Export current scene as mp4

[bhoov]

We are very close to a full pipeline for Manim development. Crucially, we are missing the final step of actually exporting a scene as an e.g., mp4 of some quality (a thought I came up with as I was writing the "sales pitch demo" #37 for this extension)

At the minimum, we want to expose a command that lets users choose the following from the manimgl tool:

1. Image quality (low, med, hd, uhd)
2. fps

(happy to discuss more advanced options like Gif?, Transparent?, background color?, etc., but I was hoping to appeal to the broadest user that would care about the quality of the mp4 they were generating)

Finally, let the user choose which file to save the output video to

[Splines]

UI: File picker

For the file picker, see this API. We could use that to let users specify a location where to save their file.

UI: Trigger export

Users somehow have to trigger the export command. Invoking it from the command palette is probably not the best choice.

• For the export, I could imagine a gutter icon (similar to the breakpoint) showing on lines where the class is started, e.g. class MyScene(Scene):. Unfortunately, the VSCode issue for on click events on the gutter icon was closed without a solution. The new issue to track this is here. In the meantime, there's also the option to provide a Export scene to the context menu that appears when you right-click on the line numbers or the area where the breakpoints live. See the contribution menus (editor/lineNumber/context).
• Another option for how to realize the export in the UI would be to show a codelens over classes, e.g. like we do right now with Preview Manim Cell.
• Manim scene detection: Just checking for inheritance of Scene or InteractiveScene is not sufficient, see my comment here.

UI: Define settings for export

Users could define settings in a multi-step quick pick. If that gets too long, we might want to use a custom webview view even if that is discouraged by VSCode. But they don't specify what you should use instead then since they also advise against using multi step quick picks to create wizards (see my comment). And in the Webview UI toolkit there are some nice elements that we could use like a dropdowns, checkboxes etc.

[Splines]

Maybe you could also vote for this issue at VSCode since they look for issues with high votes to organize their backlog. I think it'd be really cool to be able to use onClick events for gutter icons. With this we could add buttons like the "debug button" as envisioned by bhoov here.