Implement `alpha-background' on PGTK

* src/ftcrfont.c (ftcrfont_draw): Respect alpha-background where
appropriate.
* src/gtkutil.c (xg_create_frame_widgets): Swap some
conditionals around to get the right visual and signal handlers
on PGTK.
(xg_widget_style_updated): Likewise.
* src/pgtkfns.c (pgtk_set_alpha_background): New function.
(pgtk_frame_parm_handlers): Add it instead of the generic param
handler.
(Fx_create_frame): Fix typo.
* src/pgtkterm.c (pgtk_fill_rectangle):
(pgtk_set_cr_source_with_gc_foreground):
(pgtk_set_cr_source_with_gc_background):
(pgtk_set_cr_source_with_color): New argument
`respect_alpha_backend'.  All callers changed.
* src/pgtkterm.h: Update function prototypes.

1 files changed, 3 insertions, 6 deletions

diff --git a/src/pgtkterm.h b/src/pgtkterm.h
index 42b03e315ef..4d2285cdb0a 100644
--- a/src/pgtkterm.h
+++ b/src/pgtkterm.h
@@ -591,12 +591,9 @@ extern void x_set_z_group (struct frame *f, Lisp_Object new_value,
 extern void pgtk_cr_update_surface_desired_size (struct frame *, int, int, bool);
 extern cairo_t *pgtk_begin_cr_clip (struct frame *f);
 extern void pgtk_end_cr_clip (struct frame *f);
-extern void pgtk_set_cr_source_with_gc_foreground (struct frame *f,
-                                                   Emacs_GC * gc);
-extern void pgtk_set_cr_source_with_gc_background (struct frame *f,
-                                                   Emacs_GC * gc);
-extern void pgtk_set_cr_source_with_color (struct frame *f,
-                                           unsigned long color);
+extern void pgtk_set_cr_source_with_gc_foreground (struct frame *, Emacs_GC *, bool);
+extern void pgtk_set_cr_source_with_gc_background (struct frame *, Emacs_GC *, bool);
+extern void pgtk_set_cr_source_with_color (struct frame *, unsigned long, bool);
 extern void pgtk_cr_draw_frame (cairo_t * cr, struct frame *f);
 extern void pgtk_cr_destroy_frame_context (struct frame *f);
 extern Lisp_Object pgtk_cr_export_frames (Lisp_Object frames, cairo_surface_type_t surface_type);