## 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

    ca = get (f, "currentaxes");

    if (isempty (ca))

      ax = [];

    elseif (strcmp (get (ca, "tag"), "plotyy"));

      ax = get (ca, "__plotyy_axes__");

    else

      ax = ca;

    endif

    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)});

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

  addlistener (ax(2), "dataaspectratio", {@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")

  ## Store the axes handles for the sister axes.

  addproperty ("__plotyy_axes__", ax(1), "data", ax);

  addproperty ("__plotyy_axes__", ax(2), "data", ax);

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");

%!demo

%! clf

%! x = linspace (-1, 1, 201);

%! subplot (2, 2, 1)

%! plotyy (x, sin(pi*x), x, 10*cos(pi*x))

%! subplot (2, 2, 2)

%! surf (peaks (25))

%! subplot (2, 2, 3)

%! contour (peaks (25))

%! subplot (2, 2, 4)

%! plotyy (x, 10*sin(2*pi*x), x, cos(2*pi*x))

%! axis square

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");

      dataaspectratio = get (h, "dataaspectratio");

      oldposition = get (ax2, "position");

      oldview = get (ax2, "view");

      olddataaspectratio = get (ax2, "dataaspectratio");

      if (! (isequal (position, oldposition)

             && isequal (view, oldview)

             && isequal (dataaspectratio, olddataaspectratio)))

	set (ax2, "position", position,

                  "view", view,

		  "dataaspectratio", dataaspectratio);

      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