Question

So I got a canvas and a layout.
On the canvas I draw paint while in the layout is the background image being drawn onto.
After painting on the canvas, I would like to save the image drawn together with the layout background. Can anyone help me on how could I possibly do that?
Moreover, when I save the canvas, it only saves a black image.

public class paint  extends Activity implements OnTouchListener{

DrawPanel dp;
private ArrayList<Path> pointsToDraw = new ArrayList<Path>();
private Paint mPaint;
Path path;
protected Button cancel;
protected Button save;
protected FrameLayout fl;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    dp = new DrawPanel(this);
    dp.setOnTouchListener(this);
    getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    mPaint = new Paint();
    mPaint.setDither(true);
    mPaint.setColor(Color.WHITE);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.MITER);
    mPaint.setStrokeCap(Paint.Cap.BUTT);
    mPaint.setStrokeWidth(5);

    fl = new FrameLayout(this); 
    WindowManager.LayoutParams lp = new WindowManager.LayoutParams(
            LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT,
            WindowManager.LayoutParams.TYPE_APPLICATION,
            WindowManager.LayoutParams.FLAG_LAYOUT_IN_SCREEN,
            PixelFormat.TRANSPARENT);
    fl.addView(dp,370,370); 
    this.getWindowManager().addView(fl , lp);
    setContentView(R.layout.boy_crown);


    Button save = new Button(this);
    FrameLayout.LayoutParams params2 = new FrameLayout.LayoutParams( LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT );
    params2.topMargin = 375;
    params2.gravity =0;
    params2.rightMargin = 160;
    params2.gravity =0;
    save.setLayoutParams(new LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,ViewGroup.LayoutParams.WRAP_CONTENT));
    save.setPadding(0,0, 130, 60);
    fl.addView(save, params2);
    save.setOnClickListener(new ButtonClickHandler2());

}

public class ButtonClickHandler2 implements View.OnClickListener {
    public void onClick(View view) {

        dp.setDrawingCacheEnabled(true);
        Bitmap bm = dp.getDrawingCache();
        try {
            String path = Environment.getExternalStorageDirectory().toString();
            File imgDirectory = new File("/sdcard/BillysCrown");
            imgDirectory.mkdirs();
            OutputStream fOut = null;
            File file = null;
            String fileid = System.currentTimeMillis() + "";
            file = new File(path, "/BillysCrown/" + fileid + ".png");
             Toast.makeText(paint.this, "saved at: " + file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
            fOut = new FileOutputStream(file);
            bm.compress(Bitmap.CompressFormat.PNG, 100, fOut);
            fOut.flush();
            fOut.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

@Override
protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    dp.pause();
}



@Override
protected void onResume() {
    // TODO Auto-generated method stub
    super.onResume();
    dp.resume();
}



public class DrawPanel extends SurfaceView implements Runnable{

    Thread t = null;
    SurfaceHolder holder;
    boolean isItOk = false ;


    public DrawPanel(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
        holder = getHolder();

    }

    @Override
    public void run() {

        // TODO Auto-generated method stub
        while( isItOk == true){

            if(!holder.getSurface().isValid()){
                continue;
            }
            holder.setFormat(PixelFormat.TRANSPARENT);
            Canvas c = holder.lockCanvas();
            onDraw(c);
            holder.unlockCanvasAndPost(c);

        }
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        super.onDraw(canvas);
                    synchronized(pointsToDraw)
      {
        for (Path path : pointsToDraw)
        {
            canvas.drawPath(path, mPaint);
        }
       }
    }

    public void pause(){
        isItOk = false;
        while(true){
            try{
                t.join();
            }catch(InterruptedException e){
                e.printStackTrace();
            }
            break;
        }
        t = null;
    }

    public void resume(){
        isItOk = true;  
        t = new Thread(this);
        t.start();

    }


}


@Override
public boolean onTouch(View v, MotionEvent me) {
    // TODO Auto-generated method stub
            synchronized(pointsToDraw)
            {
    if(me.getAction() == MotionEvent.ACTION_DOWN){
        path = new Path();
        path.moveTo(me.getX(), me.getY());
        //path.lineTo(me.getX(), me.getY());
        pointsToDraw.add(path);
    }else if(me.getAction() == MotionEvent.ACTION_MOVE){
        path.lineTo(me.getX(), me.getY());
    }else if(me.getAction() == MotionEvent.ACTION_UP){
        //path.lineTo(me.getX(), me.getY());
    }
    }       
    return true;

}

}

Answer 1

I have written a tutorial about how you can save a screenshot from a SurfaceView.

It is basically the same for each View in Android. Just make sure you have read until the last paragraph:

That should work with other views, too. The only problem with Views in
general is, that you need to be sure that they are fully inflated, so
you can’t create a screenshot of a view while being in the onCreate()
method. You should work with the ViewTreeObserver to get a callback
when the view is fully inflated.