Is there any small and simple program (or even library) that can render LaTeX locally as you type?
I'm looking for something pretty much like this page, which auto-renders immediately as you type, except that it:
Must not need any internet connection
Should be as "lightweight" as possible (it shouldn't even depend on a browser, if that can be avoided... a standalone executable would be ideal)
(The goal is to avoid going having to go through the pain of creating LaTeX documents every time you want to write a little expression to paste somewhere else, but without needing an internet connection or another program to run it.)
If there is even a C/C++-compatible library that could convert a basic LaTeX equation to a PNG file (or SVG or whatever), that would be fine too; I could write a front-end for it pretty easily.