bug#70697: 30.0.50; Frame parameter alpha-background is ignored for fringe bitmaps & internal borders

[Eli Zaretskii <eliz@gnu.org>]

Ping! Aleksandar, can you please try Po Lu's patch and report back?

> From: Po Lu <luangruo@yahoo.com>
> Cc: Aleksandar Dimitrov <mail@aleks.bg>,  70697@debbugs.gnu.org
> Date: Sat, 15 Jun 2024 19:20:21 +0800
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > Ping!  How should we proceed with this issue?
> >
> >> From: Aleksandar Dimitrov <mail@aleks.bg>
> 
> Alexander, is there something suspicious as to your mail host that is
> prompting mine to discard your responses?  They aren't even classified
> Bulk Mail, just quietly disposed of.
> 
> >> Welp, I never said I'm good at this :D
> >> I didn't know there was a difference between the --with-toolkit and
> >> --with-x-toolkit options. The former isn't documented in ./configure
> >> --help, it seems. I've opted to only use --with-x-toolkit from now on.
> >> 
> >> I have conducted some experiments now:
> >> --with-x-toolkit=lucid & your patch:
> >> No transparency support.
> >> 
> >> --with-x-toolkit=gtk3 & your patch:
> >> Transparency in fringes works.
> >> Internal borders are NOT transparent.
> >> This is identical to my previous test with --with-toolkit=lucid, which
> >> wasn't doing what I expected it to.
> >> 
> >> --with-pgtk & your patch:
> >> Transparency in fringes DOES NOT work
> >> Internal borders ARE transparent
> >> (also, Emacs is very slow, e.g. when rendering company popups, but
> >> that's unrelated)
> >> 
> >> All of these tests are conducted with the above Emacs version and on
> >> Wayland.
> 
> Yes, thanks.  Please try the patch attached: its effect should be to
> homogenize PGTK's display with the X port's.
> 
> diff --git a/src/pgtkterm.c b/src/pgtkterm.c
> index 49b7ea406f8..e379ed33c01 100644
> --- a/src/pgtkterm.c
> +++ b/src/pgtkterm.c
> @@ -3594,20 +3594,7 @@ pgtk_draw_fringe_bitmap (struct window *w, struct glyph_row *row,
>    pgtk_clip_to_row (w, row, ANY_AREA, cr);
>  
>    if (p->bx >= 0 && !p->overlay_p)
> -    {
> -      /* In case the same realized face is used for fringes and for
> -         something displayed in the text (e.g. face `region' on
> -         mono-displays, the fill style may have been changed to
> -         FillSolid in pgtk_draw_glyph_string_background.  */
> -      if (face->stipple)
> -	fill_background_by_face (f, face, p->bx, p->by, p->nx, p->ny);
> -      else
> -	{
> -	  pgtk_set_cr_source_with_color (f, face->background, true);
> -	  cairo_rectangle (cr, p->bx, p->by, p->nx, p->ny);
> -	  cairo_fill (cr);
> -	}
> -    }
> +    fill_background_by_face (f, face, p->bx, p->by, p->nx, p->ny);
>  
>    if (p->which
>        && p->which < max_fringe_bmp
> @@ -5014,14 +5001,16 @@ pgtk_clear_under_internal_border (struct frame *f)
>  
>        if (face)
>  	{
> -	  fill_background_by_face (f, face, 0, margin, width, border);
> -	  fill_background_by_face (f, face, 0, 0, border, height);
> -	  fill_background_by_face (f, face, width - border, 0, border,
> -				   height);
> -	  fill_background_by_face (f, face, 0, (height
> -						- bottom_margin
> -						- border),
> -				   width, border);
> +	  pgtk_fill_rectangle (f, face->foreground, 0, margin, width,
> +			       border, false);
> +	  pgtk_fill_rectangle (f, face->foreground, 0, 0, border, height,
> +			       false);
> +	  pgtk_fill_rectangle (f, face->foreground, width - border, 0,
> +			       border, height, false);
> +	  pgtk_fill_rectangle (f, face->foreground, 0, (height
> +							- bottom_margin
> +							- border),
> +			       width, border, false);
>  	}
>        else
>  	{
>