<?php

/**
 * fast-image-size image type gif
 *
 * @package       fast-image-size
 * @copyright (c) Marc Alexander <[email protected]>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Nextend\Framework\FastImageSize\Type;

class TypeGif extends TypeBase {

    /** @var string GIF87a header */
    const GIF87A_HEADER = "\x47\x49\x46\x38\x37\x61";

    /** @var string GIF89a header */
    const GIF89A_HEADER = "\x47\x49\x46\x38\x39\x61";

    /** @var int GIF header size */
    const GIF_HEADER_SIZE = 6;

    /**
     * {@inheritdoc}
     */
    public function getSize($filename) {
        // Get data needed for reading image dimensions as outlined by GIF87a
        // and GIF89a specifications
        $data = $this->fastImageSize->getImage($filename, 0, self::GIF_HEADER_SIZE + self::SHORT_SIZE * 2);

        $type = substr($data, 0, self::GIF_HEADER_SIZE);
        if ($type !== self::GIF87A_HEADER && $type !== self::GIF89A_HEADER) {
            return;
        }

        $size = unpack('vwidth/vheight', substr($data, self::GIF_HEADER_SIZE, self::SHORT_SIZE * 2));

        $this->fastImageSize->setSize($size);
        $this->fastImageSize->setImageType(IMAGETYPE_GIF);
    }
}