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Graph::FAQ(3)	      User Contributed Perl Documentation	 Graph::FAQ(3)

       GD::Graph::FAQ -	Frequently asked questions

       Take a look at "DISTRIBUTION STATUS" in GD::Graph first.

   I get errors	like "Can't call method	METHOD on an undefined value". What
       You probably had	an error somewhere, most likely	in the plot() method,
       and you didn't check for	it. See	the section on Error Handling in the
       documentation for GD::Graph to find out how to deal with	this sort of
       thing, and how to get more information about what the error was.

   I am	drawing	a bar chart, and the chart area	is a lot smaller than the
       image. What is going on?
       As of version 1.30, GD::Graph automatically corrects the	width of the
       plotting	area of	a chart	if it needs to draw bars (i.e. for bars	and
       some mixed charts). This	is necessary, because rounding errors cause
       irregular gaps between or overlaps of bars if the bar is	not an exact
       integer number of pixels	wide.

       If you want the old behaviour back, set the correct_width attribute to
       a false value.

   I have my data in some format that doesn't look at all like the array that
       I am supposed to	give to	GD::Graph's plot method. Do I really need to
       mess around with	array references?
       Not necessarily.	Check out the GD::Graph::Data class.

   How do I stop those pesky accents appearing around bars or inside area
       You can set the "accent_treshold" option	to a large enough value
       (larger than your chart). Alternatively,	you may	like it	better to set
       the "borderclrs"	attribute to be	the same as the	dclrs one.

       I'll probably include an	option in a future version that	gives better
       control over this.

   Where is the	ActiveState ppm	of GD::Graph?
       Ask them. I have	asked them, but	didn't get an answer. I	don't know
       what to do to get it included in	their set of ppms, and I really	do not
       have the	time to	keep asking them.

       I believe that GD::graph	has finally made it into ActiveState's ppm
       archive.	However, I am going to leave this question here	in case	they
       get behind again.

   Do you have some example code for me?
       The distribution	has a large set	of examples in it. If you don't	have
       the original distribution, please get it	from CPAN
       ( or	some local mirror).

   Will	you support X or Y?
       If you send me a	patch that (in a decent	manner)	adds the functionality
       to the latest version, I	may very well add it for the next release. If
       you don't send me a patch, but just a question, you will	have to	be
       patient.	 (Please also see the section on bugs in the main body of

   Why does export_format give me a weird string, instead of just 'png'	or
       As of version 1.31, export_format in a list context returns all formats
       that GD can export. If you are only interested in the answer 'gif' or
       'png', make sure	that you call it in a scalar context.

	 $export_format	= GD::Graph->export_format;
	 $export_format	= $graph->export_format;
	 print "Export format is ", scalar $graph->export_format, "\n";
	 print "Export format is " .  $graph->export_format . "\n";
	 @export_formats = $graph->export_format;

   TrueType fonts don't	work when I use	GD::Graph from a CGI program.
       When your programs run as CGI, they typically do	not have the same
       environment as when you use them	from the command line. The Perl	FAQ,
       section 9, has some information on this.	It is also not guaranteed that
       your script runs	from the directory that	it is in. It is	probably
       better to include something like:

	 use GD::Text;

       See the GD::Text	documentation for more information about font paths.

   I'm trying to use GD's builtin fonts, but it's not working.
       Most likely, you	are using the font short name, like gdGiantFont	or
       gdMediumBoldFont, and you have not put a	"use GD" in your program.
       This is needed, because these short names need to be exported into your
       name space by the GD library:

	 use GD;
	 # ...

       If you don't want to include the	GD library, you	can use	the longer
       alternative names (which	is what	I'd recommend anyway):


       If you "use strict" then	you will actually get an error message if you
       try to use the short names without including the	GD module.

       Also see	the GD::Text documentation for this information.

   When	I have many data sets, some end	up having the same colour.
       The default number of colours for data sets is seven, so	if you use
       more than seven data sets, those	colours	will be	re-used	for the	higher
       data sets.

       This is described in the	entry for the "dclrs" attribute	in the
       GD::Graph documentation.

   Can you tell	me how to do X?
       Not necessarily (X might	be kind	of complicated,	after all).  Did you
       look in the samples for something similar?  If not, you're probably
       best off	seeing if you can get help from	a group	of people, rather than
       one or the other	of the overworked individuals whose e-mail addresses
       are shown below.

       If you're more comfortable with asking a	newsgroup for help, the
       canonical resource is <comp.lang.perl.misc>; if you prefer web forums,
       there is	a good one at <>.

       In either case, if you are not familiar with the	forum and its
       denizens, you might wish	to read	the following helpful guide before
       posting your question:

   Can you fix this bug	I've found?
       Well, I hope so.	 Please	see the	"BUGS" section in the main body	of
       GD::Graph for the best way to report it.

       Martien Verbruggen <>

       Current maintenance (including this release) by Benjamin	Warfield

       (c) Martien Verbruggen.

       All rights reserved. This package is free software; you can
       redistribute it and/or modify it	under the same terms as	Perl itself.

perl v5.32.1			  2013-06-22			 Graph::FAQ(3)


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