Implement `alpha-background' on non-Cairo builds

* src/frame.c (gui_set_alpha_background): Recompute basic faces
so xft face ext info gets reset.
* src/gtkutil.c (xg_create_frame_widgets): Attach to style
updated signal.
(xg_update_frame_menubar): Set menu bar visual correctly.
(xg_widget_style_updated): New function.

* src/xfns.c (x_set_alpha_background): New function.
(x_frame_parm_handlers): Use x_set_alpha_background instead.

* src/xfont.c (xfont_draw):
* src/xftfont.c (xftfont_draw): Handle `alpha-background'
parameter.

* src/xterm.c (x_xr_ensure_picture): Export function.
(x_update_opaque_region): New function.
(x_fill_rectangle): New parameter `respect_alpha_background'.
All callers changed.
(handle_one_xevent): Set opaque region on ConfigureNotify.
(x_drop_xrender_surfaces): Set opaque region.
(x_xrender_color_from_gc_foreground):
(x_xrender_color_from_gc_background): Premultiply alpha with
components if asked for.
* src/xterm.h (struct x_display_info): New atom
`Xatom_net_wm_opaque_region'.

1 files changed, 25 insertions, 0 deletions

diff --git a/src/xfont.c b/src/xfont.c
index b5765cfa7b8..7a50378a006 100644
--- a/src/xfont.c
+++ b/src/xfont.c
@@ -1003,6 +1003,31 @@ xfont_draw (struct glyph_string *s, int from, int to, int x, int y,
       unblock_input ();
     }
 
+#if defined HAVE_XRENDER && (RENDER_MAJOR > 0 || (RENDER_MINOR >= 2))
+  if (with_background
+      && FRAME_DISPLAY_INFO (s->f)->n_planes == 32
+      && FRAME_CHECK_XR_VERSION (s->f, 0, 2))
+    {
+      x_xr_ensure_picture (s->f);
+
+      if (FRAME_X_PICTURE (s->f) != None)
+	{
+	  XRenderColor xc;
+	  int height = FONT_HEIGHT (s->font), ascent = FONT_BASE (s->font);
+
+	  x_xr_apply_ext_clip (s->f, gc);
+	  x_xrender_color_from_gc_background (s->f, gc, &xc, true);
+	  XRenderFillRectangle (FRAME_X_DISPLAY (s->f),
+				PictOpSrc, FRAME_X_PICTURE (s->f),
+				&xc, x, y - ascent, s->width, height);
+	  x_xr_reset_ext_clip (s->f);
+	  x_mark_frame_dirty (s->f);
+
+	  with_background = false;
+	}
+    }
+#endif
+
   if (xfont->min_byte1 == 0 && xfont->max_byte1 == 0)
     {
       USE_SAFE_ALLOCA;