Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.graphics.apps.gnuplot > #3763

Re: pdfcairo/pngcairo file size limitations?

Show all headers | View raw

Ethan A Merritt wrote:

> 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.

It turns out that cairo handles a maximum bitmap size of 32Kx32K.

From the cairo source at
https://github.com/tordex/cairo/blob/master/src/cairo-image-surface.c

/* Limit on the width / height of an image surface in pixels.  This is
 * mainly determined by coordinates of things sent to pixman at the
 * moment being in 16.16 format. */
#define MAX_IMAGE_SIZE 32767

Back to comp.graphics.apps.gnuplot | Previous | Next — Previous in thread | Find similar

Thread

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

csiph-web