#!/usr/bin/perl
use strict;
use warnings;
use Cairo;
use constant
{
WIDTH => 600,
HEIGHT => 300,
};
{
my $surf = Cairo::ImageSurface->create ('argb32', WIDTH, HEIGHT);
my $cr = Cairo::Context->create ($surf);
$0 =~ /(.*)\.pl/;
my $out = "$1.png";
$cr->rectangle (0, 0, WIDTH, HEIGHT);
$cr->set_source_rgb (1, 1, 1);
$cr->fill;
draw_splines ($cr, WIDTH, HEIGHT);
$cr->show_page;
$surf->write_to_png ($out);
}
sub draw_spline
{
my ($cr, $height) = @_;
$cr->move_to (0, .1 * $height);
$height = .8 * $height;
$cr->rel_curve_to (-$height / 2, $height / 2, $height / 2, $height / 2,
0, $height);
$cr->stroke;
}
sub draw_splines
{
my ($cr, $width, $height) = @_;
my @tolerance = (.1, .5, 1, 5, 10);
my $line_width = .08 * $width;
my $gap = $width / 6;
$cr->set_source_rgb (0, 0, 0);
$cr->set_line_width ($line_width);
$cr->translate ($gap, 0);
for (my $i = 0; $i < 5; $i++)
{
$cr->set_tolerance ($tolerance[$i]);
draw_spline ($cr, $height);
$cr->translate ($gap, 0);
}
}