获取屏幕的截图

把这个用在DecorView上就是截图

  /**
   * 获取一个 View 的缓存视图
   *
   * @param view
   * @return
   */
  private Bitmap getCacheBitmapFromView(View view) {
    final boolean drawingCacheEnabled = true;
    view.setDrawingCacheEnabled(drawingCacheEnabled);
    view.buildDrawingCache(drawingCacheEnabled);
    
    final Bitmap drawingCache = view.getDrawingCache();
    Bitmap bitmap;
 
    if (drawingCache != null) {
      bitmap = Bitmap.createBitmap(drawingCache);
      view.setDrawingCacheEnabled(false);
    } else {
      bitmap = null;
    }

    return bitmap;
  }
}