title: The efficiency about android canvas drawing
body: <p>I've been wondering if canvas has a limit boundary.</p>
  
  <p>I mean if I use functions such as<code>drawline(), drawbitmap(), drawcircle(),</code>
  does android really draw something on the canvas and waste some CPU cycles??</p>
  
  <p>because after all the drawing functions, the actual picture print on the screen is decided
  by the screen size. And if I draw on something that is out of screen size, it doesn't show up.</p>
  
  <p>I want to do some small detail on my canvas by calling lots of drawing functions and make my surface "bling bling". If it is out of bound I don't want to use them, if they make my drawing slow down. </p>
  
  <p>I am working on a little game by the structure of surfaceview, Thanks for any advice.</p>
  
  <p>for Example:</p>
  
  <p>I have a robot walking from a &lt;-> b OUTSIDE the screen.</p>
  
  <p>it takes 20 drawing functions to draw a robot walking picture on the canvas.
  If I scroll the screen, then I can see the robot.</p>
  
  <p>So if the drawing function outside the screen really takes as much time as draw on screen.
  I have to detect that only if the robot's position can be seen by the user, then I draw.
  otherwise, i don't.</p>
  
  <p>if the drawing function doesn't waste much CPU cycles, then I can just draw everytime even if the current screen cannot see the robot.</p>