Allow face-remapping using :font, and use it in mouse-appearance-menu.

* mouse.el (mouse-appearance-menu): If x-select-font returns a
font spec, set the font directly.

* xfaces.c (merge_face_vectors): If the target font specfies a
font spec, make the font's attributes take precedence over
directly-specified attributes.
(merge_face_ref): Recognize :font.

Fixes: debbugs:3228

1 files changed, 33 insertions, 18 deletions

diff --git a/src/xfaces.c b/src/xfaces.c
index 7491802466d..8c6542ee725 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -2281,6 +2281,7 @@ merge_face_vectors (struct frame *f, Lisp_Object *from, Lisp_Object *to,
 		    struct named_merge_point *named_merge_points)
 {
   int i;
+  Lisp_Object font = Qnil;
 
   /* If FROM inherits from some other faces, merge their attributes into
      TO before merging FROM's direct attributes.  Note that an :inherit
@@ -2291,24 +2292,13 @@ merge_face_vectors (struct frame *f, Lisp_Object *from, Lisp_Object *to,
       && !NILP (from[LFACE_INHERIT_INDEX]))
     merge_face_ref (f, from[LFACE_INHERIT_INDEX], to, 0, named_merge_points);
 
-  i = LFACE_FONT_INDEX;
-  if (!UNSPECIFIEDP (from[i]))
+  if (FONT_SPEC_P (from[LFACE_FONT_INDEX]))
     {
-      if (!UNSPECIFIEDP (to[i]))
-	to[i] = merge_font_spec (from[i], to[i]);
+      if (!UNSPECIFIEDP (to[LFACE_FONT_INDEX]))
+	font = merge_font_spec (from[LFACE_FONT_INDEX], to[LFACE_FONT_INDEX]);
       else
-	to[i] = copy_font_spec (from[i]);
-      if (! NILP (AREF (to[i], FONT_FOUNDRY_INDEX)))
-	to[LFACE_FOUNDRY_INDEX] = SYMBOL_NAME (AREF (to[i], FONT_FOUNDRY_INDEX));
-      if (! NILP (AREF (to[i], FONT_FAMILY_INDEX)))
-	to[LFACE_FAMILY_INDEX] = SYMBOL_NAME (AREF (to[i], FONT_FAMILY_INDEX));
-      if (! NILP (AREF (to[i], FONT_WEIGHT_INDEX)))
-	to[LFACE_WEIGHT_INDEX] = FONT_WEIGHT_FOR_FACE (to[i]);
-      if (! NILP (AREF (to[i], FONT_SLANT_INDEX)))
-	to[LFACE_SLANT_INDEX] = FONT_SLANT_FOR_FACE (to[i]);
-      if (! NILP (AREF (to[i], FONT_WIDTH_INDEX)))
-	to[LFACE_SWIDTH_INDEX] = FONT_WIDTH_FOR_FACE (to[i]);
-      ASET (to[i], FONT_SIZE_INDEX, Qnil);
+	font = copy_font_spec (from[LFACE_FONT_INDEX]);
+      to[LFACE_FONT_INDEX] = font;
     }
 
   for (i = 1; i < LFACE_VECTOR_SIZE; ++i)
@@ -2319,8 +2309,7 @@ merge_face_vectors (struct frame *f, Lisp_Object *from, Lisp_Object *to,
 	    to[i] = merge_face_heights (from[i], to[i], to[i]);
 	    font_clear_prop (to, FONT_SIZE_INDEX);
 	  }
-	else if (i != LFACE_FONT_INDEX
-		 && ! EQ (to[i], from[i]))
+	else if (i != LFACE_FONT_INDEX && ! EQ (to[i], from[i]))
 	  {
 	    to[i] = from[i];
 	    if (i >= LFACE_FAMILY_INDEX && i <=LFACE_SLANT_INDEX)
@@ -2334,6 +2323,25 @@ merge_face_vectors (struct frame *f, Lisp_Object *from, Lisp_Object *to,
 	  }
       }
 
+  /* If FROM specifies a font spec, make its contents take precedence
+     over :family and other attributes.  This is needed for face
+     remapping using :font to work.  */
+
+  if (!NILP (font))
+    {
+      if (! NILP (AREF (font, FONT_FOUNDRY_INDEX)))
+	to[LFACE_FOUNDRY_INDEX] = SYMBOL_NAME (AREF (font, FONT_FOUNDRY_INDEX));
+      if (! NILP (AREF (font, FONT_FAMILY_INDEX)))
+	to[LFACE_FAMILY_INDEX] = SYMBOL_NAME (AREF (font, FONT_FAMILY_INDEX));
+      if (! NILP (AREF (font, FONT_WEIGHT_INDEX)))
+	to[LFACE_WEIGHT_INDEX] = FONT_WEIGHT_FOR_FACE (font);
+      if (! NILP (AREF (font, FONT_SLANT_INDEX)))
+	to[LFACE_SLANT_INDEX] = FONT_SLANT_FOR_FACE (font);
+      if (! NILP (AREF (font, FONT_WIDTH_INDEX)))
+	to[LFACE_SWIDTH_INDEX] = FONT_WIDTH_FOR_FACE (font);
+      ASET (font, FONT_SIZE_INDEX, Qnil);
+    }
+
   /* TO is always an absolute face, which should inherit from nothing.
      We blindly copy the :inherit attribute above and fix it up here.  */
   to[LFACE_INHERIT_INDEX] = Qnil;
@@ -2575,6 +2583,13 @@ merge_face_ref (struct frame *f, Lisp_Object face_ref, Lisp_Object *to,
 		  else
 		    err = 1;
 		}
+	      else if (EQ (keyword, QCfont))
+		{
+		  if (FONTP (value))
+		    to[LFACE_FONT_INDEX] = value;
+		  else
+		    err = 1;
+		}
 	      else if (EQ (keyword, QCinherit))
 		{
 		  /* This is not really very useful; it's just like a