Taking a ScreenShot of SurfaceView with Camera Pre

问题:

I am trying to Implement a Functionality that includes taking Pictures While Recording Video. That's the reason i have concluded to use the Screenshot approach of SurfaceView.
However, when i try to take the Screen Shot of SurfaceView. I am always getting a Blank Image.

Here is the code that i am using for taking a Snapshot:

View tempView = (View)MY_SURFACE_VIEW;
tempView.setDrawingCacheEnabled(true);
Bitmap tempBmp = Bitmap.createBitmap(tempView.getDrawingCache());
tempView.setDrawingCacheEnabled(false);
//Saving this Bitmap to a File....

In case you guys may think this is a duplicate Question, let me assure you that i have tried the following Solutions provided on SO for the same Problem before asking this one.

1. https://stackoverflow.com/questions/24134964/issue-with-camera-picture-taken-snapshot-using-surfaceview-in-android
2. Facing issue to take a screenshot while recording a video
3. Take camera screenshot while recording - Like in Galaxy S3?
4. Taking screen shot of a SurfaceView in android
5. Get screenshot of surfaceView in Android (This is the correct answer, but Partially Answered. I have already asked @sajar to Explain the Answer)

Other Resources on Internet:
1. http://www.coderanch.com/t/622613/Android/Mobile/capture-screenshot-simple-animation-project 2. http://www.phonesdevelopers.com/1795894/

None of this has worked so far for me. I also know that we need to create some Thread that interacts with the Surface Holder and Gets the Bitmap from It. But i am not sure how to implement that.

Any Help is Highly Appreciated.

回答1:

Here's another one: Take screenshot of SurfaceView.

SurfaceViews have a "surface" part and a "view" part; your code tries to capture the "view" part. The "surface" part is a separate layer, and there's no trivial "grab all pixels" method. The basic difficulty is that your app is on the "producer" side of the surface, rather than the "consumer" side, so reading pixels back out is problematic. Note that the underlying buffers are in whatever format is most convenient for the data producer, so for camera preview it'll be a YUV buffer.

The easiest and most efficient way to "capture" the surface pixels is to draw them twice, once for the screen and once for capture. If you do this with OpenGL ES, the YUV to RGB conversion will likely be done by a hardware module, which will be much faster than receiving camera frames in YUV buffers and doing your own conversion.

Grafika's "texture from camera" activity demonstrates manipulation of incoming video data with GLES. After rendering you can get the pixels with glReadPixels(). The performance of glReadPixels() can vary significantly between devices and different use cases. EglSurfaceBase#saveFrame() shows how to capture to a Bitmap and save as PNG.

More information about the Android graphics architecture, notably the producer-consumer nature of SurfaceView surfaces, can be found in this document.

回答2:

public class AndroidSurfaceviewExample extends Activity implements SurfaceHolder.Callback  {

static Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
static boolean boo;
static Thread x;
GLSurfaceView glSurfaceView;
public static Bitmap mBitmap;
public static Camera.Parameters param;
public static Camera.Size mPreviewSize;
public static byte[] byteArray;

PictureCallback jpegCallback;
private Bitmap inputBMP = null, bmp, bmp1;
public static ImageView imgScreen;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.camera);

    surfaceView = (SurfaceView) findViewById(R.id.surfaceView);
    surfaceHolder = surfaceView.getHolder();
    Button btnTakeScreen = (Button)findViewById(R.id.btnTakeScreen);
    imgScreen = (ImageView)findViewById(R.id.imgScreen);



    btnTakeScreen.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Bitmap screen = Bitmap.createBitmap(getBitmap());
            imgScreen.setImageBitmap(screen);
        }
    });


    // Install a SurfaceHolder.Callback so we get notified when the
    // underlying surface is created and destroyed.
    surfaceHolder.addCallback(this);

    // deprecated setting, but required on Android versions prior to 3.0
    surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    jpegCallback = new PictureCallback() {
        @SuppressLint("WrongConstant")
        public void onPictureTaken(byte[] data, Camera camera) {
            FileOutputStream outStream = null;
            try {
                outStream = new FileOutputStream(String.format("/sdcard/%d.jpg", System.currentTimeMillis()));
                outStream.write(data);
                outStream.close();
                Log.d("Log", "onPictureTaken - wrote bytes: " + data.length);
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } finally {
            }
            Toast.makeText(getApplicationContext(), "Picture Saved", 2000).show();
            refreshCamera();
        }
    };
}






public void refreshCamera() {
    if (surfaceHolder.getSurface() == null) {
        // preview surface does not exist
        return;
    }

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

    // set preview size and make any resize, rotate or
    // reformatting changes here
    // start preview with new settings
    try {
        camera.setPreviewDisplay(surfaceHolder);
        camera.startPreview();
    } catch (Exception e) {

    }
}

public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
    // Now that the size is known, set up the camera parameters and begin
    // the preview.
    refreshCamera();
}

public void surfaceCreated(SurfaceHolder holder) {


    if (camera == null) {
        try {
            camera = Camera.open();
        } catch (RuntimeException ignored) {
        }
    }

    try {
        if (camera != null) {
            WindowManager winManager = (WindowManager) getApplicationContext().getSystemService(Context.WINDOW_SERVICE);
            camera.setPreviewDisplay(surfaceHolder);
        }
    } catch (Exception e) {
        if (camera != null)
            camera.release();
        camera = null;
    }

    if (camera == null) {
        return;
    } else {
        camera.setPreviewCallback(new Camera.PreviewCallback() {
            @Override
            public void onPreviewFrame(byte[] bytes, Camera camera) {
                if (param == null) {
                    return;
                }
                byteArray = bytes;
            }
        });
    }





    param = camera.getParameters();
    mPreviewSize = param.getSupportedPreviewSizes().get(0);

    param.setColorEffect(Camera.Parameters.EFFECT_NONE);

    //set antibanding to none
    if (param.getAntibanding() != null) {
        param.setAntibanding(Camera.Parameters.ANTIBANDING_OFF);
    }

    // set white ballance
    if (param.getWhiteBalance() != null) {
        param.setWhiteBalance(Camera.Parameters.WHITE_BALANCE_CLOUDY_DAYLIGHT);
    }

    //set flash
    if (param.getFlashMode() != null) {
        param.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
    }

    //set zoom
    if (param.isZoomSupported()) {
        param.setZoom(0);
    }

    //set focus mode
    param.setFocusMode(Camera.Parameters.FOCUS_MODE_INFINITY);


    // modify parameter
    camera.setParameters(param);
    try {
        // The Surface has been created, now tell the camera where to draw
        // the preview.
        camera.setPreviewDisplay(surfaceHolder);
        camera.startPreview();
    } catch (Exception e) {
        // check for exceptions
        System.err.println(e);
        return;
    }
}

public void surfaceDestroyed(SurfaceHolder holder) {
    // stop preview and release camera
    camera.stopPreview();
    camera.release();
    camera = null;
}



public Bitmap getBitmap() {
    try {
        if (param == null)
            return null;

        if (mPreviewSize == null)
            return null;

        int format = param.getPreviewFormat();
        YuvImage yuvImage = new YuvImage(byteArray, format, mPreviewSize.width, mPreviewSize.height, null);
        ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();

        Log.i("myLog","array: "+byteArray.toString());



        Rect rect = new Rect(0, 0, mPreviewSize.width, mPreviewSize.height);

        yuvImage.compressToJpeg(rect, 75, byteArrayOutputStream);
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inPurgeable = true;
        options.inInputShareable = true;
        mBitmap = BitmapFactory.decodeByteArray(byteArrayOutputStream.toByteArray(), 0, byteArrayOutputStream.size(), options);

        byteArrayOutputStream.flush();
        byteArrayOutputStream.close();
    } catch (IOException ioe) {
        ioe.printStackTrace();
    }

    return mBitmap;
}