+## Copyright (C) 2012 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} {} rectangle ()
+## @deftypefnx {Function File} {} rectangle (@dots{}, "Position", @var{pos})
+## @deftypefnx {Function File} {} rectangle (@dots{}, "Curvature", @var{curv})
+## @deftypefnx {Function File} {} rectangle (@dots{}, "EdgeColor", @var{ec})
+## @deftypefnx {Function File} {} rectangle (@dots{}, "FaceColor", @var{fc})
+## @deftypefnx {Function File} {@var{h} =} rectangle (@dots{})
+##
+## Draw rectangular patch defined by @var{pos} and @var{curv}. The variable
+## @code{@var{pos}(1:2)} defines the lower left-hand corner of the patch
+## and @code{@var{pos}(3:4)} defines its width and height. By default, the
+## value of @var{pos} is @code{[0, 0, 1, 1]}.
+##
+## The variable @var{curv} defines the curvature of the sides of the rectangle
+## and may be a scalar or two-element vector with values between 0 and 1.
+## A value of 0 represents no curvature of the side, whereas a value of 1
+## means that the side is entirely curved into the arc of a circle.
+## If @var{curv} is a two-element vector, then the first element is the
+## curvature along the x-axis of the patch and the second along y-axis.
+##
+## If @var{curv} is a scalar, it represents the curvature of the shorter of the
+## two sides of the rectangle and the curvature of the other side is defined
+## by
+##
+## @example
+## min (pos (1:2)) / max (pos (1:2)) * curv
+## @end example
+##
+## Other properties are passed to the underlying patch command.
+##
+## The optional return value @var{h} is a graphics handle to the created
+## rectangle object.
+## @end deftypefn
+## @seealso{patch}
+
+function h = rectangle (varargin)
+
+ [hax, varargin] = __plt_get_axis_arg__ ("rectangle", varargin{:});
+
+ tmp = __rectangle__ (hax, varargin{:});
+
+ if (nargout > 0)
+ h = tmp;
+ endif
+endfunction
+
+function hg = __rectangle__ (hax, varargin)
+
+ iarg = 1;
+ pos = [0, 0, 1, 1];
+ curv2 = [0, 0];
+ ec = [0, 0, 0];
+ fc = "none";
+
+ while (iarg < length (varargin))
+ arg = varargin{iarg};
+ if (ischar(arg))
+ if (strcmpi (arg, "position"))
+ pos = varargin{iarg+1};
+ varargin(iarg:iarg+1) = [];
+ if (!isvector (pos) || numel (pos) != 4)
+ error ("rectangle: position must be a 4 element vector");
+ endif
+ elseif (strcmpi (arg, "curvature"))
+ curv2 = varargin{iarg+1};
+ varargin(iarg:iarg+1) = [];
+ if (!isnumeric (curv2) || (numel (curv2) != 1 && numel (curv2) != 2))
+ error ("rectangle: curvature must be a 2 element vector or a scalar");
+ endif
+ if (any (curv2 < 0) || any (curv2 > 1))
+ error ("rectangle: curvature values must be between 0 and 1");
+ endif
+ elseif (strcmpi (arg, "edgecolor"))
+ ec = varargin{iarg+1};
+ varargin(iarg:iarg+1) = [];
+ elseif (strcmpi (arg, "facecolor"))
+ fc = varargin{iarg+1};
+ varargin(iarg:iarg+1) = [];
+ else
+ iarg ++;
+ endif
+ else
+ iarg ++;
+ endif
+ endwhile
+
+ if (numel (curv2) == 1)
+ [a, ai] = min (pos (3 : 4));
+ [b, bi] = max (pos (3 : 4));
+ if (ai < bi)
+ curv = [curv2, curv2 .* a ./ b];
+ else
+ curv = [curv2 .* a ./ b, curv2];
+ endif
+ else
+ curv = curv2;
+ endif
+
+ if (all (curv) < 0.01)
+ ## Special case : no curvature
+ x = [pos(1), pos(1) + pos(3), pos(1) + pos(3), pos(1), pos(1)];
+ y = [pos(2), pos(2), pos(2) + pos(4), pos(2) + pos(4), pos(2)];
+ else
+ p = pi / 2 * [0 : 15] / 15;
+ c = curv .* pos(3 : 4) / 2;
+ cx = c(1) * sin (p) - c(1);
+ cy = c(2) * cos (p) - c(2);
+ x = [pos(1) - fliplr(cx), pos(1) + pos(3) + cx, ...
+ pos(1) + pos(3) + fliplr(cx), pos(1) - cx, pos(1)];
+ y = [pos(2) - fliplr(cy), pos(2) - cy, pos(2) + pos(4) + fliplr(cy), ...
+ pos(2) + pos(4) + cy, pos(2) + c(2)];
+ endif
+
+ hg = hggroup ();
+
+ h = patch ("xdata", x(:), "ydata", y(:), "facecolor", fc, "edgecolor", ec, ...
+ "parent", hg, varargin{:});
+
+ addproperty ("curvature", hg, "data", curv2);
+ addproperty ("position", hg, "data", pos);
+ addproperty ("edgecolor", hg, "patchedgecolor", get (h, "edgecolor"));
+ addproperty ("linewidth", hg, "patchlinewidth", get (h, "linewidth"));
+ addproperty ("linestyle", hg, "patchlinestyle", get (h, "linestyle"));
+ addproperty ("facecolor", hg, "patchfacecolor", get (h, "facecolor"));
+
+ addlistener (hg, "curvature", @update_data);
+ addlistener (hg, "position", @update_data);
+ addlistener (hg, "edgecolor", @update_props);
+ addlistener (hg, "linewidth", @update_props);
+ addlistener (hg, "linestyle", @update_props);
+ addlistener (hg, "facecolor", @update_props);
+endfunction
+
+function update_data (h, d)
+ persistent recursion = false;
+
+ ## Don't allow recursion
+ if (!recursion)
+ unwind_protect
+ recursion = true;
+
+ kids = get (h, "children");
+ pos = get (h, "position");
+ curv2 = get (h, "curvature");
+
+ if (numel (curv2) == 1)
+ [a, ai] = min (pos (3 : 4));
+ [b, bi] = max (pos (3 : 4));
+ if (ai < bi)
+ curv = [curv2, curv2 .* a ./ b];
+ else
+ curv = [curv2 .* a ./ b, curv2];
+ endif
+ else
+ curv = curv2;
+ endif
+
+ if (all (curv) < 0.01)
+ ## Special case : no curvature
+ x = [pos(1), pos(1) + pos(3), pos(1) + pos(3), pos(1), pos(1)];
+ y = [pos(2), pos(2), pos(2) + pos(4), pos(2) + pos(4), pos(2)];
+ else
+ p = pi / 2 * [0 : 15] / 15;
+ c = curv .* pos(3 : 4) / 2;
+ cx = c(1) * sin (p) - c(1);
+ cy = c(2) * cos (p) - c(2);
+ x = [pos(1) - fliplr(cx), pos(1) + pos(3) + cx, ...
+ pos(1) + pos(3) + fliplr(cx), pos(1) - cx, pos(1)];
+ y = [pos(2) - fliplr(cy), pos(2) - cy, pos(2) + pos(4) + fliplr(cy), ...
+ pos(2) + pos(4) + cy, pos(2) + c(2)];
+ endif
+
+ set (kids, "xdata", x, "ydata", y);
+ unwind_protect_cleanup
+ recursion = false;
+ end_unwind_protect
+ endif
+endfunction
+
+function update_props (h, d)
+ kids = get (h, "children");
+ set (kids, "edgecolor", get (h, "edgecolor"),
+ "linewidth", get (h, "linewidth"),
+ "linestyle", get (h, "linestyle"),
+ "facecolor", get (h, "facecolor"));
+endfunction
+
+
+%!demo
+%! clf
+%! axis equal
+%! rectangle ("Position", [0.05, 0.05, 0.9, 0.9], "Curvature", [0.5, 0.5]);
+
+%!demo
+%! clf
+%! axis equal
+%! rectangle ("Position", [0.05, 0.05, 0.9, 0.4], "Curvature", 1.0);
+
+%!demo
+%! clf
+%! axis equal
+%! h = rectangle ("Position", [0.05, 0.05, 0.9, 0.4], "Curvature", 1.0);
+%! set (h, "FaceColor", [0, 1, 0]);
+