CameraSource .setAutoFocusEnabled(true) returns: Camera auto focus is not supported on this device although device supports auto focus

问题

Below is my barcode scanner activity, everything works fine except for the setAutoFocusEnabled(true). It returns a message on runtime that says my device does not support auto focus although the Samsung Tab E T561 is an auto focus enabled device.

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.util.SparseArray;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.EditText;

import com.google.android.gms.vision.CameraSource;
import com.google.android.gms.vision.Detector;
import com.google.android.gms.vision.barcode.Barcode;
import com.google.android.gms.vision.barcode.BarcodeDetector;

import java.io.IOException;

import static com.google.android.gms.vision.CameraSource.CAMERA_FACING_BACK;
import static com.google.android.gms.vision.CameraSource.CAMERA_FACING_FRONT;

public class ScanBarcodeActivity extends AppCompatActivity {

    private String TAG = "ScanBarcodeActivity";
    private BarcodeDetector barcodeDetector;
    private SurfaceView cameraView;
    private CameraSource cameraSource;
    private EditText cardNo;


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

    @Override
    protected void onResume() {
        cameraView = (SurfaceView) findViewById(R.id.surfaceViewCamera);
        cardNo = (EditText) findViewById(R.id.editTextBarcode);

        scanBarcodeCam(0);
        super.onResume();
    }

    @Override
    protected void onDestroy() {
        if(cameraSource != null) {
            cameraSource.stop();
            cameraSource.release();
            cameraSource = null;
        }

        super.onDestroy();
    }

    public void switchCam(View view) {

        if(cameraSource.getCameraFacing() == CAMERA_FACING_BACK) {
            cameraSource.stop();
            cameraSource.release();
            cameraSource = null;
            scanBarcodeCam(0);
            Log.i(TAG, "switchCam to front");
        } else {
            cameraSource.stop();
            cameraSource.release();
            cameraSource = null;
            scanBarcodeCam(1);
            Log.i(TAG, "switchCam to back");
        }

    }

    public void scanBarcodeCam(int cam) {

        if(barcodeDetector == null) {
            barcodeDetector = new BarcodeDetector.Builder(this)
                    .setBarcodeFormats(Barcode.EAN_13)
                    .build();
        }

        if(cam == 0) {
            cameraSource = new CameraSource
                    .Builder(this, barcodeDetector)
                    .setRequestedPreviewSize(640, 480)
                    .setFacing(CAMERA_FACING_FRONT)
                    .setRequestedFps(30.0f)
                    .build();
        } else if(cam == 1) {
            cameraSource = new CameraSource
                    .Builder(this, barcodeDetector)
                    .setRequestedPreviewSize(640, 480)
                    .setFacing(CAMERA_FACING_BACK)
                    .setRequestedFps(30.0f)
                    .setAutoFocusEnabled(true)
                    .build();
        }

        if(!cameraView.getHolder().getSurface().isValid()) {
            Log.i(TAG, "*** new SurfaceHolder");
            cameraView.getHolder().addCallback(new SurfaceHolder.Callback() {
                @Override
                public void surfaceCreated(SurfaceHolder holder) {
                    try {
                        cameraSource.start(cameraView.getHolder());
                    } catch (IOException | RuntimeException e) {
                        Log.e(TAG, e.getMessage());
                    }
                }

                @Override
                public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {

                }

                @Override
                public void surfaceDestroyed(SurfaceHolder holder) {
                    if (cameraSource != null) {
                        cameraSource.stop();
                        cameraSource.release();
                        cameraSource = null;
                    }
                }
            });
        } else {
            try {
                cameraSource.start(cameraView.getHolder());
            } catch(IOException e) {
                Log.e(TAG, e.getMessage());
            }
        }

        barcodeDetector.setProcessor(new Detector.Processor<Barcode>() {
            @Override
            public void release() {

            }

            @Override
            public void receiveDetections(Detector.Detections<Barcode> detections) {
                final SparseArray<Barcode> barcodes = detections.getDetectedItems();

                if(barcodes.size() != 0) {
                    cardNo.post(new Runnable() {
                        @Override
                        public void run() {
                            cardNo.setText(barcodes.valueAt(0).displayValue);
                        }
                    });
                }
            }
        });
    }
}

Any help would be highly appreciated.

回答1:

So after two days of struggle I finally managed to "concoct" a fix. But Android development team should seriously look into why setAutoFocusEnabled(true) doesn't work on devices with Auto Focus.

Here is my fix, hope it saves someone else some time:

@Override
public boolean onTouchEvent(MotionEvent event) {
    if(event.getAction() == MotionEvent.ACTION_UP) {
        float x =  event.getX();
        float y = event.getY();
        float touchMajor = event.getTouchMajor();
        float touchMinor = event.getTouchMinor();

        Rect touchRect = new Rect((int)(x - touchMajor / 2), (int)(y - touchMinor / 2), (int)(x + touchMajor / 2), (int)(y + touchMinor / 2));

        this.submitFocusAreaRect(touchRect);
    }
    return super.onTouchEvent(event);
}

private void submitFocusAreaRect(final Rect touchRect) {
    Field[] declaredFields = CameraSource.class.getDeclaredFields();

    for (Field field : declaredFields) {
        if (field.getType() == Camera.class) {
            field.setAccessible(true);
            try {
                Camera camera = (Camera) field.get(cameraSource);
                if (camera != null) {
                    Camera.Parameters cameraParameters = camera.getParameters();

                    if(cameraParameters.getMaxNumFocusAreas() == 0) {
                        return;
                    }

                    Rect focusArea = new Rect();

                    focusArea.set(touchRect.left * 2000 / cameraView.getWidth() - 1000,
                            touchRect.top * 2000 / cameraView.getHeight() - 1000,
                            touchRect.right * 2000 / cameraView.getWidth() - 1000,
                            touchRect.bottom * 2000 / cameraView.getHeight() - 1000);

                    ArrayList<Camera.Area> focusAreas = new ArrayList<>();
                    focusAreas.add(new Camera.Area(focusArea, 1000));

                    cameraParameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
                    cameraParameters.setFocusAreas(focusAreas);
                    camera.setParameters(cameraParameters);

                    camera.autoFocus(this);
                }
            } catch (IllegalAccessException | RuntimeException e) {
                e.getMessage();
            }

            break;
        }
    }

}

Now I can scan barcodes with the rear camera as well. Yay!

来源：https://stackoverflow.com/questions/41629911/camerasource-setautofocusenabledtrue-returns-camera-auto-focus-is-not-suppor