title: Drawing a bitmap in a canvas after calling setBitmap doesn't work
body: <p>I'm drawing a bitmap in a canvas and I want to have the result in a new bitmap, but I still have a black screen as result.
  This is my code, part of the <code>onDraw(Canvas canvas)</code> method:</p>
  <pre><code>if (bitmapTemplate == null) { 
      canvasBis = new Canvas();
              bitmapTemplate = Bitmap.createBitmap(canvas.getWidth()+30,canvas.getHeight(),Bitmap.Config.ARGB_8888);
              drawZones(canvasBis,bitmapTemplate);
  }
  
  bitmapRes = Bitmap.createBitmap(canvas.getWidth()+30,canvas.getHeight(),Bitmap.Config.ARGB_8888);
  canvas.setBitmap(bitmapRes);
  canvas.drawBitmap(bitmapTemplate, matrix, null);
  </code></pre>
  <p>My goal is to have a new bitmap (<code>bitmapRes</code>) by applying a matrix on an existing bitmap (<code>bitmapTemplate</code>). With this code I always have a black screen, but when I remove the line <code>canvas.setBitmap(bitmapRes)</code>, I have a result but not in a new bitmap. Any ideas please? Maybe transparency? Thanks in advance.</p>
  <p><code>drawZones</code> draws some zones in <code>bitmapTemplate</code>.</p>