Android camera , onPictureTaken(byte[] imgData, Camera camera) method & PictureCallback never called

Question

I have a custom camera app , that previews the camera video output on SurfaceView and attempts to take pictures , the pics should be will be processed by “xzing “scanner API to decode any barcodes in the image.

My app previews correctly and does not throw any errors or expectations, however my onPictureTaken(byte[] imgData, Camera camera) method & PictureCallback are never called, therefore I’m unable to get the image & continue with further scanning.

Below is the actual code for activity that takes care of Camera logic. The onPictureTaken(byte[] imgData, Camera camera) method & PictureCallback are in this class(ScanVinFromBarcodeActivity.java) see blow :

package com.ty.tyownerspoc.barcode;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.ChecksumException;
import com.google.zxing.FormatException;
import com.google.zxing.MultiFormatReader;
import com.google.zxing.NotFoundException;
import com.google.zxing.RGBLuminanceSource; 
import com.google.zxing.Reader;
import com.google.zxing.Result;
import com.google.zxing.common.HybridBinarizer;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.pm.PackageManager;
import android.content.res.Configuration;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.ImageFormat;
import android.graphics.Matrix;
import android.graphics.Point;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.Display;
import android.view.SurfaceView;
import android.view.View;
import android.widget.FrameLayout;
import android.widget.TextView;
import android.widget.Toast;
import com.ty.tyownerspoc.R;

public class ScanVinFromBarcodeActivity extends Activity {

    private Camera globalCamera;
    private int cameraId = 0;
    private TextView VINtext = null;
    private View scanButton = null;
    // bitmap from camera
    private Bitmap bmpOfTheImageFromCamera = null;
    // global flag whether a camera has been detected
    private boolean isThereACamera = false;
    // surfaceView for preview object
    private FrameLayout frameLayoutBarcodeScanner = null;
    private CameraPreview newCameraPreview = null;
    private SurfaceView surfaceViewBarcodeScanner = null;
    private int counter = 0; 
    private volatile boolean finishedPictureTask  = false;
    /*
     * This method , finds FEATURE_CAMERA, opens the camera, set parameters ,
     * add CameraPreview to layout, set camera surface holder, start preview
     */
    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 = Camera.open(cameraId);

                    // pass surfaceView to CameraPreview
                    newCameraPreview = new CameraPreview(this, globalCamera);
                    // pass CameraPreview to Layout
                    frameLayoutBarcodeScanner.addView(newCameraPreview);
                    try {
                        globalCamera
                                .setPreviewDisplay(surfaceViewBarcodeScanner
                                        .getHolder());
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                    // PREVIEW
                    globalCamera.startPreview();

                    Log.d("ClassScanViewBarcodeActivity",
                            "camera opened & previewing");
                }
            }// end else ,check for front camera
        }// 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 initializeGlobalCamera() exception:",
                    exc.getMessage());
        }// 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 of camera image
        frameLayoutBarcodeScanner = (FrameLayout) findViewById(R.id.FrameLayoutForPreview);
        surfaceViewBarcodeScanner = (SurfaceView) findViewById(R.id.surfaceViewBarcodeScanner);

        initializeGlobalCamera();

        // create text area & scan button
        VINtext = (TextView) findViewById(R.id.mytext);
        scanButton = findViewById(R.id.webbutton);
        // on click listener, onClick take a picture
        scanButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                try {

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

                        //set picture format to JPEG, everytime makesure JPEg callback is called 
                         Parameters parameters = globalCamera.getParameters();              
                         parameters.setPictureFormat(ImageFormat.JPEG);
                         globalCamera.setParameters(parameters);                         
                         //take pic , should call Callback 
                        globalCamera.takePicture(null, null, jpegCallback);
                        // wait 1 sec , than start preview again
                        Thread.sleep(1000);
                        //STOP
                        globalCamera.stopPreview();
                        //start previewing again onthe SurfaceView in case use wants to take another pic/scan
                        globalCamera.startPreview();

                    }

                }// 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());
                }// end catch

            }// end on Click
        });// end OnClickListener() implementation

    }// end onCreate

    @Override
    protected void onResume() {

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

        if (globalCamera != null) {
            // START PREVIEW
            globalCamera.startPreview();
        } else {
            initializeGlobalCamera();
        }

        super.onResume();
    }

    @Override
    protected void onStop() {

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

    //callback used by takePicture()
    PictureCallback jpegCallback = new PictureCallback() {



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



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

                //save image to sd card 
                savePicture(imgData);

                // get the bitmap from camera imageData
                bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
                        imgData, 0, imgData.length);


                if (bmpOfTheImageFromCamera != null) {
                    //Galaxy S3 , incorrect rotation issue rotate to correct rotation
                    Matrix matrix = new Matrix();
                    matrix.postRotate(90);
                    Bitmap rotatedBitmap = Bitmap.createBitmap(bmpOfTheImageFromCamera, 0, 0, bmpOfTheImageFromCamera.getWidth(), bmpOfTheImageFromCamera.getHeight(), matrix, true);
                    // convert bitmap to binary bitmap
                    bitmap = cameraBytesToBinaryBitmap(rotatedBitmap);


                    if (bitmap != null) {
                        // decode the VIN
                        String VIN = decodeBitmapToString(bitmap);
                        Log.d("***ClassScanViewBarcodeActivity ,onPictureTaken(): VIN ",
                                VIN);
                        VINtext.setText(VIN);
                    } 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());
            }

        }// end onPictureTaken()
    };// jpegCallback implementation


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



    private 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()

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

    public String decodeBitmapToString(BinaryBitmap bitmap) {
        Reader reader = null;
        Result result = null;
        String textResult = null;
        try {

            reader = new MultiFormatReader();
            if (bitmap != null) {
                result = reader.decode(bitmap);
                if (result != null) {
                    textResult = result.getText();
                } else {
                    Log.d("ClassScanViewBarcodeActivity , String decodeBitmapToString (BinaryBitmap bitmap): result = ",
                            String.valueOf(result));
                }
            } else {
                Log.d("ClassScanViewBarcodeActivity , String decodeBitmapToString (BinaryBitmap bitmap): bitmap = ",
                        String.valueOf(bitmap));
            }
            /*
             * byte[] rawBytes = result.getRawBytes(); BarcodeFormat format =
             * result.getBarcodeFormat(); ResultPoint[] points =
             * result.getResultPoints();
             */

        } catch (NotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ChecksumException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (FormatException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();

        }

        return textResult;
    }// end decodeBitmapToString (BinaryBitmap bitmap)

    public BinaryBitmap cameraBytesToBinaryBitmap(Bitmap bitmap) {
        BinaryBitmap binaryBitmap = null;
        if (bitmap != null) {

            int[] pixels = new int[bitmap.getHeight() * bitmap.getWidth()];
            bitmap.getPixels(pixels, 0, 0, bitmap.getWidth() - 1,
                    bitmap.getHeight() - 1, bitmap.getWidth(),
                    bitmap.getHeight());

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

            HybridBinarizer bh = new HybridBinarizer(source);
            binaryBitmap = new BinaryBitmap(bh);
        } else {
            Log.d("ClassScanViewBarcodeActivity , cameraBytesToBinaryBitmap (Bitmap bitmap): bitmap = ",
                    String.valueOf(bitmap));
        }

        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()
}// end class ScanVinFromBarcodeActivity

Preview class used to display live camera on SurfaceView (CameraPreview.java):

package com.ty.tyownerspoc.barcode;

import java.io.IOException;
import java.util.List;

import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.ViewGroup;
import android.hardware.Camera.CameraInfo;

/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements
        SurfaceHolder.Callback {
    private SurfaceHolder mHolder;
    private Camera mCamera;
    private Context context;

    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);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the
        // preview.
        try {
            mCamera.setPreviewDisplay(holder);
            mCamera.startPreview();
        } catch (IOException e) {

        }
    }

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

    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
        }
                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);

        /*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);

        // 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;
          }

}//end Preview class

Layout for the “ScanVinFromBarcodeActivity” activity (activity_barcode_vin_scanner.xml):

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical"
    android:padding="20dip" >

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:padding="20dip"
        android:text="@string/decode_label"
        android:textColor="@color/mbackground1" />

    <TextView
        android:id="@+id/mytext"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@color/mbackground2"
        android:gravity="center_horizontal"
        android:padding="20dip"
        android:textColor="@color/mytextcolor" />

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:gravity="center_horizontal"
        android:padding="20dip"
        android:text="@string/continue_label"
        android:textColor="@color/mytextcolor" />

    <Button
        android:id="@+id/webbutton"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/web_button"
        android:textColor="@color/mytextcolor" />

    <FrameLayout
    android:id="@+id/FrameLayoutForPreview"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_weight="1">

        <SurfaceView
            android:id="@+id/surfaceViewBarcodeScanner"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

    </FrameLayout>
</LinearLayout>

Any help will be appreciated.

Thanks

Updated & working onTakePicturen method, the that works , the PictureCallback returns (stopPreview & StartPreview were moved to inside this method in its finally block).


    public void onPictureTaken(byte[] imgData, Camera camera) {
        BinaryBitmap bitmap;
        try {



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

            //save image to sd card 
            savePicture(imgData);

            // get the bitmap from camera imageData

            BitmapFactory.Options options = new BitmapFactory.Options();
              options.inSampleSize = 8; 
              //down sample
            bmpOfTheImageFromCamera = BitmapFactory.decodeByteArray(
                    imgData, 0, imgData.length,options);


            if (bmpOfTheImageFromCamera != null) {

                Log.d("***ClassScanViewBarcodeActivity ,onPictureTaken(): bmpOfTheImageFromCamera getByteCount(): ",
                        String.valueOf(bmpOfTheImageFromCamera.getByteCount()));
                //Galaxy S3 , incorrect rotation issue rotate to correct rotation
                /*Matrix matrix = new Matrix();
                matrix.postRotate(90);
                Bitmap rotatedBitmap = Bitmap.createBitmap(bmpOfTheImageFromCamera, 0, 0, bmpOfTheImageFromCamera.getWidth(), bmpOfTheImageFromCamera.getHeight(), matrix, true);*/
                // convert bitmap to binary bitmap
                bitmap = cameraBytesToBinaryBitmap(bmpOfTheImageFromCamera);


                if (bitmap != null) {
                    // decode the VIN
                    String VIN = decodeBitmapToString(bitmap);
                    Log.d("***ClassScanViewBarcodeActivity ,onPictureTaken(): VIN ",
                            VIN);
                    VINtext.setText(VIN);
                } 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
        {
            globalCamera.stopPreview();
            //start previewing again onthe SurfaceView in case use wants to take another pic/scan
            globalCamera.startPreview();
        }

    }// end onPictureTaken()
};// jpegCallback implementation

Answer 1

The only thing I can find that might be the culprit is that you're starting the preview again before the jpegCallback has returned. According to the javadoc, this is not allowed:

After calling this method, you must not call startPreview() or take another picture until the JPEG callback has returned.

The callback is actually put on the UI thread queue - which will be suspended in your Thread.sleep() and the same thread will have called stopPreview() and startPreview() before actually coming to the callback. Generally speaking, if you call Thread.sleep() on the UI thread - you're doing it wrong. So, hopefully if you remove the sleep() and put what comes after it in the jpegCallback your problem should be solved.