Fix display of composed text with :box face attribute

* src/xdisp.c (get_next_display_element): For a composition on a
display or overlay string, set the end_of_box_run_p flag if the
string ends at the last character included in the composition.
(fill_gstring_glyph_string): Fix the way the width of a gstring
glyph string is calculated: use the values calculated in
gui_produce_glyphs, since the latter adjusts the width due to the
face's ':box' attribute.
* src/xterm.c (x_draw_glyph_string_box):
* src/w32term.c (w32_draw_glyph_string_box):
* src/nsterm.m (ns_dumpglyphs_box_or_relief): Support automatic
compositions, which have the right_box_line_p flag set on the last
glyph produced from the composition.  (Bug#40687)

* src/w32term.c (w32_compute_glyph_string_overhangs): Update to be
consistent with xterm.c in its support of automatic composition
glyph strings.
* src/dispextern.h (enum glyph_type): More accurate commentary.
* src/.gdbinit (pgx): Display slice.img members only for image
glyphs.

6 files changed, 92 insertions, 26 deletions

diff --git a/src/.gdbinit b/src/.gdbinit
index 30c7b055ce0..78536fc01fb 100644
--- a/src/.gdbinit
+++ b/src/.gdbinit
@@ -500,6 +500,9 @@ define pgx
   # IMAGE_GLYPH
   if ($g.type == 3)
     printf "IMAGE[%d]", $g.u.img_id
+    if ($g.slice.img.x || $g.slice.img.y || $g.slice.img.width || $g.slice.img.height)
+      printf " slice=%d,%d,%d,%d" ,$g.slice.img.x, $g.slice.img.y, $g.slice.img.width, $g.slice.img.height
+    end
   end
   # STRETCH_GLYPH
   if ($g.type == 4)
@@ -551,9 +554,6 @@ define pgx
   if ($g.right_box_line_p)
     printf " ]"
   end
-  if ($g.slice.img.x || $g.slice.img.y || $g.slice.img.width || $g.slice.img.height)
-    printf " slice=%d,%d,%d,%d" ,$g.slice.img.x, $g.slice.img.y, $g.slice.img.width, $g.slice.img.height
-  end
   printf "\n"
 end
 document pgx
diff --git a/src/dispextern.h b/src/dispextern.h
index d6fe68cf99f..0b1f3d14aeb 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -369,7 +369,7 @@ enum glyph_type
   /* Glyph describes a character.  */
   CHAR_GLYPH,
 
-  /* Glyph describes a static composition.  */
+  /* Glyph describes a static or automatic composition.  */
   COMPOSITE_GLYPH,
 
   /* Glyph describes a glyphless character.  */
diff --git a/src/nsterm.m b/src/nsterm.m
index 5eb44639f56..a8f7540ea20 100644
--- a/src/nsterm.m
+++ b/src/nsterm.m
@@ -3872,8 +3872,21 @@ ns_dumpglyphs_box_or_relief (struct glyph_string *s)
   last_x = ((s->row->full_width_p && !s->w->pseudo_window_p)
             ? WINDOW_RIGHT_EDGE_X (s->w)
             : window_box_right (s->w, s->area));
-  last_glyph = (s->cmp || s->img
-                ? s->first_glyph : s->first_glyph + s->nchars-1);
+  if (s->cmp || s->img)
+    last_glyph = s->first_glyph;
+  else if (s->first_glyph->type == COMPOSITE_GLYPH
+           && s->first_glyph->u.cmp.automatic)
+    {
+        struct glyph *end = s->row->glyphs[s->area] + s->row->used[s->area];
+        struct glyph *g = s->first_glyph;
+        for (last_glyph = g++;
+             g < end && g->u.cmp.automatic && g->u.cmp.id == s->cmp_id
+               && g->slice.cmp.to < s->cmp_to;
+             last_glyph = g++)
+          ;
+    }
+  else
+    last_glyph = s->first_glyph + s->nchars - 1;
 
   right_x = ((s->row->full_width_p && s->extends_to_end_of_line_p
               ? last_x - 1 : min (last_x, s->x + s->background_width) - 1));
diff --git a/src/w32term.c b/src/w32term.c
index 108cb7922fb..1766b32514f 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -1101,19 +1101,28 @@ w32_set_glyph_string_clipping_exactly (struct glyph_string *src,
 static void
 w32_compute_glyph_string_overhangs (struct glyph_string *s)
 {
-  if (s->cmp == NULL
-      && s->first_glyph->type == CHAR_GLYPH
-      && !s->font_not_found_p)
+  if (s->cmp == NULL)
     {
-      struct font *font = s->font;
       struct font_metrics metrics;
+      if (s->first_glyph->type == CHAR_GLYPH && !s->font_not_found_p)
+        {
+          struct font *font = s->font;
+          font->driver->text_extents (font, s->char2b, s->nchars, &metrics);
+          s->right_overhang = (metrics.rbearing > metrics.width
+                               ? metrics.rbearing - metrics.width : 0);
+          s->left_overhang = metrics.lbearing < 0 ? -metrics.lbearing : 0;
+        }
+      else if (s->first_glyph->type == COMPOSITE_GLYPH)
+        {
+          Lisp_Object gstring = composition_gstring_from_id (s->cmp_id);
 
-      font->driver->text_extents (font, s->char2b, s->nchars, &metrics);
-      s->right_overhang = (metrics.rbearing > metrics.width
-                           ? metrics.rbearing - metrics.width : 0);
-      s->left_overhang = metrics.lbearing < 0 ? -metrics.lbearing : 0;
+          composition_gstring_width (gstring, s->cmp_from, s->cmp_to, &metrics);
+          s->right_overhang = (metrics.rbearing > metrics.width
+                               ? metrics.rbearing - metrics.width : 0);
+          s->left_overhang = metrics.lbearing < 0 ? -metrics.lbearing : 0;
+        }
     }
-  else if (s->cmp)
+  else
     {
       s->right_overhang = s->cmp->rbearing - s->cmp->pixel_width;
       s->left_overhang = -s->cmp->lbearing;
@@ -1725,10 +1734,26 @@ w32_draw_glyph_string_box (struct glyph_string *s)
             ? WINDOW_RIGHT_EDGE_X (s->w)
             : window_box_right (s->w, s->area));
 
-  /* The glyph that may have a right box line.  */
-  last_glyph = (s->cmp || s->img
-                ? s->first_glyph
-                : s->first_glyph + s->nchars - 1);
+  /* The glyph that may have a right box line.  For static
+     compositions and images, the right-box flag is on the first glyph
+     of the glyph string; for other types it's on the last glyph.  */
+  if (s->cmp || s->img)
+    last_glyph = s->first_glyph;
+  else if (s->first_glyph->type == COMPOSITE_GLYPH
+           && s->first_glyph->u.cmp.automatic)
+    {
+      /* For automatic compositions, we need to look up the last glyph
+         in the composition.  */
+        struct glyph *end = s->row->glyphs[s->area] + s->row->used[s->area];
+        struct glyph *g = s->first_glyph;
+        for (last_glyph = g++;
+             g < end && g->u.cmp.automatic && g->u.cmp.id == s->cmp_id
+               && g->slice.cmp.to < s->cmp_to;
+             last_glyph = g++)
+          ;
+    }
+  else
+    last_glyph = s->first_glyph + s->nchars - 1;
 
   vwidth = eabs (s->face->box_vertical_line_width);
   hwidth = eabs (s->face->box_horizontal_line_width);
diff --git a/src/xdisp.c b/src/xdisp.c
index 01f272033e5..32588939564 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -7617,7 +7617,13 @@ get_next_display_element (struct it *it)
               /* Otherwise, the box comes from the underlying face.
                  If this is the last string character displayed, check
                  the next buffer location.  */
-              else if ((IT_STRING_CHARPOS (*it) >= SCHARS (it->string) - 1)
+              else if (((IT_STRING_CHARPOS (*it) >= SCHARS (it->string) - 1)
+                        /* For a composition, see if the string ends
+                           at the last character included in the
+                           composition.  */
+                        || (it->what == IT_COMPOSITION
+                            && (IT_STRING_CHARPOS (*it) + it->cmp_it.nchars
+                                >= SCHARS (it->string))))
                        /* n_overlay_strings is unreliable unless
                           overlay_string_index is non-negative.  */
                        && ((it->current.overlay_string_index >= 0
@@ -27567,12 +27573,18 @@ fill_gstring_glyph_string (struct glyph_string *s, int face_id,
   s->face = FACE_FROM_ID (s->f, face_id);
   lgstring = composition_gstring_from_id (s->cmp_id);
   s->font = XFONT_OBJECT (LGSTRING_FONT (lgstring));
+  /* The width of a composition glyph string is the sum of the
+     composition's glyph widths.  */
+  s->width = s->first_glyph->pixel_width;
   glyph++;
   while (glyph < last
          && glyph->u.cmp.automatic
          && glyph->u.cmp.id == s->cmp_id
          && s->cmp_to == glyph->slice.cmp.from)
-    s->cmp_to = (glyph++)->slice.cmp.to + 1;
+    {
+      s->width += glyph->pixel_width;
+      s->cmp_to = (glyph++)->slice.cmp.to + 1;
+    }
 
   for (i = s->cmp_from; i < s->cmp_to; i++)
     {
@@ -27582,7 +27594,7 @@ fill_gstring_glyph_string (struct glyph_string *s, int face_id,
       /* Ensure that the code is only 2 bytes wide.  */
       s->char2b[i] = code & 0xFFFF;
     }
-  s->width = composition_gstring_width (lgstring, s->cmp_from, s->cmp_to, NULL);
+
   return glyph - s->row->glyphs[s->area];
 }
 
diff --git a/src/xterm.c b/src/xterm.c
index afe9c3da5b8..7989cecec7f 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -2986,10 +2986,26 @@ x_draw_glyph_string_box (struct glyph_string *s)
             ? WINDOW_RIGHT_EDGE_X (s->w)
             : window_box_right (s->w, s->area));
 
-  /* The glyph that may have a right box line.  */
-  last_glyph = (s->cmp || s->img
-                ? s->first_glyph
-                : s->first_glyph + s->nchars - 1);
+  /* The glyph that may have a right box line.  For static
+     compositions and images, the right-box flag is on the first glyph
+     of the glyph string; for other types it's on the last glyph.  */
+  if (s->cmp || s->img)
+    last_glyph = s->first_glyph;
+  else if (s->first_glyph->type == COMPOSITE_GLYPH
+           && s->first_glyph->u.cmp.automatic)
+    {
+      /* For automatic compositions, we need to look up the last glyph
+         in the composition.  */
+        struct glyph *end = s->row->glyphs[s->area] + s->row->used[s->area];
+        struct glyph *g = s->first_glyph;
+        for (last_glyph = g++;
+             g < end && g->u.cmp.automatic && g->u.cmp.id == s->cmp_id
+               && g->slice.cmp.to < s->cmp_to;
+             last_glyph = g++)
+          ;
+    }
+  else
+    last_glyph = s->first_glyph + s->nchars - 1;
 
   vwidth = eabs (s->face->box_vertical_line_width);
   hwidth = eabs (s->face->box_horizontal_line_width);