NAME¶
GD::Graph::FAQ - Frequently asked questions
DESCRIPTION¶
I get errors like "Can't call method METHOD on an undefined
value". What gives?¶
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.
Not necessarily. Check out the GD::Graph::Data class.
How do I stop those pesky accents appearing around bars or inside
area charts?¶
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 (
http://www.cpan.org/ 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 GD::Graph.)
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;
GD::Text->font_path("/path/to/my/font_dir");
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;
# ...
$graph->set_x_axis_font(gdMediumBoldFont);
If you don't want to include the GD library, you can use the longer alternative
names (which is what I'd recommend anyway):
$graph1->set_x_axis_font(GD::Font->MediumBold);
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 <
http://www.perlmonks.org>.
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:
http://www.perlmonks.org/?node_id=172086
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.
AUTHOR¶
Martien Verbruggen <mgjv@tradingpost.com.au>
Current maintenance (including this release) by Benjamin Warfield
<bwarfield@cpan.org>
(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.