Re: image plot not displayed with small images on windows terminal

[Ethan M. <merritt@u.washington.edu>]

On Friday 06 November 2009 13:49:05 Benjamin Lindner wrote:
> Hello,
> 
> This is a bug that was reported on octave's bug list.
> I am moving the topic here, since I believe there is an issue with
> gnuplot's windows terminal.

gnuplot> help failsafe

 Some terminal drivers provide code to optimize rendering of image data
 within a rectangular 2D area.  However this code is known to be imperfect.
 This optimized code may be disabled by using the keyword `failsafe`. 
 E.g.
       plot 'data' with image failsafe


I am not at all familiar with the optimized image implementation in the
windows terminal driver.  If it is so problematic that it becomes a
usability issue, then we should probably disable it and let the
higher level code default to the "failsafe" mode.

As a work-around, Octave could add the "failsafe" keyword if it's
sending output to the windows terminal.

	Ethan


> 
> The problem is that images plotted are not drawn if the images are
> small and the x/y ranges are shrinked.
> 
> Following testcase:
> 
> set term windows
> plot "-" matrix with image
> 1 2
> 3 4
> e
> e
> 
> works ok, but if you add
> 
> set xrange [0:1]; set yrange [0:1];
> 
> then the plot window is blank.
> 
> This is the same if you increase the matrix size.
> For 6x6 it shows a blank window:
> 
> set term windows
> set xrange [0:5]; set yrange [0:5]
> plot "-" matrix with image
> 1 0 0 0 0 0
> 0 1 0 0 0 0
> 0 0 1 0 0 0
> 0 0 0 1 0 0
> 0 0 0 0 1 0
> 0 0 0 0 0 1
> e
> e
> 
> 
> For 7x7 it now works
> 
> set term windows
> set xrange [0:6]; set yrange [0:6]
> plot "-" matrix with image
> 1 0 0 0 0 0 0
> 0 1 0 0 0 0 0
> 0 0 1 0 0 0 0
> 0 0 0 1 0 0 0
> 0 0 0 0 1 0 0
> 0 0 0 0 0 1 0
> 0 0 0 0 0 0 1
> e
> e
> 
> An interesting artefact is when you do
> 
> set term windows
> set xrange [1:6]; set yrange [1:6]
> plot "-" matrix with image
> 1 0 0 0 0 0
> 0 1 0 0 0 0
> 0 0 1 0 0 0
> 0 0 0 1 0 0
> 0 0 0 0 1 0
> 0 0 0 0 0 1
> e
> e
> 
> Which shows a single yellow rectangle in the upper right corner of the graph
> 
> All these work for the wxt terminal.
> 
> I tested this using the 2009-07-08 CVS 4.3.0 snapshot under windows.
> 
> benjamin
> 
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-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle 98195-7742