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25
26## -*- texinfo -*-
27## @deftypefn  {} {} ishold
28## @deftypefnx {} {} ishold (@var{hax})
29## @deftypefnx {} {} ishold (@var{hfig})
30## Return true if the next plot will be added to the current plot, or
31## false if the plot device will be cleared before drawing the next plot.
32##
33## If the first argument is an axes handle @var{hax} or figure handle
34## @var{hfig} then operate on this plot rather than the current one.
35## @seealso{hold, newplot}
36## @end deftypefn
37
38function retval = ishold (h)
39
40  if (nargin > 1)
41    print_usage ();
42  endif
43
44  if (nargin == 0)
45    fig = gcf ();
46    ax = get (fig, "currentaxes");
47  else
48    if (! ishghandle (h))
49      error ("ishold: H must be an axes or figure graphics handle");
50    endif
51
52    switch (get (h, "type"))
53      case "figure"
54        fig = h;
55        ax = get (fig, "currentaxes");
56
57      case "axes"
58        ax = h;
59        fig = ancestor (ax, "figure");
60
61      otherwise
62        error ("ishold: H must be an axes or figure graphics handle");
63
64    endswitch
65  endif
66
67  retval = (strcmp (get (fig, "nextplot"), "add")
68            && ! isempty (ax) && strcmp (get (ax, "nextplot"), "add"));
69
70endfunction
71
72
73%!test
74%! hf = figure ("visible", "off");
75%! unwind_protect
76%!   assert (! ishold);
77%!   assert (isempty (get (hf, "currentaxes")));
78%!   assert (get (hf, "NextPlot"), "add");
79%!   l = plot ([0 1]);
80%!   assert (! ishold);
81%!   assert (! ishold (gca));
82%!   assert (get (gca, "NextPlot"), "replace");
83%!   assert (get (hf, "NextPlot"), "add");
84%!   hold;
85%!   assert (ishold);
86%!   assert (ishold (gca));
87%!   assert (get (gca, "NextPlot"), "add");
88%!   assert (get (hf, "NextPlot"), "add");
89%!   p = fill ([0 1 1], [0 0 1],"black");
90%!   assert (length (get (hf, "children")), 1);
91%!   assert (length (get (gca, "children")), 2);
92%! unwind_protect_cleanup
93%!   close (hf);
94%! end_unwind_protect
95