Can the size of web page forms be determined without passing the date through the browser?

For example I am automatically sending a GET-request to a specific website with python/java. Then I want to build a DOM-tree, and calculate the size (ex. length, width, position relative to (0; 0) point for my screen resolution) for the nodes, which correspond to separate "forms" on the page. Is this at all possible?

Unfortunately I am almost not familiar with web-development. The question is related to determining the "main" content of the web site (an process only this data further).