Re: SVG widget in GNU Emacs

[Akira Kyle]

On Wed, Oct 27, 2021 at 3:47 AM Po Lu <luangruo@yahoo.com> wrote:
>
> Even though it's not very polished at present, I've seen a great deal of
> code rely on the existing xwidgets support.  I think it would be best to
> not make it obsolete.

I'd be curious to see anyone in the past several years on a GNU/linux
system that actually uses xwidgets given that last I checked it
suffered from a rather severe flickering bug. I know people on macOS
regularly use it, especially since the popular homebrew-emacs-plus
formula enables it.

> I understand what the problem in this area is.  But I'd rather have the
> existing and (mostly) working xwidgets feature fixed than to waste time
> implementing a new one.

If you do figure out the flickering problem, I'd be very interested in
were the bug is. Last year I tried tracking it down to no avail. I
think I started to suspect it was a bug somewhere between the way GTK
handles offscreen rendering and the way emacs tries to take control of
GTK's event loop.

> The pure GTK port will do nothing to resolve the issues here.  I worked
> with that port a while ago, eventually porting it to GTK 4, but quickly
> lost interest not soon after that.

I didn't say it would, just that I think it should be a higher
priority project than resurrecting xwidgets on gtk.

> In fact, I don't even see the problem with running Emacs in Xwayland.
> I've been doing that for years ever since Fedora switched to using
> Wayland by default, and I've never had any non-minor problems.

I don't think it currently is, or ever will be, a technical problem.
The xwayland devs have made sure of that. I think its more of a
perception problem as wayland becomes adopted and users see apps
requiring xwayland as increasingly "unmaintained", "legacy" apps. I've
certainly seen such questions come up with newcomers, especially when
it comes to users on HiDPI displays so users can see a tangible
difference in the default font rendering between xwayland and native
wayland apps.

> All and all, the PGTK port still keeps the existing X11+Cairo display
> architecture.  On the GTK3 version of that port, xwidgets still work
> like they do on X and NS.  They will not work on GTK 4 anyway, as the
> GTK developers have deleted the ability to draw off-screen.

Exactly why I think for the sake of future compatibility with GTK 4,
it's best not to rely on off-screen rendering.

> It uses WebRender as a window system for Emacs, not Servo.

Yes, I was being loose with my terminology, given webrender is a
component of servo and at one point servo was the more well known
project. Since firefox adopting webrender, and stopping support for
servo development, I suppose the opposite case is now true.