Explictly specify whether or not to respect alpha-background on Cairo

* src/ftcrfont.c (ftcrfont_draw): Don't respect
`alpha-background' if drawing cursor.  (bug#53890)
* src/xterm.c (x_set_cr_source_with_gc_foreground):
(x_set_cr_source_with_gc_background): New parameters
`respect_alpha_background'.  All callers changed.
* src/xterm.h: Update protoypes.

3 files changed, 38 insertions, 22 deletions

diff --git a/src/ftcrfont.c b/src/ftcrfont.c
index a0a3490c494..4d1ecee3788 100644
--- a/src/ftcrfont.c
+++ b/src/ftcrfont.c
@@ -566,7 +566,7 @@ ftcrfont_draw (struct glyph_string *s,
     {
 #ifndef USE_BE_CAIRO
 #ifdef HAVE_X_WINDOWS
-      x_set_cr_source_with_gc_background (f, s->gc);
+      x_set_cr_source_with_gc_background (f, s->gc, s->hl != DRAW_CURSOR);
 #else
       pgtk_set_cr_source_with_color (f, s->xgcv.background, true);
 #endif
@@ -595,7 +595,7 @@ ftcrfont_draw (struct glyph_string *s,
     }
 #ifndef USE_BE_CAIRO
 #ifdef HAVE_X_WINDOWS
-  x_set_cr_source_with_gc_foreground (f, s->gc);
+  x_set_cr_source_with_gc_foreground (f, s->gc, false);
 #else
   pgtk_set_cr_source_with_color (f, s->xgcv.foreground, false);
 #endif
diff --git a/src/xterm.c b/src/xterm.c
index 9b480069275..aed97fb37e9 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -875,20 +875,35 @@ x_end_cr_clip (struct frame *f)
 }
 
 void
-x_set_cr_source_with_gc_foreground (struct frame *f, GC gc)
+x_set_cr_source_with_gc_foreground (struct frame *f, GC gc,
+                                    bool respect_alpha_background)
 {
   XGCValues xgcv;
   XColor color;
+  unsigned int depth;
 
   XGetGCValues (FRAME_X_DISPLAY (f), gc, GCForeground, &xgcv);
   color.pixel = xgcv.foreground;
   x_query_colors (f, &color, 1);
-  cairo_set_source_rgb (FRAME_CR_CONTEXT (f), color.red / 65535.0,
-                        color.green / 65535.0, color.blue / 65535.0);
+  depth = FRAME_DISPLAY_INFO (f)->n_planes;
+
+  if (f->alpha_background < 1.0 && depth == 32
+      && respect_alpha_background)
+    {
+      cairo_set_source_rgba (FRAME_CR_CONTEXT (f), color.red / 65535.0,
+                             color.green / 65535.0, color.blue / 65535.0,
+                             f->alpha_background);
+
+      cairo_set_operator (FRAME_CR_CONTEXT (f), CAIRO_OPERATOR_SOURCE);
+    }
+  else
+    cairo_set_source_rgb (FRAME_CR_CONTEXT (f), color.red / 65535.0,
+                          color.green / 65535.0, color.blue / 65535.0);
 }
 
 void
-x_set_cr_source_with_gc_background (struct frame *f, GC gc)
+x_set_cr_source_with_gc_background (struct frame *f, GC gc,
+                                    bool respect_alpha_background)
 {
   XGCValues xgcv;
   XColor color;
@@ -901,7 +916,8 @@ x_set_cr_source_with_gc_background (struct frame *f, GC gc)
 
   depth = FRAME_DISPLAY_INFO (f)->n_planes;
 
-  if (f->alpha_background < 1.0 && depth == 32)
+  if (f->alpha_background < 1.0 && depth == 32
+      && respect_alpha_background)
     {
       cairo_set_source_rgba (FRAME_CR_CONTEXT (f), color.red / 65535.0,
                              color.green / 65535.0, color.blue / 65535.0,
@@ -912,7 +928,6 @@ x_set_cr_source_with_gc_background (struct frame *f, GC gc)
   else
     cairo_set_source_rgb (FRAME_CR_CONTEXT (f), color.red / 65535.0,
                           color.green / 65535.0, color.blue / 65535.0);
-
 }
 
 static const cairo_user_data_key_t xlib_surface_key, saved_drawable_key;
@@ -1097,7 +1112,7 @@ x_cr_draw_image (struct frame *f, GC gc, cairo_pattern_t *image,
     cairo_rectangle (cr, dest_x, dest_y, width, height);
   else
     {
-      x_set_cr_source_with_gc_background (f, gc);
+      x_set_cr_source_with_gc_background (f, gc, false);
       cairo_rectangle (cr, dest_x, dest_y, width, height);
       cairo_fill_preserve (cr);
     }
@@ -1114,7 +1129,7 @@ x_cr_draw_image (struct frame *f, GC gc, cairo_pattern_t *image,
     }
   else
     {
-      x_set_cr_source_with_gc_foreground (f, gc);
+      x_set_cr_source_with_gc_foreground (f, gc, false);
       cairo_clip (cr);
       cairo_mask (cr, image);
     }
@@ -1325,7 +1340,7 @@ x_fill_rectangle (struct frame *f, GC gc, int x, int y, int width, int height,
          regarded as Pixmap of unspecified size filled with ones.  */
       || (xgcv.stipple & ((Pixmap) 7 << (sizeof (Pixmap) * CHAR_BIT - 3))))
     {
-      x_set_cr_source_with_gc_foreground (f, gc);
+      x_set_cr_source_with_gc_foreground (f, gc, respect_alpha_background);
       cairo_rectangle (cr, x, y, width, height);
       cairo_fill (cr);
     }
@@ -1333,14 +1348,14 @@ x_fill_rectangle (struct frame *f, GC gc, int x, int y, int width, int height,
     {
       eassert (xgcv.fill_style == FillOpaqueStippled);
       eassert (xgcv.stipple != None);
-      x_set_cr_source_with_gc_background (f, gc);
+      x_set_cr_source_with_gc_background (f, gc, respect_alpha_background);
       cairo_rectangle (cr, x, y, width, height);
       cairo_fill_preserve (cr);
 
       cairo_pattern_t *pattern = x_bitmap_stipple (f, xgcv.stipple);
       if (pattern)
         {
-          x_set_cr_source_with_gc_foreground (f, gc);
+          x_set_cr_source_with_gc_foreground (f, gc, respect_alpha_background);
           cairo_clip (cr);
           cairo_mask (cr, pattern);
         }
@@ -1384,7 +1399,7 @@ x_clear_rectangle (struct frame *f, GC gc, int x, int y, int width, int height,
   cairo_t *cr;
 
   cr = x_begin_cr_clip (f, gc);
-  x_set_cr_source_with_gc_background (f, gc);
+  x_set_cr_source_with_gc_background (f, gc, respect_alpha_background);
   cairo_rectangle (cr, x, y, width, height);
   cairo_fill (cr);
   x_end_cr_clip (f);
@@ -1430,7 +1445,7 @@ x_draw_rectangle (struct frame *f, GC gc, int x, int y, int width, int height)
   cairo_t *cr;
 
   cr = x_begin_cr_clip (f, gc);
-  x_set_cr_source_with_gc_foreground (f, gc);
+  x_set_cr_source_with_gc_foreground (f, gc, false);
   cairo_rectangle (cr, x + 0.5, y + 0.5, width, height);
   cairo_set_line_width (cr, 1);
   cairo_stroke (cr);
@@ -1448,7 +1463,7 @@ x_clear_window (struct frame *f)
   cairo_t *cr;
 
   cr = x_begin_cr_clip (f, NULL);
-  x_set_cr_source_with_gc_background (f, f->output_data.x->normal_gc);
+  x_set_cr_source_with_gc_background (f, f->output_data.x->normal_gc, true);
   cairo_paint (cr);
   x_end_cr_clip (f);
 #else
@@ -1471,7 +1486,7 @@ x_fill_trapezoid_for_relief (struct frame *f, GC gc, int x, int y,
   cairo_t *cr;
 
   cr = x_begin_cr_clip (f, gc);
-  x_set_cr_source_with_gc_foreground (f, gc);
+  x_set_cr_source_with_gc_foreground (f, gc, false);
   cairo_move_to (cr, top_p ? x : x + height, y);
   cairo_line_to (cr, x, y + height);
   cairo_line_to (cr, top_p ? x + width - height : x + width, y + height);
@@ -1498,7 +1513,7 @@ x_erase_corners_for_relief (struct frame *f, GC gc, int x, int y,
   int i;
 
   cr = x_begin_cr_clip (f, gc);
-  x_set_cr_source_with_gc_background (f, gc);
+  x_set_cr_source_with_gc_background (f, gc, false);
   for (i = 0; i < CORNER_LAST; i++)
     if (corners & (1 << i))
       {
@@ -1531,7 +1546,7 @@ x_draw_horizontal_wave (struct frame *f, GC gc, int x, int y,
   int xoffset, n;
 
   cr = x_begin_cr_clip (f, gc);
-  x_set_cr_source_with_gc_foreground (f, gc);
+  x_set_cr_source_with_gc_foreground (f, gc, false);
   cairo_rectangle (cr, x, y, width, height);
   cairo_clip (cr);
 
@@ -4840,7 +4855,8 @@ x_clear_area (struct frame *f, int x, int y, int width, int height)
   eassert (width > 0 && height > 0);
 
   cr = x_begin_cr_clip (f, NULL);
-  x_set_cr_source_with_gc_background (f, f->output_data.x->normal_gc);
+  x_set_cr_source_with_gc_background (f, f->output_data.x->normal_gc,
+                                      true);
   cairo_rectangle (cr, x, y, width, height);
   cairo_fill (cr);
   x_end_cr_clip (f);
diff --git a/src/xterm.h b/src/xterm.h
index 1ce3e7a6cf8..435569943c4 100644
--- a/src/xterm.h
+++ b/src/xterm.h
@@ -1267,8 +1267,8 @@ extern void x_cr_destroy_frame_context (struct frame *);
 extern void x_cr_update_surface_desired_size (struct frame *, int, int);
 extern cairo_t *x_begin_cr_clip (struct frame *, GC);
 extern void x_end_cr_clip (struct frame *);
-extern void x_set_cr_source_with_gc_foreground (struct frame *, GC);
-extern void x_set_cr_source_with_gc_background (struct frame *, GC);
+extern void x_set_cr_source_with_gc_foreground (struct frame *, GC, bool);
+extern void x_set_cr_source_with_gc_background (struct frame *, GC, bool);
 extern void x_cr_draw_frame (cairo_t *, struct frame *);
 extern Lisp_Object x_cr_export_frames (Lisp_Object, cairo_surface_type_t);
 #endif