Revert "Revert "Improve last change to xfaces.c" (05ece1eb8b)"

This reverts commit b8d2ec920f37f5d77d32440eefc97dd5e8c2c7dc.

Not only does it make debugging Emacs harder for users, that change is
unsafe for the Haiku port.

1 files changed, 59 insertions, 52 deletions

diff --git a/src/xfaces.c b/src/xfaces.c
index 643f4365896..7dbcacb35ac 100644
--- a/src/xfaces.c
+++ b/src/xfaces.c
@@ -6014,6 +6014,21 @@ realize_non_ascii_face (struct frame *f, Lisp_Object font_object,
 }
 #endif  /* HAVE_WINDOW_SYSTEM */
 
+/* Remove the attribute at INDEX from the font object if SYMBOL
+   appears in `font-fallback-ignored-attributes'.  */
+
+static void
+font_maybe_unset_attribute (Lisp_Object font_object,
+                            enum font_property_index index, Lisp_Object symbol)
+{
+  Lisp_Object tail = Vface_font_lax_matched_attributes;
+
+  FOR_EACH_TAIL_SAFE (tail)
+    {
+      if (EQ (XCAR (tail), symbol))
+        ASET (font_object, index, Qnil);
+    }
+}
 
 /* Realize the fully-specified face with attributes ATTRS in face
    cache CACHE for ASCII characters.  Do it for GUI frame CACHE->f.
@@ -6073,38 +6088,33 @@ realize_gui_face (struct face_cache *cache, Lisp_Object attrs[LFACE_VECTOR_SIZE]
       if (! FONT_OBJECT_P (attrs[LFACE_FONT_INDEX]))
         {
           Lisp_Object spec = copy_font_spec (attrs[LFACE_FONT_INDEX]);
-#define   MAYBE_UNSET_ATTRIBUTE(ATTR)                   \
-          if (realize_gui_face_ignored_spec_attributes  \
-              & (1 << FONT_##ATTR##_INDEX))             \
-            ASET (spec, FONT_##ATTR##_INDEX, Qnil);
-          /* The default value of
-             realize_gui_face_ignored_spec_attributes unsets the
-             weight, slant and width in spec.  The best possible
-             values for these attributes is determined in
-             font_find_for_lface, called by font_load_for_lface, when
-             the candidate list returned by font_list_entities is
-             sorted by font_select_entity (which calls
-             font_sort_entities, which calls font_score).  If these
-             attributes are not unset here, the candidate font list
-             returned by font_list_entities only contains fonts that
-             are exact matches for these weight, slant and width
-             attributes, which leads to suboptimal or wrong font
-             choices.  See bug#59347.  */
-          MAYBE_UNSET_ATTRIBUTE (WEIGHT);
-          MAYBE_UNSET_ATTRIBUTE (SLANT);
-          MAYBE_UNSET_ATTRIBUTE (WIDTH);
+
+          /* Maybe unset several values in SPEC, usually the width,
+             slant, and weight.  The best possible values for these
+             attributes are determined in font_find_for_lface, called
+             by font_load_for_lface, when the list of candidate fonts
+             returned by font_list_entities is sorted by font_select_entity
+             (which calls font_sort_entities, which calls font_score).
+             If these attributes are not unset here, the candidate
+             font list returned by font_list_entities only contains
+             fonts that are exact matches for these weight, slant, and
+             width attributes, which could lead to suboptimal or wrong
+             font selection.  (bug#5934) */
+          font_maybe_unset_attribute (spec, FONT_WEIGHT_INDEX, QCweight);
+          font_maybe_unset_attribute (spec, FONT_SLANT_INDEX, QCslant);
+          font_maybe_unset_attribute (spec, FONT_WIDTH_INDEX, QCwidth);
           /* Also allow unsetting other attributes for debugging
-             purposes.  */
-          MAYBE_UNSET_ATTRIBUTE (FAMILY);
-          MAYBE_UNSET_ATTRIBUTE (FOUNDRY);
-          MAYBE_UNSET_ATTRIBUTE (REGISTRY);
-          MAYBE_UNSET_ATTRIBUTE (ADSTYLE);
-          MAYBE_UNSET_ATTRIBUTE (SIZE);
-          MAYBE_UNSET_ATTRIBUTE (DPI);
-          MAYBE_UNSET_ATTRIBUTE (SPACING);
-          MAYBE_UNSET_ATTRIBUTE (AVGWIDTH);
-          MAYBE_UNSET_ATTRIBUTE (EXTRA);
-#undef    MAYBE_UNSET_ATTRIBUTE
+             purposes.  But not FONT_EXTRA_INDEX; that is not safe to
+             touch, at least in the Haiku font backend.  */
+          font_maybe_unset_attribute (spec, FONT_FAMILY_INDEX, QCfamily);
+          font_maybe_unset_attribute (spec, FONT_FOUNDRY_INDEX, QCfoundry);
+          font_maybe_unset_attribute (spec, FONT_REGISTRY_INDEX, QCregistry);
+          font_maybe_unset_attribute (spec, FONT_ADSTYLE_INDEX, QCadstyle);
+          font_maybe_unset_attribute (spec, FONT_SIZE_INDEX, QCsize);
+          font_maybe_unset_attribute (spec, FONT_DPI_INDEX, QCdpi);
+          font_maybe_unset_attribute (spec, FONT_SPACING_INDEX, QCspacing);
+          font_maybe_unset_attribute (spec, FONT_AVGWIDTH_INDEX, QCavgwidth);
+
           attrs[LFACE_FONT_INDEX] = font_load_for_lface (f, attrs, spec);
         }
       if (FONT_OBJECT_P (attrs[LFACE_FONT_INDEX]))
@@ -7394,27 +7404,24 @@ Lisp programs that change the value of this variable should also
 clear the face cache, see `clear-face-cache'.  */);
   face_near_same_color_threshold = 30000;
 
-  DEFVAR_INT ("realize-gui-face-ignored-spec-attributes",
-              realize_gui_face_ignored_spec_attributes,
-              doc: /* Ignored font-spec attributes in realize_gui_face.
-
-The value is an integer number and represents a bit mask.
-The attribute corresponding to each bit that is set is cleared in
-realize_gui_face.  The bits are: 1 = :foundry, 2 = :family,
-3 = :adstyle, 4 = :registry, 5 = :weight, 6 = :slant, 7 = :width,
-8 = :size, 9 = :dpi, 10 = :spacing, 11 = :avgwidth, 12 = extra
-attributes (:name, :script, :lang and :otf).
-
-Bits 5 to 7 are set in the default value.  When these bits are not
-set, and when the font chosen for the default face has a weight, slant
-or width that is not supported by other available fonts on the system,
-such as 'medium', Emacs may select suboptimal fonts for other faces.
-
-There is no reason to change that value except for debugging purposes.  */);
-  realize_gui_face_ignored_spec_attributes =
-    (1 << FONT_WEIGHT_INDEX) |
-    (1 << FONT_SLANT_INDEX) |
-    (1 << FONT_WIDTH_INDEX);
+  DEFVAR_LISP ("face-font-lax-matched-attributes",
+               Vface_font_lax_matched_attributes,
+               doc: /* Font-related face attributes to match in lax manner when realizing faces.
+
+The value should be a list of font-related face attribute symbols;
+see `set-face-attribute' for the full list of attributes.  The
+corresponding face attributes will be treated as "soft" constraints
+when looking for suitable fonts: if an exact match is not possible,
+a font can be selected that is a close, but not an exact, match.  For
+example, looking for a semi-bold font might select a bold or a medium
+font if no semi-bold font matching other attributes is found.  Emacs
+still tries to find a font that is the closest possible match; in
+particular, if a font is available that matches the face attributes
+exactly, it will be selected.
+
+Note that if the `:extra' attribute is present in the value, it
+will be ignored.  */);
+  Vface_font_lax_matched_attributes = list3 (QCweight, QCslant, QCwidth);
 
 #ifdef HAVE_WINDOW_SYSTEM
   defsubr (&Sbitmap_spec_p);