Camera Preview not reinitializing => A good Android Camera implementation?

Question

I am having a slight problem with my camera implementation. Currently when i open the camera preview and i lock the phone and then unlock it when coming back the preview is okay and still there running.

Problem is that when i press the phone's home button the preview is not showing anymore when coming back to the application, just a black screen, no crash but also no preview.

Here's my code. I am guessing the mistake should be somewhere the methods onResume(), onPause(), onStop() but i am not able to figure it out exactly.

THIS IS MY UPDATED SOULUTION:::::

package ro.gebs.captoom.activities;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.hardware.Camera;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.RelativeLayout;
import android.widget.Toast;

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

import ro.gebs.captoom.R;
import ro.gebs.captoom.asynctasks.SavePictAsync;
import ro.gebs.captoom.interfaces.FinishTakePictureCallback;
import ro.gebs.captoom.utils.Utils;
import ro.gebs.captoom.utils.fonts.CustomFontButton;
import ro.gebs.captoom.utils.fonts.TopMenu;

@SuppressLint("SimpleDateFormat")
public class TakePicture extends Activity implements FinishTakePictureCallback {


    private SurfaceView surfaceView = null;
    private Camera camera = null;
    private Button buttonTakePicture;
    private boolean isFlashOn = false;
    private long the_folder_id;
    private boolean inPreview = true;

    Camera.AutoFocusCallback myAutoFocusCallback = new Camera.AutoFocusCallback() {
        @Override
        public void onAutoFocus(boolean success, Camera arg1) {
            if (success) {
                camera.takePicture(null, null, myPictureCallback_JPG);
            } else {
                Utils.showToast(TakePicture.this, "Not focused, try again", Toast.LENGTH_SHORT);
                buttonTakePicture.setEnabled(true);
            }
        }
    };

    final Camera.PictureCallback myPictureCallback_JPG = new Camera.PictureCallback() {
        @Override
        public void onPictureTaken(byte[] arg0, Camera arg1) {
            new SavePictAsync(arg0, TakePicture.this, camera, the_folder_id, buttonTakePicture).execute();
        }
    };


    @Override
    protected void onCreate(Bundle savedInstanceState) {

        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        requestWindowFeature(Window.FEATURE_NO_TITLE);

        super.onCreate(savedInstanceState);

        setContentView(R.layout.camera_control);

        surfaceView = (SurfaceView) findViewById(R.id.preview);
        surfaceView.getHolder().setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        surfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {

            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                System.out.println("------------ surf Created");

                if (camera == null) {
                    camera = Camera.open();
                    Camera.Parameters params = camera.getParameters();
                    params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                    camera.setParameters(params);

                    try {
                        System.out.println("------------ 1");

                        camera.setPreviewDisplay(holder);

                        Camera.Parameters parameters = camera.getParameters();

                        List<Size> sizes = parameters.getSupportedPreviewSizes();
                        for (Size size : sizes) {
                            Log.d("TakePicture", size.height + "X" + size.width + "height" + surfaceView.getHeight() + "width" + surfaceView.getWidth());
                        }
                        Size optimalSize = getOptimalPreviewSize(sizes, surfaceView.getHeight(), surfaceView.getWidth());
                        parameters.setPreviewSize(optimalSize.width, optimalSize.height);

                        camera.setDisplayOrientation(90);
                        camera.setParameters(parameters);

                        camera.startPreview();
                        inPreview = true;
                    } catch (IOException e) {
                        Log.e("Take Picture", "Error", e);
                    }
                }
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                System.out.println("------------ surf Destroyed");
                if (inPreview) {
                    try {
                        if (camera != null) {
                            camera.cancelAutoFocus();
                            camera.stopPreview();
                        }
                        inPreview = false;
                    } catch (RuntimeException e) {
                        e.printStackTrace();
                    } finally {
                        if (camera != null) {
                            camera.release();
                            camera = null;
                        }
                    }
                }
            }


            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                if (!inPreview) {
                    try {
                        System.out.println("------------ surf Changed");
                        camera = Camera.open();
                        camera.setPreviewDisplay(surfaceView.getHolder());
                        camera.setDisplayOrientation(90);
                        camera.startPreview();
                        inPreview = true;
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }


        }

        );

        LayoutInflater controlInflater = LayoutInflater.from(getBaseContext());
        ViewGroup viewControl = (ViewGroup) controlInflater.inflate(R.layout.camera_control, null);

        assert viewControl != null;
        final CustomFontButton cancel_btn = (CustomFontButton) findViewById(R.id.cancel_btn);
        cancel_btn.setOnClickListener(new View.OnClickListener()

        {
            @Override
            public void onClick(View v) {
                finish();
            }
        }

        );

        buttonTakePicture = (Button) findViewById(R.id.take_picture);

        buttonTakePicture.setOnClickListener(new Button.OnClickListener()

        {
            @Override
            public void onClick(View arg0) {
                try {
                    Utils.showToast(TakePicture.this, "Focusing...", Toast.LENGTH_SHORT);
                    camera.autoFocus(myAutoFocusCallback);
                    buttonTakePicture.setEnabled(false);
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        }

        );

        RelativeLayout headerView = (RelativeLayout) findViewById(R.id.top_header_green);
        ImageButton menu_btn = (ImageButton) findViewById(R.id.menu_btn);
        new

                TopMenu(this, this, headerView, menu_btn);


        ImageButton flashBtn = (ImageButton) findViewById(R.id.flash_btn);
        flashBtn.setOnClickListener(new View.OnClickListener()

        {
            @Override
            public void onClick(View view) {
                Context context = getApplicationContext();
                if (context.getPackageManager().hasSystemFeature(getPackageManager().FEATURE_CAMERA_FLASH)) {
                    Camera.Parameters params = camera.getParameters();
                    if (isFlashOn) {
                        params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                        camera.setParameters(params);
                        isFlashOn = false;
                        Utils.showToast(context, getString(R.string.FlashOff), Toast.LENGTH_SHORT);
                    } else {
                        params.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);
                        camera.setParameters(params);
                        isFlashOn = true;
                        Utils.showToast(context, getString(R.string.FlashAuto), Toast.LENGTH_SHORT);
                    }
                }
            }

        }

        );

    }

    @Override
    public void finishTakePicture() {
        finish();
    }

    @Override
    protected void onResume() {
        the_folder_id = getIntent().getLongExtra("the_folder_id", 0);
        buttonTakePicture.setEnabled(true);
        super.onResume();
    }

    @Override
    public void onBackPressed() {
        super.onBackPressed();
        if (PreviewPhoto.photos != null) {
            for (String image : PreviewPhoto.photos) {
                File file = new File(image);
                file.delete();
            }
            PreviewPhoto.photos.clear();
        }
    }

    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) w / h;
        if (sizes == null)
            return null;

        Log.d("TakePicture", "TargetRatio: " + targetRatio);
        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        for (Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE)
                continue;
            if (Math.abs(size.height - h) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - h);
            }
        }

        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes) {
                if (Math.abs(size.height - h) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - h);
                }
            }
        }
        Log.d("TakePicture", "The optimal size is:" + optimalSize.height + "X" + optimalSize.width);
        return optimalSize;
    }
}

Since i was already overriding surfaceDestroyed, surfaceCreated there was not much left to do in the onPause, onResume methods.

Hope this question helps out a lot of people since it proves to be a good Camera impementation for android.

What do you think?

Since this is a working solution i was wondering if you guys think this is an efficient implementation? I am asking this because i have only tested it on some devices...

Answer 1

Put some breakpoints in the onPause and onResume methods and see what happens. This is kinda odd what you is happening. Also try taking a picture or record a video when the preview is black and see what happens. Post the logcat