Re: Support for background transparency

[Håkon Flatval]

Hi again - sorry for the long radio silence.

>Posting the resulting patch (or a series of patches, depending on how
>much code it is) is the preferred method to get code reviews.

I've attached a patch that implements basic support for background transparency. I have only considered GDK+Cairo build configurations here, as a start.

I believe the gui_set_alpha_background​ function in frame.c​ should return some error message when the frame does not support 32 bits of depth, but am not sure how to do this best. I considered adding a new error code similar to the one used by wrong_type_argument​ (also called from gui_set_...​), but it seemed to be a bit excessive to create a  specific "frame-does-not-support-adequate-bit-depth"-error type when most other error types are of the more general forms "value-out-of-range" or "wrong-length-argument". Does anyone have suggestions on how to best communicate failure in setting alpha to the user?

Newbie question: I can't guarantee that this patch works perfectly with all build variations using GDK+Cairo, nor in all (desktop) environments where Emacs might be used. How, in general, is Emacs tested before release to ensure (most) such edge cases are caught?

I'm currently working on implementing this feature for other XLib-based build configurations too, offline, planning to submit another patch for those in the not-so-distant future.

Best,

Håkon Flatval

---

Fra: Lars Ingebrigtsen <larsi@gnus.org>
Sendt: torsdag 4. november 2021 21:17
Til: Håkon Flatval <hkon20@hotmail.com>
Kopi: emacs-devel@gnu.org <emacs-devel@gnu.org>
Emne: Re: Support for background transparency

 

Håkon Flatval <hkon20@hotmail.com> writes:

> I have implemented partial support for background transparency in Emacs.

Great!  It's a feature that has been requested many times.

> As I'm completely new to the community, I'd also like some input as to how
> one proceeds with planning and implementation given there is interest for
> this to be made reality. I would be happy to work on this, but not sure I feel
> comfortable / knowledgable enough to do everything on my own.

Posting the resulting patch (or a series of patches, depending on how
much code it is) is the preferred method to get code reviews.

--
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

gdk-cairo-background-transparency-001.patch
Description: gdk-cairo-background-transparency-001.patch