## Copyright (C) 1995-2013 John W. Eaton
##
## 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} {} subplot (@var{rows}, @var{cols}, @var{index})
## @deftypefnx {Function File} {} subplot (@var{rcn})
## @deftypefnx {Function File} {} subplot (@var{hax})
## @deftypefnx {Function File} {} subplot (@dots{}, "align")
## @deftypefnx {Function File} {} subplot (@dots{}, "replace")
## @deftypefnx {Function File} {} subplot (@dots{}, "position", @var{pos})
## @deftypefnx {Function File} {} subplot (@dots{}, @var{prop}, @var{val}, @dots{})
## @deftypefnx {Function File} {@var{hax} =} subplot (@dots{})
## Set up a plot grid with @var{rows} by @var{cols} subwindows and set the
## current axes for plotting (@code{gca}) to the location given by @var{index}.
##
## If only one numeric argument is supplied, then it must be a three digit
## value specifying the number of rows in digit 1, the number of
## columns in digit 2, and the plot index in digit 3.
##
## The plot index runs row-wise; First, all columns in a row are numbered
## and then the next row is filled.
##
## For example, a plot with 2x3 grid will have plot indices running as follows:
## @tex
## \vskip 10pt
## \hfil\vbox{\offinterlineskip\hrule
## \halign{\vrule#&&\qquad\hfil#\hfil\qquad\vrule\cr
## height13pt&1&2&3\cr height12pt&&&\cr\noalign{\hrule}
## height13pt&4&5&6\cr height12pt&&&\cr\noalign{\hrule}}}
## \hfil
## \vskip 10pt
## @end tex
## @ifnottex
##
## @example
## @group
## +-----+-----+-----+
## |  1  |  2  |  3  |
## +-----+-----+-----+
## |  4  |  5  |  6  |
## +-----+-----+-----+
## @end group
## @end example
##
## @end ifnottex
##
## @var{index} may also be a vector.  In this case, the new axis will enclose
## the grid locations specified.  The first demo illustrates this:
##
## @example
## demo ("subplot", 1)
## @end example
##
## The index of the subplot to make active may also be specified by its axes
## handle, @var{hax}, returned from a previous @code{subplot} command.
##
## If the option @qcode{"align"} is given then the plot boxes of the subwindows
## will align, but this may leave no room for axis tick marks or labels.
##
## If the option @qcode{"replace"} is given then the subplot axis will be
## reset, rather than just switching the current axis for plotting to the
## requested subplot.
##
## The @qcode{"position"} property can be used to exactly position the subplot
## axes within the current figure.  The option @var{pos} is a 4-element vector
## [x, y, width, height] that determines the location and size of the axes.
## The values in @var{pos} are normalized in the range [0,1].
##
## Any property/value pairs are passed directly to the underlying axes object.
##
## If the output @var{hax} is requested, subplot returns the axis handle for
## the subplot.  This is useful for modifying the properties of a subplot
## using @code{set}.
## @seealso{axes, plot, gca, set}
## @end deftypefn

## Author: Vinayak Dutt <Dutt.Vinayak@mayo.EDU>
## Adapted-By: jwe

function h = subplot (varargin)

  align_axes = false;
  replace_axes = false;
  have_position = false;
  initial_args_decoded = false;

  if (nargin >= 3)
    ## R, C, N?
    arg1 = varargin{1};
    arg2 = varargin{2};
    arg3 = varargin{3};
    if (   isnumeric (arg1) && isscalar (arg1)
        && isnumeric (arg2) && isscalar (arg2)
        && isnumeric (arg3))
      rows = arg1;
      cols = arg2;
      index = arg3;
      varargin(1:3) = [];
      initial_args_decoded = true;
    endif
  endif

  if (! initial_args_decoded && nargin > 1)
    ## check for "position", pos, ...
    if (strcmpi (varargin{1}, "position"))
      arg = varargin{2};
      if (isnumeric (arg) && numel (arg) == 4)
        pos = arg;
        varargin(1:2) = [];
        have_position = true;
        initial_args_decoded = true;
      else
        error ("subplot: POSITION must be a 4-element numeric array");
      endif
    endif
  endif

  if (! initial_args_decoded && nargin > 0)
    arg = varargin{1};
    if (nargin == 1 && isaxes (arg))
      ## Axes handle
      axes (arg);
      cf = get (0, "currentfigure");
      set (cf, "nextplot", "add");
      return;
    elseif (isscalar (arg) && arg >= 0)
      ## RCN?
      index = rem (arg, 10);
      arg = (arg - index) / 10;
      cols = rem (arg, 10);
      arg = (arg - cols) / 10;
      rows = rem (arg, 10);
      varargin(1) = [];
      initial_args_decoded = true;
    else
      error ("subplot: expecting axes handle or RCN argument");
    endif
  endif

  if (! initial_args_decoded)
    print_usage ();
  endif

  if (! have_position)
    cols = round (cols);
    rows = round (rows);
    index = round (index);

    if (any (index < 1) || any (index > rows*cols))
      error ("subplot: INDEX value must be >= 1 and <= ROWS*COLS");
    endif

    if (rows < 1 || cols < 1 || index < 1)
      error ("subplot: ROWS, COLS, and INDEX must be be positive");
    endif
  endif

  ## Process "align" and "replace" options
  idx = strcmpi (varargin, "align");
  if (any (idx))
    align_axes = true;
    varargin(idx) = [];
  endif

  idx = strcmpi (varargin, "replace");
  if (any (idx))
    replace_axes = true;
    varargin(idx) = [];
  endif

  axesunits = get (0, "defaultaxesunits");
  cf = gcf ();
  figureunits = get (cf, "units");
  unwind_protect
    set (0, "defaultaxesunits", "normalized");
    set (cf, "units", "pixels");

    ## FIXME: At the moment we force gnuplot to use the aligned mode
    ##        which will set "activepositionproperty" to "position".
    ##        This can yield to text overlap between labels and titles.
    ##        See bug #31610.
    if (strcmp (get (cf, "__graphics_toolkit__"), "gnuplot"))
      align_axes = true;
    endif

    ## Oh, the things we do for Matlab compatibility.  Using the "position"
    ## argument changes things so much that it became clearer to replicate
    ## large chunks of code rather than have lots of if/else statements.
    if (! have_position)
      ## Normal case where subplot indices have been given
      pos = subplot_position (rows, cols, index, "position");
      outerpos = subplot_position (rows, cols, index, "outerposition");
      box = [pos(1:2), pos(1:2)+pos(3:4)];
      outerbox = [outerpos(1:2), outerpos(1:2)+outerpos(3:4)];
      looseinset = [box(1:2)-outerbox(1:2), outerbox(3:4)-box(3:4)];

      if (align_axes)
        activepositionproperty = "position";
      else
        activepositionproperty = "outerposition";
      endif

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

      found = false;
      kids = get (cf, "children");
      for child = kids(:)'
        ## Check whether this child is still valid; this might not be the
        ## case anymore due to the deletion of previous children (due to
        ## "deletefcn" callback or for legends/colorbars that are deleted
        ## with their corresponding axes).
        if (! ishandle (child))
          continue;
        endif
        if (strcmp (get (child, "type"), "axes"))
          ## Skip legend and colorbar objects.
          if (any (strcmp (get (child, "tag"), {"legend", "colorbar"})))
            continue;
          endif
          objpos = get (child, "outerposition");
          if (all (abs (objpos - outerpos) < eps) && ! replace_axes)
            ## If the new axes are in exactly the same position
            ## as an existing axes object, use the existing axes.
            found = true;
            hsubplot = child;
          else
            ## If the new axes overlap an old axes object, delete the old axes.
            if (align_axes)
              objpos = get (child, "position");
            endif
            x0 = pos(1);
            x1 = x0 + pos(3);
            y0 = pos(2);
            y1 = y0 + pos(4);
            objx0 = objpos(1);
            objx1 = objx0 + objpos(3);
            objy0 = objpos(2);
            objy1 = objy0 + objpos(4);
            if (! (x0 >= objx1 || x1 <= objx0 || y0 >= objy1 || y1 <= objy0))
              delete (child);
            endif
          endif
        endif
      endfor

      if (found)
        ## Switch to existing subplot
        set (cf, "currentaxes", hsubplot);
      else
        hsubplot = axes ("box", "off",
                         "position", pos,
                         "looseinset", looseinset,
                         "activepositionproperty", activepositionproperty,
                         varargin{:});
        addproperty ("subplot_align", hsubplot, "boolean", true);
        addlistener (hsubplot, "position", @subplot_align);
        if (! align_axes)
          set (hsubplot, "subplot_align", false)
          subplot_align (hsubplot)
        endif
      endif
    else
      ## "position" attribute given
      if (align_axes)
        activepositionproperty = "position";
      else
        activepositionproperty = "outerposition";
      endif

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

      found = false;
      kids = get (cf, "children");
      for child = kids(:)'
        ## Check whether this child is still valid; this might not be the
        ## case anymore due to the deletion of previous children (due to
        ## "deletefcn" callback or for legends/colorbars that are deleted
        ## with their corresponding axes).
        if (! ishandle (child))
          continue;
        endif
        if (strcmp (get (child, "type"), "axes"))
          ## Skip legend and colorbar objects.
          if (any (strcmp (get (child, "tag"), {"legend", "colorbar"})))
            continue;
          endif
          objpos = get (child, "position");
          if (all (abs (objpos - pos) < eps) && ! replace_axes)
            ## If the new axes are in exactly the same position
            ## as an existing axes object, use the existing axes.
            found = true;
            hsubplot = child;
          else
            ## If the new axes overlap an old axes object, delete the old axes.
            x0 = pos(1);
            x1 = x0 + pos(3);
            y0 = pos(2);
            y1 = y0 + pos(4);
            objx0 = objpos(1);
            objx1 = objx0 + objpos(3);
            objy0 = objpos(2);
            objy1 = objy0 + objpos(4);
            if (! (x0 >= objx1 || x1 <= objx0 || y0 >= objy1 || y1 <= objy0))
              delete (child);
            endif
          endif
        endif
      endfor

      if (found)
        ## Switch to existing subplot
        set (cf, "currentaxes", hsubplot);
      else
        hsubplot = axes ("box", "off",
                         "position", pos,
                         "activepositionproperty", activepositionproperty,
                         varargin{:});
        addproperty ("subplot_align", hsubplot, "boolean", true);
        addlistener (hsubplot, "position", @subplot_align);
        if (! align_axes)
          set (hsubplot, "subplot_align", false)
          subplot_align (hsubplot)
        endif
      endif
    endif  # ! have_position

  unwind_protect_cleanup
    set (0, "defaultaxesunits", axesunits);
    set (cf, "units", figureunits);
  end_unwind_protect

  if (nargout > 0)
    h = hsubplot;
  endif

endfunction

function pos = subplot_position (rows, cols, index, position_property)

  if (rows == 1 && cols == 1)
    ## Trivial result for subplot (1,1,1)
    if (strcmpi (position_property, "position"))
      pos = get (0, "defaultaxesposition");
    else
      pos = get (0, "defaultaxesouterposition");
    endif
    return;
  endif

  if (strcmp (position_property, "outerposition"))
    margins.left   = 0.05;
    margins.bottom = 0.05;
    margins.right  = 0.05;
    margins.top    = 0.05;
    margins.column = 0.04 / cols;
    margins.row    = 0.04 / rows;
    width = 1 - margins.left - margins.right - (cols-1)*margins.column;
    width = width / cols;
    height = 1 - margins.top - margins.bottom - (rows-1)*margins.row;
    height = height / rows;
  else
    defaultaxesposition = get (0, "defaultaxesposition");

    ## The outer margins surrounding all subplot "positions" are independent
    ## of the number of rows and/or columns
    margins.left   = defaultaxesposition(1);
    margins.bottom = defaultaxesposition(2);
    margins.right  = 1.0 - margins.left - defaultaxesposition(3);
    margins.top    = 1.0 - margins.bottom - defaultaxesposition(4);

    ## Fit from Matlab experiments
    pc = 1 ./ [0.1860, (margins.left + margins.right - 1)];
    margins.column = 1 ./ polyval (pc , cols);
    pr = 1 ./ [0.2282, (margins.top + margins.bottom - 1)];
    margins.row    = 1 ./ polyval (pr , rows);

    ## Calculate the width/height of the subplot axes "position".
    ## This is also consistent with Matlab
    width = 1 - margins.left - margins.right - (cols-1)*margins.column;
    width = width / cols;
    height = 1 - margins.top - margins.bottom - (rows-1)*margins.row;
    height = height / rows;
  endif

  ## Index offsets from the lower left subplot
  yi = fix ((index(:)-1)/cols);
  xi = index(:) - yi*cols - 1;
  yi = (rows - 1) - yi;

  ## Lower left corner of the subplot, i.e., position(1:2)
  x0 = xi .* (width + margins.column) + margins.left;
  y0 = yi .* (height + margins.row) + margins.bottom;

  if (numel (x0) > 1)
    ## subplot (row, col, m:n)
    x1 = max (x0(:)) + width;
    y1 = max (y0(:)) + height;
    x0 = min (x0(:));
    y0 = min (y0(:));
    pos = [x0, y0, x1-x0, y1-y0];
  else
    ## subplot (row, col, num)
    pos = [x0, y0, width, height];
  endif

endfunction

function subplot_align (h, varargin)
  persistent updating = false;

  if (! updating)
    unwind_protect
      updating = true;
      hfig = ancestor (h, "figure");
      hsubplots = findall (hfig, "type", "axes", "subplot_align", "off");
      if (! isempty (hsubplots))
        tightinset = get (hsubplots, "tightinset");
        if (iscell (tightinset))
          tightinset = max (cell2mat (tightinset));
        endif
        looseinset = get (hsubplots, "looseinset");
        if (iscell (looseinset))
          looseinset = max (cell2mat (looseinset));
        endif
        looseinset = max (tightinset, looseinset);
        set (hsubplots, "looseinset", looseinset);
      endif
    unwind_protect_cleanup
      updating = false;
    end_unwind_protect
  endif

endfunction


%!demo
%! clf;
%! r = 3;
%! c = 3;
%! fmt = {'horizontalalignment', 'center', 'verticalalignment', 'middle'};
%! for n = 1 : r*c
%!   subplot (r, c, n);
%!   xlabel (sprintf ('xlabel #%d', n));
%!   ylabel (sprintf ('ylabel #%d', n));
%!   title (sprintf ('title #%d', n));
%!   text (0.5, 0.5, sprintf ('subplot(%d,%d,%d)', r, c, n), fmt{:});
%!   axis ([0 1 0 1]);
%! end
%! subplot (r, c, 1:3);
%! xlabel (sprintf ('xlabel #%d:%d', 1, 3));
%! ylabel (sprintf ('ylabel #%d:%d', 1, 3));
%! title (sprintf ('title #%d:%d', 1, 3));
%! text (0.5, 0.5, sprintf ('subplot(%d,%d,%d:%d)', r, c, 1, 3), fmt{:});
%! axis ([0 1 0 1]);

%!demo
%! clf;
%! x = 0:1;
%! for n = 1:4
%!   subplot (2,2,n, 'align');
%!   plot (x, x);
%!   xlabel (sprintf ('xlabel (2,2,%d)', n));
%!   ylabel (sprintf ('ylabel (2,2,%d)', n));
%!   title (sprintf ('title (2,2,%d)', n));
%! end
%! subplot (1,2,1, 'align');
%! plot (x, x);
%! xlabel ('xlabel (1,2,1)');
%! ylabel ('ylabel (1,2,1)');
%! title ('title (1,2,1)');

%!demo
%! clf;
%! x = 0:10;
%! ax(1) = subplot (221);
%! set (ax(1), 'tag', '1');
%! plot (x, rand (3, 11))
%! title ('x & y labels & ticklabels');
%! xlabel xlabel
%! ylabel ylabel
%! ax(2) = subplot (222);
%! set (ax(2), 'tag', '2');
%! plot (x, rand (3, 11))
%! title ('no labels');
%! axis ('nolabel','tic')
%! ax(3) = subplot (223);
%! set (ax(3), 'tag', '3');
%! plot (x, rand (3, 11))
%! title ('no labels');
%! axis ('nolabel','tic')
%! ax(4) = subplot (224);
%! set (ax(4), 'tag', '4');
%! plot (x, rand (3, 11))
%! title ('x & y labels & ticklabels');
%! xlabel xlabel
%! ylabel ylabel

%!demo
%! x = 0:10;
%! subplot (221);
%! plot (x, rand (3, 11))
%! ylim ([0, 1]);
%! text (0.5, 0.5, '{x,y}labels & {x,y}ticklabels', ...
%!       'horizontalalignment', 'center', ...
%!       'units', 'normalized');
%! xlabel xlabel
%! ylabel ylabel
%! title title
%! subplot (222);
%! plot (x, rand (3, 11))
%! axis ('labely');
%! ylabel ylabel
%! text (0.5, 0.5, 'no xlabels, xticklabels', ...
%!       'horizontalalignment', 'center', ...
%!       'units', 'normalized');
%! subplot (223);
%! plot (x, rand (3, 11))
%! axis ('labelx');
%! text (0.5, 0.5, 'no ylabels, yticklabels', ...
%!       'horizontalalignment', 'center', ...
%!       'units', 'normalized');
%! xlabel xlabel
%! title title
%! subplot (224);
%! plot (x, rand (3, 11))
%! axis ('nolabel','tic');
%! text (0.5, 0.5, 'no {x,y}labels, {x,y}ticklabels', ...
%!       'horizontalalignment', 'center', ...
%!       'units', 'normalized');