Discovery of replacing display properties now uses the same code

as the display engine.  Tested OK with display properties whose
value is a list.

 src/dispextern.h (struct bidi_it): New member frame_window_p.
 (bidi_init_it, compute_display_string_pos): Update prototypes.
 src/bidi.c (bidi_fetch_char): Accept additional argument
 FRAME_WINDOW_P and pass it to compute_display_string_pos.  All
 callers changed.
 (bidi_init_it): Accept additional argument FRAME_WINDOW_P and use
 it to initialize the frame_window_p member of struct bidi_it.
 src/xdisp.c (handle_display_spec): New function, refactored from the
 last portion of handle_display_prop.
 (compute_display_string_pos): Accept additional argument
 FRAME_WINDOW_P.  Call handle_display_spec to determine whether the
 value of a `display' property is a "replacing spec".
 (handle_single_display_spec): Accept 2 additional arguments BUFPOS
 and FRAME_WINDOW_P.  If IT is NULL, don't set up the iterator from
 the display property, but just return a value indicating whether
 the display property will replace the characters it covers.
 (Fcurrent_bidi_paragraph_direction): Initialize the nchars and
 frame_window_p members of struct bidi_it.

4 files changed, 300 insertions, 180 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index fdb98351672..f7807b90941 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,26 @@
+2011-05-21  Eli Zaretskii  <eliz@gnu.org>
+
+	* xdisp.c (handle_display_spec): New function, refactored from the
+	last portion of handle_display_prop.
+	(compute_display_string_pos): Accept additional argument
+	FRAME_WINDOW_P.  Call handle_display_spec to determine whether the
+	value of a `display' property is a "replacing spec".
+	(handle_single_display_spec): Accept 2 additional arguments BUFPOS
+	and FRAME_WINDOW_P.  If IT is NULL, don't set up the iterator from
+	the display property, but just return a value indicating whether
+	the display property will replace the characters it covers.
+	(Fcurrent_bidi_paragraph_direction): Initialize the nchars and
+	frame_window_p members of struct bidi_it.
+
+	* bidi.c (bidi_fetch_char): Accept additional argument
+	FRAME_WINDOW_P and pass it to compute_display_string_pos.  All
+	callers changed.
+	(bidi_init_it): Accept additional argument FRAME_WINDOW_P and use
+	it to initialize the frame_window_p member of struct bidi_it.
+
+	* dispextern.h (struct bidi_it): New member frame_window_p.
+	(bidi_init_it, compute_display_string_pos): Update prototypes.
+
 2011-05-14  Eli Zaretskii  <eliz@gnu.org>
 
 	* xdisp.c (compute_display_string_pos): Non-trivial implementation.
diff --git a/src/bidi.c b/src/bidi.c
index 742224607e4..17cb1214c73 100644
--- a/src/bidi.c
+++ b/src/bidi.c
@@ -581,7 +581,7 @@ bidi_line_init (struct bidi_it *bidi_it)
    string.  */
 static INLINE int
 bidi_fetch_char (EMACS_INT bytepos, EMACS_INT charpos, EMACS_INT *disp_pos,
-		 EMACS_INT *ch_len, EMACS_INT *nchars)
+		 int frame_window_p, EMACS_INT *ch_len, EMACS_INT *nchars)
 {
   int ch;
 
@@ -589,7 +589,7 @@ bidi_fetch_char (EMACS_INT bytepos, EMACS_INT charpos, EMACS_INT *disp_pos,
   /* If we got past the last known position of display string, compute
      the position of the next one.  That position could be at BYTEPOS.  */
   if (charpos < ZV && charpos > *disp_pos)
-    *disp_pos = compute_display_string_pos (charpos);
+    *disp_pos = compute_display_string_pos (charpos, frame_window_p);
 
   /* Fetch the character at BYTEPOS.  */
   if (bytepos >= ZV_BYTE)
@@ -625,7 +625,7 @@ bidi_fetch_char (EMACS_INT bytepos, EMACS_INT charpos, EMACS_INT *disp_pos,
   /* If we just entered a run of characters covered by a display
      string, compute the position of the next display string.  */
   if (charpos + *nchars <= ZV && charpos + *nchars > *disp_pos)
-    *disp_pos = compute_display_string_pos (charpos + *nchars);
+    *disp_pos = compute_display_string_pos (charpos + *nchars, frame_window_p);
 
   return ch;
 }
@@ -754,7 +754,8 @@ bidi_paragraph_init (bidi_dir_t dir, struct bidi_it *bidi_it, int no_default_p)
       do {
 	bytepos = pstartbyte;
 	pos = BYTE_TO_CHAR (bytepos);
-	ch = bidi_fetch_char (bytepos, pos, &disp_pos, &ch_len, &nchars);
+	ch = bidi_fetch_char (bytepos, pos, &disp_pos, bidi_it->frame_window_p,
+			      &ch_len, &nchars);
 	type = bidi_get_type (ch, NEUTRAL_DIR);
 
 	for (pos += nchars, bytepos += ch_len;
@@ -778,7 +779,8 @@ bidi_paragraph_init (bidi_dir_t dir, struct bidi_it *bidi_it, int no_default_p)
 		break;
 	      }
 	    /* Fetch next character and advance to get past it.  */
-	    ch = bidi_fetch_char (bytepos, pos, &disp_pos, &ch_len, &nchars);
+	    ch = bidi_fetch_char (bytepos, pos, &disp_pos,
+				  bidi_it->frame_window_p, &ch_len, &nchars);
 	    pos += nchars;
 	    bytepos += ch_len;
 	  }
@@ -840,12 +842,14 @@ bidi_set_paragraph_end (struct bidi_it *bidi_it)
 
 /* Initialize the bidi iterator from buffer/string position CHARPOS.  */
 void
-bidi_init_it (EMACS_INT charpos, EMACS_INT bytepos, struct bidi_it *bidi_it)
+bidi_init_it (EMACS_INT charpos, EMACS_INT bytepos, int frame_window_p,
+	      struct bidi_it *bidi_it)
 {
   if (! bidi_initialized)
     bidi_initialize ();
   bidi_it->charpos = charpos;
   bidi_it->bytepos = bytepos;
+  bidi_it->frame_window_p = frame_window_p;
   bidi_it->nchars = -1;	/* to be computed in bidi_resolve_explicit_1 */
   bidi_it->first_elt = 1;
   bidi_set_paragraph_end (bidi_it);
@@ -996,7 +1000,7 @@ bidi_resolve_explicit_1 (struct bidi_it *bidi_it)
 	 display string, treat the entire run of covered characters as
 	 a single character u+FFFC.  */
       curchar = bidi_fetch_char (bidi_it->bytepos, bidi_it->charpos,
-				 &bidi_it->disp_pos,
+				 &bidi_it->disp_pos, bidi_it->frame_window_p,
 				 &bidi_it->ch_len, &bidi_it->nchars);
     }
   bidi_it->ch = curchar;
@@ -1674,11 +1678,13 @@ bidi_level_of_next_char (struct bidi_it *bidi_it)
       EMACS_INT disp_pos = bidi_it->disp_pos;
       EMACS_INT nc = bidi_it->nchars;
       bidi_type_t chtype;
+      int fwp = bidi_it->frame_window_p;
 
       if (bidi_it->nchars <= 0)
 	abort ();
       do {
-	ch = bidi_fetch_char (bpos += clen, cpos += nc, &disp_pos, &clen, &nc);
+	ch = bidi_fetch_char (bpos += clen, cpos += nc, &disp_pos, fwp,
+			      &clen, &nc);
 	if (ch == '\n' || ch == BIDI_EOB /* || ch == LINESEP_CHAR */)
 	  chtype = NEUTRAL_B;
 	else
diff --git a/src/dispextern.h b/src/dispextern.h
index f5036169f75..6c09f21a78f 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -1847,6 +1847,7 @@ struct bidi_it {
   int first_elt;		/* if non-zero, examine current char first */
   bidi_dir_t paragraph_dir;	/* current paragraph direction */
   int new_paragraph;		/* if non-zero, we expect a new paragraph */
+  int frame_window_p;		/* non-zero if displaying on a GUI frame */
   EMACS_INT separator_limit;	/* where paragraph separator should end */
   EMACS_INT disp_pos;		/* position of display string after ch */
 };
@@ -2945,7 +2946,7 @@ enum tool_bar_item_image
 
 /* Defined in bidi.c */
 
-extern void bidi_init_it (EMACS_INT, EMACS_INT, struct bidi_it *);
+extern void bidi_init_it (EMACS_INT, EMACS_INT, int, struct bidi_it *);
 extern void bidi_move_to_visually_next (struct bidi_it *);
 extern void bidi_paragraph_init (bidi_dir_t, struct bidi_it *, int);
 extern int  bidi_mirror_char (int);
@@ -3006,7 +3007,7 @@ extern void reseat_at_previous_visible_line_start (struct it *);
 extern Lisp_Object lookup_glyphless_char_display (int, struct it *);
 extern int calc_pixel_width_or_height (double *, struct it *, Lisp_Object,
                                        struct font *, int, int *);
-extern EMACS_INT compute_display_string_pos (EMACS_INT);
+extern EMACS_INT compute_display_string_pos (EMACS_INT, int);
 extern EMACS_INT compute_display_string_end (EMACS_INT);
 
 #ifdef HAVE_WINDOW_SYSTEM
diff --git a/src/xdisp.c b/src/xdisp.c
index 6ea6f92a3f7..8665acf8fdd 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -884,9 +884,11 @@ static void compute_string_pos (struct text_pos *, struct text_pos,
                                 Lisp_Object);
 static int face_before_or_after_it_pos (struct it *, int);
 static EMACS_INT next_overlay_change (EMACS_INT);
+static int handle_display_spec (struct it *, Lisp_Object, Lisp_Object,
+				Lisp_Object, struct text_pos *, EMACS_INT, int);
 static int handle_single_display_spec (struct it *, Lisp_Object,
                                        Lisp_Object, Lisp_Object,
-                                       struct text_pos *, int);
+                                       struct text_pos *, EMACS_INT, int, int);
 static int underlying_face_id (struct it *);
 static int in_ellipses_for_invisible_text_p (struct display_pos *,
                                              struct window *);
@@ -2564,7 +2566,7 @@ init_iterator (struct it *it, struct window *w,
 	it->paragraph_embedding = R2L;
       else
 	it->paragraph_embedding = NEUTRAL_DIR;
-      bidi_init_it (charpos, bytepos, &it->bidi_it);
+      bidi_init_it (charpos, bytepos, FRAME_WINDOW_P (it->f), &it->bidi_it);
     }
 
   /* If a buffer position was specified, set the iterator there,
@@ -3086,37 +3088,54 @@ next_overlay_change (EMACS_INT pos)
 }
 
 /* Return the character position of a display string at or after CHARPOS.
-   If no display string exist at or after CHARPOS, return ZV.  A
+   If no display string exists at or after CHARPOS, return ZV.  A
    display string is either an overlay with `display' property whose
-   value is a string or a `display' text property whose value is a
-   string.  */
+   value is a string, or a `display' text property whose value is a
+   string.  FRAME_WINDOW_P is non-zero when we are displaying a window
+   on a GUI frame.  */
 EMACS_INT
-compute_display_string_pos (EMACS_INT charpos)
+compute_display_string_pos (EMACS_INT charpos, int frame_window_p)
 {
   /* FIXME: Support display properties on strings (object = Qnil means
      current buffer).  */
   Lisp_Object object = Qnil;
-  Lisp_Object pos = make_number (charpos);
+  Lisp_Object pos, spec;
+  struct text_pos position;
+  EMACS_INT bufpos;
 
   if (charpos >= ZV)
     return ZV;
 
   /* If the character at CHARPOS is where the display string begins,
      return CHARPOS.  */
-  if (!NILP (Fget_char_property (pos, Qdisplay, object))
+  pos = make_number (charpos);
+  CHARPOS (position) = charpos;
+  BYTEPOS (position) = CHAR_TO_BYTE (charpos);
+  bufpos = charpos;	/* FIXME! support strings as well */
+  if (!NILP (spec = Fget_char_property (pos, Qdisplay, object))
       && (charpos <= BEGV
-	  || NILP (Fget_char_property (make_number (charpos - 1), Qdisplay,
-				       object))))
+	  || !EQ (Fget_char_property (make_number (charpos - 1), Qdisplay,
+				      object),
+		  spec)))
+      && handle_display_spec (NULL, spec, object, Qnil, &position, bufpos,
+			      frame_window_p))
     return charpos;
 
-  /* Look forward for the first character where the `display' property
-     changes from nil to non-nil.  */
+  /* Look forward for the first character with a `display' property
+     that will replace the underlying text when displayed.  */
   do {
     pos = Fnext_single_char_property_change (pos, Qdisplay, object, Qnil);
-  } while (XFASTINT (pos) < ZV
-	   && NILP (Fget_char_property (pos, Qdisplay, object)));
+    CHARPOS (position) = XFASTINT (pos);
+    BYTEPOS (position) = CHAR_TO_BYTE (CHARPOS (position));
+    if (CHARPOS (position) >= ZV)
+      break;
+    spec = Fget_char_property (pos, Qdisplay, object);
+    bufpos = CHARPOS (position);	/* FIXME! support strings as well */
+  } while (NILP (spec)
+	   || !handle_display_spec (NULL, spec, object, Qnil, &position, bufpos,
+				    frame_window_p));
 
-  return XFASTINT (pos);
+  return CHARPOS (position);
 }
 
 /* Return the character position of the end of the display string that
@@ -3802,8 +3821,9 @@ setup_for_ellipsis (struct it *it, int len)
 static enum prop_handled
 handle_display_prop (struct it *it)
 {
-  Lisp_Object prop, object, overlay;
+  Lisp_Object propval, object, overlay;
   struct text_pos *position;
+  EMACS_INT bufpos;
   /* Nonzero if some property replaces the display of the text itself.  */
   int display_replaced_p = 0;
 
@@ -3811,11 +3831,13 @@ handle_display_prop (struct it *it)
     {
       object = it->string;
       position = &it->current.string_pos;
+      bufpos = CHARPOS (it->current.pos);
     }
   else
     {
       XSETWINDOW (object, it->w);
       position = &it->current.pos;
+      bufpos = CHARPOS (*position);
     }
 
   /* Reset those iterator values set from display property values.  */
@@ -3830,9 +3852,9 @@ handle_display_prop (struct it *it)
   if (!it->string_from_display_prop_p)
     it->area = TEXT_AREA;
 
-  prop = get_char_property_and_overlay (make_number (position->charpos),
-					Qdisplay, object, &overlay);
-  if (NILP (prop))
+  propval = get_char_property_and_overlay (make_number (position->charpos),
+					   Qdisplay, object, &overlay);
+  if (NILP (propval))
     return HANDLED_NORMALLY;
   /* Now OVERLAY is the overlay that gave us this property, or nil
      if it was a text property.  */
@@ -3840,59 +3862,88 @@ handle_display_prop (struct it *it)
   if (!STRINGP (it->string))
     object = it->w->buffer;
 
-  if (CONSP (prop)
-      /* Simple properties.  */
-      && !EQ (XCAR (prop), Qimage)
-      && !EQ (XCAR (prop), Qspace)
-      && !EQ (XCAR (prop), Qwhen)
-      && !EQ (XCAR (prop), Qslice)
-      && !EQ (XCAR (prop), Qspace_width)
-      && !EQ (XCAR (prop), Qheight)
-      && !EQ (XCAR (prop), Qraise)
+  display_replaced_p = handle_display_spec (it, propval, object, overlay,
+					    position, bufpos,
+					    FRAME_WINDOW_P (it->f));
+
+  return display_replaced_p ? HANDLED_RETURN : HANDLED_NORMALLY;
+}
+
+/* Subroutine of handle_display_prop.  Returns non-zero if the display
+   specification in SPEC is a replacing specification, i.e. it would
+   replace the text covered by `display' property with something else,
+   such as an image or a display string.
+
+   See handle_single_display_spec for documentation of arguments.
+   frame_window_p is non-zero if the window being redisplayed is on a
+   GUI frame; this argument is used only if IT is NULL, see below.
+
+   IT can be NULL, if this is called by the bidi reordering code
+   through compute_display_string_pos, which see.  In that case, this
+   function only examines SPEC, but does not otherwise "handle" it, in
+   the sense that it doesn't set up members of IT from the display
+   spec.  */
+static int
+handle_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
+		     Lisp_Object overlay, struct text_pos *position,
+		     EMACS_INT bufpos, int frame_window_p)
+{
+  int replacing_p = 0;
+
+  if (CONSP (spec)
+      /* Simple specerties.  */
+      && !EQ (XCAR (spec), Qimage)
+      && !EQ (XCAR (spec), Qspace)
+      && !EQ (XCAR (spec), Qwhen)
+      && !EQ (XCAR (spec), Qslice)
+      && !EQ (XCAR (spec), Qspace_width)
+      && !EQ (XCAR (spec), Qheight)
+      && !EQ (XCAR (spec), Qraise)
       /* Marginal area specifications.  */
-      && !(CONSP (XCAR (prop)) && EQ (XCAR (XCAR (prop)), Qmargin))
-      && !EQ (XCAR (prop), Qleft_fringe)
-      && !EQ (XCAR (prop), Qright_fringe)
-      && !NILP (XCAR (prop)))
+      && !(CONSP (XCAR (spec)) && EQ (XCAR (XCAR (spec)), Qmargin))
+      && !EQ (XCAR (spec), Qleft_fringe)
+      && !EQ (XCAR (spec), Qright_fringe)
+      && !NILP (XCAR (spec)))
     {
-      for (; CONSP (prop); prop = XCDR (prop))
+      for (; CONSP (spec); spec = XCDR (spec))
 	{
-	  if (handle_single_display_spec (it, XCAR (prop), object, overlay,
-					  position, display_replaced_p))
+	  if (handle_single_display_spec (it, XCAR (spec), object, overlay,
+					  position, bufpos, replacing_p,
+					  frame_window_p))
 	    {
-	      display_replaced_p = 1;
+	      replacing_p = 1;
 	      /* If some text in a string is replaced, `position' no
 		 longer points to the position of `object'.  */
-	      if (STRINGP (object))
+	      if (!it || STRINGP (object))
 		break;
 	    }
 	}
     }
-  else if (VECTORP (prop))
+  else if (VECTORP (spec))
     {
       int i;
-      for (i = 0; i < ASIZE (prop); ++i)
-	if (handle_single_display_spec (it, AREF (prop, i), object, overlay,
-					position, display_replaced_p))
+      for (i = 0; i < ASIZE (spec); ++i)
+	if (handle_single_display_spec (it, AREF (spec, i), object, overlay,
+					position, bufpos, replacing_p,
+					frame_window_p))
 	  {
-	    display_replaced_p = 1;
+	    replacing_p = 1;
 	    /* If some text in a string is replaced, `position' no
 	       longer points to the position of `object'.  */
-	    if (STRINGP (object))
+	    if (!it || STRINGP (object))
 	      break;
 	  }
     }
   else
     {
-      if (handle_single_display_spec (it, prop, object, overlay,
-				      position, 0))
-	display_replaced_p = 1;
+      if (handle_single_display_spec (it, spec, object, overlay,
+				      position, bufpos, 0, frame_window_p))
+	replacing_p = 1;
     }
 
-  return display_replaced_p ? HANDLED_RETURN : HANDLED_NORMALLY;
+  return replacing_p;
 }
 
-
 /* Value is the position of the end of the `display' property starting
    at START_POS in OBJECT.  */
 
@@ -3916,10 +3967,12 @@ display_prop_end (struct it *it, Lisp_Object object, struct text_pos start_pos)
 
 /* Set up IT from a single `display' property specification SPEC.  OBJECT
    is the object in which the `display' property was found.  *POSITION
-   is the position at which it was found.  DISPLAY_REPLACED_P non-zero
-   means that we previously saw a display specification which already
-   replaced text display with something else, for example an image;
-   we ignore such properties after the first one has been processed.
+   is the position in OBJECT at which the `display' property was found.
+   BUFPOS is the buffer position of OBJECT (different from POSITION if
+   OBJECT is not a buffer).  DISPLAY_REPLACED_P non-zero means that we
+   previously saw a display specification which already replaced text
+   display with something else, for example an image; we ignore such
+   properties after the first one has been processed.
 
    OVERLAY is the overlay this `display' property came from,
    or nil if it was a text property.
@@ -3928,17 +3981,22 @@ display_prop_end (struct it *it, Lisp_Object object, struct text_pos start_pos)
    cases too, set *POSITION to the position where the `display'
    property ends.
 
+   If IT is NULL, only examine the property specification in SPEC, but
+   don't set up IT.  In that case, FRAME_WINDOW_P non-zero means SPEC
+   is intended to be displayed in a window on a GUI frame.
+
    Value is non-zero if something was found which replaces the display
    of buffer or string text.  */
 
 static int
 handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 			    Lisp_Object overlay, struct text_pos *position,
-			    int display_replaced_p)
+			    EMACS_INT bufpos, int display_replaced_p,
+			    int frame_window_p)
 {
   Lisp_Object form;
   Lisp_Object location, value;
-  struct text_pos start_pos;
+  struct text_pos start_pos = *position;
   int valid_p;
 
   /* If SPEC is a list of the form `(when FORM . VALUE)', evaluate FORM.
@@ -3962,11 +4020,12 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 	 buffer or string.  Bind `position' to the position in the
 	 object where the property was found, and `buffer-position'
 	 to the current position in the buffer.  */
+
+      if (NILP (object))
+	XSETBUFFER (object, current_buffer);
       specbind (Qobject, object);
       specbind (Qposition, make_number (CHARPOS (*position)));
-      specbind (Qbuffer_position,
-		make_number (STRINGP (object)
-			     ? IT_CHARPOS (*it) : CHARPOS (*position)));
+      specbind (Qbuffer_position, make_number (bufpos));
       GCPRO1 (form);
       form = safe_eval (form);
       UNGCPRO;
@@ -3981,63 +4040,66 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
       && EQ (XCAR (spec), Qheight)
       && CONSP (XCDR (spec)))
     {
-      if (!FRAME_WINDOW_P (it->f))
-	return 0;
-
-      it->font_height = XCAR (XCDR (spec));
-      if (!NILP (it->font_height))
+      if (it)
 	{
-	  struct face *face = FACE_FROM_ID (it->f, it->face_id);
-	  int new_height = -1;
+	  if (!FRAME_WINDOW_P (it->f))
+	    return 0;
 
-	  if (CONSP (it->font_height)
-	      && (EQ (XCAR (it->font_height), Qplus)
-		  || EQ (XCAR (it->font_height), Qminus))
-	      && CONSP (XCDR (it->font_height))
-	      && INTEGERP (XCAR (XCDR (it->font_height))))
-	    {
-	      /* `(+ N)' or `(- N)' where N is an integer.  */
-	      int steps = XINT (XCAR (XCDR (it->font_height)));
-	      if (EQ (XCAR (it->font_height), Qplus))
-		steps = - steps;
-	      it->face_id = smaller_face (it->f, it->face_id, steps);
-	    }
-	  else if (FUNCTIONP (it->font_height))
-	    {
-	      /* Call function with current height as argument.
-		 Value is the new height.  */
-	      Lisp_Object height;
-	      height = safe_call1 (it->font_height,
-				   face->lface[LFACE_HEIGHT_INDEX]);
-	      if (NUMBERP (height))
-		new_height = XFLOATINT (height);
-	    }
-	  else if (NUMBERP (it->font_height))
+	  it->font_height = XCAR (XCDR (spec));
+	  if (!NILP (it->font_height))
 	    {
-	      /* Value is a multiple of the canonical char height.  */
-	      struct face *f;
+	      struct face *face = FACE_FROM_ID (it->f, it->face_id);
+	      int new_height = -1;
 
-	      f = FACE_FROM_ID (it->f,
-				lookup_basic_face (it->f, DEFAULT_FACE_ID));
-	      new_height = (XFLOATINT (it->font_height)
-			    * XINT (f->lface[LFACE_HEIGHT_INDEX]));
-	    }
-	  else
-	    {
-	      /* Evaluate IT->font_height with `height' bound to the
-		 current specified height to get the new height.  */
-	      int count = SPECPDL_INDEX ();
+	      if (CONSP (it->font_height)
+		  && (EQ (XCAR (it->font_height), Qplus)
+		      || EQ (XCAR (it->font_height), Qminus))
+		  && CONSP (XCDR (it->font_height))
+		  && INTEGERP (XCAR (XCDR (it->font_height))))
+		{
+		  /* `(+ N)' or `(- N)' where N is an integer.  */
+		  int steps = XINT (XCAR (XCDR (it->font_height)));
+		  if (EQ (XCAR (it->font_height), Qplus))
+		    steps = - steps;
+		  it->face_id = smaller_face (it->f, it->face_id, steps);
+		}
+	      else if (FUNCTIONP (it->font_height))
+		{
+		  /* Call function with current height as argument.
+		     Value is the new height.  */
+		  Lisp_Object height;
+		  height = safe_call1 (it->font_height,
+				       face->lface[LFACE_HEIGHT_INDEX]);
+		  if (NUMBERP (height))
+		    new_height = XFLOATINT (height);
+		}
+	      else if (NUMBERP (it->font_height))
+		{
+		  /* Value is a multiple of the canonical char height.  */
+		  struct face *f;
 
-	      specbind (Qheight, face->lface[LFACE_HEIGHT_INDEX]);
-	      value = safe_eval (it->font_height);
-	      unbind_to (count, Qnil);
+		  f = FACE_FROM_ID (it->f,
+				    lookup_basic_face (it->f, DEFAULT_FACE_ID));
+		  new_height = (XFLOATINT (it->font_height)
+				* XINT (f->lface[LFACE_HEIGHT_INDEX]));
+		}
+	      else
+		{
+		  /* Evaluate IT->font_height with `height' bound to the
+		     current specified height to get the new height.  */
+		  int count = SPECPDL_INDEX ();
 
-	      if (NUMBERP (value))
-		new_height = XFLOATINT (value);
-	    }
+		  specbind (Qheight, face->lface[LFACE_HEIGHT_INDEX]);
+		  value = safe_eval (it->font_height);
+		  unbind_to (count, Qnil);
 
-	  if (new_height > 0)
-	    it->face_id = face_with_height (it->f, it->face_id, new_height);
+		  if (NUMBERP (value))
+		    new_height = XFLOATINT (value);
+		}
+
+	      if (new_height > 0)
+		it->face_id = face_with_height (it->f, it->face_id, new_height);
+	    }
 	}
 
       return 0;
@@ -4048,12 +4110,15 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
       && EQ (XCAR (spec), Qspace_width)
       && CONSP (XCDR (spec)))
     {
-      if (!FRAME_WINDOW_P (it->f))
-	return 0;
+      if (it)
+	{
+	  if (!FRAME_WINDOW_P (it->f))
+	    return 0;
 
-      value = XCAR (XCDR (spec));
-      if (NUMBERP (value) && XFLOATINT (value) > 0)
-	it->space_width = value;
+	  value = XCAR (XCDR (spec));
+	  if (NUMBERP (value) && XFLOATINT (value) > 0)
+	    it->space_width = value;
+	}
 
       return 0;
     }
@@ -4064,20 +4129,23 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
     {
       Lisp_Object tem;
 
-      if (!FRAME_WINDOW_P (it->f))
-	return 0;
-
-      if (tem = XCDR (spec), CONSP (tem))
+      if (it)
 	{
-	  it->slice.x = XCAR (tem);
-	  if (tem = XCDR (tem), CONSP (tem))
+	  if (!FRAME_WINDOW_P (it->f))
+	    return 0;
+
+	  if (tem = XCDR (spec), CONSP (tem))
 	    {
-	      it->slice.y = XCAR (tem);
+	      it->slice.x = XCAR (tem);
 	      if (tem = XCDR (tem), CONSP (tem))
 		{
-		  it->slice.width = XCAR (tem);
+		  it->slice.y = XCAR (tem);
 		  if (tem = XCDR (tem), CONSP (tem))
-		    it->slice.height = XCAR (tem);
+		    {
+		      it->slice.width = XCAR (tem);
+		      if (tem = XCDR (tem), CONSP (tem))
+			it->slice.height = XCAR (tem);
+		    }
 		}
 	    }
 	}
@@ -4090,36 +4158,43 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
       && EQ (XCAR (spec), Qraise)
       && CONSP (XCDR (spec)))
     {
-      if (!FRAME_WINDOW_P (it->f))
-	return 0;
+      if (it)
+	{
+	  if (!FRAME_WINDOW_P (it->f))
+	    return 0;
 
 #ifdef HAVE_WINDOW_SYSTEM
-      value = XCAR (XCDR (spec));
-      if (NUMBERP (value))
-	{
-	  struct face *face = FACE_FROM_ID (it->f, it->face_id);
-	  it->voffset = - (XFLOATINT (value)
-			   * (FONT_HEIGHT (face->font)));
-	}
+	  value = XCAR (XCDR (spec));
+	  if (NUMBERP (value))
+	    {
+	      struct face *face = FACE_FROM_ID (it->f, it->face_id);
+	      it->voffset = - (XFLOATINT (value)
+			       * (FONT_HEIGHT (face->font)));
+	    }
 #endif /* HAVE_WINDOW_SYSTEM */
+	}
 
       return 0;
     }
 
   /* Don't handle the other kinds of display specifications
      inside a string that we got from a `display' property.  */
-  if (it->string_from_display_prop_p)
+  if (it && it->string_from_display_prop_p)
     return 0;
 
   /* Characters having this form of property are not displayed, so
      we have to find the end of the property.  */
-  start_pos = *position;
-  *position = display_prop_end (it, object, start_pos);
+  if (it)
+    {
+      start_pos = *position;
+      *position = display_prop_end (it, object, start_pos);
+    }
   value = Qnil;
 
   /* Stop the scan at that end position--we assume that all
      text properties change there.  */
-  it->stop_charpos = position->charpos;
+  if (it)
+    it->stop_charpos = position->charpos;
 
   /* Handle `(left-fringe BITMAP [FACE])'
      and `(right-fringe BITMAP [FACE])'.  */
@@ -4128,12 +4203,16 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 	  || EQ (XCAR (spec), Qright_fringe))
       && CONSP (XCDR (spec)))
     {
-      int face_id = lookup_basic_face (it->f, DEFAULT_FACE_ID);
       int fringe_bitmap;
 
-      if (!FRAME_WINDOW_P (it->f))
-	/* If we return here, POSITION has been advanced
-	   across the text with this property.  */
+      if (it)
+	{
+	  if (!FRAME_WINDOW_P (it->f))
+	    /* If we return here, POSITION has been advanced
+	       across the text with this property.  */
+	    return 0;
+	}
+      else if (!frame_window_p)
 	return 0;
 
 #ifdef HAVE_WINDOW_SYSTEM
@@ -4144,42 +4223,47 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 	   across the text with this property.  */
 	return 0;
 
-      if (CONSP (XCDR (XCDR (spec))))
+      if (it)
 	{
-	  Lisp_Object face_name = XCAR (XCDR (XCDR (spec)));
-	  int face_id2 = lookup_derived_face (it->f, face_name,
-					      FRINGE_FACE_ID, 0);
-	  if (face_id2 >= 0)
-	    face_id = face_id2;
-	}
+	  int face_id = lookup_basic_face (it->f, DEFAULT_FACE_ID);;
 
-      /* Save current settings of IT so that we can restore them
-	 when we are finished with the glyph property value.  */
-      push_it (it, position);
+	  if (CONSP (XCDR (XCDR (spec))))
+	    {
+	      Lisp_Object face_name = XCAR (XCDR (XCDR (spec)));
+	      int face_id2 = lookup_derived_face (it->f, face_name,
+						  FRINGE_FACE_ID, 0);
+	      if (face_id2 >= 0)
+		face_id = face_id2;
+	    }
 
-      it->area = TEXT_AREA;
-      it->what = IT_IMAGE;
-      it->image_id = -1; /* no image */
-      it->position = start_pos;
-      it->object = NILP (object) ? it->w->buffer : object;
-      it->method = GET_FROM_IMAGE;
-      it->from_overlay = Qnil;
-      it->face_id = face_id;
+	  /* Save current settings of IT so that we can restore them
+	     when we are finished with the glyph property value.  */
+	  push_it (it, position);
 
-      /* Say that we haven't consumed the characters with
-	 `display' property yet.  The call to pop_it in
-	 set_iterator_to_next will clean this up.  */
-      *position = start_pos;
+	  it->area = TEXT_AREA;
+	  it->what = IT_IMAGE;
+	  it->image_id = -1; /* no image */
+	  it->position = start_pos;
+	  it->object = NILP (object) ? it->w->buffer : object;
+	  it->method = GET_FROM_IMAGE;
+	  it->from_overlay = Qnil;
+	  it->face_id = face_id;
 
-      if (EQ (XCAR (spec), Qleft_fringe))
-	{
-	  it->left_user_fringe_bitmap = fringe_bitmap;
-	  it->left_user_fringe_face_id = face_id;
-	}
-      else
-        {
-	  it->right_user_fringe_bitmap = fringe_bitmap;
-	  it->right_user_fringe_face_id = face_id;
+	  /* Say that we haven't consumed the characters with
+	     `display' property yet.  The call to pop_it in
+	     set_iterator_to_next will clean this up.  */
+	  *position = start_pos;
+
+	  if (EQ (XCAR (spec), Qleft_fringe))
+	    {
+	      it->left_user_fringe_bitmap = fringe_bitmap;
+	      it->left_user_fringe_face_id = face_id;
+	    }
+	  else
+	    {
+	      it->right_user_fringe_bitmap = fringe_bitmap;
+	      it->right_user_fringe_face_id = face_id;
+	    }
 	}
 #endif /* HAVE_WINDOW_SYSTEM */
       return 1;
@@ -4222,12 +4306,16 @@ handle_single_display_spec (struct it *it, Lisp_Object spec, Lisp_Object object,
 
   valid_p = (STRINGP (value)
 #ifdef HAVE_WINDOW_SYSTEM
-             || (FRAME_WINDOW_P (it->f) && valid_image_p (value))
+             || ((it ? FRAME_WINDOW_P (it->f) : frame_window_p)
+		 && valid_image_p (value))
 #endif /* not HAVE_WINDOW_SYSTEM */
              || (CONSP (value) && EQ (XCAR (value), Qspace)));
 
   if (valid_p && !display_replaced_p)
     {
+      if (!it)
+	return 1;
+
       /* Save current settings of IT so that we can restore them
 	 when we are finished with the glyph property value.  */
       push_it (it, position);
@@ -18080,6 +18168,8 @@ See also `bidi-paragraph-direction'.  */)
 	bytepos--;
       itb.charpos = pos;
       itb.bytepos = bytepos;
+      itb.nchars = -1;
+      itb.frame_window_p = FRAME_WINDOW_P (SELECTED_FRAME ()); /* guesswork */
       itb.first_elt = 1;
       itb.separator_limit = -1;
       itb.paragraph_dir = NEUTRAL_DIR;