java - Android AutoFocusCallback 未被调用或未返回

Question

我正在开发具有以下功能的条形码扫描应用程序:

• 访问设备相机，在 SurfaceView 上预览相机，并自动重新对焦

• 尝试使用两种方法解码条码

a) 在使用 onTouchEvent(MotionEvent event) 的 SurfaceView 触摸上，尝试拍摄条形码的照片，但得到 java.lang.RuntimeException: takePicture failed

b) 或者 Preferator ，可以在 onAutoFocus(boolean success, Camera camera) 成功时拍照，但不会调用 onAutoFocus()

我正在实现“AutoFocusCallback”，并在名为“ScanVinFromBarcodeActivity”的扫描 Activity 中设置回相机对象。

下面是我的“ScanVinFromBarcodeActivity”，它负责相机功能:

 package com.t.t.barcode;

    /* I removed import statements because of character limit*/
    import com.t.t.R;

public class ScanVinFromBarcodeActivity extends Activity {

    private Camera globalCamera;
    private int cameraId = 0;
    private TextView VINtext = null;
    private Bitmap bmpOfTheImageFromCamera = null;
    private boolean isThereACamera = false;
    private RelativeLayout RelativeLayoutBarcodeScanner = null;
    private CameraPreview newCameraPreview = null;
    private SurfaceView surfaceViewBarcodeScanner = null;
    private String VIN = null; 
    private boolean  globalFocusedBefore = false;

     //This method , finds FEATURE_CAMERA, opens the camera, set parameters ,

    @SuppressLint("InlinedApi")
    private void initializeGlobalCamera() {

        try {
            if (!getPackageManager().hasSystemFeature(
                    PackageManager.FEATURE_CAMERA)) {
                Toast.makeText(this, "No camera on this device",
                        Toast.LENGTH_LONG).show();
            } else { // check for front camera ,and get the ID
                cameraId = findFrontFacingCamera();
                if (cameraId < 0) {

                    Toast.makeText(this, "No front facing camera found.",
                            Toast.LENGTH_LONG).show();
                } else {

                    Log.d("ClassScanViewBarcodeActivity",
                            "camera was found , ID: " + cameraId);
                    // camera was found , set global camera flag to true
                    isThereACamera = true;
                    // OPEN
                    globalCamera = getGlobalCamera(cameraId);
                    //PARAMETERS FOR AUTOFOCUS 
                    globalCamera.getParameters().setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
                    //set auto focus callback , called  when autofocus has completed 

globalCamera.autoFocus(autoFocusCallback); //将 surfaceView 传递给 CameraPreview newCameraPreview = new CameraPreview(this, globalCamera) {

                        @Override
                        public boolean onTouchEvent(MotionEvent event) {
                            Log.d("ClassScanViewBarcodeActivity"," onTouchEvent(MotionEvent event) ");

                            takePicture();
                            return super.onTouchEvent(event);
                        }

                    };

                    // pass CameraPreview to Layout
                    RelativeLayoutBarcodeScanner.addView(newCameraPreview);
                    //give reference SurfaceView to camera object 
                        globalCamera
                                .setPreviewDisplay(surfaceViewBarcodeScanner
                                        .getHolder());


                    // PREVIEW
                    globalCamera.startPreview();

                    Log.d("ClassScanViewBarcodeActivity",
                            "camera opened & previewing");
                }
            }// end else 
        }// end try
        catch (Exception exc) {

            //  resources & cleanup
            if (globalCamera != null) {
                globalCamera.stopPreview();
                globalCamera.setPreviewCallback(null);
                globalCamera.release();
                globalCamera = null;

            }
            Log.d("ClassScanViewBarcodeActivity initializeGlobalCamera() exception:",
                    exc.getMessage());
            exc.printStackTrace();
        }// end catch

    }

    // onCreate, instantiates layouts & surfaceView used for video preview
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_barcode_vin_scanner);
        Log.d("ClassScanViewBarcodeActivity", "onCreate ");

        // create surfaceView for previewing 
        RelativeLayoutBarcodeScanner = (RelativeLayout) findViewById(R.id.LayoutForPreview);
        surfaceViewBarcodeScanner = (SurfaceView) findViewById(R.id.surfaceViewBarcodeScanner);

        initializeGlobalCamera();

    }// end onCreate

    @Override
    protected void onResume() {

        Log.d("ClassScanViewBarcodeActivity, onResume() globalCamera:",
                String.valueOf(globalCamera));

        initializeGlobalCamera();

        super.onResume();
    }

    @Override
    protected void onStop() {

        if (globalCamera != null) {
            globalCamera.stopPreview();
            globalCamera.setPreviewCallback(null);
            globalCamera.release();
            globalCamera = null;
        }
        super.onStop();
    }

    @Override
    protected void onPause() {
        if (globalCamera != null) {
            globalCamera.stopPreview();
            globalCamera.setPreviewCallback(null);
            globalCamera.release();
            globalCamera = null;
        }
        super.onPause();
    }// end onPause()

    // callback used by takePicture()

        @SuppressLint("NewApi")
        public void onPictureTaken(byte[] imgData, Camera camera) {
            BinaryBitmap bitmap = null ;
            try {

                Log.d("ClassScanViewBarcodeActivity", "onPictureTaken()");

                 // 1)down-sampled the image via to  prevent MemoryOutOfBounds exception.


                BitmapFactory.Options options = new BitmapFactory.Options();
                options.inSampleSize = 4;
                options.inPreferQualityOverSpeed =true;

                bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
                        imgData, 0, imgData.length, options);

                if (bmpOfTheImageFromCamera != null) {

                    // 2) Samsung galaxy S only , rotate to correct orientation 

                    Matrix rotationMatrix90CounterClockWise = new Matrix();
                    rotationMatrix90CounterClockWise.postRotate(90);

                    bmpOfTheImageFromCamera = Bitmap.createBitmap(
                            bmpOfTheImageFromCamera, 0, 0,
                            bmpOfTheImageFromCamera.getWidth(),
                            bmpOfTheImageFromCamera.getHeight(),
                            rotationMatrix90CounterClockWise, true);

                    // 3) calculate relative x,y & width & height , because SurfaceView coordinates are different than the coordinates of the image
                    guidanceRectangleCoordinatesCalculations newguidanceRectangleCoordinatesCalculations = new guidanceRectangleCoordinatesCalculations(
                            bmpOfTheImageFromCamera.getWidth(),
                            bmpOfTheImageFromCamera.getHeight());


                    // 4) crop & only take image/data that is within the bounding rectangle 
                    Bitmap croppedBitmap = Bitmap
                            .createBitmap(
                                    bmpOfTheImageFromCamera,
                                    newguidanceRectangleCoordinatesCalculations
                                            .getGuidanceRectangleStartX(),
                                    newguidanceRectangleCoordinatesCalculations
                                            .getGuidanceRectangleStartY(),
                                    newguidanceRectangleCoordinatesCalculations
                                            .getGuidanceRectangleEndX()
                                            - newguidanceRectangleCoordinatesCalculations
                                                    .getGuidanceRectangleStartX(),
                                    newguidanceRectangleCoordinatesCalculations
                                            .getGuidanceRectangleEndY()
                                            - newguidanceRectangleCoordinatesCalculations
                                                    .getGuidanceRectangleStartY());



                    //Bitmap to BinaryBitmap
                    bitmap = cameraBytesToBinaryBitmap(croppedBitmap);

                    //early cleanup 
                    croppedBitmap.recycle();
                    croppedBitmap = null; 

                    if (bitmap != null) {
                        // 7) decode the VIN

                        VIN = decodeBitmapToString(bitmap);
            Log.("***ClassScanViewBarcodeActivity ,onPictureTaken(): VIN ",
                                VIN);
                        if (VIN!=null)
                        {
                            //original before sharpen
                            byte [] bytesImage = bitmapToByteArray ( croppedBitmap );
                            savePicture(bytesImage, 0 , "original");

                            //after sharpen         
                            croppedBitmap = sharpeningKernel (croppedBitmap);

                            bytesImage = bitmapToByteArray ( croppedBitmap );
                            savePicture(bytesImage, 0 , "sharpened");



                            Toast toast= Toast.makeText(getApplicationContext(), 
                                    "VIN:"+VIN, Toast.LENGTH_SHORT);  
                                    toast.setGravity(Gravity.TOP|Gravity.CENTER_HORIZONTAL, 0, 0);
                                    toast.show();
                        }
                    } else {
                        Log.d("ClassScanViewBarcodeActivity ,onPictureTaken(): bitmap=",
                                String.valueOf(bitmap));

                    }
                } else {
                    Log.d("ClassScanViewBarcodeActivity , onPictureTaken(): bmpOfTheImageFromCamera = ",
                            String.valueOf(bmpOfTheImageFromCamera));

                }

            }// end try

            catch (Exception exc) {
                exc.getMessage();

                Log.d("ClassScanViewBarcodeActivity , scanButton.setOnClickListener(): exception = ",
                        exc.getMessage());
            }

            finally {

                // start previewing again onthe SurfaceView in case use wants to
                // take another pic/scan

                globalCamera.startPreview();
                bitmap = null; 
            }

        }// end onPictureTaken()
    };//end 
    //autoFocuscallback
    AutoFocusCallback autoFocusCallback = new AutoFocusCallback() {
          @Override
          public void onAutoFocus(boolean success, Camera camera) {
              Log.d("***onAutoFocus(boolean success, Camera camera)","success: "+success); 


              if (success)
              {

                 globalFocusedBefore = true;
                  takePicture();
              }



          }
        };//end 

        public Camera getGlobalCamera(int CameraId)
        {
            if (globalCamera==null)
            {
                // OPEN
                globalCamera = Camera.open( CameraId);
            }

            return globalCamera;

        }

        /* find camera on device */
        public static int findFrontFacingCamera() {
            int cameraId = -1;
            // Search for the front facing camera
            int numberOfCameras = Camera.getNumberOfCameras();
            for (int i = 0; i < numberOfCameras; i++) {
                CameraInfo info = new CameraInfo();
                Camera.getCameraInfo(i, info);
                if (info.facing == CameraInfo.CAMERA_FACING_BACK) {
                    Log.d("ClassScanViewBarcodeActivity , findFrontFacingCamera(): ",
                            "Camera found");
                    cameraId = i;
                    break;
                }
            }
            return cameraId;
        }// end findFrontFacingCamera()

    /*
     * created savePicture(byte [] data) for testing
     */
    public void savePicture(byte[] data, double sizeInPercent , String title) {
        Log.d("ScanVinFromBarcodeActivity ", "savePicture(byte [] data)");
        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyymmddhhmmss");
        String date = dateFormat.format(new Date());
        String photoFile = "Picture_sample_sizePercent_" + sizeInPercent + "_" + title + "_"
                + date + ".jpg";

        File sdDir = Environment
                .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES);

        String filename = sdDir + File.separator + photoFile;

        File pictureFile = new File(filename);

        try {
            FileOutputStream fos = new FileOutputStream(pictureFile);
            fos.write(data);
            fos.close();

            Toast.makeText(this, "New Image saved:" + photoFile,
                    Toast.LENGTH_LONG).show();

        } catch (Exception error) {
            Log.d("File not saved: ", error.getMessage());
            Toast.makeText(this, "Image could not be saved.", Toast.LENGTH_LONG)
                    .show();
        }

    }

    /*
     * Attempts to decode barcode data inside the input bitmap. Uses zxing API */
    @SuppressWarnings("finally")
    public String decodeBitmapToString(BinaryBitmap bitmap) {

        Log.d("ClassScanViewBarcodeActivity",
                "decodeBitmapToString(BinaryBitmap bitmap");
        Reader reader = null;
        Result result = null;
        String textResult = null;
        Hashtable<DecodeHintType, Object> decodeHints = null; 

        try {

             decodeHints = new Hashtable<DecodeHintType, Object>();
            decodeHints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
            decodeHints.put(DecodeHintType.PURE_BARCODE, Boolean.TRUE);

            reader = new MultiFormatReader();
            if (bitmap != null) {
                result = reader.decode(bitmap, decodeHints);
                if (result != null) {
                    Log.d("decodeBitmapToString (BinaryBitmap bitmap): result = ",
                            String.valueOf(result));

                    Log.d("decodeBitmapToString (BinaryBitmap bitmap): result = ",
                            String.valueOf(result.getBarcodeFormat().toString()));

                    textResult = result.getText();

                } else {
                    Log.d("decodeBitmapToString (BinaryBitmap bitmap): result = ",
                            String.valueOf(result));
                }
            } else {
                Log.d("decodeBitmapToString (BinaryBitmap bitmap): bitmap = ",
                        String.valueOf(bitmap));
            }


        } catch (NotFoundException e) {
            // TODO Auto-generated catch block

            textResult = "Unable to decode. Please try again.";
            e.printStackTrace();
            Log.d("ClassScanViewBarcodeActivity, NotFoundException:",
                    e.getMessage());

        } catch (ChecksumException e) {

            textResult = "Unable to decode. Please try again.";
            e.printStackTrace();
            Log.d("ClassScanViewBarcodeActivity, ChecksumException:",
                    e.getMessage());

        } catch (FormatException e) {

            textResult = "Unable to decode. Please try again.";
            e.printStackTrace();
            Log.d("ClassScanViewBarcodeActivity, FormatException:",
                    e.getMessage());

        }

        finally {
            //cleanup 
            reader = null;
            result = null;
            decodeHints = null; 
            return textResult;
        }
    }// end decodeBitmapToString ()

    @SuppressWarnings("finally")
    public BinaryBitmap cameraBytesToBinaryBitmap(Bitmap bitmap) {
        Log.d("ClassScanViewBarcodeActivity , cameraBytesToBinaryBitmap (Bitmap bitmap):",
                "");
        BinaryBitmap binaryBitmap = null;
        RGBLuminanceSource source = null; 
        HybridBinarizer bh = null; 
        try {

            if (bitmap != null) {                   
                //bitmap.getPixels(pixels, 0, bitmap.getWidth(), 0, 0,bitmap.getWidth(), bitmap.getHeight());

                //RGBLuminanceSource source = new RGBLuminanceSource(bitmap.getWidth(), bitmap.getHeight(), pixels);

                source = new RGBLuminanceSource(bitmap);
                 bh = new HybridBinarizer(source);

                binaryBitmap = new BinaryBitmap(bh);

            } else {
                Log.d("ClassScanViewBarcodeActivity , cameraBytesToBinaryBitmap (Bitmap bitmap): bitmap = ",
                        String.valueOf(bitmap));
            }
        } catch (Exception exc) {
            exc.printStackTrace();
        } finally {


         source = null; 
        bh = null;
            return binaryBitmap;
        }
    }

    @SuppressLint("NewApi")
    @SuppressWarnings("deprecation")
    /*
     * The method getScreenOrientation() return screen orientation either
     * landscape or portrait. IF width < height , than orientation = portrait,
     * ELSE landscape For backwards compatibility we use to methods to detect
     * the orientation. The first method is for API versions prior to 13 or
     * HONEYCOMB.
     */
    public int getScreenOrientation() {

        int currentapiVersion = android.os.Build.VERSION.SDK_INT;
        // if API version less than 13
        Display getOrient = getWindowManager().getDefaultDisplay();
        int orientation = Configuration.ORIENTATION_UNDEFINED;

        if (currentapiVersion < android.os.Build.VERSION_CODES.HONEYCOMB) {
            // Do something for API version less than HONEYCOMB

            if (getOrient.getWidth() == getOrient.getHeight()) {
                orientation = Configuration.ORIENTATION_SQUARE;
            } else {
                if (getOrient.getWidth() < getOrient.getHeight()) {
                    orientation = Configuration.ORIENTATION_PORTRAIT;
                } else {
                    orientation = Configuration.ORIENTATION_LANDSCAPE;
                }
            }
        } else {
            // Do something for API version greater or equal to HONEYCOMB

            Point size = new Point();
            this.getWindowManager().getDefaultDisplay().getSize(size);
            int width = size.x;
            int height = size.y;

            if (width < height) {
                orientation = Configuration.ORIENTATION_PORTRAIT;
            } else {
                orientation = Configuration.ORIENTATION_LANDSCAPE;
            }
        }

        return orientation;

    }// end getScreenOrientation()


    public Bitmap sharpeningKernel (Bitmap bitmap)
    {

        if (bitmap!=null)
        {

            int result = 0 ;
            int pixelAtXY = 0; 
            for (int i=0 ; i<bitmap.getWidth(); i++)
            {

                for (int j=0 ; j<bitmap.getHeight(); j++)
                {
                    //piecewise multiply with kernel
                    //add multiplication result to total / sum of kernel values 
                    /* Conceptual kernel
                     * int kernel [][]= 
                {{0,-1,0},
                {-1,5,-1},
                {0,-1,0}};
                     */
             pixelAtXY = bitmap.getPixel(i, j);

                result = ((pixelAtXY * -1) + (pixelAtXY * -1) + (pixelAtXY * 5)+ (pixelAtXY * -1)  + (pixelAtXY * -1)); 
                 bitmap.setPixel(i, j,result);
                }
            }
        }

        return bitmap;
    }//end 

    public byte [] bitmapToByteArray (Bitmap bitmap)
    {
        ByteArrayOutputStream baoStream = new ByteArrayOutputStream();
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100,
                baoStream);
        return baoStream.toByteArray();
    }


        public void takePicture()
        {
            Log.d("ClassScanViewBarcodeActivity","takePicture()");
            try {

                // if true take a picture
                if (isThereACamera) {
                    Log.d("ClassScanViewBarcodeActivity",
                            "setOnClickListener() isThereACamera: "
                                    + isThereACamera);

                    // set picture format to JPEG, everytime makesure JPEg
                    globalCamera.getParameters().setPictureFormat(ImageFormat.JPEG);

                        if ( globalFocusedBefore = true)
                        {
                    // take pic , should call Callback
                    globalCamera.takePicture(null, null, jpegCallback);
                    //reset autofocus flag 
                     globalFocusedBefore = false; 
                        }

                }

            }// end try
            catch (Exception exc) {

                // in case of exception release resources & cleanup
                if (globalCamera != null) {
                    globalCamera.stopPreview();
                    globalCamera.setPreviewCallback(null);
                    globalCamera.release();
                    globalCamera = null;

                }
                Log.d("ClassScanViewBarcodeActivity setOnClickListener() exceprtion:",
                        exc.getMessage());
                exc.printStackTrace();
            }// end catch

        }// end takePicture()

}// end activity class

下面是我的预览类，它显示来自相机的实时图像

package com.t.t.barcode;

/* I removed imports due to character limit on Stackoverflow*/

package com.t.t.barcode;

/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements
        SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    private Camera mCamera;
    private Context context;
    //
    private int guidanceRectangleStartX;
    private int guidanceRectangleStartY;
    private int guidanceRectangleEndX;
    private int guidanceRectangleEndY;
    //
    private ImageView imageView = null; 
    private  Bitmap guidanceScannerFrame = null; 

    public CameraPreview(Context context, Camera camera) {
        super(context);

        mCamera = camera;
        this.context = context;
        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = getHolder();
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

          setWillNotDraw(false);
          setFocusable(true); 
          requestFocus(); 

          guidanceScannerFrame  =  getBitmapFromResourcePath("res/drawable/scanner_frame.png");

    }

    public void drawGuidance(Canvas canvas)
    {


    Paint paintRed = new Paint();
    paintRed.setStyle(Paint.Style.STROKE);
    paintRed.setStrokeWidth(6f);
    paintRed.setAntiAlias(true);
    paintRed.setColor(Color.RED);

    //drawMiddleline
     canvas.drawLine(0,this.getHeight()/2, this.getWidth(),this.getHeight()/2, paintRed);


    if (guidanceScannerFrame!=null)
    {

        Paint paint = new Paint();
        paint.setFilterBitmap(true);


int diffInWidth =0;
int diffInHeight = 0;

try
{

diffInWidth = this.getWidth() - guidanceScannerFrame.getScaledWidth(canvas);
diffInHeight = this.getHeight() - guidanceScannerFrame.getScaledHeight(canvas);

//
    canvas.drawBitmap(guidanceScannerFrame,(diffInWidth/2),(diffInHeight/2) , paint);
}
catch (NullPointerException exc)
{
    exc.printStackTrace();
}

/*create rectangle that is relative to the SurfaceView coordinates and fits inside the Bitmap rectangle, 
 * this coordinates will later be used to crop inside of the Bitmap to take in the only the barcode's picture*/

Paint paintGray = new Paint();
paintGray.setStyle(Paint.Style.STROKE);
paintGray.setStrokeWidth(2f);
paintGray.setAntiAlias(true);
paintGray.setColor(Color.GRAY);
//drawRect
canvas.drawRect((diffInWidth/2), (diffInHeight/2), (diffInWidth/2)+guidanceScannerFrame.getScaledWidth(canvas),(diffInHeight/2)+guidanceScannerFrame.getScaledHeight(canvas), paintGray);


this.guidanceRectangleStartX = this.getWidth()/12;
this.guidanceRectangleStartY=  this.getHeight()/3;
this.guidanceRectangleEndX = this.getWidth()-this.getWidth()/12;
this.guidanceRectangleEndY =(this.getHeight()/3)+( 2 *(this.getHeight()/3));
    }

    }

      @Override 
      public void onDraw(Canvas canvas) { 

          //drawGuidance
          drawGuidance(canvas);



      } 


    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the
        // preview.
        try {

            Camera.Parameters p = mCamera.getParameters();

            // get width & height of the SurfaceView
            int SurfaceViewWidth = this.getWidth();
            int SurfaceViewHeight = this.getHeight();

            List<Size> sizes = p.getSupportedPreviewSizes();
            Size optimalSize = getOptimalPreviewSize(sizes, SurfaceViewWidth, SurfaceViewHeight);


            // set parameters
            p.setPreviewSize(optimalSize.width, optimalSize.height);
            p.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);

            /*rotate the image by 90 degrees clockwise , in order to correctly displayed the image , images seem to be -90 degrees (counter clockwise) rotated 
             * I even tried setting it to  p.setRotation(0); , but still no effect.
             */
            mCamera.setDisplayOrientation(90);


            mCamera.setParameters(p);
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();


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

    public void surfaceDestroyed(SurfaceHolder holder) {
        // empty. Take care of releasing the Camera preview in your activity.
    }

    @SuppressLint("InlinedApi")
    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null) {
            // preview surface does not exist
            return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e) {
            // ignore: tried to stop a non-existent preview
        }


        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e) {
            Log.d("CameraPreview ,  surfaceCreated() , orientation: ",
                    String.valueOf(e.getMessage()));
        }
    }// end surfaceChanged()


     static Size getOptimalPreviewSize(List <Camera.Size>sizes, int w, int h) {
            final double ASPECT_TOLERANCE = 0.1;
            final double MAX_DOWNSIZE = 1.5;

            double targetRatio = (double) w / h;
            if (sizes == null) return null;

            Size optimalSize = null;
            double minDiff = Double.MAX_VALUE;

            int targetHeight = h;

            // Try to find an size match aspect ratio and size
            for (Camera.Size size : sizes) {
              double ratio = (double) size.width / size.height;
              double downsize = (double) size.width / w;
              if (downsize > MAX_DOWNSIZE) {
                //if the preview is a lot larger than our display surface ignore it
                //reason - on some phones there is not enough heap available to show the larger preview sizes
                continue;
              }
              if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
              if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
              }
            }
            // Cannot find the one match the aspect ratio, ignore the requirement
            //keep the max_downsize requirement
            if (optimalSize == null) {
              minDiff = Double.MAX_VALUE;
              for (Size size : sizes) {
                double downsize = (double) size.width / w;
                if (downsize > MAX_DOWNSIZE) {
                  continue;
                }
                if (Math.abs(size.height - targetHeight) < minDiff) {
                  optimalSize = size;
                  minDiff = Math.abs(size.height - targetHeight);
                }
              }
            }
            //everything else failed, just take the closest match
            if (optimalSize == null) {
              minDiff = Double.MAX_VALUE;
              for (Size size : sizes) {
                if (Math.abs(size.height - targetHeight) < minDiff) {
                  optimalSize = size;
                  minDiff = Math.abs(size.height - targetHeight);
                }
              }
            }
            return optimalSize;
          }


     public Bitmap getBitmapFromResourcePath (String path)
     {
         InputStream in =null;
         Bitmap guidanceBitmap = null;

         try
         {
         if (path!=null)
         {

          in = this.getClass().getClassLoader().getResourceAsStream(path);

          guidanceBitmap = BitmapFactory.decodeStream(in);

         }
         }
         catch (Exception exc)
         {
             exc.printStackTrace();
         }
         finally
         {
             if (in!=null)
             {
                 try {
                    in.close();
                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
             }
         }
         return guidanceBitmap;
     }

    public int getGuidanceRectangleStartX() {
        return guidanceRectangleStartX;
    }


    public int getGuidanceRectangleStartY() {
        return guidanceRectangleStartY;
    }


    public int getGuidanceRectangleEndX() {
        return guidanceRectangleEndX;
    }

    public int getGuidanceRectangleEndY() {
        return guidanceRectangleEndY;
    }


}//end preview class

屏幕截图 Activity GUI:

任何帮助将不胜感激，谢谢。

Answer 1

您在预览类中调用 Oncreate 上的自动对焦它应该在表面创建或表面改变时调用因为一旦启动相机预览就会发生自动对焦看看这段代码，我已经处理过了，它正在运行

private void tryAutoFocus() {
    if( MyDebug.LOG )
        Log.d(TAG, "tryAutoFocus");
    if( camera == null ) {
        if( MyDebug.LOG )
            Log.d(TAG, "no camera");
    }
    else if( !this.has_surface ) {
        if( MyDebug.LOG )
            Log.d(TAG, "preview surface not yet available");
    }
    else if( !this.is_preview_started ) {
        if( MyDebug.LOG )
            Log.d(TAG, "preview not yet started");
    }
    else if( is_taking_photo ) {
        if( MyDebug.LOG )
            Log.d(TAG, "currently taking a photo");
    }
    else {
        // if a focus area is set, we always call autofocus even if it isn't supported, so we get the focus box
        // otherwise, it's only worth doing it when autofocus has an effect (i.e., auto or macro mode)
        Camera.Parameters parameters = camera.getParameters();
        String focus_mode = parameters.getFocusMode();
        if( has_focus_area || focus_mode.equals(Camera.Parameters.FOCUS_MODE_AUTO) || focus_mode.equals(Camera.Parameters.FOCUS_MODE_MACRO) ) {
            if( MyDebug.LOG )
                Log.d(TAG, "try to start autofocus");
            Camera.AutoFocusCallback autoFocusCallback = new Camera.AutoFocusCallback() {
                @Override
                public void onAutoFocus(boolean success, Camera camera) {
                    if( MyDebug.LOG )
                        Log.d(TAG, "autofocus complete: " + success);
                    focus_success = success ? FOCUS_SUCCESS : FOCUS_FAILED;
                    focus_complete_time = System.currentTimeMillis();
                    if(_automationStarted){
                        takeSnapPhoto();
                    }
                }
            };
            this.focus_success = FOCUS_WAITING;
            this.focus_complete_time = -1;
            camera.autoFocus(autoFocusCallback);
        }
    }
}

public void surfaceCreated(SurfaceHolder holder) {
    if( MyDebug.LOG )
        Log.d(TAG, "surfaceCreated()");
    // The Surface has been created, acquire the camera and tell it where to draw.
    this.has_surface = true;
    this.openCamera(false); // if setting up for the first time, we wait until the surfaceChanged call to start the preview
    this.setWillNotDraw(false); // see http://stackoverflow.com/questions/2687015/extended-surfaceviews-ondraw-method-never-called
}
public void surfaceDestroyed(SurfaceHolder holder) {
    if( MyDebug.LOG )
        Log.d(TAG, "surfaceDestroyed()");
    // Surface will be destroyed when we return, so stop the preview.
    // Because the CameraDevice object is not a shared resource, it's very
    // important to release it when the activity is paused.
    this.has_surface = false;
    this.closeCamera();
}
public void takeSnapPhoto() {
    camera.setOneShotPreviewCallback(new Camera.PreviewCallback() {
        @Override
        public void onPreviewFrame(byte[] data, Camera camera) {
            Camera.Parameters parameters = camera.getParameters();
            int format = parameters.getPreviewFormat();
            //YUV formats require more conversion
            if (format == ImageFormat.NV21 || format == ImageFormat.YUY2 || format == ImageFormat.NV16) {
                int w = parameters.getPreviewSize().width;
                int h = parameters.getPreviewSize().height;
                // Get the YuV image
                YuvImage yuv_image = new YuvImage(data, format, w, h, null);
                // Convert YuV to Jpeg
                Rect rect = new Rect(0, 0, w, h);
                ByteArrayOutputStream output_stream = new ByteArrayOutputStream();
                yuv_image.compressToJpeg(rect, 100, output_stream);
                byte[] byt = output_stream.toByteArray();
                FileOutputStream outStream = null;
                try {
                    // Write to SD Card
                    File file = createFileInSDCard(FOLDER_PATH, "Image_"+System.currentTimeMillis()+".jpg");
                    //Uri uriSavedImage = Uri.fromFile(file);
                    outStream = new FileOutputStream(file);
                    outStream.write(byt);
                    outStream.close();
                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                } finally {
                }
            }
        }
    });
}

当你初始化相机时(或在这种情况下打开相机)

 private void openCamera(boolean start_preview) {
      tryautofocus();//call this after setting camera parameters 
        }