Re: Introducing emacs-webkit and more thoughts on Emacs rendering (was Rethinking the design of xwidgets)

[Arthur Miller]

Alan Third <alan@idiocy.org> writes:

> On Mon, Nov 23, 2020 at 03:59:31PM +0100, Arthur Miller wrote:
>> Just a curious question: have you ever looked at libmpv?
>> Would it be possible to embedd video via livmpv in an image container
>> just as jpg, png etc?
>> 
>> libmpv is a C library for mpv player ment to be embedded, and works in
>> all 3 major desktop platforms.
>> 
>> https://github.com/mpv-player/mpv-examples/tree/master/libmpv
>> 
>> Mpv itself comes with crap-load of video codecs and image formats already
>> built-in; it is a fork mplayer2. What is good, if one could create a
>> OpenGL context for an Emacs window (X11/Win32 Window - shouldn't be
>> hard), you could controll rendering directly, since they don't take over
>> your even loop:
>> 
>> "You will have to simulate this with the mouse/keypress/keydown/keyup 
>> commands."
>> 
>> It would probably fit into Emacs well.
>> 
>> I don't know myself how to implement "new image format" for Emacs; too
>> much to look through the spaghetty of if-defs in image.c, 
>
> IIRC it's actually possible to load videos using the imagemagick
> backend, the trouble is that Emacs can't really handle them as it
> decodes and stores each frame individually.
>
> Emacs has no way to "remember" where it is in a file, as each image is
> loaded and stored individually.
>
> For example, to display an animated gif Emacs opens the file, decodes
> frame one, closes the file and then displays the frame. When asked to
> display frame two it opens the file, decodes frame two (which in the
> case of a gif involves decoding frame one again) closes the file and
> displays it. To display frame three it opens the file, decodes frame
> three (which involves decoding frames one and two again), closes the
> file and displays it. And so on and so on.
Ouch, that sounds like very inneficient way to do things (and very
Eamcs-y too :-)).

> I think it's like this because it was only intended for displaying
> occasional graphics like the fringe bitmaps and similar, and, IMHO, to
> do anything different would require a major overhaul of image.c, and
> probably the lisp image API while maintaining backwards compatibility.
Given a place to render, libmpv does it's own rendering, it requires
just a place to render, and it has it's own event loop so Emacs does not
need to do so much more then just provide a rectangle for it to render.
I thought it would be maybe possible to do same as with jpegs and pngs,
but I never figured out how they are placed in an Emacs frame myself :-).