# HG changeset patch
# User David Bateman <dbateman@free.fr>
# Date 1225321985 -3600
# Node ID ac7f334d96525c6aaaaadd7a34ce84a1e999c23d
# Parent  2368aa769ab9312b6473cf68dc1f7fec4b8e9d91
Add contour group objects and the clabel function

diff --git a/doc/ChangeLog b/doc/ChangeLog
--- a/doc/ChangeLog
+++ b/doc/ChangeLog
@@ -1,3 +1,7 @@
+2008-10-30  David Bateman  <dbateman@free.fr>
+
+	* interpreter/plot.txi: Document contour groups.
+
 2008-10-29  Thorsten Meyer  <tmeyier@gmx.de>
 
 	* interpreter/system.txi, interpreter/poly.txi,
diff --git a/doc/interpreter/plot.txi b/doc/interpreter/plot.txi
--- a/doc/interpreter/plot.txi
+++ b/doc/interpreter/plot.txi
@@ -1710,7 +1710,76 @@
 @cindex series objects
 @cindex contour series
 
-TO BE WRITTEN
+Contour group objects are created by the @code{contour}, @code{contourf}
+and @code{contour3} functions. The are equally one of the handles returned
+by the @code{surfc} and @code{meshc} functions. The properties of the contour
+group are
+
+@table @code
+@item contourmatrix
+A read only property that contains the data return by @code{contourc} used to
+create the contours of the plot.
+
+@item fill
+A radio property that can have the values "on" or "off" that flags whether the
+contours to plot are to be filled.
+
+@item zlevelmode
+@itemx zlevel
+The radio property @code{zlevelmode} can have the values "none", "auto" or 
+"manual". When its value is "none" there is no z component to the plotted
+contours. When its value is "auto" the z value of the plotted contours is 
+at the same value as the contour itself. If the value is "manual", then the
+z value at which to plot the contour is determined by the @code{zlevel}
+property.
+
+@item levellistmode
+@itemx levellist
+@itemx levelstepmode
+@itemx levelstep
+If @code{levellistmode} is "manual", then the levels at whch to plot the 
+contours is determined by @code{levellist}. If @code{levellistmode} is
+set to "auto", then the distance between contours is determined by 
+@code{levelstep}. If both @code{levellistmode} and @code{levelstepmode}
+are set to "auto", then there are assumed to be 10 equal spaced contours.
+
+@item textlistmode
+@itemx textlist
+@itemx textstepmode
+@itemx textstep
+If @code{textlistmode} is "manual", then the labelled contours 
+is determined by @code{textlist}. If @code{textlistmode} is set to 
+"auto", then the distance between labelled contours is determined by 
+@code{textstep}. If both @code{textlistmode} and @code{textstepmode}
+are set to "auto", then there are assumed to be 10 equal spaced 
+labelled contours.
+
+@item showtext
+Flag whether the contour labels are shown or not.
+
+@item labelspacing
+The distance between labels on a single contour in points.
+
+@item linewidth
+@item linestyle
+@item linecolor
+The properties of the contour lines. The properties @code{linewidth} and
+@code{linestyle} are similar to the correponding properties for lines. The
+property @code{linecolor} is a color property (@xref{Colors}), that can also
+have the values of "none" or "auto". If @code{linecolor} is "none", then no
+contour line is drawn. If @code{linecolor} is "auto" then the line color is
+determined by the colormap.
+
+@item xdata
+@itemx ydata
+@itemx zdata
+The original x, y, and z data of the contour lines.
+
+@item xdatasource
+@itemx ydatasource
+@itemx zdatasource
+Data source variables.
+@end table
 
 @node Error bar series
 @subsubsection Error bar series
diff --git a/scripts/ChangeLog b/scripts/ChangeLog
--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,3 +1,12 @@
+2008-10-30  David Bateman  <dbateman@free.fr>
+
+	* plot/__clabel__.m, plot/clabel.m: New functions.
+	* plot/Makefile.in (SOURCES): Add them here.
+	* plot/__contour__.m: Rewrite to use contour groups.
+	* plot/contourf.m: Call __contour__ instead of using specific code.
+	* plot/contour.m, plot/contour3.m: Minor modification to allow for
+	new interface to __contour__.
+
 2008-10-29  Thorsten Meyer  <thorsten.meyier@gmx.de>
 
 	* set/create_set.m, set/ismember.m, set/union.m, set/complement.m:
diff --git a/scripts/plot/Makefile.in b/scripts/plot/Makefile.in
--- a/scripts/plot/Makefile.in
+++ b/scripts/plot/Makefile.in
@@ -40,6 +40,7 @@
   __axis_label__.m \
   __bar__.m \
   __bars__.m \
+  __clabel__.m \
   __contour__.m \
   __default_plot_options__.m \
   __errcomm__.m \
@@ -82,6 +83,7 @@
   box.m \
   caxis.m \
   cla.m \
+  clabel.m \
   clf.m \
   close.m \
   closereq.m \
diff --git a/scripts/plot/__clabel__.m b/scripts/plot/__clabel__.m
new file mode 100644
--- /dev/null
+++ b/scripts/plot/__clabel__.m
@@ -0,0 +1,112 @@
+## Copyright (C) 2008 David Bateman
+##
+## This file is part of Octave.
+##
+## Octave 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 3 of the License, or (at
+## your option) any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## Undocumented internal function.
+
+function h = __clabel__ (c, v, hparent, LabelSpacing, z, varargin)
+  ## FIXME
+  ## Assume that the plot size is 4 by 3 inches.
+  lims = axis ();
+  xspacing = 72 * 4 / abs(lims(1) - lims(2));
+  yspacing = 72 * 3 / abs(lims(3) - lims(4));
+
+  if (isscalar (hparent) && ishandle(hparent) && 
+	strcmp (get (hparent, "type"), "hggroup"))
+    x = get (hparent, "xdata");
+    xmin = min (x(:));
+    xmax = max (x(:));
+    y = get (hparent, "ydata");
+    ymin = min (y(:));
+    ymax = max (y(:));
+  else
+    i1 = 1;
+    while (i1 < length (c))
+      clev = c(1,i1);
+      clen = c(2,i1);
+      p = c(:, i1+1:i1+clen)      
+
+      xmin = min (c(1,:));
+      xmax = max (c(1,:));
+      ymin = min (c(2,:));
+      ymax = max (c(2,:));
+
+      i1 += clen+1;
+    endwhile
+  endif
+
+  ## Decode contourc output format and place labels.
+  i1 = 1;
+  h = [];
+  while (i1 < length (c))
+    clev = c(1,i1);
+    clen = c(2,i1);
+
+    if (!isempty (v) && ! any (find (clev == v)))
+      i1 += clen+1;
+      continue;
+    endif
+
+    p = c(:, i1+1:i1+clen) .* repmat ([xspacing; yspacing], 1, clen);
+    d = sqrt (sumsq (diff (p, 1, 2)));
+    cumd = cumsum (d);
+    td = sum(d);
+    ntag = ceil (td / LabelSpacing);
+
+    if (all (c(:,i1+1) == c(:,i1+clen)))
+      Spacing = td / ntag;
+      pos = Spacing / 2 + [0:ntag-1] * Spacing;
+    else
+      pos = zeros(1, ntag);
+      pos(1) = (td - LabelSpacing * (ntag - 1)) ./ 2;
+      pos(2:ntag) = pos(1) + [1:ntag-1] * LabelSpacing;
+    endif
+
+    j1 = 2;
+    tlabel = sprintf ("%g", clev);
+    for i = 1 : ntag
+      tagpos = pos(i);
+      
+      while (j1 < clen && cumd(j1) < tagpos)
+	j1++;
+      endwhile
+      tpos = sum(c(:,i1+j1-1:i1+j1), 2) ./ 2;
+
+      if (tpos(1) != xmin &&  tpos(1) != xmax && 
+	  tpos(2) != ymin &&  tpos(2) != ymax)
+	trot = 180 / pi * atan2 (diff (c(2,i1+j1-1:i1+j1)),
+				 diff (c(1,i1+j1-1:i1+j1)));
+
+	if (ischar (z))
+	  ht = text (tpos(1), tpos(2), clev, tlabel, "rotation", trot, 
+		     "parent", hparent, "horizontalalignment", "center",
+		     "userdata", clev, varargin{:});
+	elseif (!isempty (z))
+	  ht = text (tpos(1), tpos(2), z, tlabel, "rotation", trot, 
+		     "parent", hparent, "horizontalalignment", "center",
+		     "userdata", clev, varargin{:});
+	else
+	  ht = text (tpos(1), tpos(2), tlabel, "rotation", trot,
+		     "parent", hparent, "horizontalalignment", "center",
+		     "userdata", clev, varargin{:});
+	endif
+	h = [h; ht];
+      endif
+    endfor
+    i1 += clen+1;
+  endwhile
+endfunction 
\ No newline at end of file
diff --git a/scripts/plot/__contour__.m b/scripts/plot/__contour__.m
--- a/scripts/plot/__contour__.m
+++ b/scripts/plot/__contour__.m
@@ -18,19 +18,19 @@
 
 ## Undocumented internal function.
 
-function [c, h] = __contour__ (varargin)
-
+function [c, hg] = __contour__ (varargin)
   ax = varargin{1};
-  z = varargin{2};
+  zlevel = varargin{2};
+  filled = "off";
 
   linespec.linestyle = "-";
-  linespec.color = "flat";
+  linespec.color = "auto";
   for i = 3 : nargin
     arg = varargin {i};
     if ((ischar (arg) || iscell (arg)))
-      [linespec, valid] = __pltopt__ ("contour", arg, false);
+      [linespec, valid] = __pltopt__ ("__contour__", arg, false);
       if (isempty (linespec.color))
-	linespec.color = "flat";
+	linespec.color = "auto";
       endif
       if (valid)
 	have_line_spec = true;
@@ -44,55 +44,431 @@
   i = 3;
   while (i < length (varargin))
     if (ischar (varargin {i}))
-      opts{end+1} = varargin{i};
-      varargin(i) = [];
-      opts{end+1} = varargin{i};
-      varargin(i) = [];
+      if (strcmpi (varargin{i}, "fill"))
+	filled = varargin {i + 1};
+	varargin(i:i+1) = [];
+      elseif (strcmpi (varargin{i}, "linecolor"))
+	linespec.color = varargin {i + 1};
+	varargin(i:i+1) = [];
+      else
+	opts{end+1} = varargin{i};
+        varargin(i) = [];
+        opts{end+1} = varargin{i};
+        varargin(i) = [];
+      endif
     else
       i++;
     endif
   endwhile
 
-  if (ischar (z))
-    if (strcmpi (z, "none"))
-      z = NaN;
-    elseif (strcmpi (z, "base"))
+  if (length(varargin) < 5)
+    z1 = varargin{3};
+    x1 = 1 : rows(z1);
+    y1 = 1 : columns(z1);
+  else
+    x1 = varargin{3};
+    y1 = varargin{4};
+    z1 = varargin{5};
+  endif
+  if (length (varargin) == 4 || length (varargin) == 6)
+    vn = varargin {end};
+    vnauto = false;
+  else
+    vnauto = true;
+    vn = 10; 
+  endif
+
+  if (strcmpi (filled, "on"))
+    if (isvector (x1) || isvector (y1))
+      [x1, y1] = meshgrid (x1, y1);
+    endif
+    [nr, nc] = size (z1);
+    x0 = prepad(x1, nc+1, 2 * x1(1, 1) - x1(1, 2), 2);
+    x0 = postpad(x0, nc+2, 2 * x1(1, nc) - x1(1, nc - 1), 2);
+    x0 = [x0(1, :); x0; x0(1, :)];
+    y0 = prepad(y1, nr+1, 2 * y1(1, 1) - y1(2, 1), 1);
+    y0 = postpad(y0, nr+2, 2 * y1(nr, 1) - y1(nr - 1, 1));
+    y0 = [y0(:, 1), y0, y0(:, 1)];
+    z0 = -Inf(nr+2, nc+2);
+    z0(2:nr+1, 2:nc+1) = z1;
+    [c, lev] = contourc (x0, y0, z0, vn);
+  else
+    [c, lev] = contourc (x1, y1, z1, vn);
+  endif
+
+  hg = hggroup ();
+  opts = __add_datasource__ ("__countour__", hg, {"x", "y", "z"}, opts{:});
+
+  addproperty ("xdata", hg, "data", x1);
+  addproperty ("ydata", hg, "data", y1);
+  addproperty ("zdata", hg, "data", z1);
+  addproperty ("contourmatrix", hg, "data", c);
+
+  addlistener (hg, "xdata", @update_data);
+  addlistener (hg, "ydata", @update_data);
+  addlistener (hg, "zdata", @update_data);
+  addlistener (hg, "contourmatrix", @update_data);
+
+  addproperty ("fill", hg, "radio", "on|{off}", filled);
+
+  ## The properties zlevel and zlevelmode don't exist in matlab, but
+  ## allow the use of contourgroups with the contour3, meshc and surfc 
+  ## functions. 
+  if (isnumeric (zlevel))
+    addproperty ("zlevelmode", hg, "radio", "{none}|auto|manual", "manual")
+    addproperty ("zlevel", hg, "data", zlevel);
+  else
+    addproperty ("zlevelmode", hg, "radio", "{none}|auto|manual", zlevel)
+    if (ischar (zlevel) && strcmpi (zlevel, "manual"))
       z = varargin{3};
       z = 2 * (min (z(:)) - max (z(:)));
-    elseif (! strcmpi (z, "level"))
-      error ("unrecognized z argument");
+      addproperty ("zlevel", hg, "data", z);
+    else
+      addproperty ("zlevel", hg, "data", 0.);
     endif
   endif
 
-  [c, lev] = contourc (varargin{3:end});
+  if (isscalar (vn))
+    lvlstep = (max(z1(:)) - min(z1(:))) / vn;
+  else
+    lvlstep = (max(z1(:)) - min(z1(:))) / 10;
+  endif
+
+  addproperty ("levellist", hg, "data", lev);
+  addproperty ("levelstep", hg, "double", lvlstep);
+  if (vnauto)
+    addproperty ("levellistmode", hg, "radio", "{auto}|manual", "auto");
+    addproperty ("levelstepmode", hg, "radio", "{auto}|manual", "auto");
+  elseif (isscalar (vn))
+    addproperty ("levellistmode", hg, "radio", "{auto}|manual", "auto");
+    addproperty ("levelstepmode", hg, "radio", "{auto}|manual", "manual");
+  else
+    addproperty ("levellistmode", hg, "radio", "{auto}|manual", "manual");
+    addproperty ("levelstepmode", hg, "radio", "{auto}|manual", "auto");
+  endif
+
+  addproperty ("labelspacing", hg, "double", 144);
+  addproperty ("textlist", hg, "data", lev);
+  addproperty ("textlistmode", hg, "radio", "{auto}|manual", "auto");
+  addproperty ("textstep", hg, "double", lvlstep);
+  addproperty ("textstepmode", hg, "radio", "{auto}|manual", "auto");
+  addproperty ("showtext", hg, "radio", "on|{off}", "off");
+
+  addproperty ("linecolor", hg, "color", linespec.color, "{auto}|none");
+  addproperty ("linestyle", hg, "linelinestyle", linespec.linestyle);
+  addproperty ("linewidth", hg, "linelinewidth", 0.5);
+
+  addlistener (hg, "fill", @update_data);
+
+  addlistener (hg, "zlevelmode", @update_zlevel);
+  addlistener (hg, "zlevel", @update_zlevel);
+
+  addlistener (hg, "levellist", @update_data);
+  addlistener (hg, "levelstep", @update_data);
+  addlistener (hg, "levellistmode", @update_data);
+  addlistener (hg, "levelstepmode", @update_data);
+
+  addlistener (hg, "labelspacing", @update_text);
+  addlistener (hg, "textlist", @update_text);
+  addlistener (hg, "textlistmode", @update_text);
+  addlistener (hg, "textstep", @update_text);
+  addlistener (hg, "textstepmode", @update_text);
+  addlistener (hg, "showtext", @update_text);
+
+  addlistener (hg, "linecolor", @update_line);
+  addlistener (hg, "linestyle", @update_line);
+  addlistener (hg, "linewidth", @update_line);
+
+  add_patch_children (hg);
+
+  if (!isempty (opts))
+    set (hg, opts{:});
+  endif
+endfunction
+
+function add_patch_children (hg)
+  c = get (hg, "contourmatrix");
+  lev = get (hg, "levellist");
+  fill = get (hg, "fill");
+  z = get (hg, "zlevel");
+  zmode = get (hg, "zlevelmode");
+  lc = get (hg, "linecolor");
+  lw = get (hg, "linewidth");
+  ls = get (hg, "linestyle");
+  filled = get (hg, "fill");
+
+  if (strcmpi (lc, "auto"))
+    lc = "flat";
+  endif
 
-  ## Decode contourc output format.
-  i1 = 1;
-  h = [];
-  while (i1 < length (c))
-    clev = c(1,i1);
-    clen = c(2,i1);
+  if (strcmpi (filled, "on"))
+    if (diff (lev) < 10*eps) 
+      lvl_eps = 1e-6;
+    else
+      lvl_eps = min (diff (lev)) / 1000.0;
+    endif
+
+    ## Decode contourc output format.
+    i1 = 1;
+    ncont = 0;
+    while (i1 < columns (c))
+      ncont++;
+      cont_lev(ncont) = c(1, i1);
+      cont_len(ncont) = c(2, i1);
+      cont_idx(ncont) = i1+1;
+
+      ii = i1+1:i1+cont_len(ncont);
+      cur_cont = c(:, ii);
+      startidx = ii(1);
+      stopidx = ii(end);
+      cont_area(ncont) = polyarea (c(1, ii), c(2, ii));
+      i1 += c(2, i1) + 1;
+    endwhile
 
-    if (all (c(:,i1+1) == c(:,i1+clen)))
-      p = c(:, i1+1:i1+clen-1);
-    else
-      p = [c(:, i1+1:i1+clen), NaN(2, 1)];
+    ## Handle for each level the case where we have (a) hole(s) in a patch.
+    ## Those are to be filled with the color of level below or with the
+    ## background colour.
+    for k = 1:numel (lev)
+      lvl_idx = find (abs (cont_lev - lev(k)) < lvl_eps);
+      len = numel (lvl_idx);
+      if (len > 1)
+	## mark = logical(zeros(size(lvl_idx)));
+	mark = false (size (lvl_idx));
+	a = 1;
+	while (a < len)
+	  ## take 1st patch
+          b = a + 1;
+          pa_idx = lvl_idx(a);
+          ## get pointer to contour start, and contour length
+          curr_ct_idx = cont_idx(pa_idx);
+          curr_ct_len = cont_len(pa_idx);
+	  ## get contour
+          curr_ct = c(:, curr_ct_idx:curr_ct_idx+curr_ct_len-1);
+          b_vec = (a+1):len;
+          next_ct_pt_vec = c(:, cont_idx(lvl_idx(b_vec)));
+          in = inpolygon (next_ct_pt_vec(1,:), next_ct_pt_vec(2,:),
+			  curr_ct(1, :), curr_ct(2, :));
+          mark(b_vec(in)) = !mark(b_vec(in));
+          a++;
+	endwhile
+	if (numel (mark) > 0)
+	  ## All marked contours describe a hole in a larger contour of
+	  ## the same level and must be filled with colour of level below.
+          ma_idx = lvl_idx(mark);
+          if (k > 1)
+	    ## Find color of level below.
+            tmp = find(abs(cont_lev - lev(k - 1)) < lvl_eps);
+            lvl_bel_idx = tmp(1);
+	    ## Set color of patches found.
+	    cont_lev(ma_idx) = cont_lev(lvl_bel_idx);
+          else
+	    ## Set lowest level contour to NaN.
+	    cont_lev(ma_idx) = NaN;
+          endif
+	endif
+      endif
+    endfor
+
+    ## The algorithm can create patches with the size of the plotting
+    ## area, we would like to draw only the patch with the highest level.
+    del_idx = [];
+    max_idx = find (cont_area == max (cont_area));
+    if (numel (max_idx) > 1)
+      ## delete double entries
+      del_idx = max_idx(1:end-1);
+      cont_area(del_idx) = cont_lev(del_idx) = [];
+      cont_len(del_idx) = cont_idx(del_idx) = [];
     endif
 
-    if (isnan (z))
-      h = [h; patch(ax, p(1,:), p(2,:), "facecolor", "none", 
-		    "edgecolor", linespec.color, "linestyle", 
-		    linespec.linestyle, "cdata", clev, opts{:})];
-    elseif (!ischar(z))
-      h = [h; patch(ax, p(1,:), p(2,:), z * ones (1, columns (p)), "facecolor",
-		    "none", "edgecolor", linespec.color, 
-		    "linestyle", linespec.linestyle, "cdata", clev, opts{:})];
+    ## Now we have everything together and can start plotting the patches
+    ## beginning with largest area.
+    [tmp, svec] = sort (cont_area);
+    len = ncont - numel (del_idx);
+    h = [];
+    for n = 1:len
+      idx = svec(n);
+      ctmp = c(:, cont_idx(idx):cont_idx(idx) + cont_len(idx) - 1);
+      if (all (ctmp(:,1) == ctmp(:,end)))
+        ctmp(:, end) = [];
+      else
+	## Special case unclosed contours
+      endif
+      h = [h; patch(ctmp(1, :), ctmp(2, :), cont_lev(idx), "edgecolor", lc, 
+		    "linestyle", ls, "linewidth", lw, "parent", hg)];
+    endfor
+
+    if (min (lev) == max (lev))
+      set (gca (), "clim", [min(lev)-1, max(lev)+1]);
     else
-      h = [h; patch(ax, p(1,:), p(2,:), clev * ones (1, columns (p)),
-		    "facecolor", "none", "edgecolor", linespec.color, 
-		    "linestyle", linespec.linestyle, "cdata", clev, opts{:})];
+      set (gca(), "clim", [min(lev), max(lev)]);
+    endif
+
+    set (gca (), "layer", "top");
+  else
+    ## Decode contourc output format.
+    i1 = 1;
+    h = [];
+    while (i1 < length (c))
+      clev = c(1,i1);
+      clen = c(2,i1);
+
+      if (all (c(:,i1+1) == c(:,i1+clen)))
+	p = c(:, i1+1:i1+clen-1);
+      else
+	p = [c(:, i1+1:i1+clen), NaN(2, 1)];
+      endif
+
+      switch (zmode)
+	case "none"
+	  h = [h; patch(p(1,:), p(2,:), "facecolor", "none", 
+			"edgecolor", lc, "linestyle", ls, "linewidth", lw,
+			"cdata", clev, "parent", hg)]; 
+	case "auto"
+	  h = [h; patch(p(1,:), p(2,:), clev * ones (1, columns (p)),
+			"facecolor", "none", "edgecolor", lc, 
+			"linestyle", ls, "linewidth", lw, "cdata", clev, 
+			"parent", hg)];
+	otherwise
+	  h = [h; patch(p(1,:), p(2,:), z * ones (1, columns (p)),
+			"facecolor", "none", "edgecolor", lc,
+			"linestyle", ls, "linewidth", lw, "cdata", clev,
+			"parent", hg)];
+      endswitch
+      i1 += clen+1;
+    endwhile
+  endif
+
+endfunction
+
+function update_zlevel (h, d)
+  z = get (h, "zlevel");
+  zmode = get (h, "zlevelmode");
+  kids = get (h, "children");
+
+  switch (zmode)
+    case "none"
+      set (kids, "zdata", []);
+    case "auto"
+      for i = 1 : length (kids)
+	set (kids(i), "zdata", get (kids (i), "cdata") .* 
+	     ones (size (get (kids (i), "xdata"))));
+      endfor
+    otherwise
+      for i = 1 : length (kids)
+	set (kids(i), "zdata", z .* ones (size (get (kids (i), "xdata"))));
+      endfor
+  endswitch
+endfunction
+
+function update_line (h, d)
+  lc = get (h, "linecolor");
+  if (strcmpi (lc, "auto"))
+    lc = "flat";
+  endif
+  set (findobj (h, "type", "patch"), "edgecolor", lc,
+       "linewidth", get (h, "linewidth"), "linestyle", get (h, "linestyle"));
+endfunction
+
+function update_data (h, d)
+  persistent recursive = false;
+
+  if (!recursive)
+    recursive = true;
+
+    delete (get (h, "children"));
+
+    if (strcmpi (get (h, "levellistmode"), "manual"))
+      lvl = get (h, "levellist");
+    elseif (strcmpi (get (h, "levelstepmode"), "manual"))
+      z = get (h, "zdata");
+      lvl = ceil ((max(z(:)) - min (z(:)) ./ get (h, "levelstep")));
+    else
+      lvl = 10;
     endif
-    i1 += clen+1;
-  endwhile
-  
+
+    if (strcmpi (get (h, "fill"), "on"))
+      X = get (h, "xdata");
+      Y = get (h, "ydata");
+      Z = get (h, "zdata");
+      if (isvector (X) || isvector (Y))
+	[X, Y] = meshgrid (X, Y);
+      endif
+      [nr, nc] = size (Z);
+      X0 = prepad(X, nc+1, 2 * X(1, 1) - X(1, 2), 2);
+      X0 = postpad(X0, nc+2, 2 * X(1, nc) - X(1, nc - 1), 2);
+      X0 = [X0(1, :); X0; X0(1, :)];
+      Y0 = prepad(Y, nr+1, 2 * Y(1, 1) - Y(2, 1), 1);
+      Y0 = postpad(Y0, nr+2, 2 * Y(nr, 1) - Y(nr - 1, 1));
+      Y0 = [Y0(:, 1), Y0, Y0(:, 1)];
+      Z0 = -Inf(nr+2, nc+2);
+      Z0(2:nr+1, 2:nc+1) = Z;
+      [c, lev] = contourc (X0, Y0, Z0, lvl);
+    else
+      [c, lev] = contourc (get (h, "xdata"), get (h, "ydata"), 
+			   get (h, "zdata"), lvl); 
+    endif
+    set (h, "contourmatrix", c);
+
+    if (strcmpi (get (h, "levellistmode"), "manual"))
+      ## Do nothing
+    elseif (strcmpi (get (h, "levelstepmode"), "manual"))
+      set (h, "levellist", lev);
+    else
+      set (h, "levellist", lev);
+      z = get (h, "zdata");
+      lvlstep = (max(z(:)) - min(z(:))) / 10;
+      set (h, "levelstep", lvlstep);
+    endif
+
+    add_patch_children (h);
+    update_text (h, d);
+  endif
+
+  recursive = false;
 endfunction
+
+function update_text (h, d)
+  persistent recursive = false;
+
+  if (!recursive)
+    recursive = true;
+
+    delete (findobj (h, "type", "text"));
+
+    if (strcmpi (get (h, "textlistmode"), "manual"))
+      lvl = get (h, "textlist");
+    elseif (strcmpi (get (h, "textstepmode"), "manual"))
+      lev = get (h, "levellist");
+
+      if (diff (lev) < 10*eps) 
+	lvl_eps = 1e-6;
+      else
+	lvl_eps = min (abs (diff (lev))) / 1000.0;
+      endif
+
+      stp = get (h, "textstep");
+      t = [0, floor(cumsum(diff (lev)) / (abs(stp) - lvl_eps))];
+      lvl = lev([true, t(1:end-1) != t(2:end)]);
+      set (h, "textlist", lvl);
+    else
+      lvl = get (h, "levellist");
+      set (h, "textlist", lvl, "textstep", get (h, "levelstep"));
+    endif
+
+    if (strcmpi (get (h, "showtext"), "on"))
+      switch (get (h, "zlevelmode"))
+	case "manual"
+	  __clabel__ (get (h, "contourmatrix"), lvl, h, 
+		      get (h, "labelspacing"), get (h, "zlevel"));
+	case "auto"
+	  __clabel__ (get (h, "contourmatrix"), lvl, h,
+		      get (h, "labelspacing"), "auto");
+	otherwise
+	  __clabel__ (get (h, "contourmatrix"), lvl, h,
+		      get (h, "labelspacing"), []);
+      endswitch
+    endif
+  endif
+
+  recursive = false;
+endfunction
diff --git a/scripts/plot/clabel.m b/scripts/plot/clabel.m
new file mode 100644
--- /dev/null
+++ b/scripts/plot/clabel.m
@@ -0,0 +1,137 @@
+## Copyright (C) 2008 David Bateman
+##
+## This file is part of Octave.
+##
+## Octave 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 3 of the License, or (at
+## your option) any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} clabel (@var{c}, @var{h})
+## @deftypefnx {Function File} {} clabel (@var{c}, @var{h}, @var{v})
+## @deftypefnx {Function File} {} clabel (@var{c}, @var{h}, "manual")
+## @deftypefnx {Function File} {} clabel (@var{c})
+## @deftypefnx {Function File} {} clabel (@var{c}, @var{h})
+## @deftypefnx {Function File} {} clabel (@dots{}, @var{prop}, @var{val}, @dots{})
+## @deftypefnx {Function File} {@var{h} =} clabel (@dots{})
+## Adds labels to the contours of a contour plot. The contour plot is specified
+## by the contour matrix @var{c} and optionally the contourgroup object @var{h}
+## that are returned by @code{contour}, @code{contourf} and @code{contour3}.
+## The contour labels are rotated and placed in the contour itself.
+##
+## By default, all contours are labelled. However, the conours to label can be
+## specified by the vector @var{v}. If the "manual" argument is given then
+## the contours to label can be selected with the mouse.
+##
+## Additional property/value pairs that are valid properties of text objects
+## can be given and are passed to the underlying text cobjects. Additionally,
+## the property "LabelSpacing" is available allowing the spacing between labels
+## on a contour (in points) to be specified. The default is 144 points, or 2
+## inches.
+##
+## The returned value @var{h} is the set of text object that represent the
+## contour labels. The "userdata" property of the text objects contains the
+## numerical value of the contour label.
+##
+## An example of the use of @code{clabel} is
+##
+## @example
+## @group
+## [c, h] = contour (peaks(), -4 : 6);
+## clabel (c, h, -4 : 2 : 6, 'fontsize', 12);
+## @end group
+## @end example
+##
+## @seealso{contour, contourf, contour3, meshc, surfc, text}
+## @end deftypefn
+
+function retval = clabel (c, varargin)
+  label_spacing = 2 * 72;
+  have_hg = false;
+  have_labelspacing = false;
+
+  if (nargin < 1)
+    print_usage()
+  elseif (nargin == 1)
+    hparent = gca ();
+  else
+    arg = varargin{1};
+    if (isscalar (arg) && ishandle(arg) && 
+	strcmp (get (arg, "type"), "hggroup"))
+      obj = get (arg);
+      if (! isfield (obj, "contourmatrix"))
+	error ("clabel: expecting the handle to be a contour group");
+      endif
+      hg = arg;
+      have_hg = true;
+      varargin(1) = [];
+    else
+      hparent = gca ();
+    endif
+  endif
+
+  if (length(varargin) > 0 && isnumeric (varargin{1}))
+    v = varargin{1}(:);
+    varargin(1) = [];
+  else
+    v = [];
+  endif
+
+  for i = 1 : length (varargin) - 1
+    arg = varargin{i};
+    if (strcmpi (arg, "labelspacing"))
+      label_spacing = varargin{i+1};
+      have_labelspacing = true;
+      varargin(i:i+1) = [];
+      break;
+    endif
+  endfor
+
+  for i = 1 : length (varargin)
+    arg = varargin{i};
+    if (strcmpi (arg, "manual"))
+      error ("clabel: manual contouring mode not supported");
+    endif
+  endfor
+
+  if (have_hg)
+    if (! isempty (v))
+      if (have_labelspacing)
+	set (hg, "textlistmode", "manual", "textlist", v, 
+	     "labelspacing", label_spacing, "showtext", "on");
+      else
+	set (hg, "textlistmode", "manual", "textlist", v, "showtext", "on");
+      endif
+    else
+      if (have_labelspacing)
+	set (hg,"showtext", "on", "labelspacing", label_spacing);
+      else
+	set (hg,"showtext", "on");
+      endif
+    endif
+    retval = findobj (hg, "type", "text");
+    if (! isempty (varargin))
+      set (retval, varargin {:});
+    endif
+  else
+    retval =  __clabel__ (c, v, hparent, label_spacing, [], varargin{:});
+  endif
+endfunction
+
+%!demo
+%! [c, h] = contour (peaks(), -4 : 6);
+%! clabel (c, h, -4 : 2 : 6, 'fontsize', 12);
+
+%!demo
+%! [c, h] = contourf (peaks(), -7 : 6);
+%! clabel (c, h, -6 : 2 : 6, 'fontsize', 12);
diff --git a/scripts/plot/contour.m b/scripts/plot/contour.m
--- a/scripts/plot/contour.m
+++ b/scripts/plot/contour.m
@@ -59,7 +59,7 @@
   unwind_protect
     axes (xh);
     newplot ();
-    [ctmp, htmp] = __contour__ (xh, NaN, varargin{:});
+    [ctmp, htmp] = __contour__ (xh, "none", varargin{:});
   unwind_protect_cleanup
     axes (oldh);
   end_unwind_protect
diff --git a/scripts/plot/contour3.m b/scripts/plot/contour3.m
--- a/scripts/plot/contour3.m
+++ b/scripts/plot/contour3.m
@@ -57,7 +57,7 @@
   unwind_protect
     axes (xh);
     newplot ();
-    [ctmp, htmp] = __contour__ (xh, "level", varargin{:});
+    [ctmp, htmp] = __contour__ (xh, "auto", varargin{:});
   unwind_protect_cleanup
     axes (oldh);
   end_unwind_protect
@@ -68,7 +68,7 @@
 
   if (nargout > 0)
     c = ctmp;
-    h = htmp
+    h = htmp;
   endif
 
 endfunction
diff --git a/scripts/plot/contourf.m b/scripts/plot/contourf.m
--- a/scripts/plot/contourf.m
+++ b/scripts/plot/contourf.m
@@ -57,204 +57,24 @@
 ## Author: Kai Habel <kai.habel@gmx.de>
 ## Author: Shai Ayal <shaiay@users.sourceforge.net>
 
-function varargout = contourf (varargin)
-
-  [ax, varargin] = __plt_get_axis_arg__ ("contourf", varargin{:});
-
-  [X, Y, Z, lvl, patch_props] = parse_args (varargin);
-
-  [nr, nc] = size (Z);
-
-  [minx, maxx] = deal (min (X(:)), max (X(:)));
-  [miny, maxy] = deal (min (Y(:)), max (Y(:)));
-
-  if (diff (lvl) < 10*eps) 
-    lvl_eps = 1e-6;
-  else
-    lvl_eps = min (diff (lvl)) / 1000.0;
-  endif
-
-  X0 = prepad(X, nc+1, 2 * X(1, 1) - X(1, 2), 2);
-  X0 = postpad(X0, nc+2, 2 * X(1, nc) - X(1, nc - 1), 2);
-  X0 = [X0(1, :); X0; X0(1, :)];
-  Y0 = prepad(Y, nr+1, 2 * Y(1, 1) - Y(2, 1), 1);
-  Y0 = postpad(Y0, nr+2, 2 * Y(nr, 1) - Y(nr - 1, 1));
-  Y0 = [Y0(:, 1), Y0, Y0(:, 1)];
+function [c, h] = contourf (varargin)
 
-  Z0 = -Inf(nr+2, nc+2);
-  Z0(2:nr+1, 2:nc+1) = Z;
-  [c, lev] = contourc (X0, Y0, Z0, lvl);
-  cmap = colormap ();
-
-  levx = linspace (min (lev), max (lev), size (cmap, 1));
-
-  newplot ();
-
-  ## Decode contourc output format.
-  i1 = 1;
-  ncont = 0;
-  while (i1 < columns (c))
-    ncont++;
-    cont_lev(ncont) = c(1, i1);
-    cont_len(ncont) = c(2, i1);
-    cont_idx(ncont) = i1+1;
-
-    ii = i1+1:i1+cont_len(ncont);
-    cur_cont = c(:, ii);
-    c(:, ii);
-    startidx = ii(1);
-    stopidx = ii(end);
-    cont_area(ncont) = polyarea (c(1, ii), c(2, ii));
-    i1 += c(2, i1) + 1;
-  endwhile
+  [xh, varargin] = __plt_get_axis_arg__ ("contour", varargin{:});
 
-  ## Handle for each level the case where we have (a) hole(s) in a patch.
-  ## Those are to be filled with the color of level below or with the
-  ## background colour.
-  for k = 1:numel (lev)
-    lvl_idx = find (abs (cont_lev - lev(k)) < lvl_eps);
-    len = numel (lvl_idx);
-    if (len > 1)
-      ## mark = logical(zeros(size(lvl_idx)));
-      mark = false (size (lvl_idx));
-      a = 1;
-      while (a < len)
-        # take 1st patch
-        b = a + 1;
-        pa_idx = lvl_idx(a);
-        # get pointer to contour start, and contour length
-        curr_ct_idx = cont_idx(pa_idx);
-        curr_ct_len = cont_len(pa_idx);
-        # get contour
-        curr_ct = c(:, curr_ct_idx:curr_ct_idx+curr_ct_len-1);
-        b_vec = (a+1):len;
-        next_ct_pt_vec = c(:, cont_idx(lvl_idx(b_vec)));
-        in = inpolygon (next_ct_pt_vec(1,:), next_ct_pt_vec(2,:),
-			curr_ct(1, :), curr_ct(2, :));
-        mark(b_vec(in)) = !mark(b_vec(in));
-        a++;
-      endwhile
-      if (numel (mark) > 0)
-	## All marked contours describe a hole in a larger contour of
-	## the same level and must be filled with colour of level below.
-        ma_idx = lvl_idx(mark);
-        if (k > 1)
-	  ## Find color of level below.
-          tmp = find(abs(cont_lev - lev(k - 1)) < lvl_eps);
-          lvl_bel_idx = tmp(1);
-	  ## Set color of patches found.
-	  cont_lev(ma_idx) = cont_lev(lvl_bel_idx);
-        else
-	  ## Set lowest level contour to NaN.
-	  cont_lev(ma_idx) = NaN;
-        endif
-      endif
-    endif
-  endfor
-
-  ## The algorithm can create patches with the size of the plotting
-  ## area, we would like to draw only the patch with the highest level.
-  del_idx = [];
-  max_idx = find (cont_area == max (cont_area));
-  if (numel (max_idx) > 1)
-    # delete double entries
-    del_idx = max_idx(1:end-1);
-    cont_area(del_idx) = cont_lev(del_idx) = [];
-    cont_len(del_idx) = cont_idx(del_idx) = [];
-  endif
-
-  ## Now we have everything together and can start plotting the patches
-  ## beginning with largest area.
-  [tmp, svec] = sort (cont_area);
-  len = ncont - numel (del_idx);
-  h = zeros (1, len);
-  for n = 1:len
-    idx = svec(n);
-    ii = cont_idx(idx):cont_idx(idx) + cont_len(idx) - 2;
-    h(n) = patch (c(1, ii), c(2, ii), cont_lev(idx), patch_props{:});
-  endfor
-
-  if (min (lev) == max (lev))
-    set (gca (), "clim", [min(lev)-1, max(lev)+1]);
-  else
-    set (gca(), "clim", [min(lev), max(lev)]);
-  endif
-
-  set (gca (), "layer", "top");
+  oldh = gca ();
+  unwind_protect
+    axes (xh);
+    newplot ();
+    [ctmp, htmp] = __contour__ (xh, "none", "fill", "on",
+				"linecolor", "black", varargin{:});
+  unwind_protect_cleanup
+    axes (oldh);
+  end_unwind_protect
 
   if (nargout > 0)
-    varargout{2} = h;
-    varargout{1} = c;
-  endif
-
-endfunction
-
-function [X, Y, Z, lvl, patch_props] = parse_args (arg)
-
-  patch_props = {};
-  nolvl = false;
-
-  for n = 1:numel (arg)
-    if (ischar (arg{n}))
-      patch_props = arg(n:end);
-      arg(n:end) = [];
-      break;
-    endif
-  endfor
-
-  if (mod (numel (patch_props), 2) != 0)
-    error ("patch: property value is missing");
-  endif
-
-  if (numel (arg) < 3)
-    Z = arg{1};
-    [X, Y] = meshgrid (1:columns (Z), 1:rows (Z));
+    c = ctmp;
+    h = htmp;
   endif
-
-  if (numel (arg) == 1)
-    nolvl = true;
-    arg(1) = [];
-  elseif (numel (arg) == 2)
-    lvl = arg{2};
-    arg(1:2) = [];
-  elseif (numel (arg) == 3)
-    arg{1:3};
-    [X, Y, Z] = deal (arg{1:3});
-    arg(1:3) = [];
-    nolvl = true;
-  elseif (numel (arg) == 4)
-    [X, Y, Z, lvl] = deal (arg{1:4});
-    arg(1:4) = [];
-  endif
-
-  if (! ((isvector (X) && isvector (Y)) || size_equal (X, Y)))
-    error ("patch: X and Y must be of same size")
-  endif
-
-  if (isvector (X) || isvector (Y))
-    [X, Y] = meshgrid (X, Y);
-  endif
-
-  Z_no_inf = Z(!isinf (Z));
-  [minz, maxz] = deal (min (Z_no_inf(:)), max (Z_no_inf(:)));
-  Z(isnan (Z)) = -Inf;
-
-  if (nolvl)
-    lvl = linspace (minz, maxz, 12);
-  endif
-
-  if (isscalar (lvl))
-    lvl = linspace (minz, maxz, lvl + 2)(1:end-1);
-  else
-    idx1 = find(lvl < minz);
-    idx2 = find(lvl > maxz);
-    lvl(idx1(1:end-1)) = [];
-    lvl(idx2) = [];
-    if (isempty (lvl))
-      lvl = [minz, minz];
-    endif
-  endif
-
 endfunction
 
 %!demo