I need a browser extension

. To be a little more specific, I'm looking for a browser extension which will identify space that is a variable distance from any text or hyperlinked image for any given web page. The extension should create a map for that space and display a color of choice chosen by the user in those mapped areas of space. By variable distance, I mean that the user can choose a distance of 10 pixels minimum, for example, or a distance of 2% of the width of the browser window. I want this for Chrome and Firefox with source code.