Android :: How To Get WebView Content Into Bitmap?

I am trying to get the webview's content on a bitmap so that i can save it as a image. But I am unable to so. I am getting the BLACK image save instead. All content is missing. Here is my code:
//create a webview WebView w = new WebView(this);
//Loads the url w.loadUrl("http://www.yahoo.com");
//After loading completely, take its picture Picture picture = w.capturePicture();
//Create a new canvas Canvas mCanvas = new Canvas();
//Draw the Picture into the Canvas picture.draw(mCanvas);
//Create a Bitmap Bitmap sreenshot = Bitmap.createBitmap(picture.getWidth(), picture.getHeight(),Config.ARGB_8888);
//copy the content fron Canvas to Bitmap mCanvas.drawBitmap(mBitmapScreenshot, 0, 0, null);
//Save the Bitmap to local filesystem if(sreenshot != null) {
ByteArrayOutputStream mByteArrayOpStream = new ByteArrayOutputStream();
screenshot.compress(Bitmap.CompressFormat.JPEG, 90, mByteArrayOpStream);
try { fos = openFileOutput("yahoo.jpg", MODE_WORLD_WRITEABLE);
fos.write(mByteArrayOpStream.toByteArray()); fos.close();
} catch (FileNotFoundException e) { e.printStackTrace();
} catch (IOException e) { e.printStackTrace(); } }