[Octave-bug-tracker] [bug #49756] Crash when panning an image to top of axes

[Pantxo Diribarne]

Follow-up Comment #9, bug #49756 (project octave):

In opengl_renderer::draw_image
(https://octave.org/doxygen/4.4/dd/d82/gl-render_8cc_source.html#l03609) we
compute the pixel size in screen-pixels and normalized units


if (h > 1)
 {
   pix_dy = (p1(1) - p0(1)) / (h-1);
   nor_dy = (y(1) - y(0)) / (h-1);
 }
...


using ydata. This results in negative pixel size if ydata=[ymax ymin]. 
 
I think "get (gca, "ylim")" always returns [ymin ymax] whatever the "ydir",
and images should also do the same.

It would be interesting to test the following in Matlab


h = image (rand (20, 20, 3));
ylim (gca)
set (h, 'ydata', [20 1]); %error?
get (h, 'ydata')
ylim (gca)



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