mp = MediaPlayer.create(MainActivity.this, R.raw.barcode);
                            mp.start();

Answer 1

要在cameraSource.stop()之后重新启动，您需要：

cameraSource.start(surfaceView.getHolder());