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Android picture call back data is null

Posted by: admin June 15, 2020 Leave a comment

Questions:

I am using camera code for Android after taking the picture the byte[] imageData parameter is null, I don’t know why.

package com.pictures;

import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;


import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.PixelFormat;
import android.graphics.Bitmap.CompressFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnClickListener;
import android.view.View.OnTouchListener;

public class CamaraView extends Activity implements SurfaceHolder.Callback,
        OnClickListener {
    static final int FOTO_MODE = 0;
    private static final String TAG = "CameraTest";
    Camera mCamera;
    boolean mPreviewRunning = false;
    private Context mContext = this;

    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);

        Log.e(TAG, "onCreate");

        Bundle extras = getIntent().getExtras();

        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
                WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(R.layout.main);
        mSurfaceView = (SurfaceView) findViewById(R.id.surface_camera);
        mSurfaceView.setOnClickListener(this);
        mSurfaceHolder = mSurfaceView.getHolder();
        mSurfaceHolder.addCallback(this);
        mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
    }

    Camera.PictureCallback mPictureCallback = new Camera.PictureCallback() {
        public void onPictureTaken(byte[] imageData, Camera c) {

            if (imageData != null) {

                Intent mIntent = new Intent();

                StoreByteImage(mContext, imageData, 50,
                        "ImageName");
                mCamera.startPreview();

                setResult(FOTO_MODE, mIntent);
                finish();

            }
        }
    };

    protected void onResume() {
        Log.e(TAG, "onResume");
        super.onResume();
    }

    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
    }

    protected void onStop() {
        Log.e(TAG, "onStop");
        super.onStop();
    }

    public void surfaceCreated(SurfaceHolder holder) {
        Log.e(TAG, "surfaceCreated");
        mCamera = Camera.open();

    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        Log.e(TAG, "surfaceChanged");


        // XXX stopPreview() will crash if preview is not running
        if (mPreviewRunning) {
            mCamera.stopPreview();
        }

        Camera.Parameters p = mCamera.getParameters();
        p.setPreviewSize(w, h);
        mCamera.setParameters(p);

        try {
            mCamera.setPreviewDisplay(holder);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            System.out.println("Caught exception in surface chagned");
            e.printStackTrace();
        }
        mCamera.startPreview();
        mPreviewRunning = true;

    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        Log.e(TAG, "surfaceDestroyed");
        mCamera.stopPreview();
        mPreviewRunning = false;
        mCamera.release();
    }

    private SurfaceView mSurfaceView;
    private SurfaceHolder mSurfaceHolder;

    public void onClick(View arg0) {

        mCamera.takePicture(null, mPictureCallback, mPictureCallback);

    }

    public static boolean StoreByteImage(Context mContext, byte[] imageData,
            int quality, String expName) {

        File sdImageMainDirectory = new File("/sdcard");
        FileOutputStream fileOutputStream = null;
        String nameFile;
        try {

            BitmapFactory.Options options=new BitmapFactory.Options();
            options.inSampleSize = 5;

            Bitmap myImage = BitmapFactory.decodeByteArray(imageData, 0,
                    imageData.length,options);


            fileOutputStream = new FileOutputStream(
                    sdImageMainDirectory.toString() +"/image.jpg");


            BufferedOutputStream bos = new BufferedOutputStream(
                    fileOutputStream);

            myImage.compress(CompressFormat.JPEG, quality, bos);

            bos.flush();
            bos.close();

        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return true;
    }

}
How to&Answers:

Ok, I see the problem. You are reusing picture callback for both raw and jpeg callbacks. ANd from javadoc you can read:

Triggers an asynchronous image capture. The camera service will
initiate a series of callbacks to the application as the image capture
progresses. The shutter callback occurs after the image is captured.
This can be used to trigger a sound to let the user know that image
has been captured. The raw callback occurs when the raw image data is
available (NOTE: the data will be null if there is no raw image
callback buffer available or the raw image callback buffer is not
large enough to hold the raw image). The postview callback occurs when
a scaled, fully processed postview image is available (NOTE: not all
hardware supports this). The jpeg callback occurs when the compressed
image is available. If the application does not need a particular
callback, a null can be passed instead of a callback method.

So if it was called as raw callback, data could be null.
If you do not like raw data, just use:

 mCamera.takePicture(null, null, mPictureCallback);