Android camera , onPictureTaken(byte[] imgData, Camera camera) method & PictureCallback never called
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.
cyber101
Updated on June 13, 2022Comments
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cyber101 almost 2 years
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
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Alex Cohn over 10 yearsAlso,
stopPreview()
is not necessary after takePicture(). System will stop preview after the image is taken. -
cyber101 over 10 years@ Pescis you are absolutely write I moved the stopPreview() & startPreview() at end of the takePictiure method and the methods works now , new code is above.
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Arpit Patel over 7 yearsplease ans this question stackoverflow.com/questions/39061991/…