View生成bitmap方法

网上找了好几种都不能用，生成的bitmap为null，不知道怎么回事，
这一种可以，所以记录下来，以后万一哪天用到了呢?

    private BitmapDescriptor getMarkerBigBitmap(int count){
         View view = LayoutInflater.from(this).inflate(R.layout.markerbig, null);
         TextView tv_count = (TextView)view.findViewById(R.id.tv_markercount);
         tv_count.setText(count+"");
         view.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
         view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());
          view.buildDrawingCache();
        Bitmap bitmap = view.getDrawingCache();
        if(bitmap == null){
            Logger.e(TAG, "bitmap is null");
        }

         BitmapDescriptor bitmap1 = BitmapDescriptorFactory.fromBitmap(bitmap);

         return bitmap1; 

    }