[cairo] Very large number of lines

[necko necko]

As for the cairo version, I simply followed the steps for Ubuntu, from
http://www.cairographics.org/download/
This means I only typed
sudo apt-get install libcairo2-dev

Below is the code that reproduces the problem. Setting ITER_NO to
20000, for example, produces regular pdf file. But, setting it to
20000000 seems not to be appropriate.

I hope you would have suggestions on how to achieve the goal of
representing large number of lines.
Also, I'm interested in whether the png version of the resulting output
file would be lighter and easier (less time consuming) to view using regular
viewer. Your suggestions on this might also be helpful.
code:

#include <cairo.h>
#include <cairo-pdf.h>
#include <sstream>
#include <cmath>  
#include <vector>   
#include <limits.h>
#include <queue>
#include <algorithm>
#include <numeric>
#include <iostream>
int main() {
  cairo_surface_t *surface;
  cairo_t *cr;

  std::stringstream myOut; int k=1;
  myOut<<"forGallery"<<k<< ".pdf";
  surface = cairo_pdf_surface_create(myOut.str().c_str(), 1432, 1606);
  cr = cairo_create(surface);
  cairo_translate (cr, -229770, 26573.7); // -40, 50: for margin -37, 53

  unsigned int t=0; unsigned int ITER_NO=20000000;
  while(t<ITER_NO) {
      cairo_move_to (cr, 229770, -26573.7);
      cairo_line_to (cr, 231202, -24967.3);
      std::cout<<"Drawn so far:"<<((double)t/(double)ITER_NO)*100<<"%"<<std::endl;
      ++t;
  }
  
  cairo_stroke(cr);
  cairo_show_page(cr);
  cairo_surface_destroy(surface);
  cairo_destroy(cr);

  return 0;

}

> Date: Sun, 29 Aug 2010 21:41:23 +0200
> Subject: Re: [cairo] Very large number of lines
> From: a.g.nienhuis at gmail.com
> To: opustenom at hotmail.com
> CC: cairo at cairographics.org; cairo-bugs at cairographics.org
> 
> What version of cairo do use?
> Did you finish() the surface?
> Can you send a simple program (source code) that reproduces the problem?
> 
> Groeten, Arjen
> 
> On Sunday, August 29, 2010, necko necko <opustenom at hotmail.com> wrote:
> >
> >
> >
> >
> >
> > The pdf output file is supposed to display very large number of lines, connections
> > between a number of points. This is the code sample which specifies around 8million
> > lines:
> > .............
> > while (myIter!=edges.end()) {
> >      .......
> >     cairo_move_to (cr, *firstIter, *(firstIter+1));
> >     cairo_line_to (cr, *secondIter, *(secondIter+1));
> >     ..........
> >     ++myIter;
> > }
> > cairo_set_line_width (cr, .05);
> > cairo_stroke (cr);
> > .........................
> > Note that the above code produces pdf files which were viewed with Evince, but not
> > with Adobe Reader (drawing error occurred, shown in the report window).
> > I used the same code for showing larger number of lines, more than 20million. The output
> > pdf files had names as specified, but their size was around 400 bytes, and when I try to
> > open them, they are simply empty(white, in Evince), while Adobe says that the file has no
> > pages to display.
> > In order to overcome this problem, I put stroke() within the while() loop, but when I tried
> > to draw files showing more than 20million lines, the process got "Killed" (Ubuntu Linux) at
> > around 33% of the total.
> > .............................
> > What would be the way to properly draw the pdf file specifying very large number of lines?
> > What would be the code to try? Note that the variations work properly with smaller number
> > of lines.
> >
> > Thanks
> >  		 	   		
> >
 		 	   		  
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