[Octave-bug-tracker] [bug #44567] Qt graphics toolkit displays twice when opening a new figure via plot or image.

[Rik]

Update of bug #44567 (project octave):

                  Status:                    None => Fixed                  
             Open/Closed:                    Open => Closed                 

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Follow-up Comment #1:

The root cause is in image.m.


 h = __go_image__ (hax, "cdata", img, "xdata", xdata, "ydata", ydata,
                         "cdatamapping", "direct", varargin{:});

  if (do_new && ! ishold (hax))
    ## Set axis properties for new images

    if (! isempty (img))
      if (isscalar (get (hax, "children")))
        axis (hax, "tight");
      endif


The image is drawn by __go_image__ which apparently uses automatic scaling of
the axes limits.  This is appropriate for ordinary data plots, but not for
images where the axis should just contain the object.  So, the next thing the
m-file does is apply 'axis (hax, "tight")', but only if it is a new figure
(do_new).

Incidentally, I get a doubly drawn image with both the FLTK and Qt toolkits.

I pushed a cset to fix this
http://hg.savannah.gnu.org/hgweb/octave/rev/2e7497ff2535.

Using test code:


tic; image(32*rand(5000,1000)); toc


I find the previous implementation took 3.4 second while the new one takes 0.6
seconds.

I didn't see any problems with other image demos so I don't think it impacted
the correctness of the function.


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