## Copyright (C) 2007, 2008, 2009 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} {} plotyy (@var{x1}, @var{y1}, @var{x2}, @var{y2})

 ## @deftypefnx {Function File} {} plotyy (@dots{}, @var{fun})

 ## @deftypefnx {Function File} {} plotyy (@dots{}, @var{fun1}, @var{fun2})

 ## @deftypefnx {Function File} {} plotyy (@var{h}, @dots{})

 ## @deftypefnx {Function File} {[@var{ax}, @var{h1}, @var{h2}] =} plotyy (@dots{})

 ## Plots two sets of data with independent y-axes.  The arguments @var{x1} and

 ## @var{y1} define the arguments for the first plot and @var{x1} and @var{y2}

 ## for the second. 

 ##

 ## By default the arguments are evaluated with 

 ## @code{feval (@@plot, @var{x}, @var{y})}.  However the type of plot can be

 ## modified with the @var{fun} argument, in which case the plots are

 ## generated by @code{feval (@var{fun}, @var{x}, @var{y})}.  @var{fun} can be 

 ## a function handle, an inline function or a string of a function name.

 ##

 ## The function to use for each of the plots can be independently defined 

 ## with @var{fun1} and @var{fun2}.

 ##

 ## If given, @var{h} defines the principal axis in which to plot the @var{x1}

 ## and @var{y1} data.  The return value @var{ax} is a two element vector with

 ## the axis handles of the two plots.  @var{h1} and @var{h2} are handles to

 ## the objects generated by the plot commands.

 ##

 ## @example

 ## @group

 ## x = 0:0.1:2*pi; 

 ## y1 = sin (x);

 ## y2 = exp (x - 1);

 ## ax = plotyy (x, y1, x - 1, y2, @@plot, @@semilogy);

 ## xlabel ("X");

 ## ylabel (ax(1), "Axis 1");

 ## ylabel (ax(2), "Axis 2");

 ## @end group

 ## @end example

 ## @end deftypefn

 function [Ax, H1, H2] = plotyy (varargin)

   ## Don't use __plt_get_axis_arg__ here as ax is a two vector for plotyy

   if (nargin > 1 && length (varargin{1}) == 2 && ishandle(varargin{1}(1)) 

       &&  ishandle(varargin{1}(2)) && 

       all (floor (varargin{1}) != varargin{1}))

     obj1 = get (varargin{1}(1));

     obj2 = get (varargin{1}(2));

     if (strcmp (obj1.type, "axes") || strcmp (obj2.type, "axes"))

       ax = [obj1, obj2];

       varargin(1) = [];

       if (isempty (varargin))

 	varargin = {};

       endif

     else

       error ("plotyy: expecting first argument to be axes handle");

     endif

   else

     f = get (0, "currentfigure");

     if (isempty (f))

       f = figure ();

     endif

     ax = get (f, "children");

     if (length (ax) > 2)

       for i = 3 : length (ax)

         delete (ax (i));

       endfor

       ax = ax(1:2);

     elseif (length (ax) == 1)

       ax(2) = axes ();

     elseif (isempty (ax))

       ax(1) = axes ();

       ax(2) = axes ();

     endif

     if (nargin < 2)

       varargin = {};

     endif

   endif 

   if (nargin < 4)

     print_usage ();

   endif

   oldh = gca ();

   unwind_protect

     [ax, h1, h2] = __plotyy__ (ax, varargin{:});

   unwind_protect_cleanup

     ## Only change back to the old axis if we didn't delete it

     if (ishandle(oldh) && strcmp (get (oldh, "type"), "axes"))

       axes (oldh);

     endif

   end_unwind_protect

   if (nargout > 0)

     Ax = ax;

     H1 = h1;

     H2 = h2;

   endif

 endfunction

 function [ax, h1, h2] = __plotyy__ (ax, x1, y1, x2, y2, varargin)

   if (nargin > 5)

     fun1 = varargin{1};

   else

     fun1 = @plot;

   endif

   if (nargin > 6)

     fun2 = varargin{2};

   else

     fun2 = fun1;

   endif

   xlim = [min([x1(:); x2(:)]), max([x1(:); x2(:)])];

   if (ishandle(ax(1)) && strcmp (get (ax(1), "type"), "axes"))

     axes (ax(1));

   else

     ax(1) = axes ();

   endif

   newplot ();

   h1 = feval (fun1, x1, y1);

   set (ax(1), "ycolor", getcolor (h1(1)));

   set (ax(1), "xlim", xlim);

   cf = gcf ();

   set (cf, "nextplot", "add");

   if (ishandle(ax(2)) && strcmp (get (ax(2), "type"), "axes"))

     axes (ax(2));

   else

     ax(2) = axes ();

   endif

   newplot ();

   colors = get (ax(1), "colororder");

   set (ax(2), "colororder", [colors(2:end,:); colors(1,:)]);

   h2 = feval (fun2, x2, y2);

   set (ax(2), "yaxislocation", "right");

   set (ax(2), "ycolor", getcolor (h2(1)));

   set (ax(2), "position", get (ax(1), "position"));

   set (ax(2), "xlim", xlim);

   set (ax(2), "color", "none");

   ## Add invisible text objects that when destroyed, 

   ## also remove the other axis

   t1 = text (0, 0, "", "parent", ax(1), "tag", "plotyy", 

 	     "handlevisibility", "off", "visible", "off",

 	     "xliminclude", "off", "yliminclude", "off");

   t2 = text (0, 0, "", "parent", ax(2), "tag", "plotyy", 

 	     "handlevisibility", "off", "visible", "off",

 	     "xliminclude", "off", "yliminclude", "off");

   set (t1, "deletefcn", {@deleteplotyy, ax(2), t2});

   set (t2, "deletefcn", {@deleteplotyy, ax(1), t1});

   addlistener (ax(1), "position", {@update_position, ax(2)});

   addlistener (ax(2), "position", {@update_position, ax(1)});

   addlistener (ax(1), "view", {@update_position, ax(2)});

   addlistener (ax(2), "view", {@update_position, ax(1)});

   ## Tag the plotyy axes, so we can use that information

   ## not to mirror the y axis tick marks

   set (ax, "tag", "plotyy")

 endfunction

 %!demo

 %! clf

 %! x = 0:0.1:2*pi; 

 %! y1 = sin (x);

 %! y2 = exp (x - 1);

 %! ax = plotyy (x, y1, x - 1, y2, @plot, @semilogy);

 %! xlabel ("X");

 %! ylabel (ax(1), "Axis 1");

 %! ylabel (ax(2), "Axis 2");

 function deleteplotyy (h, d, ax2, t2)

   if (ishandle (ax2) && strcmp (get (ax2, "type"), "axes") && 

       (isempty (gcbf()) || strcmp (get (gcbf(), "beingdeleted"),"off")) &&

       strcmp (get (ax2, "beingdeleted"), "off"))

     set (t2, "deletefcn", []);

     delete (ax2);

   endif

 endfunction

 function update_position (h, d, ax2)

   persistent recursion = false;

   ## Don't allow recursion

   if (! recursion)

     unwind_protect

       recursion = true;

       position = get (h, "position");

       view = get (h, "view");

       oldposition = get (ax2, "position");

       oldview = get (ax2, "view");

       if (! (isequal (position, oldposition) && isequal (view, oldview)))

 	set (ax2, "position", position, "view", view);

       endif

     unwind_protect_cleanup

       recursion = false;

     end_unwind_protect

   endif  

 endfunction

 function color = getcolor (ax)

   obj = get (ax);

   if (isfield (obj, "color"))

     color = obj.color;

   elseif (isfield (obj, "facecolor") && ! ischar (obj.facecolor))

     color = obj.facecolor;

   elseif (isfield (obj, "edgecolor") && !  ischar (obj.edgecolor))

     color = obj.edgecolor;

   else

     color = [0, 0, 0];

   endif

 endfunction