qrcode.psgi

use 5.10.0;
use warnings;
use utf8;
use Plack::Request;
use Encode;
use GD::Barcode::QRcode;
use Try::Tiny;

my $app = sub {
    my $env = shift;
    my $req = Plack::Request->new($env);

    my $t = $req->param('t') // '';
    my $e = $req->param('e') // 'M';
    my $p = $req->param('p') // 0;
    my $r = $req->param('r') || 1;

    my $qr;
    my $msg;
    for my $v ( 1 .. 40 ) {
        try {
            $qr = GD::Barcode::QRcode->new(
                encode_utf8($t),
                { Ecc => $e, Version => $v },
            );
        } catch {
            $msg = shift;
        };
        last if $qr;
    }

    # error
    if ( ! $qr ) {
        return [
            500,
            [ 'Content-Type' => 'text/plain' ],
            [ $msg ],
        ];
    }

    my $img_qr = $qr->plot();
    my $pr = 4 * $r;  # 4 は 生成時に付加されるパディング [px]

    my ($w0, $h0) = $img_qr->getBounds();
    my ($w1, $h1) = ( int($w0 * $r), int($h0 * $r) );

    my $img = GD::Image->new(
        $w1 - 2 * ($pr - $p),
        $h1 - 2 * ($pr - $p),
    );
    $img->copyResized(
        $img_qr,
        - ($pr - $p), - ($pr - $p),
        0, 0,
        $w1, $h1,
        $w0, $h0,
    );

    return [
        200,
        [ 'Content-Type' => 'image/png' ],
        [ $img->png ],
    ];
};