--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/gutter.c	Mon Aug 13 11:13:30 2007 +0200
@@ -0,0 +1,1202 @@
+/* Gutter implementation.
+   Copyright (C) 1999 Andy Piper.
+
+This file is part of XEmacs.
+
+XEmacs is free software; you can redistribute it and/or modify it
+under the terms of the GNU General Public License as published by the
+Free Software Foundation; either version 2, or (at your option) any
+later version.
+
+XEmacs is distributed in the hope that it will be useful, but WITHOUT
+ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+for more details.
+
+You should have received a copy of the GNU General Public License
+along with XEmacs; see the file COPYING.  If not, write to
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+/* Synched up with: Not in FSF. */
+
+/* written by Andy Piper <andy@xemacs.org> with specifiers partially
+   ripped-off from toolbar.c */
+
+#include <config.h>
+#include "lisp.h"
+
+#include "buffer.h"
+#include "frame.h"
+#include "device.h"
+#include "faces.h"
+#include "glyphs.h"
+#include "redisplay.h"
+#include "window.h"
+#include "gutter.h"
+
+Lisp_Object Vgutter[4];
+Lisp_Object Vgutter_size[4];
+Lisp_Object Vgutter_visible_p[4];
+Lisp_Object Vgutter_border_width[4];
+
+Lisp_Object Vdefault_gutter, Vdefault_gutter_visible_p;
+Lisp_Object Vdefault_gutter_width, Vdefault_gutter_height;
+Lisp_Object Vdefault_gutter_border_width;
+
+Lisp_Object Vdefault_gutter_position;
+
+Lisp_Object Qgutter_size;
+
+#define SET_GUTTER_WAS_VISIBLE_FLAG(frame, pos, flag)	\
+  do {							\
+    switch (pos)					\
+      {							\
+      case TOP_GUTTER:					\
+	(frame)->top_gutter_was_visible = flag;		\
+	break;						\
+      case BOTTOM_GUTTER:				\
+	(frame)->bottom_gutter_was_visible = flag;	\
+	break;						\
+      case LEFT_GUTTER:					\
+	(frame)->left_gutter_was_visible = flag;	\
+	break;						\
+      case RIGHT_GUTTER:				\
+	(frame)->right_gutter_was_visible = flag;	\
+	break;						\
+      default:						\
+	abort ();					\
+      }							\
+  } while (0)
+
+static int gutter_was_visible (struct frame* frame, enum gutter_pos pos)
+{
+  switch (pos)
+    {
+    case TOP_GUTTER:
+      return frame->top_gutter_was_visible;
+    case BOTTOM_GUTTER:
+      return frame->bottom_gutter_was_visible;
+    case LEFT_GUTTER:
+      return frame->left_gutter_was_visible;
+    case RIGHT_GUTTER:
+      return frame->right_gutter_was_visible;
+    default:
+      abort ();
+    }
+}
+
+static Lisp_Object
+frame_topmost_window (struct frame *f)
+{
+  Lisp_Object w = FRAME_ROOT_WINDOW (f);
+
+  do {
+    while (!NILP (XWINDOW (w)->vchild))
+      {
+	w = XWINDOW (w)->vchild;
+      }
+  } while (!NILP (XWINDOW (w)->hchild) && !NILP (w = XWINDOW (w)->hchild));
+
+  return w;
+}
+
+static Lisp_Object
+frame_bottommost_window (struct frame *f)
+{
+  Lisp_Object w = FRAME_ROOT_WINDOW (f);
+
+  do {
+    while (!NILP (XWINDOW (w)->vchild))
+      {
+	w = XWINDOW (w)->vchild;
+	while (!NILP (XWINDOW (w)->next))
+	  {
+	    w = XWINDOW (w)->next;
+	  }
+      }
+  } while (!NILP (XWINDOW (w)->hchild) && !NILP (w = XWINDOW (w)->hchild));
+
+  return w;
+}
+
+#if 0
+static Lisp_Object
+frame_leftmost_window (struct frame *f)
+{
+  Lisp_Object w = FRAME_ROOT_WINDOW (f);
+
+  do {
+    while (!NILP (XWINDOW (w)->hchild))
+      {
+	w = XWINDOW (w)->hchild;
+      }
+  } while (!NILP (XWINDOW (w)->vchild) && !NILP (w = XWINDOW (w)->vchild));
+
+  return w;
+}
+
+static Lisp_Object
+frame_rightmost_window (struct frame *f)
+{
+  Lisp_Object w = FRAME_ROOT_WINDOW (f);
+
+  do {
+    while (!NILP (XWINDOW (w)->hchild))
+      {
+	w = XWINDOW (w)->hchild;
+	while (!NILP (XWINDOW (w)->next))
+	  {
+	    w = XWINDOW (w)->next;
+	  }
+      }
+  } while (!NILP (XWINDOW (w)->vchild) && !NILP (w = XWINDOW (w)->vchild));
+  return w;
+}
+#endif
+
+/* calculate the coordinates of a gutter for the current frame and
+   selected window. we have to be careful in calculating this as we
+   need to use *two* windows, the currently selected window will give
+   us the actual height, width and contents of the gutter, but if we
+   use this for calculating the gutter positions we run into trouble
+   if it is not the window nearest the gutter. Instead we predetermine
+   the nearest window and then use that.*/
+static void
+get_gutter_coords (struct frame *f, enum gutter_pos pos, int *x, int *y,
+		   int *width, int *height)
+{
+  struct window
+    * top = XWINDOW (frame_topmost_window (f)),
+    * bot = XWINDOW (frame_bottommost_window (f));
+  /* The top and bottom gutters take precedence over the left and
+     right. */
+  switch (pos)
+    {
+    case TOP_GUTTER:
+      *x = FRAME_LEFT_BORDER_END (f);
+      *y = FRAME_TOP_BORDER_END (f);
+      *width = FRAME_RIGHT_BORDER_START (f) 
+	- FRAME_LEFT_BORDER_END (f);
+      *height = FRAME_TOP_GUTTER_BOUNDS (f);
+      break;
+
+    case BOTTOM_GUTTER:
+      *x = FRAME_LEFT_BORDER_END (f);
+      *y = WINDOW_BOTTOM (bot)
+	- FRAME_BOTTOM_GUTTER_BOUNDS (f);
+      *width = FRAME_RIGHT_BORDER_START (f) 
+	- FRAME_LEFT_BORDER_END (f);
+      *height = FRAME_BOTTOM_GUTTER_BOUNDS (f);
+      break;
+
+    case LEFT_GUTTER:
+      *x = FRAME_LEFT_BORDER_END (f);
+      *y = WINDOW_TEXT_TOP (top);
+      *width = FRAME_LEFT_GUTTER_BOUNDS (f);
+      *height = WINDOW_BOTTOM (bot)
+	- (WINDOW_TEXT_TOP (top)
+	   + FRAME_BOTTOM_GUTTER_BOUNDS (f));
+      break;
+      
+    case RIGHT_GUTTER:
+      *x = FRAME_RIGHT_BORDER_START (f)
+	- FRAME_RIGHT_GUTTER_BOUNDS (f);
+      *y = WINDOW_TEXT_TOP (top);
+      *width = FRAME_RIGHT_GUTTER_BOUNDS (f);
+      *height = WINDOW_BOTTOM (bot)
+	- (WINDOW_TEXT_TOP (top) 
+	   + FRAME_BOTTOM_GUTTER_BOUNDS (f));
+      break;
+
+    default:
+      abort ();
+    }
+}
+
+static void
+output_gutter (struct frame *f, enum gutter_pos pos)
+{
+  Lisp_Object frame;
+  Lisp_Object window = FRAME_LAST_NONMINIBUF_WINDOW (f);
+  struct device *d = XDEVICE (f->device);
+  struct window* w = XWINDOW (window);
+  int x, y, width, height, ypos;
+  int line, border_width;
+  face_index findex;
+  display_line_dynarr* ddla, *cdla;
+  struct display_line *dl;
+  int cdla_len;
+
+  if (!WINDOW_LIVE_P (w))
+    return;
+
+  border_width = FRAME_GUTTER_BORDER_WIDTH (f, pos);
+  findex = get_builtin_face_cache_index (w, Vgui_element_face);
+
+  if (!f->current_display_lines)
+    f->current_display_lines = Dynarr_new (display_line);
+  if (!f->desired_display_lines)
+    f->desired_display_lines = Dynarr_new (display_line);
+
+  ddla = f->desired_display_lines;
+  cdla = f->current_display_lines;
+  cdla_len = Dynarr_length (cdla);
+
+  XSETFRAME (frame, f);
+
+  get_gutter_coords (f, pos, &x, &y, &width, &height);
+  /* generate some display lines */
+  generate_displayable_area (w, WINDOW_GUTTER (w, pos),
+			     x + border_width, y + border_width,
+			     width - 2 * border_width, 
+			     height - 2 * border_width, ddla, 0, findex);
+  /* Output each line. */
+  for (line = 0; line < Dynarr_length (ddla); line++)
+    {
+      output_display_line (w, cdla, ddla, line, -1, -1);
+    }
+
+  /* If the number of display lines has shrunk, adjust. */
+  if (cdla_len > Dynarr_length (ddla))
+    {
+      Dynarr_length (cdla) = Dynarr_length (ddla);
+    }
+
+  /* grab coordinates of last line and blank after it. */
+  dl = Dynarr_atp (ddla, Dynarr_length (ddla) - 1);
+  ypos = dl->ypos + dl->descent - dl->clip;
+  redisplay_clear_region (window, findex, x + border_width , ypos,
+			  width - 2 * border_width, height - (ypos - y) - border_width);
+  /* bevel the gutter area if so desired */
+  if (border_width != 0)
+    {
+      MAYBE_DEVMETH (d, bevel_area, 
+		     (w, findex, x, y, width, height, border_width,
+		      EDGE_ALL, EDGE_BEVEL_OUT));
+    }
+}
+
+/* sizing gutters is a pain so we try and help the user by detemining
+   what height will accommodate all lines. This is useless on left and
+   right gutters as we always have a maximal number of lines. */
+static Lisp_Object
+calculate_gutter_size (struct window *w, enum gutter_pos pos)
+{
+  struct frame* f = XFRAME (WINDOW_FRAME (w));
+  int ypos;
+  display_line_dynarr* ddla;
+  struct display_line *dl;
+
+  /* we cannot autodetect gutter sizes for the left and right as there
+     is no reasonable metric to use */
+  assert (pos == TOP_GUTTER || pos == BOTTOM_GUTTER);
+  /* degenerate case */
+  if (NILP (WINDOW_GUTTER (w, pos))
+      ||
+      !FRAME_VISIBLE_P (f)
+      ||
+      NILP (w->buffer))
+    return Qnil;
+
+  ddla = Dynarr_new (display_line);
+  /* generate some display lines */
+  generate_displayable_area (w, WINDOW_GUTTER (w, pos),
+			     FRAME_LEFT_BORDER_END (f),
+			     0,
+			     FRAME_RIGHT_BORDER_START (f)
+			     - FRAME_LEFT_BORDER_END (f),
+			     200,
+			     ddla, 0, 0);
+  /* grab coordinates of last line  */
+  if (Dynarr_length (ddla))
+    {
+      dl = Dynarr_atp (ddla, Dynarr_length (ddla) - 1);
+      ypos = dl->ypos + dl->descent - dl->clip;
+      free_display_lines (ddla);
+      return make_int (ypos);
+    }
+  else
+    {
+      free_display_lines (ddla);
+      return Qnil;
+    }
+}
+
+static void
+clear_gutter (struct frame *f, enum gutter_pos pos)
+{
+  int x, y, width, height;
+  Lisp_Object window = FRAME_LAST_NONMINIBUF_WINDOW (f);
+  face_index findex = get_builtin_face_cache_index (XWINDOW (window),
+						    Vgui_element_face);
+  get_gutter_coords (f, pos, &x, &y, &width, &height);
+
+  SET_GUTTER_WAS_VISIBLE_FLAG (f, pos, 0);
+
+  redisplay_clear_region (window, findex, x, y, width, height);
+}
+
+void
+update_frame_gutters (struct frame *f)
+{
+  if (f->gutter_changed || f->clear ||
+      f->glyphs_changed || f->subwindows_changed || 
+      f->windows_changed || f->windows_structure_changed || 
+      f->extents_changed || f->faces_changed)
+    {
+      enum gutter_pos pos;
+      
+      /* We don't actually care about these when outputting the gutter
+         so locally disable them. */
+      int local_clip_changed = f->clip_changed;
+      int local_buffers_changed = f->buffers_changed;
+      f->clip_changed = 0;
+      f->buffers_changed = 0;
+
+      /* and output */
+      GUTTER_POS_LOOP (pos)
+	{
+	  if (FRAME_GUTTER_VISIBLE (f, pos))
+	      output_gutter (f, pos);
+	  else if (gutter_was_visible (f, pos))
+	    clear_gutter (f, pos);
+	}
+      f->clip_changed = local_clip_changed;
+      f->buffers_changed = local_buffers_changed;
+      f->gutter_changed = 0;
+    }
+}
+
+void
+reset_gutter_display_lines (struct frame* f)
+{
+  if (f->current_display_lines)
+    Dynarr_reset (f->current_display_lines);
+}
+
+static void
+redraw_exposed_gutter (struct frame *f, enum gutter_pos pos, int x, int y,
+		       int width, int height)
+{
+  int g_x, g_y, g_width, g_height;
+
+  get_gutter_coords (f, pos, &g_x, &g_y, &g_width, &g_height);
+
+  if (((y + height) < g_y) || (y > (g_y + g_height)) || !height || !width || !g_height || !g_width)
+    return;
+  if (((x + width) < g_x) || (x > (g_x + g_width)))
+    return;
+
+  /* #### optimize this - redrawing the whole gutter for every expose
+     is very expensive. We reset the current display lines because if
+     they're being exposed they are no longer current. */
+  reset_gutter_display_lines (f);
+
+  /* Even if none of the gutter is in the area, the blank region at
+     the very least must be because the first thing we did is verify
+     that some portion of the gutter is in the exposed region. */
+  output_gutter (f, pos);
+}
+
+void
+redraw_exposed_gutters (struct frame *f, int x, int y, int width,
+			int height)
+{
+  enum gutter_pos pos;
+  GUTTER_POS_LOOP (pos)
+    {
+      if (FRAME_GUTTER_VISIBLE (f, pos))
+	redraw_exposed_gutter (f, pos, x, y, width, height);
+    }
+}
+
+void
+free_frame_gutters (struct frame *f)
+{
+  if (f->current_display_lines)
+    {
+      free_display_lines (f->current_display_lines);
+      f->current_display_lines = 0;
+    }
+  if (f->desired_display_lines)
+    {
+      free_display_lines (f->desired_display_lines);
+      f->desired_display_lines = 0;
+    }
+}
+
+static enum gutter_pos
+decode_gutter_position (Lisp_Object position)
+{
+  if (EQ (position, Qtop))    return TOP_GUTTER;
+  if (EQ (position, Qbottom)) return BOTTOM_GUTTER;
+  if (EQ (position, Qleft))   return LEFT_GUTTER;
+  if (EQ (position, Qright))  return RIGHT_GUTTER;
+  signal_simple_error ("Invalid gutter position", position);
+
+  return TOP_GUTTER; /* not reached */
+}
+
+DEFUN ("set-default-gutter-position", Fset_default_gutter_position, 1, 1, 0, /*
+Set the position that the `default-gutter' will be displayed at.
+Valid positions are 'top, 'bottom, 'left and 'right.
+See `default-gutter-position'.
+*/
+       (position))
+{
+  enum gutter_pos cur = decode_gutter_position (Vdefault_gutter_position);
+  enum gutter_pos new = decode_gutter_position (position);
+
+  if (cur != new)
+    {
+      /* The following calls will automatically cause the dirty
+	 flags to be set; we delay frame size changes to avoid
+	 lots of frame flickering. */
+      /* #### I think this should be GC protected. -sb */
+      hold_frame_size_changes ();
+      set_specifier_fallback (Vgutter[cur], list1 (Fcons (Qnil, Qnil)));
+      set_specifier_fallback (Vgutter[new], Vdefault_gutter);
+      set_specifier_fallback (Vgutter_size[cur], list1 (Fcons (Qnil, Qzero)));
+      set_specifier_fallback (Vgutter_size[new],
+			      new == TOP_GUTTER || new == BOTTOM_GUTTER
+			      ? Vdefault_gutter_height
+			      : Vdefault_gutter_width);
+      set_specifier_fallback (Vgutter_border_width[cur],
+			      list1 (Fcons (Qnil, Qzero)));
+      set_specifier_fallback (Vgutter_border_width[new],
+			      Vdefault_gutter_border_width);
+      set_specifier_fallback (Vgutter_visible_p[cur],
+			      list1 (Fcons (Qnil, Qt)));
+      set_specifier_fallback (Vgutter_visible_p[new],
+			      Vdefault_gutter_visible_p);
+      Vdefault_gutter_position = position;
+      unhold_frame_size_changes ();
+    }
+
+  return position;
+}
+
+DEFUN ("default-gutter-position", Fdefault_gutter_position, 0, 0, 0, /*
+Return the position that the `default-gutter' will be displayed at.
+The `default-gutter' will only be displayed here if the corresponding
+position-specific gutter specifier does not provide a value.
+*/
+       ())
+{
+  return Vdefault_gutter_position;
+}
+
+DEFUN ("gutter-pixel-width", Fgutter_pixel_width, 0, 2, 0, /*
+Return the pixel width of the gutter at POS in LOCALE.
+POS defaults to the default gutter position. LOCALE defaults to
+the current window.
+*/
+       (pos, locale))
+{
+  int x, y, width, height;
+  enum gutter_pos p = TOP_GUTTER;
+  struct frame *f = decode_frame (FW_FRAME (locale));
+
+  if (NILP (pos))
+    pos = Vdefault_gutter_position;
+  p = decode_gutter_position (pos);
+
+  get_gutter_coords (f, p, &x, &y, &width, &height);
+  width -= (FRAME_GUTTER_BORDER_WIDTH (f, p) * 2);
+
+  return make_int (width);
+}
+
+DEFUN ("gutter-pixel-height", Fgutter_pixel_height, 0, 2, 0, /*
+Return the pixel height of the gutter at POS in LOCALE.
+POS defaults to the default gutter position. LOCALE defaults to
+the current window.
+*/
+       (pos, locale))
+{
+  int x, y, width, height;
+  enum gutter_pos p = TOP_GUTTER;
+  struct frame *f = decode_frame (FW_FRAME (locale));
+
+  if (NILP (pos))
+    pos = Vdefault_gutter_position;
+  p = decode_gutter_position (pos);
+
+  get_gutter_coords (f, p, &x, &y, &width, &height);
+  height -= (FRAME_GUTTER_BORDER_WIDTH (f, p) * 2);
+
+  return make_int (height);
+}
+
+DEFINE_SPECIFIER_TYPE (gutter);
+
+static void
+gutter_after_change (Lisp_Object specifier, Lisp_Object locale)
+{
+  MARK_GUTTER_CHANGED;
+}
+
+static void
+gutter_validate (Lisp_Object instantiator)
+{
+  if (NILP (instantiator))
+    return;
+
+  if (!STRINGP (instantiator))
+    signal_simple_error ("Gutter spec must be string or nil", instantiator);
+}
+
+DEFUN ("gutter-specifier-p", Fgutter_specifier_p, 1, 1, 0, /*
+Return non-nil if OBJECT is a gutter specifier.
+Gutter specifiers are used to specify the format of a gutter.
+The values of the variables `default-gutter', `top-gutter',
+`left-gutter', `right-gutter', and `bottom-gutter' are always
+gutter specifiers.
+
+Valid gutter instantiators are called "gutter descriptors"
+and are lists of vectors.  See `default-gutter' for a description
+of the exact format.
+*/
+       (object))
+{
+  return GUTTER_SPECIFIERP (object) ? Qt : Qnil;
+}
+
+
+/*
+  Helper for invalidating the real specifier when default
+  specifier caching changes
+*/
+static void
+recompute_overlaying_specifier (Lisp_Object real_one[4])
+{
+  enum gutter_pos pos = decode_gutter_position (Vdefault_gutter_position);
+  Fset_specifier_dirty_flag (real_one[pos]);
+}
+
+static void
+gutter_specs_changed (Lisp_Object specifier, struct window *w,
+		       Lisp_Object oldval)
+{
+  enum gutter_pos pos;
+  GUTTER_POS_LOOP (pos)
+    {
+      w->real_gutter_size[pos] = w->gutter_size[pos];
+      if (EQ (w->real_gutter_size[pos], Qautodetect)
+	  && !NILP (w->gutter_visible_p[pos]))
+	{
+	  w->real_gutter_size [pos] = calculate_gutter_size (w, pos);
+	}
+    }
+  MARK_GUTTER_CHANGED;
+  MARK_WINDOWS_CHANGED (w);
+}
+
+static void
+default_gutter_specs_changed (Lisp_Object specifier, struct window *w,
+			       Lisp_Object oldval)
+{
+  recompute_overlaying_specifier (Vgutter);
+}
+
+static void
+gutter_geometry_changed_in_window (Lisp_Object specifier, struct window *w,
+				    Lisp_Object oldval)
+{
+  enum gutter_pos pos;
+  GUTTER_POS_LOOP (pos)
+    {
+      w->real_gutter_size[pos] = w->gutter_size[pos];
+      if (EQ (w->real_gutter_size[pos], Qautodetect)
+	  && !NILP (w->gutter_visible_p[pos]))
+	{
+	  w->real_gutter_size [pos] = calculate_gutter_size (w, pos);
+	}
+    }
+  
+  MARK_GUTTER_CHANGED;
+  MARK_WINDOWS_CHANGED (w);
+}
+
+static void
+default_gutter_size_changed_in_window (Lisp_Object specifier, struct window *w,
+					Lisp_Object oldval)
+{
+  recompute_overlaying_specifier (Vgutter_size);
+}
+
+static void
+default_gutter_border_width_changed_in_window (Lisp_Object specifier,
+						struct window *w,
+						Lisp_Object oldval)
+{
+  recompute_overlaying_specifier (Vgutter_border_width);
+}
+
+static void
+default_gutter_visible_p_changed_in_window (Lisp_Object specifier,
+					     struct window *w,
+					     Lisp_Object oldval)
+{
+  recompute_overlaying_specifier (Vgutter_visible_p);
+}
+
+
+DECLARE_SPECIFIER_TYPE (gutter_size);
+#define GUTTER_SIZE_SPECIFIERP(x) SPECIFIER_TYPEP (x, gutter_size)
+DEFINE_SPECIFIER_TYPE (gutter_size);
+
+static void
+gutter_size_validate (Lisp_Object instantiator)
+{
+  if (NILP (instantiator))
+    return;
+
+  if (!INTP (instantiator) && !EQ (instantiator, Qautodetect))
+    signal_simple_error ("Gutter size must be an integer or 'autodetect", instantiator);
+}
+
+DEFUN ("gutter-size-specifier-p", Fgutter_size_specifier_p, 1, 1, 0, /*
+Return non-nil if OBJECT is a gutter-size specifier.
+*/
+       (object))
+{
+  return GUTTER_SIZE_SPECIFIERP (object) ? Qt : Qnil;
+}
+
+DEFUN ("redisplay-gutter-area", Fredisplay_gutter_area, 0, 0, 0, /*
+Ensure that all gutters are correctly showing their gutter specifier.
+*/
+       ())
+{
+  Lisp_Object devcons, concons;
+
+  DEVICE_LOOP_NO_BREAK (devcons, concons)
+    {
+      struct device *d = XDEVICE (XCAR (devcons));
+      Lisp_Object frmcons;
+
+      DEVICE_FRAME_LOOP (frmcons, d)
+	{
+	  struct frame *f = XFRAME (XCAR (frmcons));
+
+	  if (FRAME_REPAINT_P (f))
+	    {
+	      update_frame_gutters (f);
+	    }
+	}
+
+      /* We now call the output_end routine for tty frames.  We delay
+	 doing so in order to avoid cursor flicker.  So much for 100%
+	 encapsulation. */
+      if (DEVICE_TTY_P (d))
+	DEVMETH (d, output_end, (d));
+    }
+
+  return Qnil;
+}
+
+void
+init_frame_gutters (struct frame *f)
+{
+  enum gutter_pos pos;
+  struct window* w = XWINDOW (FRAME_LAST_NONMINIBUF_WINDOW (f));
+  /* We are here as far in frame creation so cached specifiers are
+     already recomputed, and possibly modified by resource
+     initialization. We need to recalculate autodetected gutters. */
+  GUTTER_POS_LOOP (pos)
+    {
+      w->real_gutter_size[pos] = w->gutter_size[pos];
+      if (EQ (w->gutter_size[pos], Qautodetect)
+	  && !NILP (w->gutter_visible_p[pos]))
+	{
+	  w->real_gutter_size [pos] = calculate_gutter_size (w, pos);
+	  MARK_GUTTER_CHANGED;
+	  MARK_WINDOWS_CHANGED (w);
+	}
+    }
+}
+
+void
+syms_of_gutter (void)
+{
+  DEFSUBR (Fgutter_specifier_p);
+  DEFSUBR (Fgutter_size_specifier_p);
+  DEFSUBR (Fset_default_gutter_position);
+  DEFSUBR (Fdefault_gutter_position);
+  DEFSUBR (Fgutter_pixel_height);
+  DEFSUBR (Fgutter_pixel_width);
+  DEFSUBR (Fredisplay_gutter_area);
+
+  defsymbol (&Qgutter_size, "gutter-size");
+}
+
+void
+vars_of_gutter (void)
+{
+  staticpro (&Vdefault_gutter_position);
+  Vdefault_gutter_position = Qtop;
+
+  Fprovide (Qgutter);
+}
+
+void
+specifier_type_create_gutter (void)
+{
+  INITIALIZE_SPECIFIER_TYPE (gutter, "gutter", "gutter-specifier-p");
+
+  SPECIFIER_HAS_METHOD (gutter, validate);
+  SPECIFIER_HAS_METHOD (gutter, after_change);
+
+  INITIALIZE_SPECIFIER_TYPE (gutter_size, "gutter-size", "gutter-size-specifier-p");
+
+  SPECIFIER_HAS_METHOD (gutter_size, validate);
+}
+
+void
+reinit_specifier_type_create_gutter (void)
+{
+  REINITIALIZE_SPECIFIER_TYPE (gutter);
+  REINITIALIZE_SPECIFIER_TYPE (gutter_size);
+}
+
+void
+specifier_vars_of_gutter (void)
+{
+  Lisp_Object fb;
+
+  DEFVAR_SPECIFIER ("default-gutter", &Vdefault_gutter /*
+Specifier for a fallback gutter.
+Use `set-specifier' to change this.
+
+The position of this gutter is specified in the function
+`default-gutter-position'.  If the corresponding position-specific
+gutter (e.g. `top-gutter' if `default-gutter-position' is 'top)
+does not specify a gutter in a particular domain (usually a window),
+then the value of `default-gutter' in that domain, if any, will be
+used instead.
+
+Note that the gutter at any particular position will not be
+displayed unless its visibility flag is true and its thickness
+\(width or height, depending on orientation) is non-zero.  The
+visibility is controlled by the specifiers `top-gutter-visible-p',
+`bottom-gutter-visible-p', `left-gutter-visible-p', and
+`right-gutter-visible-p', and the thickness is controlled by the
+specifiers `top-gutter-height', `bottom-gutter-height',
+`left-gutter-width', and `right-gutter-width'.
+
+Note that one of the four visibility specifiers inherits from
+`default-gutter-visibility' and one of the four thickness
+specifiers inherits from either `default-gutter-width' or
+`default-gutter-height' (depending on orientation), just
+like for the gutter description specifiers (e.g. `top-gutter')
+mentioned above.
+
+Therefore, if you are setting `default-gutter', you should control
+the visibility and thickness using `default-gutter-visible-p',
+`default-gutter-width', and `default-gutter-height', rather than
+using position-specific specifiers.  That way, you will get sane
+behavior if the user changes the default gutter position.
+
+The gutter value should be a string or nil. You can attach extents and
+glyphs to the string and hence display glyphs and text in other fonts
+in the gutter area.
+
+*/ );
+
+  Vdefault_gutter = Fmake_specifier (Qgutter);
+  /* #### It would be even nicer if the specifier caching
+     automatically knew about specifier fallbacks, so we didn't
+     have to do it ourselves. */
+  set_specifier_caching (Vdefault_gutter,
+			 offsetof (struct window, default_gutter),
+			 default_gutter_specs_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("top-gutter",
+		    &Vgutter[TOP_GUTTER] /*
+Specifier for the gutter at the top of the frame.
+Use `set-specifier' to change this.
+See `default-gutter' for a description of a valid gutter instantiator.
+*/ );
+  Vgutter[TOP_GUTTER] = Fmake_specifier (Qgutter);
+  set_specifier_caching (Vgutter[TOP_GUTTER],
+			 offsetof (struct window, gutter[TOP_GUTTER]),
+			 gutter_specs_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("bottom-gutter",
+		    &Vgutter[BOTTOM_GUTTER] /*
+Specifier for the gutter at the bottom of the frame.
+Use `set-specifier' to change this.
+See `default-gutter' for a description of a valid gutter instantiator.
+
+Note that, unless the `default-gutter-position' is `bottom', by
+default the height of the bottom gutter (controlled by
+`bottom-gutter-height') is 0; thus, a bottom gutter will not be
+displayed even if you provide a value for `bottom-gutter'.
+*/ );
+  Vgutter[BOTTOM_GUTTER] = Fmake_specifier (Qgutter);
+  set_specifier_caching (Vgutter[BOTTOM_GUTTER],
+			 offsetof (struct window, gutter[BOTTOM_GUTTER]),
+			 gutter_specs_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("left-gutter",
+		    &Vgutter[LEFT_GUTTER] /*
+Specifier for the gutter at the left edge of the frame.
+Use `set-specifier' to change this.
+See `default-gutter' for a description of a valid gutter instantiator.
+
+Note that, unless the `default-gutter-position' is `left', by
+default the height of the left gutter (controlled by
+`left-gutter-width') is 0; thus, a left gutter will not be
+displayed even if you provide a value for `left-gutter'.
+*/ );
+  Vgutter[LEFT_GUTTER] = Fmake_specifier (Qgutter);
+  set_specifier_caching (Vgutter[LEFT_GUTTER],
+			 offsetof (struct window, gutter[LEFT_GUTTER]),
+			 gutter_specs_changed,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("right-gutter",
+		    &Vgutter[RIGHT_GUTTER] /*
+Specifier for the gutter at the right edge of the frame.
+Use `set-specifier' to change this.
+See `default-gutter' for a description of a valid gutter instantiator.
+
+Note that, unless the `default-gutter-position' is `right', by
+default the height of the right gutter (controlled by
+`right-gutter-width') is 0; thus, a right gutter will not be
+displayed even if you provide a value for `right-gutter'.
+*/ );
+  Vgutter[RIGHT_GUTTER] = Fmake_specifier (Qgutter);
+  set_specifier_caching (Vgutter[RIGHT_GUTTER],
+			 offsetof (struct window, gutter[RIGHT_GUTTER]),
+			 gutter_specs_changed,
+			 0, 0);
+
+  /* initially, top inherits from default; this can be
+     changed with `set-default-gutter-position'. */
+  fb = list1 (Fcons (Qnil, Qnil));
+  set_specifier_fallback (Vdefault_gutter, fb);
+  set_specifier_fallback (Vgutter[TOP_GUTTER], Vdefault_gutter);
+  set_specifier_fallback (Vgutter[BOTTOM_GUTTER], fb);
+  set_specifier_fallback (Vgutter[LEFT_GUTTER],   fb);
+  set_specifier_fallback (Vgutter[RIGHT_GUTTER],  fb);
+
+  DEFVAR_SPECIFIER ("default-gutter-height", &Vdefault_gutter_height /*
+*Height of the default gutter, if it's oriented horizontally.
+This is a specifier; use `set-specifier' to change it.
+
+The position of the default gutter is specified by the function
+`set-default-gutter-position'.  If the corresponding position-specific
+gutter thickness specifier (e.g. `top-gutter-height' if
+`default-gutter-position' is 'top) does not specify a thickness in a
+particular domain (a window or a frame), then the value of
+`default-gutter-height' or `default-gutter-width' (depending on the
+gutter orientation) in that domain, if any, will be used instead.
+
+Note that `default-gutter-height' is only used when
+`default-gutter-position' is 'top or 'bottom, and `default-gutter-width'
+is only used when `default-gutter-position' is 'left or 'right.
+
+Note that all of the position-specific gutter thickness specifiers
+have a fallback value of zero when they do not correspond to the
+default gutter.  Therefore, you will have to set a non-zero thickness
+value if you want a position-specific gutter to be displayed.
+
+If you set the height to 'autodetect the size of the gutter will be
+calculated to be large enough to hold the contents of the gutter. This
+is the default.
+*/ );
+  Vdefault_gutter_height = Fmake_specifier (Qgutter_size);
+  set_specifier_caching (Vdefault_gutter_height,
+			 offsetof (struct window, default_gutter_height),
+			 default_gutter_size_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("default-gutter-width", &Vdefault_gutter_width /*
+*Width of the default gutter, if it's oriented vertically.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vdefault_gutter_width = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vdefault_gutter_width,
+			 offsetof (struct window, default_gutter_width),
+			 default_gutter_size_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("top-gutter-height",
+		    &Vgutter_size[TOP_GUTTER] /*
+*Height of the top gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_size[TOP_GUTTER] = Fmake_specifier (Qgutter_size);
+  set_specifier_caching (Vgutter_size[TOP_GUTTER],
+			 offsetof (struct window, gutter_size[TOP_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("bottom-gutter-height",
+		    &Vgutter_size[BOTTOM_GUTTER] /*
+*Height of the bottom gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_size[BOTTOM_GUTTER] = Fmake_specifier (Qgutter_size);
+  set_specifier_caching (Vgutter_size[BOTTOM_GUTTER],
+			 offsetof (struct window, gutter_size[BOTTOM_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("left-gutter-width",
+		    &Vgutter_size[LEFT_GUTTER] /*
+*Width of left gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_size[LEFT_GUTTER] = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vgutter_size[LEFT_GUTTER],
+			 offsetof (struct window, gutter_size[LEFT_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("right-gutter-width",
+		    &Vgutter_size[RIGHT_GUTTER] /*
+*Width of right gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_size[RIGHT_GUTTER] = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vgutter_size[RIGHT_GUTTER],
+			 offsetof (struct window, gutter_size[RIGHT_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  fb = Qnil;
+#ifdef HAVE_TTY
+  fb = Fcons (Fcons (list1 (Qtty), Qautodetect), fb);
+#endif
+#ifdef HAVE_X_WINDOWS
+  fb = Fcons (Fcons (list1 (Qx), Qautodetect), fb);
+#endif
+#ifdef HAVE_MS_WINDOWS
+  fb = Fcons (Fcons (list1 (Qmsprinter), Qautodetect), fb);
+  fb = Fcons (Fcons (list1 (Qmswindows), Qautodetect), fb);
+#endif
+  if (!NILP (fb))
+    set_specifier_fallback (Vdefault_gutter_height, fb);
+
+  fb = Qnil;
+#ifdef HAVE_TTY
+  fb = Fcons (Fcons (list1 (Qtty), Qzero), fb);
+#endif
+#ifdef HAVE_X_WINDOWS
+  fb = Fcons (Fcons (list1 (Qx), make_int (DEFAULT_GUTTER_WIDTH)), fb);
+#endif
+#ifdef HAVE_MS_WINDOWS
+  fb = Fcons (Fcons (list1 (Qmsprinter), Qzero), fb);
+  fb = Fcons (Fcons (list1 (Qmswindows), 
+		     make_int (DEFAULT_GUTTER_WIDTH)), fb);
+#endif
+  if (!NILP (fb))
+    set_specifier_fallback (Vdefault_gutter_width, fb);
+
+  set_specifier_fallback (Vgutter_size[TOP_GUTTER], Vdefault_gutter_height);
+  fb = list1 (Fcons (Qnil, Qzero));
+  set_specifier_fallback (Vgutter_size[BOTTOM_GUTTER], fb);
+  set_specifier_fallback (Vgutter_size[LEFT_GUTTER],   fb);
+  set_specifier_fallback (Vgutter_size[RIGHT_GUTTER],  fb);
+
+  DEFVAR_SPECIFIER ("default-gutter-border-width",
+		    &Vdefault_gutter_border_width /*
+*Width of the border around the default gutter.
+This is a specifier; use `set-specifier' to change it.
+
+The position of the default gutter is specified by the function
+`set-default-gutter-position'.  If the corresponding position-specific
+gutter border width specifier (e.g. `top-gutter-border-width' if
+`default-gutter-position' is 'top) does not specify a border width in a
+particular domain (a window or a frame), then the value of
+`default-gutter-border-width' in that domain, if any, will be used
+instead.
+
+*/ );
+  Vdefault_gutter_border_width = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vdefault_gutter_border_width,
+			 offsetof (struct window, default_gutter_border_width),
+			 default_gutter_border_width_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("top-gutter-border-width",
+		    &Vgutter_border_width[TOP_GUTTER] /*
+*Border width of the top gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_border_width[TOP_GUTTER] = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vgutter_border_width[TOP_GUTTER],
+			 offsetof (struct window,
+				   gutter_border_width[TOP_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("bottom-gutter-border-width",
+		    &Vgutter_border_width[BOTTOM_GUTTER] /*
+*Border width of the bottom gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_border_width[BOTTOM_GUTTER] = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vgutter_border_width[BOTTOM_GUTTER],
+			 offsetof (struct window,
+				   gutter_border_width[BOTTOM_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("left-gutter-border-width",
+		    &Vgutter_border_width[LEFT_GUTTER] /*
+*Border width of left gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_border_width[LEFT_GUTTER] = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vgutter_border_width[LEFT_GUTTER],
+			 offsetof (struct window,
+				   gutter_border_width[LEFT_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("right-gutter-border-width",
+		    &Vgutter_border_width[RIGHT_GUTTER] /*
+*Border width of right gutter.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-height' for more information.
+*/ );
+  Vgutter_border_width[RIGHT_GUTTER] = Fmake_specifier (Qnatnum);
+  set_specifier_caching (Vgutter_border_width[RIGHT_GUTTER],
+			 offsetof (struct window,
+				   gutter_border_width[RIGHT_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  fb = Qnil;
+#ifdef HAVE_TTY
+  fb = Fcons (Fcons (list1 (Qtty), Qzero), fb);
+#endif
+#ifdef HAVE_X_WINDOWS
+  fb = Fcons (Fcons (list1 (Qx), make_int (DEFAULT_GUTTER_BORDER_WIDTH)), fb);
+#endif
+#ifdef HAVE_MS_WINDOWS
+  fb = Fcons (Fcons (list1 (Qmsprinter), Qzero), fb);
+  fb = Fcons (Fcons (list1 (Qmswindows), make_int (DEFAULT_GUTTER_BORDER_WIDTH)), fb);
+#endif
+  if (!NILP (fb))
+    set_specifier_fallback (Vdefault_gutter_border_width, fb);
+
+  set_specifier_fallback (Vgutter_border_width[TOP_GUTTER], Vdefault_gutter_border_width);
+  fb = list1 (Fcons (Qnil, Qzero));
+  set_specifier_fallback (Vgutter_border_width[BOTTOM_GUTTER], fb);
+  set_specifier_fallback (Vgutter_border_width[LEFT_GUTTER],   fb);
+  set_specifier_fallback (Vgutter_border_width[RIGHT_GUTTER],  fb);
+
+  DEFVAR_SPECIFIER ("default-gutter-visible-p", &Vdefault_gutter_visible_p /*
+*Whether the default gutter is visible.
+This is a specifier; use `set-specifier' to change it.
+
+The position of the default gutter is specified by the function
+`set-default-gutter-position'.  If the corresponding position-specific
+gutter visibility specifier (e.g. `top-gutter-visible-p' if
+`default-gutter-position' is 'top) does not specify a visible-p value
+in a particular domain (a window or a frame), then the value of
+`default-gutter-visible-p' in that domain, if any, will be used
+instead.
+
+`default-gutter-visible-p' and all of the position-specific gutter
+visibility specifiers have a fallback value of true.
+*/ );
+  Vdefault_gutter_visible_p = Fmake_specifier (Qboolean);
+  set_specifier_caching (Vdefault_gutter_visible_p,
+			 offsetof (struct window,
+				   default_gutter_visible_p),
+			 default_gutter_visible_p_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("top-gutter-visible-p",
+		    &Vgutter_visible_p[TOP_GUTTER] /*
+*Whether the top gutter is visible.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-visible-p' for more information.
+*/ );
+  Vgutter_visible_p[TOP_GUTTER] = Fmake_specifier (Qboolean);
+  set_specifier_caching (Vgutter_visible_p[TOP_GUTTER],
+			 offsetof (struct window,
+				   gutter_visible_p[TOP_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("bottom-gutter-visible-p",
+		    &Vgutter_visible_p[BOTTOM_GUTTER] /*
+*Whether the bottom gutter is visible.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-visible-p' for more information.
+*/ );
+  Vgutter_visible_p[BOTTOM_GUTTER] = Fmake_specifier (Qboolean);
+  set_specifier_caching (Vgutter_visible_p[BOTTOM_GUTTER],
+			 offsetof (struct window,
+				   gutter_visible_p[BOTTOM_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("left-gutter-visible-p",
+		    &Vgutter_visible_p[LEFT_GUTTER] /*
+*Whether the left gutter is visible.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-visible-p' for more information.
+*/ );
+  Vgutter_visible_p[LEFT_GUTTER] = Fmake_specifier (Qboolean);
+  set_specifier_caching (Vgutter_visible_p[LEFT_GUTTER],
+			 offsetof (struct window,
+				   gutter_visible_p[LEFT_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  DEFVAR_SPECIFIER ("right-gutter-visible-p",
+		    &Vgutter_visible_p[RIGHT_GUTTER] /*
+*Whether the right gutter is visible.
+This is a specifier; use `set-specifier' to change it.
+
+See `default-gutter-visible-p' for more information.
+*/ );
+  Vgutter_visible_p[RIGHT_GUTTER] = Fmake_specifier (Qboolean);
+  set_specifier_caching (Vgutter_visible_p[RIGHT_GUTTER],
+			 offsetof (struct window,
+				   gutter_visible_p[RIGHT_GUTTER]),
+			 gutter_geometry_changed_in_window,
+			 0, 0);
+
+  /* initially, top inherits from default; this can be
+     changed with `set-default-gutter-position'. */
+  fb = list1 (Fcons (Qnil, Qt));
+  set_specifier_fallback (Vdefault_gutter_visible_p, fb);
+  set_specifier_fallback (Vgutter_visible_p[TOP_GUTTER],
+			  Vdefault_gutter_visible_p);
+  set_specifier_fallback (Vgutter_visible_p[BOTTOM_GUTTER], fb);
+  set_specifier_fallback (Vgutter_visible_p[LEFT_GUTTER],   fb);
+  set_specifier_fallback (Vgutter_visible_p[RIGHT_GUTTER],  fb);
+}