Fix and document display of glyphless characters.

 src/xdisp.c (set_cursor_from_row): Fix cursor positioning on
 zero-width characters.
 (syms_of_xdisp) <glyphless-char-display>: Doc fix.
 src/.gdbinit (pgx): Adapt to latest changes in `struct glyph'.
 src/w32term.c (x_draw_glyphless_glyph_string_foreground): Draw the
 box before drawing the glyphs inside it.
 src/dispextern.h (enum glyphless_display_method): Rename
 GLYPHLESS_DISPLAY_HEXA_CODE to GLYPHLESS_DISPLAY_HEX_CODE.  All
 users changed.
 src/term.c (append_glyphless_glyph, produce_glyphless_glyph): Fix
 comments.
 (produce_glyphless_glyph): Enclose "U+nnnn" and "empty box"
 whitespace in "[]", to simulate a box.  Don't use uninitialized
 variable `width'.
 lisp/international/characters.el (glyphless-char-display-control):
 Renamed from glyphless-char-control; all users changed.  Doc fix.
 Signal an error if display method is not one of the recognized
 symbols.
 doc/emacs/rmail.texi (Rmail Coding): Characters with no fonts are not
 necessarily displayed as empty boxes.
 doc/emacs/mule.texi (Language Environments, Fontsets): Characters with no
 fonts are not necessarily displayed as empty boxes.
 doc/emacs/display.texi (Text Display): Document display of glyphless
 characters.
 doc/lispref/display.texi (Usual Display): Characters with no fonts are not
 necessarily displayed as empty boxes.
 etc/NEWS: Document display of glyphless characters.

7 files changed, 90 insertions, 49 deletions

diff --git a/src/.gdbinit b/src/.gdbinit
index b3bb6b58267..73fecea5972 100644
--- a/src/.gdbinit
+++ b/src/.gdbinit
@@ -494,14 +494,30 @@ define pgx
   end
   # COMPOSITE_GLYPH
   if ($g->type == 1)
-    printf "COMP[%d (%d..%d)]", $g->u.cmp.id, $g->u.cmp.from, $g->u.cmp.to
+    printf "COMP[%d (%d..%d)]", $g->u.cmp.id, $g->slice.cmp.from, $g->slice.cmp.to
   end
-  # IMAGE_GLYPH
+  # GLYPHLESS_GLYPH
   if ($g->type == 2)
+    printf "GLYPHLESS["
+    if ($g->u.glyphless.method == 0)
+      printf "THIN]"
+    end
+    if ($g->u.glyphless.method == 1)
+      printf "EMPTY]"
+    end
+    if ($g->u.glyphless.method == 2)
+      printf "ACRO]"
+    end
+    if ($g->u.glyphless.method == 3)
+      printf "HEX]"
+    end
+  end
+  # IMAGE_GLYPH
+  if ($g->type == 3)
     printf "IMAGE[%d]", $g->u.img_id
   end
   # STRETCH_GLYPH
-  if ($g->type == 3)
+  if ($g->type == 4)
     printf "STRETCH[%d+%d]", $g->u.stretch.height, $g->u.stretch.ascent
   end
   xgettype ($g->object)
@@ -544,8 +560,8 @@ define pgx
   if ($g->right_box_line_p)
     printf " ]"
   end
-  if ($g->slice.x || $g->slice.y || $g->slice.width || $g->slice.height)
-    printf " slice=%d,%d,%d,%d" ,$g->slice.x, $g->slice.y, $g->slice.width, $g->slice.height
+  if ($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
diff --git a/src/ChangeLog b/src/ChangeLog
index 13f90d12790..2bac819c0d5 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,25 @@
+2010-11-13  Eli Zaretskii  <eliz@gnu.org>
+
+        * xdisp.c (set_cursor_from_row): Fix cursor positioning on
+        zero-width characters.
+
+        * .gdbinit (pgx): Adapt to latest changes in `struct glyph'.
+
+        * w32term.c (x_draw_glyphless_glyph_string_foreground): Draw the
+        box before drawing the glyphs inside it.
+
+        * xdisp.c (syms_of_xdisp) <glyphless-char-display>: Doc fix.
+
+        * dispextern.h (enum glyphless_display_method): Rename
+        GLYPHLESS_DISPLAY_HEXA_CODE to GLYPHLESS_DISPLAY_HEX_CODE.  All
+        users changed.
+
+        * term.c (append_glyphless_glyph, produce_glyphless_glyph): Fix
+        comments.
+        (produce_glyphless_glyph): Enclose "U+nnnn" and "empty box"
+        whitespace in "[]", to simulate a box.  Don't use uninitialized
+        variable `width'.
+
 2010-11-11  Julien Danjou  <julien@danjou.info>
 
         * xsettings.c (init_xsettings): Use already fetch atoms.
diff --git a/src/dispextern.h b/src/dispextern.h
index 30bd051b0ac..0786fff67cc 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -371,12 +371,11 @@ struct glyph
      displaying.  The member `pixel_width' above is set to 1.  */
   unsigned padding_p : 1;
 
-  /* 1 means the actual glyph is not available, draw a box instead.
-     This can happen when a font couldn't be loaded, or a character
-     doesn't have a glyph in a font.  */
+  /* 1 means the actual glyph is not available, draw using `struct
+     glyphless' below instead.  This can happen when a font couldn't
+     be loaded, or a character doesn't have a glyph in a font.  */
   unsigned glyph_not_available_p : 1;
 
- 
   /* Non-zero means don't display cursor here.  */
   unsigned avoid_cursor_p : 1;
 
@@ -1997,14 +1996,15 @@ enum line_wrap_method
 
 enum glyphless_display_method
   {
-    /* Display a thin (1-pixel width) space.  */
+    /* Display a thin (1-pixel width) space.  On a TTY, display a
+       1-character width space.  */
     GLYPHLESS_DISPLAY_THIN_SPACE,
     /* Display an empty box of proper width.  */
     GLYPHLESS_DISPLAY_EMPTY_BOX,
     /* Display an acronym string in a box.  */
     GLYPHLESS_DISPLAY_ACRONYM,
-    /* Display a hexadecimal character code in a box.  */
-    GLYPHLESS_DISPLAY_HEXA_CODE
+    /* Display the hexadecimal code of the character in a box.  */
+    GLYPHLESS_DISPLAY_HEX_CODE
   };
 
 struct it_slice
diff --git a/src/term.c b/src/term.c
index dbbdc03f190..71df92822ac 100644
--- a/src/term.c
+++ b/src/term.c
@@ -1850,9 +1850,9 @@ produce_composite_glyph (struct it *it)
 
 
 /* Append a glyph for a glyphless character to IT->glyph_row.  FACE_ID
-   is a face ID to be used for the glyph.  What actually appended are
-   glyphs of type CHAR_GLYPH of which characters are in STR
-   (it->nglyphs bytes).  */
+   is a face ID to be used for the glyph.  What is actually appended
+   are glyphs of type CHAR_GLYPH whose characters are in STR (which
+   comes from it->nglyphs bytes).  */
 
 static void
 append_glyphless_glyph (struct it *it, int face_id, char *str)
@@ -1923,7 +1923,7 @@ extern Lisp_Object Qglyphless_char;
 /* Produce glyphs for a glyphless character for iterator IT.
    IT->glyphless_method specifies which method to use for displaying
    the character.  See the description of enum
-   glyphless_display_method in dispextern.h for the detail.
+   glyphless_display_method in dispextern.h for the details.
 
    FOR_NO_FONT is nonzero if and only if this is for a character that
    is not supproted by the coding system of the terminal.  ACRONYM, if
@@ -1935,11 +1935,11 @@ static void
 produce_glyphless_glyph (struct it *it, int for_no_font, Lisp_Object acronym)
 {
   int face_id;
-  int width, len;
-  char buf[9], *str = "    ";
+  int len;
+  char buf[11], *str = "    ";
 
   /* Get a face ID for the glyph by utilizing a cache (the same way as
-     doen for `escape-glyph' in get_next_display_element).  */
+     done for `escape-glyph' in get_next_display_element).  */
   if (it->f == last_glyphless_glyph_frame
       && it->face_id == last_glyphless_glyph_face_id)
     {
@@ -1956,8 +1956,8 @@ produce_glyphless_glyph (struct it *it, int for_no_font, Lisp_Object acronym)
 
   if (it->glyphless_method == GLYPHLESS_DISPLAY_THIN_SPACE)
     {
-      /* As there's no way to produce a thin space, we produce
-         a space of canonical width..  */
+      /* As there's no way to produce a thin space, we produce a space
+         of canonical width.  */
       len = 1;
     }
   else if (it->glyphless_method == GLYPHLESS_DISPLAY_EMPTY_BOX)
@@ -1965,8 +1965,11 @@ produce_glyphless_glyph (struct it *it, int for_no_font, Lisp_Object acronym)
       len = CHAR_WIDTH (it->c);
       if (len == 0)
         len = 1;
-      else if (width > 4)
+      else if (len > 4)
         len = 4;
+      sprintf (buf, "[%.*s]", len, str);
+      len += 2;
+      str = buf;
     }
   else
     {
@@ -1983,11 +1986,11 @@ produce_glyphless_glyph (struct it *it, int for_no_font, Lisp_Object acronym)
         }
       else
         {
-          xassert (it->glyphless_method == GLYPHLESS_DISPLAY_HEXA_CODE);
-          len = (it->c < 0x100 ? sprintf (buf, "U+%02X", it->c)
-                 : it->c < 0x10000 ? sprintf (buf, "U+%04X", it->c)
-                 : it->c <= MAX_UNICODE_CHAR ? sprintf (buf, "U+%06X", it->c)
-                 : sprintf (buf, "E+%06X", it->c));
+          xassert (it->glyphless_method == GLYPHLESS_DISPLAY_HEX_CODE);
+          len = (it->c < 0x100 ? sprintf (buf, "[U+%02X]", it->c)
+                 : it->c < 0x10000 ? sprintf (buf, "[U+%04X]", it->c)
+                 : it->c <= MAX_UNICODE_CHAR ? sprintf (buf, "[U+%06X]", it->c)
+                 : sprintf (buf, "[E+%06X]", it->c));
         }
       str = buf;
     }
diff --git a/src/w32term.c b/src/w32term.c
index a93bc064c39..33b60c568c0 100644
--- a/src/w32term.c
+++ b/src/w32term.c
@@ -1440,7 +1440,7 @@ x_draw_glyphless_glyph_string_foreground (struct glyph_string *s)
                 str = (char *) SDATA (acronym);
             }
         }
-      else if (glyph->u.glyphless.method == GLYPHLESS_DISPLAY_HEXA_CODE)
+      else if (glyph->u.glyphless.method == GLYPHLESS_DISPLAY_HEX_CODE)
         {
           sprintf ((char *) buf, "%0*X",
                    glyph->u.glyphless.ch < 0x10000 ? 4 : 6,
@@ -1448,6 +1448,11 @@ x_draw_glyphless_glyph_string_foreground (struct glyph_string *s)
           str = buf;
         }
 
+      if (glyph->u.glyphless.method != GLYPHLESS_DISPLAY_THIN_SPACE)
+        w32_draw_rectangle (s->hdc, s->gc,
+                            x, s->ybase - glyph->ascent,
+                            glyph->pixel_width - 1,
+                            glyph->ascent + glyph->descent - 1);
       if (str)
         {
           struct font *font = s->font;
@@ -1456,7 +1461,7 @@ x_draw_glyphless_glyph_string_foreground (struct glyph_string *s)
           HFONT old_font;
 
           old_font = SelectObject (s->hdc, FONT_HANDLE (font));
-          /* It is assured that all LEN characters in STR is ASCII.  */
+          /* It is certain that all LEN characters in STR are ASCII.  */
           for (j = 0; j < len; j++)
             {
               code = font->driver->encode_char (font, str[j]);
@@ -1472,11 +1477,6 @@ x_draw_glyphless_glyph_string_foreground (struct glyph_string *s)
                               with_background);
           SelectObject (s->hdc, old_font);
         }
-      if (glyph->u.glyphless.method != GLYPHLESS_DISPLAY_THIN_SPACE)
-        w32_draw_rectangle (s->hdc, s->gc,
-                            x, s->ybase - glyph->ascent,
-                            glyph->pixel_width - 1,
-                            glyph->ascent + glyph->descent - 1);
       x += glyph->pixel_width;
    }
 }
diff --git a/src/xdisp.c b/src/xdisp.c
index 928a37a2b50..21c89088383 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -971,7 +971,7 @@ Lisp_Object Vglyphless_char_display;
 Lisp_Object Qglyphless_char_display;
 
 /* Method symbols for Vglyphless_char_display.  */
-static Lisp_Object Qhexa_code, Qempty_box, Qthin_space, Qzero_width;
+static Lisp_Object Qhex_code, Qempty_box, Qthin_space, Qzero_width;
 
 /* Default pixel width of `thin-space' display method.  */
 #define THIN_SPACE_WIDTH 1
@@ -5813,8 +5813,8 @@ lookup_glyphless_char_display (int c, struct it *it)
     it->glyphless_method = GLYPHLESS_DISPLAY_THIN_SPACE;
   else if (EQ (glyphless_method, Qempty_box))
     it->glyphless_method = GLYPHLESS_DISPLAY_EMPTY_BOX;
-  else if (EQ (glyphless_method, Qhexa_code))
-    it->glyphless_method = GLYPHLESS_DISPLAY_HEXA_CODE;
+  else if (EQ (glyphless_method, Qhex_code))
+    it->glyphless_method = GLYPHLESS_DISPLAY_HEX_CODE;
   else if (STRINGP (glyphless_method))
     it->glyphless_method = GLYPHLESS_DISPLAY_ACRONYM;
   else
@@ -12871,10 +12871,10 @@ set_cursor_from_row (struct window *w, struct glyph_row *row,
                || (row->truncated_on_left_p && pt_old < bpos_min)
                || (row->truncated_on_right_p && pt_old > bpos_max)
                /* Zero-width characters produce no glyphs.  */
-               || ((row->reversed_p
-                    ? glyph_after > glyphs_end
-                    : glyph_after < glyphs_end)
-                   && eabs (glyph_after - glyph_before) == 1))
+               || (!string_seen
+                   && (row->reversed_p
+                       ? glyph_after > glyphs_end
+                       : glyph_after < glyphs_end)))
         {
           cursor = glyph_after;
           x = -1;
@@ -22292,7 +22292,7 @@ calc_line_height_property (struct it *it, Lisp_Object val, struct font *font,
    and only if this is for a character for which no font was found.
 
    If the display method (it->glyphless_method) is
-   GLYPHLESS_DISPLAY_ACRONYM or GLYPHLESS_DISPLAY_HEXA_CODE, LEN is a
+   GLYPHLESS_DISPLAY_ACRONYM or GLYPHLESS_DISPLAY_HEX_CODE, LEN is a
    length of the acronym or the hexadecimal string, UPPER_XOFF and
    UPPER_YOFF are pixel offsets for the upper part of the string,
    LOWER_XOFF and LOWER_YOFF are for the lower part.
@@ -22441,7 +22441,7 @@ produce_glyphless_glyph (struct it *it, int for_no_font, Lisp_Object acronym)
         }
       else
         {
-          xassert (it->glyphless_method == GLYPHLESS_DISPLAY_HEXA_CODE);
+          xassert (it->glyphless_method == GLYPHLESS_DISPLAY_HEX_CODE);
           sprintf (buf, "%0*X", it->c < 0x10000 ? 4 : 6, it->c);
           str = buf;
         }
@@ -27057,7 +27057,7 @@ cursor shapes.  */);
   hourglass_shown_p = 0;
 
   DEFSYM (Qglyphless_char, "glyphless-char");
-  DEFSYM (Qhexa_code, "hexa-code");
+  DEFSYM (Qhex_code, "hex-code");
   DEFSYM (Qempty_box, "empty-box");
   DEFSYM (Qthin_space, "thin-space");
   DEFSYM (Qzero_width, "zero-width");
@@ -27073,13 +27073,13 @@ cursor shapes.  */);
                doc: /* Char-table to control displaying of glyphless characters.
 Each element, if non-nil, is an ASCII acronym string (displayed in a box)
 or one of these symbols:
-  hexa-code: display with hexadecimal character code in a box
-  empty-box: display with an empty box
-  thin-space: display with 1-pixel width space
+  hex-code:   display the hexadecimal code of a character in a box
+  empty-box:  display as an empty box
+  thin-space: display as 1-pixel width space
   zero-width: don't display
 
 It has one extra slot to control the display of a character for which
-no font is found.  The value of the slot is `hexa-code' or `empty-box'.
+no font is found.  The value of the slot is `hex-code' or `empty-box'.
 The default is `empty-box'.  */);
   Vglyphless_char_display = Fmake_char_table (Qglyphless_char_display, Qnil);
   Fset_char_table_extra_slot (Vglyphless_char_display, make_number (0),
diff --git a/src/xterm.c b/src/xterm.c
index e58d072e59f..f8b7b2a630c 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -1369,7 +1369,7 @@ x_draw_glyphless_glyph_string_foreground (struct glyph_string *s)
                 str = (char *) SDATA (acronym);
             }
         }
-      else if (glyph->u.glyphless.method == GLYPHLESS_DISPLAY_HEXA_CODE)
+      else if (glyph->u.glyphless.method == GLYPHLESS_DISPLAY_HEX_CODE)
         {
           sprintf ((char *) buf, "%0*X",
                    glyph->u.glyphless.ch < 0x10000 ? 4 : 6,