title: How to use beginBitmapFill?
body: <p>I'm trying to draw a bitmap in flex,the original bitmap is</p>
  
  <p><img src="https://i.stack.imgur.com/UKg9i.png" alt="enter image description here"></p>
  
  <p>but, actually it show up in the app looks like</p>
  
  <p><img src="https://i.stack.imgur.com/Zjwd4.png" alt="enter image description here"></p>
  
  <p>here is the code:</p>
  
  <pre><code>this.component.graphics.beginBitmapFill(leakBitmapData);
  this.component.graphics.drawRect(leakPoint.x-halfWidth,leakPoint.y-halfHeight,leakBitmapData.width,leakBitmapData.height);
  this.component.graphics.endFill();
  </code></pre>
  
  <p>only when I draw the rect at (0,0),it looks right.
  Why?</p>