<?php

namespace Mpdf\Gif;

/**
 * GIF Util - (C) 2003 Yamasoft (S/C)
 *
 * All Rights Reserved
 *
 * This file can be freely copied, distributed, modified, updated by anyone under the only
 * condition to leave the original address (Yamasoft, http://www.yamasoft.com) and this header.
 *
 * @link http://www.yamasoft.com
 */
class FileHeader {

    var $m_lpVer;

    var $m_nWidth;

    var $m_nHeight;

    var $m_bGlobalClr;

    var $m_nColorRes;

    var $m_bSorted;

    var $m_nTableSize;

    var $m_nBgColor;

    var $m_nPixelRatio;

    /**
     * @var \Mpdf\Gif\ColorTable
     */
    var $m_colorTable;

    public function __construct() {
        unset($this->m_lpVer);
        unset($this->m_nWidth);
        unset($this->m_nHeight);
        unset($this->m_bGlobalClr);
        unset($this->m_nColorRes);
        unset($this->m_bSorted);
        unset($this->m_nTableSize);
        unset($this->m_nBgColor);
        unset($this->m_nPixelRatio);
        unset($this->m_colorTable);
    }

    function load($lpData, &$hdrLen) {
        $hdrLen = 0;

        $this->m_lpVer = substr($lpData, 0, 6);
        if (($this->m_lpVer <> "GIF87a") && ($this->m_lpVer <> "GIF89a")) {
            return false;
        }

        $this->m_nWidth = $this->w2i(substr($lpData, 6, 2));
        $this->m_nHeight = $this->w2i(substr($lpData, 8, 2));
        if (!$this->m_nWidth || !$this->m_nHeight) {
            return false;
        }

        $b = ord(substr($lpData, 10, 1));
        $this->m_bGlobalClr = ($b & 0x80) ? true : false;
        $this->m_nColorRes = ($b & 0x70) >> 4;
        $this->m_bSorted = ($b & 0x08) ? true : false;
        $this->m_nTableSize = 2 << ($b & 0x07);
        $this->m_nBgColor = ord(substr($lpData, 11, 1));
        $this->m_nPixelRatio = ord(substr($lpData, 12, 1));
        $hdrLen = 13;

        if ($this->m_bGlobalClr) {
            $this->m_colorTable = new ColorTable();
            if (!$this->m_colorTable->load(substr($lpData, $hdrLen), $this->m_nTableSize)) {
                return false;
            }
            $hdrLen += 3 * $this->m_nTableSize;
        }

        return true;
    }

    function w2i($str) {
        return ord(substr($str, 0, 1)) + (ord(substr($str, 1, 1)) << 8);
    }
}
