title: canvas draw not smooth circles
body: <p>At the first of my game, I draw some circles from alpha 0 to 255 using canvas(it's like making a fade_in animation by myself)</p>
  
  <p>But if you see in picture(this picture captured in alpha 230),from alpha 0 to 254 these circles aren't smooth!(click on picture to see what I mean)</p>
  
  <p>(and only when alpha become 255 the circles become smooth)
  <a href="https://i.stack.imgur.com/RRZT8.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/RRZT8.png" alt="enter image description here"></a>
  What's the problem and how can I fix this?</p>
  
  <p>my code:
  I have a game loop, that get canvas </p>
  
  <p><code>canvas = gameView.getHolder().lockCanvas();
  </code></p>
  
  <p>then in my view ,at first I set :</p>
  
  <pre><code>    paintAlpha = 0;
      paint = new Paint();
      paint.setAntiAlias(true);
      paint.setFlags(Paint.ANTI_ALIAS_FLAG);
      paint.setStyle(Paint.Style.FILL);
      paint.setStrokeJoin(Paint.Join.ROUND);
      paint.setStrokeCap(Paint.Cap.ROUND);
      paint.setAlpha(paintAlpha);
      paint.setColor(Color.parseColor(color));
  </code></pre>
  
  <p>then in every loop(every ticks) I do this:</p>
  
  <pre><code>    if(paintAlpha &lt; 255) {
          paintAlpha+=1;
          paint.setAlpha(paintAlpha);
      }
      canvas.drawCircle(cx, cy, currentRadius, paint);
  </code></pre>
  
  <p>Solution:
  Thanks to @nitesh.
  The problem was because of surfaceView that can't set anti alias to canvas (in View you don't have this problem ,I don't know why)
  By using Bitmap and draw on it and finally draw bitmap by canvas , the problem solved (instead of drawing on canvas directly)</p>