Re: Strange autoscaling with rgbimage and inverted yranges

[Ethan A M. <me...@uw...>]

On Wednesday, 9 September 2020 02:07:50 PDT Dima Kogan wrote:
> Hi. I vaguely recall mentioning this already, but I don't see it in my
> email. Apologies if this has already been reported. I have this script:
> 
>     set yrange [:] reverse
>     set size ratio -1
>     plot "/tmp/gray.jpg" binary filetype=auto flipy with rgbimage,'-'   using 1:2 notitle with points pt 3 ps 3 
[snip]
>     e
> 
> I.e. we plot some points on top of the attached image. The contents of
> the image don't matter. Here we just have a gray field. I'm using the
> latest master branch, but I belive 5.4 does this too.
> 
> 1. Running that script in an interactive terminal (I tried x11 and qt),
>    the plot pops up just fine: the autoscale considered the image AND the
>    points
> 
> 2. We interactively zoom on any area with the mouse. This works too
> 
> 3. We press 'u' to zoom out. The expectation is that we get back to the
>    full view after step 1. Instead we get to a new view, zoomed-in on
>    the points only, NOT on the image.

Hmm.  
But if you press 'p' for "previous" the unzoom works correctly.
That is probably a clue.

Also, if the inline data is replaced by a datablock the problem goes away.

I think the issue is that because your example uses in-line data it
cannot be re-read.  The program tries to work around this by reusing
the contents of the various internal data structures but in this case the
workaround fails.  Possibly fixable, but I think the primary lesson is
that data blocks are much preferred to in-line data if you are going to be
manipulating/re-drawing the plot.

	Ethan

> Something about the reverse yrange is confusing I think. Have I reported
> this already?
> 
> Thanks.