Problem using PNG images created by GD::Graphs in an API2 PDF doc

jmo0099 has asked for the wisdom of the Perl Monks concerning the following question:

Hi:

I am trying to create a PDF document using API2. I need to include a png image that I create using GD::Graphs. When I try to read in the the image I get the following error:

substr outside of string at /usr/lib/perl5/site_perl/5.8.3/PDF/API2/PDF/ImagePNG.pm line 137.

I am running on RedHat 9. I am using Perl v5.8.3, GD v1.53, and API2 v0.3r77...these should all be the latest available revisions from CPAN. The png file I create can be read in through various Linux and Windoz utilities, so I am fairly sure the file is for the most part valid.

If anyone has experienced this problem, I would appreciate any advice you might have. Also, if anyone has any links to good tutorials on GD, GD::Graph, and/or API2, this will help me out a lot. It is not always easy to see how all the pieces fit together by looking at the pod.

TIA,

John

P.S. -- below is a stripped down version of what I am trying to accomplish...thanks!

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#!/usr/bin/perl -w 
use strict; 
use GD::Graph::bars; 
use PDF::API2; 
createGraph(); 
createPdf(); 
exit; 

sub createGraph { 
  my @xLabels = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
+ 
  my @data2002 = qw( 17 19 26 38 56 64 67 53 40 29 21 13 ); 
  my @data2003 = qw( 19 24 27 41 56 69 75 60 44 33 22 15 ); 
  my @data = ( \@xLabels, \@data2002, \@data2003 ); 
  my $graph = GD::Graph::bars->new( 800, 600 ); 
  $graph->set( title => "Rainfall 2002/2003", y_label => "Millimetres"
+ ); 
  my $image = $graph->plot( \@data ) or die( "Cannot create image" ); 
  open OUT, ">demo.png"; 
  binmode OUT; 
  print OUT $image->png(); 
  close OUT; 
} 

sub createPdf { 
  my $hPdf = PDF::API2->new(-file => "demo.pdf"); 
  my $hPage = $hPdf->page(); 
  my $hGfx = $hPage->gfx(); 
  $hPage->mediabox(300, 300); 
  my $hImg = $hPdf->image('demo.png'); 
  $hGfx->image($hImg, 0, 0); 
  print $hPdf->stringify(); 
  $hPdf->end; 
}
[download]

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20040510 Edit by Corion: Changed formatting of code to use CODE tags
Edit by castaway, added readmore tags

Comment on Problem using PNG images created by GD::Graphs in an API2 PDF doc Download Code

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Re: Problem using PNG images created by GD::Graphs in an API2 PDF doc by dragonchild (Archbishop) on May 10, 2004 at 13:38 UTC
Send the bug to the author. A quick glance of the code has a ton of bitshifting and bitmasking that I just don't want to figure out. shudders Ideally, I would write the testcase up as a .t file that the author can include in his/her tests from now on. (Plus, it's easier to debug that way.) ------ We are the carpenters and bricklayers of the Information Age. Then there are Damian modules.... sigh* ... that's not about being less-lazy -- that's about being on some really good drugs -- you know, there is no spoon.* - flyingmoose I shouldn't have to say this, but any code, unless otherwise stated, is untested	[reply]
Re: Re: Problem using PNG images created by GD::Graphs in an API2 PDF doc by jmo0099 (Initiate) on May 10, 2004 at 14:22 UTC
That is probably an excellent suggestion, but...I'm not sure where the problem actually resides. I spent the weekend trying to prove that it is either GD::Graphs or API2. I can create png files with GD::Graphs and view them in various utilites, and edit them with Gimp, which tells me GD::Graphs is working correctly. With API2 I can create PDFs and have them include png files that I have found laying about, which tells me that API2 is working correctly. Each seems to be working, I just can't get the two to play nicely together. John	[reply]
Re: Problem using PNG images created by GD::Graphs in an API2 PDF doc by Albannach (Monsignor) on May 10, 2004 at 14:22 UTC
I don't pretend to know what is going on, but as I was bored, here are a couple of things that I did to your code, and I did end up with a functioning PDF: use non-interlaced PNG with `$image->interlaced(undef);` in the PNG sub throw in a `$hPdf->save;` at the end of the PDF sub make sure your media box is large enough (at least 800x600 in your case) Hope this helps! Update: Versions I used (: Perl 5.8.3 as ActiveState build 809 on Win2k GD::Graph::bars 1.25 PDF::API2 0.3r77 It also appears that the `stringify` is messing things up - either put the save before it or just remove it altogether as it serves no useful purpose (at least in this code fragment). -- I'd like to be able to assign to an luser	[reply] [d/l] [select]
Re: Re: Problem using PNG images created by GD::Graphs in an API2 PDF doc by jmo0099 (Initiate) on May 12, 2004 at 17:49 UTC
Thanks for taking the time to track down that info. For some odd reason this did not take care of the problem, I still get the same error. I am running the same package revisions as you are, with the only difference that I can see is that I am running Linux (RedHat 9) and you are running windows. Its hard (and scarey) to believe that this would make such a difference in the operation of these packages. Maybe I need to uninstall + re-install all packages to make sure that I have complete distributions. Thanks, John	[reply]
Re: Re: Problem using PNG images created by GD::Graphs in an API2 PDF doc by jmo0099 (Initiate) on May 10, 2004 at 23:18 UTC
I tried your suggestions. What I did was: Added "$image->interlaced(undef);" in the line after I call the plot method. Added "$hPdf->save;" in the line after I called the stringify method. Changed the dimensions of the mediabox to be 1200x900. Unfortunately, after all this I am still having the same problem. When the PDF file is created it starts printing out "substr outside of string at /usr/lib/perl5/site_perl/5.8.3/PDF/API2/PDF/ImagePNG.pm line 137.". Do you know what versions of these packages you are running? Maybe there is some incompatability if I am on the bleeding edge of releases. Thanks for your help, John	[reply]