I've upgraded my site's layout - changed it completly and built a new one from scratch (even though I did not use dynamically generated content, ajax calls or parallax effects).
I kept the same content (same text and same page names), but changed the layout (and, of course, the css).
Will this change affect my search ranking?
From what I know, google reads only the text within pages, so that would mean it's totally safe to upgrade my site. Am I correct?
There are many variables in place here. You need to ask yourself the following questions.
Google's algorithm takes many things into consideration when scoring your website. It's not just about content it's about the user experience you're delivering to your traffic.
If you build your website to enhance the experience of your traffic more than likely it will greatly help your rankings with Google since this is what their business is built on with everything else falling in place around it.
So to answer your question yes it may affect your ranking depending on how you answer those question I have given. It is hard for us to critique because we don't know what site it is you're asking the question about.
And just for future reference Google reads more than just text on a page. They are analyzing just about everything now days.
