I've worked with the R.Net graphics library to write a svg device that I serialize to my clients. I'm adding a PNG device. There were a couple of serious kinks I had to work out, including what I think is a bug with R's graphics engine (that's not worth fixing since there's a decent workaround).
You can do this purely in R by saving to a file as you suggest, but if you allow for dynamic R code execution from users, then that involves injecting and/or modifying the R payload before its sent to the engine.
You can do this purely in R by saving to a file as you suggest, but if you allow for dynamic R code execution from users, then that involves injecting and/or modifying the R payload before its sent to the engine.