NAME

GD::Arrow - draw arrows using GD

SYNOPSIS

use GD;
use GD::Arrow;

my $width = 8;
my ($x1, $y1) = (100, 10);
my ($x2, $y2) = (100, 190);
my ($x3, $y3) = (10, 30);
my ($x4, $y4) = (190, 75);

my $arrow = GD::Arrow::Full->new( 
                -X1    => $x1, 
                -Y1    => $y1, 
                -X2    => $x2, 
                -Y2    => $y2, 
                -WIDTH => $width,
            );

my $image = GD::Image->new(200, 200);
my $white = $image->colorAllocate(255, 255, 255);
my $black = $image->colorAllocate(0, 0, 0);
my $blue = $image->colorAllocate(0, 0, 255);
my $yellow = $image->colorAllocate(255, 255, 0);
$image->transparent($white);

$image->filledPolygon($arrow,$blue);
$image->polygon($arrow,$black);

my $half_arrow_1 = GD::Arrow::LeftHalf->new( 
                       -X1    => $x3, 
                       -Y1    => $y3, 
                       -X2    => $x4, 
                       -Y2    => $y4, 
                       -WIDTH => $width,
                   );

my $half_arrow_2 = GD::Arrow::LeftHalf->new( 
                       -X1    => $x4, 
                       -Y1    => $y4, 
                       -X2    => $x3, 
                       -Y2    => $y3, 
                       -WIDTH => $width 
                   );

$image->filledPolygon($half_arrow_1,$blue);
$image->polygon($half_arrow_1,$black);

$image->filledPolygon($half_arrow_2,$yellow);
$image->polygon($half_arrow_2,$black);

open IMAGE, "> image.png" or die $!;
binmode(IMAGE, ":raw");
print IMAGE $image->png;
close IMAGE;

exit(0);

DESCRIPTION

This is a subclass of GD::Polygon used to draw an arrow between two vertices.

GD::Arrow::Full draws a full arrow between two verticies.

                                |\
         +----------------------+ \
(X2, Y2) *                         * (X1, Y1)
         +----------------------+ /
                                |/

GD::Arrow::RightHalf draws a half arrow between two verticies.

(X2, Y2) *-------------------------* (X1, Y1)
         +----------------------+ /
                                |/

GD::Arrow::LeftHalf draws a half arrow between two verticies.

                                |\
         +----------------------+ \
(X2, Y2) *-------------------------* (X1, Y1)

SEE ALSO

GD::Polygon

CREDITS

The equations used to determine the critical verticies to represent a GD::Arrow was based on Hideki Ono's makefeedmap software. Makefeedmap can be found at http://www.ono.org/software/makefeedmap/.

AUTHOR

Todd Caine, <todd@pobox.com>

COPYRIGHT AND LICENSE

Copyright 2004 by Todd Caine

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