#!/usr/bin/perl
use strict;
use warnings;
use Cairo;
use constant
{
WIDTH => 750,
HEIGHT => 500,
};
{
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);
$cr->fill;
draw_outlines ($cr, WIDTH, HEIGHT);
$cr->show_page;
$surf->write_to_png ($out);
}
sub create_gradient
{
my ($cr, $width, $height) = @_;
my $gradient = Cairo::LinearGradient->create (0, 0, $width, 0);
$gradient->add_color_stop_rgb (0.0, 0., 0., 0.);
$gradient->add_color_stop_rgb (0.5, 1., 1., 1.);
$gradient->add_color_stop_rgb (1.0, 0., 0., 0.);
return $gradient;
}
sub draw_outlines
{
my ($cr, $surface_width, $surface_height) = @_;
my $gradient;
my ($width, $height, $pad);
$width = $surface_width / 4.0;
$pad = ($surface_width - (3 * $width)) / 2.0;
$height = $surface_height;
$gradient = create_gradient ($cr, $width, $height);
$cr->set_source ($gradient);
draw_flat ($cr, $width, $height);
$cr->translate ($width + $pad, 0);
$cr->set_source ($gradient);
draw_tent ($cr, $width, $height);
$cr->translate ($width + $pad, 0);
$cr->set_source ($gradient);
draw_cylinder ($cr, $width, $height);
$cr->restore;
}
sub draw_flat
{
my ($cr, $width, $height) = @_;
my $hwidth = $width / 2.0;
$cr->rectangle (0, $hwidth, $width, $height - $hwidth);
$cr->fill;
}
sub draw_tent
{
my ($cr, $width, $height) = @_;
my $hwidth = $width / 2.0;
$cr->move_to ( 0, $hwidth);
$cr->rel_line_to ( $hwidth, -$hwidth);
$cr->rel_line_to ( $hwidth, $hwidth);
$cr->rel_line_to ( 0, $height - $hwidth);
$cr->rel_line_to (-$hwidth, -$hwidth);
$cr->rel_line_to (-$hwidth, $hwidth);
$cr->close_path;
$cr->fill;
}
sub draw_cylinder
{
my ($cr, $width, $height) = @_;
my $hwidth = $width / 2.0;
$cr->move_to (0, $hwidth);
$cr->rel_curve_to (0, -$hwidth, $width, -$hwidth, $width, 0);
$cr->rel_line_to (0, $height - $hwidth);
$cr->rel_curve_to (0, -$hwidth, -$width, -$hwidth, -$width, 0);
$cr->close_path;
$cr->fill;
}