title: How could I improve my android app? Lot of lag drawing to an imageview
body: <p>I'm developing an app that draws a circle into an image when the user touch the screen, and also the user can move this circle moving the finger over the screen. But in the action of move, I can see a lot of lag...</p>
  
  <p>The user open an image of this gallery, and after that, what I do is:</p>
  
  <p>1)the user touch the screen</p>
  
  <p>2)calculate de correspondence between screen-point and image-point (+100ms)</p>
  
  <p>3)drawing:(+200ms)</p>
  
  <pre><code>-create a bitmap with the size of the original image
  
  -create a canvas based on the previous bitmap
  
  -canvas.drawimage, draw the original image
  
  -canvas.drawcircle, draw the circle
  </code></pre>
  
  <p>4)set the result bitmap to an imageview(+100ms)</p>
  
  <p>Every time that the user move his finger, I waste 400ms doing all the process...a lot of time</p>
  
  <p>I know that the resolution of the image it's very important, but I'm using a 640x480 image ...so it's not a very very big image...and I am testing my app in a samsung galaxy s2, so I was specting better results...</p>