########################################################################
##
## Copyright (C) 2007-2022 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## 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.
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## 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
## <https://www.gnu.org/licenses/>.
##
########################################################################

function plotimages (d, nm, typ)

  if (strcmp (typ , "txt"))
    image_as_txt (d, nm);
    return;
  endif

  set_graphics_toolkit ();
  set_print_size ();
  hide_output ();
  outfile = fullfile (d, [nm "." typ]);
  if (strcmp (typ, "png"))
    set (groot, "defaulttextfontname", "*");
  endif
  if (strcmp (typ, "eps"))
    d_typ = "-depsc2";
  else
    d_typ = ["-d", typ];
  endif

  if (strcmp (nm, "plot"))
    x = -10:0.1:10;
    plot (x, sin (x));
    xlabel ("x");
    ylabel ("sin (x)");
    title ("Simple 2-D Plot");
    print (outfile, d_typ);
  elseif (strcmp (nm, "hist"))
    randn ("state", 1);
    hist (randn (10000, 1), 30);
    xlabel ("Value");
    ylabel ("Count");
    title ("Histogram of 10,000 normally distributed random numbers");
    print (outfile, d_typ);
  elseif (strcmp (nm, "errorbar"))
    rand ("state", 2);
    x = 0:0.1:10;
    y = sin (x);
    lerr = 0.1 .* rand (size (x));
    uerr = 0.1 .* rand (size (x));
    errorbar (x, y, lerr, uerr);
    axis ([0, 10, -1.1, 1.1]);
    xlabel ("x");
    ylabel ("sin (x)");
    title ("Errorbar plot of sin (x)");
    print (outfile, d_typ);
  elseif (strcmp (nm, "polar"))
    polar (0:0.1:10*pi, 0:0.1:10*pi);
    title ("Example polar plot from 0 to 10*pi");
    print (outfile, d_typ);
  elseif (strcmp (nm, "mesh"))
    tx = ty = linspace (-8, 8, 41)';
    [xx, yy] = meshgrid (tx, ty);
    r = sqrt (xx .^ 2 + yy .^ 2) + eps;
    tz = sin (r) ./ r;
    mesh (tx, ty, tz);
    xlabel ("tx");
    ylabel ("ty");
    zlabel ("tz");
    title ("3-D Sombrero plot");
    print (outfile, d_typ);
  elseif (strcmp (nm, "plot3"))
    t = 0:0.1:10*pi;
    r = linspace (0, 1, numel (t));
    z = linspace (0, 1, numel (t));
    plot3 (r.*sin (t), r.*cos (t), z);
    xlabel ("r.*sin (t)");
    ylabel ("r.*cos (t)");
    zlabel ("z");
    title ("plot3 display of 3-D helix");
    print (outfile, d_typ);
  elseif (strcmp (nm, "extended"))
    x = 0:0.01:3;
    plot (x, erf (x));
    hold on;
    plot (x, x, "r");
    axis ([0, 3, 0, 1]);
    xlabel ("x");
    ylabel ("erf (x)");
    title ("erf (x) with text annotation");
    if (strcmp (typ, "pdf") && ! strcmp (graphics_toolkit, "gnuplot"))
      text (0.65, 0.6175, ['$\displaystyle\leftarrow x = {2\over\sqrt{\pi}}'...
                           '\int_{0}^{x}e^{-t^2} dt = 0.6175$'],
            "interpreter", "latex");
      ## Be very careful about modifying this.  pdflatex expects to be in
      ## the same directory as the file it is operating on.
      cd (make_absolute_filename (d));
      print ([nm ".pdf"], "-dpdflatexstandalone");
      [status, output] = system (["pdflatex " nm]);
      if (status)
        error ("plotimages: Failed to run pdflatex on <extended.pdf>");
      endif
      delete ([nm ".aux"], [nm "-inc.pdf"], [nm ".log"], [nm ".tex"]);
    else
      text (0.65, 0.6175, ['\leftarrow x = {2/\surd\pi {\fontsize{16}' ...
            '\int_{\fontsize{8}0}^{\fontsize{8}x}} e^{-t^2} dt} = 0.6175']);
      print (outfile, d_typ);
    endif
  elseif (strcmp (nm, "precisiondate"))
    rand ("state", 1);
    t = datenum (2020, 1, 1):(1/1440):datenum (2020, 1, 2);
    x = -cos (2*pi*t) + rand (size (t)) / 10;
    subplot (1, 2, 1);
    plot (t, x);
    datetick ("x");
    xlabel ("serial date");
    title ("problem");
    subplot (1, 2, 2);
    plot (t - 730485, x);
    datetick ("x");
    xlabel ("2000 years off");
    title ("workaround");
    # set wider aspect ratio
    image_size = [8.25, 3.5]; # in inches, 5:2 format
    border = 0;              # For postscript use 50/72
    set (gcf, "papersize", image_size + 2*border);
    set (gcf, "paperposition", [border, border, image_size]);
    print (outfile, d_typ);
  else
    error ("unrecognized plot requested");
  endif
  hide_output ();
endfunction

## This function no longer sets the graphics toolkit; That is now done
## automatically by C++ code which will ordinarily choose 'qt', but might
## choose gnuplot on older systems.  Only a complete lack of plotting is a
## problem.
function set_graphics_toolkit ()
  if (isempty (available_graphics_toolkits ()))
    error ("no graphics toolkit available for plotting");
  elseif (strcmp ("qt", graphics_toolkit ())
          && __have_feature__ ("QT_OFFSCREEN"))
    ## Use qt with QOffscreenSurface for plot
  elseif (! strcmp ("gnuplot", graphics_toolkit ()))
    if (! any (strcmp ("gnuplot", available_graphics_toolkits ())))
      error ("no graphics toolkit available for offscreen plotting");
    else
      graphics_toolkit ("gnuplot");
    endif
  endif
endfunction

function set_print_size ()
  image_size = [5.0, 3.5]; # in inches, 16:9 format
  border = 0;              # For postscript use 50/72
  set (groot, "defaultfigurepapertype", "<custom>");
  set (groot, "defaultfigurepaperorientation", "landscape");
  set (groot, "defaultfigurepapersize", image_size + 2*border);
  set (groot, "defaultfigurepaperposition", [border, border, image_size]);
endfunction

## Use this function before plotting commands and after every call to print
## since print() resets output to stdout (unfortunately, gnuplot can't pop
## output as it can the terminal type).
function hide_output ()
  hf = figure (1, "visible", "off");
endfunction

## generate something for the texinfo @image command to process
function image_as_txt (d, nm)
  fid = fopen (fullfile (d, [nm ".txt"]), "wt");
  fputs (fid, "\n");
  fputs (fid, "+---------------------------------+\n");
  fputs (fid, "| Image unavailable in text mode. |\n");
  fputs (fid, "+---------------------------------+\n");
  fclose (fid);
endfunction