Re: [g-a-devel] No module anymore & perfect zoom feature

[Bastien Nocera <hadess hadess net>]

On Mon, 2018-03-05 at 15:05 +0100, Samuel Thibault wrote:
> Hello,
>
> Emmanuele Bassi, on jeu. 01 mars 2018 20:27:04 +0000, wrote:
> > I was not claiming that the Shell’s zoom is perfect; I’m saying
> > that the Shell
> > is where things need to be fixed, as it’s where things are
> > implemented already.
>
> Well, that is for gnome.  Users shouldn't be tied with gnome just to
> get
> good zoom of gtk applications, and we want good zoom of other widget
> libraries too, so we need a window magnification interface which is
> independent from gnome.

If you implement the feature in GTK+ and gnome-shell in a way that
makes either of those replaceable, you can then add support for non-
GTK+ apps, or non-gnome-shell compositors.

I don't see how you could implement it without the compositor knowing
about the feature. The compositor already knows how to modify what
appears on the screen, can modify on-screen data quickly (for all the
brightness, contrast, etc. changes), and using the GPU knows how to
scale.

> > The shell does not currently ask the toolkit to render an area at a
> > different
> > scaling factor, but it could. The shell can also change the
> > rendering pipeline
> > to apply an effect like color inversion.
>
> But that means it'll only benefit the gnome shell, and not other
> desktops.  Writing a *good* magnifier, which means not only just the
> graphical effect, but also mouse tracking, focus tracking, smooth
> transition, etc. is not something that we want to see having to be
> implemented several times for several desktops, there are not enough
> people who have the skills, context, and time to do that.

Perhaps, but you'd be doing a disservice to your users trying to
implement this as a "can run anywhere" solution. I don't think there's
any way you can implement this generically so that there's no work
needed on other desktops.

Implementing this in GTK+ and gnome-shell gives you the opportunity to
experiment with an interface that should hopefully be applicable to
other compositors, and compositing window managers.