root/lang/perl/misc/kaleid.pl

#!/usr/bin/perl
use strict;
use warnings;

use Imager;
use Imager::Fill;
use Getopt::Long;
use File::Basename;

GetOptions(
    'file=s'     => \my $file,
    'maxwidth=i' => \my $maxwidth,
    'width=i'    => \my $width,
    'out=s',     => \my $outfile,
);

$maxwidth ||= 1024;
unless ($outfile) {
    my $ext = ( fileparse( $file, '\..*' ) )[2];
    ( $outfile = $file ) =~ s/$ext/-kaleid$ext/;
}

my $orig = Imager->new();
$orig->read( file => $file ) or die $orig->errstr();
$orig = $orig->crop( width => $width, height => $width );

# make the right uppper triangle of "d" from the left lower triangle of "p"
my $flip = $orig->copy->flip( dir => "v" )->rotate( degrees => 90 );

my $polygon = Imager->new(
    xsize    => $orig->getwidth,
    ysize    => $orig->getheight,
    channels => 4
);
$polygon->box(
    fill => Imager::Fill->new( image => $flip, combine => 'normal' ) );
$polygon->polygon(
    points => [
        [ 0,               0 ],
        [ 0,               $orig->getheight ],
        [ $orig->getwidth, $orig->getheight ]
    ],
    color => Imager::Color->new( 0, 0, 0, 0 ),    #transparent
);

## paste triangle on orignal image
$orig->box(
    fill => Imager::Fill->new( image => $polygon, combine => 'normal' ) );

my $out = gen_kaleid( $orig, $maxwidth );
$out->write( file => $outfile );

sub gen_kaleid {
    my ( $input, $xmax ) = @_;
    my $kal = sub {
        my ($img) = @_;
        my $h_flip  = $img->copy->flip( dir => "h" );
        my $v_flip  = $img->copy->flip( dir => "v" );
        my $vh_flip = $img->copy->flip( dir => "vh" );
        my $result  = Imager->new(
            xsize    => $img->getwidth * 2,
            ysize    => $img->getheight * 2,
            bits     => $img->bits,
            channels => $img->getchannels
        );
        $result->paste(
            left => 0,
            top  => 0,
            src  => $img
        );
        $result->paste(
            left => $img->getwidth,
            top  => 0,
            src  => $h_flip
        );
        $result->paste(
            left => 0,
            top  => $img->getheight,
            src  => $v_flip
        );
        $result->paste(
            left => $img->getwidth,
            top  => $img->getheight,
            src  => $vh_flip
        );
        return $result;
    };
    $input = $kal->($input) while ( $input && $input->getwidth < $xmax );
    return $input;
}