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Re: pdfcairo/pngcairo file size limitations?

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Ethan A Merritt wrote:

> Karl Ratzsch wrote:
> 
>> Am 28.09.2017 um 15:07 schrieb schwarz.cd48@gmail.com:
>>> gnuplot version 5.0 patchlevel 0
>> 
>>> I am trying to make a matrix plot of a file that is made up of 48
>>> columns and 50000 lines. Each column contains integers between 0 -
>>> 140. I also want to produce a pdf in the end. The script for the plot
>>> looks like
>> 
>>>     plot 'data.file' u 1:2:3 matrix wi image
>>> 
>>> The problem is that in the output.pdf the plot area/canvas is empty
>>> and only the xtics, ytics, and cbtics are shown. If I open gnuplot in
>>> the terminal and just do the plot in the standard qt terminal I will
>>> see the plot normally as expected, but it won't be produced in the
>>> pdf. The same goes for the pngcairo terminal. On the other hand, if I
>>> use
>>> 
>>>     set terminal postscript eps enhanced
>>> 
>>> then the output.eps will contain the plot with no problems and I can
>>> convert eps to pdf.
>>> 
>>> But why does the pdfcairo/pngcairo not work?
>>> 
>>> I also found that if I reduce the number of lines in my 'data.file'
>>> from 50000 to 30000 (cutting off 2/5 of my data), then I will get a
>>> normal plot in my output.pdf. If I increase it again to 40000, the
>>> canvas will again be empty again. Does pdfcairo have some limitations
>>> here?
>> 
>> 
>> Yes, there is a problem. The following script produces a dataset
>> like yours and works on qt and windows terminal, crashes wxt, and
>> leaves an empty canvas with pdfcairo. (Tested on gp5.2pl0)
>> 
>> 
>> t=time(0)
>> n=40000
>> m=48
>> set print $dat;do for [i=1:n] {
>>   s=""
>>   do for [j=1:m] {s=s.sprintf(" %.2f",rand(0.))}
>>   if (i%1000==0) {set print; print i." of ".n;set print $dat append}
>>   print s}
>> set print
>> print time(0)-t
>> 
>> plot $dat us 1:2:3 matrix w image
> 
> Your test script fails here under linux, but it fails because the string
> in $dat  gets too long.
> If I change it to write to a file then I see no problem.
> Tested with qt, wxt, pdfcairo terminals.
> 
> On a system+terminal where you see problems, can it correctly process
> a large *.png or *.jpg image?  Take some multi-megapixel photo and try
> displaying it with
> 
> gnuplot>   plot 'photo.jpeg' binary filetype=jpeg with rgbimage

Aha.  I tried on another machine and got a cairo error message from the
long-string failure:

Cairo is unhappy: invalid value (typically too big) for the 
                  size of the input (surface, pattern, etc.)

That error message comes from a maximum length limit inside the
cairo library.

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pdfcairo/pngcairo file size limitations? schwarz.cd48@gmail.com - 2017-09-28 06:07 -0700
  Re: pdfcairo/pngcairo file size limitations? Karl Ratzsch <mail.kfr@gmx.net> - 2017-09-28 22:47 +0200
    Re: pdfcairo/pngcairo file size limitations? schwarz.cd48@gmail.com - 2017-09-29 02:18 -0700
    Re: pdfcairo/pngcairo file size limitations? Ethan A Merritt <EAMerritt@gmail.com> - 2017-10-02 09:18 -0700
      Re: pdfcairo/pngcairo file size limitations? Ethan A Merritt <sfeam@users.sourceforge.net> - 2017-10-02 11:44 -0700
        Re: pdfcairo/pngcairo file size limitations? Ethan A Merritt <sfeam@users.sourceforge.net> - 2017-10-02 13:52 -0700

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