Re: New Plotting Functions: findall.m and allchild.m

[Bill Denney]

John W. Eaton wrote:
> | Also, I was trying to write hgsave and hgload, but I could not find a 
> | way to create a handle without using the plotting functions.  Is there a 
> | way to generate handle objects without going through the plotting functions?
>
> Not that I know of, so at least part of hgload may need to be in C++.
>
> If you could create graphics handles without generating a graph, how
> would you want to do that?  What data do you have available when you
> want to create the graphics object?
>   
Attached is what I wrote for hgsave.  I was thinking that hgload would 
essentially do what hgsave does in reverse, but assigning new handle 
numbers to everything.  It's a little more complex because there are 
child handles in places other than the children field (i.e. the title, 
xlabel, ylabel, and zlabel), but that was the general idea I had for it.

The alternative to the approach that I have there is to make 
hgsave/hgload generate what is essentially an .m file that would execute 
to generate the figure.  That struck me as likely less efficient, so I 
started with this method.

Have a good day,

Bill

## Copyright (C) 2008 Bill Denney
##
## 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
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} {} hgsave ()
## Save a graphics object.
## @seealso{hgload}
## @end deftypefn

## Author: Bill Denney <address@hidden>

function hgsave (varargin)

  if ((nargin < 1) || (nargin > 3))
    print_usage ();
  endif

  h = [];

  ## process the input arguments
  idx = 1;
  if isfigure (varargin{idx})
    h = varargin{idx};
    idx += 1;
  endif
  if (numel (varargin) >= idx)
    if (ischar (varargin{idx})) && (size (varargin{idx}, 1) == 1)
      filename = varargin{idx};
      idx += 1;
    endif
  endif
  if length (varargin) >= idx
    ## FIXME
    warning (["Additional arguments beyond handle and filename are not "
              "yet supported."])
  endif

  if isempty (h)
    h = gca ();
  endif
  if isempty (filename)
    error ("Filename not given");
  endif

  handlist = h;
  handdata{1} = get (h);
  c = allchild (h);
  while ~ isempty (c)
    if ~ ismember (c(1), handlist)
      ## only save objects that we have not yet seen.
      handlist(end+1) = c(1);
      handdata{end+1} = get (c(1));
      ctmp = allchild (c(1));
      if ~ isempty (ctmp)
        c(end+1:numel(ctmp)) = ctmp;
      endif
    endif
    c(1) = [];
  endwhile

  save (filename, "handlist", "handdata");
endfunction