title: android drawing on touch event
body: <p>I'm trying to make an application which enables user to touch the screen and draw image based on users' finger coordinates. Here's my code :</p>
  
  <pre><code>public class DrawingBoard extends View {
  
          Drawable editIcon = getResources().getDrawable(R.drawable.icon);
          Bitmap mBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.background);
  
          float xPos = 0;
          float yPos = 0; 
  
          public DrawingBoard (Context context) {
              // TODO Auto-generated constructor stub
              super (context);            
          }
          @Override
          protected void onDraw (Canvas canvas) {
              super.onDraw(canvas);
  
              canvas.save();
              canvas.drawBitmap(mBitmap, 0, 0, null);
              canvas.translate(xPos, yPos);
              editIcon.draw(canvas);
              canvas.restore();
  
              invalidate();
          }
          @Override
          public boolean onTouchEvent (MotionEvent event) {
  
              switch (event.getAction()) {
                  case MotionEvent.ACTION_DOWN : 
                      xPos = event.getX();
                      yPos = event.getY();
                      break;
              }
  
              return true;
  
          }
      }
  }
  </code></pre>
  
  <p>But, whenever I try to click on a screen in emulator, there's no image shown....</p>
  
  <p>pls point out my mistake... THX</p>