On 2016-07-05 18:59, Richard Stallman wrote:
> I think it would be safer to add a feature to make a screenshot
> whenever Emacs redisplays than to add a hook that might do anything whatever.

I think a feature to make Emacs capture a screenshot of itself would be very nice (and hey, in the future, it could even be SVG instead pixel-based! That would be wonderful). 

And yet I'm not sure whether adding a flag to capture a screenshot after each redisplay cycle is the way to go. People often surprise me with the stuff they come up with Emacs, so adding a general post-redisplay-hook may enable plenty of things that we're not thinking about (and at worst, people won't use it much, just like the currently existing pre-redisplay-function).

Plus, it's not obvious that we could stretch such a capture-after-redisplay flag to cover all screencasting use cases. For example, since capturing and saving a screenshot takes time, we'd probably want to let Lisp code decide for each redisplay cycle whether to take a screenshot or not; it could decide this based on time elapsed since the last screenshot, or other factors.

What do you think?

Clément.