title: C# WinForm Drawing - how to clear and redraw
body: <p>Here is screen shot of my game. On the left is my problem, seem "old draw" still existing. On the right is what it should be.</p>
  
  <p><a href="http://img682.imageshack.us/img682/1058/38995989.jpg" rel="nofollow noreferrer">http://img682.imageshack.us/img682/1058/38995989.jpg</a></p>
  
  <p>drawing code</p>
  
  <pre><code>        Graphics g = e.Graphics;
  
          for (int i = 1; i &lt; 27; i += 1)
          {
              for (int j = 0; j &lt; 18; j += 1)
              {
                  ZPoint zp = zpoints[i, j];
  
                  if (zp != null)
                  {
                      g.DrawImage(zp.sprite_index, new Point(zp.x, zp.y));
  
                      Image arrow;
                      if (zp.sprite_index == spr_green_zpoint)
                      {
                          arrow = spr_green_arrows[zp.image_index];
                      }
                      else if (zp.sprite_index == spr_red_zpoint)
                      {
                          arrow = spr_red_arrows[zp.image_index];
                      }
                      else
                      {
                          arrow = spr_grey_arrows[zp.image_index];
                      }
  
                      g.DrawImage(arrow, new Point(zp.x - 4, zp.y - 4));
                  }
              }
          }
  
          if (latest_p1 != -1 &amp;&amp; latest_p2 != -1)
          {
              ZPoint zp = zpoints[latest_p1, latest_p2];
  
              if (zp != null)
              {
                  g.DrawImage(spr_focus, new Point(zp.x - 6, zp.y - 6));
              }
          }
  </code></pre>