How to properly zoom a WebView together with it's background image?

I'm using the following code which only zooms the loadData. How is it possible to zoom the image inside? Thank you in advance!

WebView web = (WebView) findViewByI开发者_StackOverflowd(R.id.myid);    
web.loadUrl("file:///android_asset/image.jpg");
web.getSettings().setBuiltInZoomControls(true);
web.setBackgroundColor(0);
web.setVisibility(ImageView.VISIBLE);
web.setBackgroundResource(R.drawable.myimage);

I finally did it by insersting the image.jpg in an html file which took the place of loadUrl().