Yuki Kimoto's Perl Blog

Write sin curve using Imager.

Chart::GGPlot author say to me "It is hard to use graphic basic library for me".

so I want to illustrate basic drawing.

Cairo seems to be good as features but portability is not good.

so I try to plot sin curve by Imager.

Curve is continue of very short lines.

I wrote a graph of sin.

Performance is very fast. Generation of graph is in a second.

use strict;
use warnings;

use Imager;

use Imager::Color;

use Math::Spline;

use Math::Trig 'pi';

my $xsize = 500;

my $ysize = 500;

my $x_offset = 250;

my $y_offset = 250;

my $img = Imager->new(xsize => $xsize, ysize => $ysize, channels => 4);

my $scale = 100;

my $min = -pi();

my $max = 2*pi();

my $kannkaku = 0.1;

my $points = [];

for (my $x = $min; $x < $max; $x += 0.1) {

  my $y = sin($x);

  my $point = [$x * $scale + $x_offset, $y * $scale + $y_offset];

  push @$points, $point;

}



# my @ys = map { xx($_) } @xs;

# my $spline = Math::Spline->new(\@xs, \@ys);

# my $x = 5;

# my $y = $spline->evaluate($x);

my $blue = Imager::Color->new( 0, 0, 255 );

# my $fill = Imager::Fill->new(hatch=>'stipple');

$img->box(color => Imager::Color->new(255, 255, 255), xmin=>0, ymin=>0, xmax=>400, ymax=>300, 

          filled=>1);

$img->polyline(points => $points, color => $blue, aa => 1);

$img->flip(dir => 'v');

# Jpeg、画質 90% で保存

$img->write( file => 'graph.png', jpegquality => 90 )

  or die $img->errstr;