Re: maximing/resizing multiple x11: change of palette

[Daniel J S. <dan...@ie...>]

Petr Mikulik wrote:
> This is an old bug (August 2004, see below). What do you think nowadays 
> about fixing it?

Petr,

Attached is a freshened version of the patch for the bug fix.  Give it a try and if you think it solves the problem please consider moving into CVS.

As a reminder to others, we had a big discussion about this bug.  (Go back to about Sep  9, 2004.)  In addition to the initial problem Petr found, I think this patch also has a bug fix for what I thought was a memory leak.  It also rid that difficult to decipher code with "recursive" in it.

In summary, it is a linked list of color maps separate from the linked list for X11 plots.  (Hey, I like linked lists; what can I say?)  Basically, whenever a new palette (i.e., different than any other already in the list) comes over the link it is placed in the list.  Whenever a figure is destroyed and the associated palette is not used by a different plot, that palette is discarded from the list.

Dan

 
> ***
> 
> There is a bug in the color palette treatment in the X11 terminal: when
> using multiple X11 terminals, window redraw (requested e.g. by a window
> manager) will change its palette.
> 
> Try this script:
> 
> 
> set pm3d map
> 
> set term x11 10
> set title '10 gray levels'
> set palette gray
> set palette maxcolors 10
> splot x*x
> 
> set term x11 2
> set title '2 colors'
> set palette color
> set palette maxcolors 2
> splot x
> 
> 
> Now, maximize or resize window #10 by mouse => it will change from gray map
> with 10 gray levels to color map with 2 colors.
> 
> 
> 
> 
>>> Yes, every x11 windows should have its own copy of the palette. When 
>>> there
>>> is a new (re)plot, x11 should copy the current gnuplot palette into 
>>> palette
>>> of the active window, and use that.
>>
>>
>> I don't like hacking stuff, and this may take some consideration.  I'm 
>> wondering how this should be structured, and whether we should be 
>> conservative with palette usage in order to not consume too much 
>> memory. Are palettes memory consumers?  If so, it might be wise to not 
>> save a color map with every plot.  That is, say there is a fairly 
>> large palette, and then someone creates twenty plots.  If all those 
>> plots have a similar palette, it may be an inefficient use of memory.
>>
>> Rather, it might be wise to have a linked-list of palettes.  Whenever 
>> a new palette is created, it is put in the linked list.  Then, when a 
>> palette is changed at the gnuplot command line, gplt_x11.c will search 
>> through the plot list and see if any of the plots is using the old 
>> palette.  If not, that color map can be discarded from the list.
>>
>> It sounds unnecessarily tedious, but it really does seem like the 
>> thing to do, and it actually might simplify the various uses of 
>> XAllocColor and XFreeColors.
> 
> 
> 
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-- 

Dan Sebald
phone: 608 256 7718
email: daniel DOT sebald AT ieee DOT org
URL: http://webpages DOT charter DOT net/dsebald/