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<?php

/**
 * Classes used for reading gif files (in case PHP's GD doesn't provide the
 * proper gif-functions).
 *
 * Gif Util copyright 2003 by Yamasoft (S/C). All rights reserved.
 * Do not remove this portion of the header, or use these functions except
 * from the original author. To get it, please navigate to:
 * http://www.yamasoft.com/php-gif.zip
 *
 * Simple Machines Forum (SMF)
 *
 * @package SMF
 * @author Simple Machines http://www.simplemachines.org
 * @copyright 2019 Simple Machines and individual contributors
 * @license http://www.simplemachines.org/about/smf/license.php BSD
 *
 * @version 2.1 RC1
 */

if (!defined('SMF'))
    die('No direct access...');

/**
 * Class gif_lzw_compression
 *
 * An implementation of the LZW compression algorithm
 */
class gif_lzw_compression
{
    public $MAX_LZW_BITS;
    public $Fresh, $CodeSize, $SetCodeSize, $MaxCode, $MaxCodeSize, $FirstCode, $OldCode;
    public $ClearCode, $EndCode, $Next, $Vals, $Stack, $sp, $Buf, $CurBit, $LastBit, $Done, $LastByte;

    public function __construct()
    {
        $this->MAX_LZW_BITS = 12;
        unset($this->Next, $this->Vals, $this->Stack, $this->Buf);

        $this->Next = range(0, (1 << $this->MAX_LZW_BITS) - 1);
        $this->Vals = range(0, (1 << $this->MAX_LZW_BITS) - 1);
        $this->Stack = range(0, (1 << ($this->MAX_LZW_BITS + 1)) - 1);
        $this->Buf = range(0, 279);
    }

    public function decompress($data, &$datLen)
    {
        $stLen = strlen($data);
        $datLen = 0;
        $ret = '';

        $this->LZWCommand($data, true);

        while (($iIndex = $this->LZWCommand($data, false)) >= 0)
            $ret .= chr($iIndex);

        $datLen = $stLen - strlen($data);

        if ($iIndex != -2)
            return false;

        return $ret;
    }

    public function LZWCommand(&$data, $bInit)
    {
        if ($bInit)
        {
            $this->SetCodeSize = ord($data[0]);
            $data = substr($data, 1);

            $this->CodeSize = $this->SetCodeSize + 1;
            $this->ClearCode = 1 << $this->SetCodeSize;
            $this->EndCode = $this->ClearCode + 1;
            $this->MaxCode = $this->ClearCode + 2;
            $this->MaxCodeSize = $this->ClearCode << 1;

            $this->GetCode($data, $bInit);

            $this->Fresh = 1;
            for ($i = 0; $i < $this->ClearCode; $i++)
            {
                $this->Next[$i] = 0;
                $this->Vals[$i] = $i;
            }

            for (; $i < (1 << $this->MAX_LZW_BITS); $i++)
            {
                $this->Next[$i] = 0;
                $this->Vals[$i] = 0;
            }

            $this->sp = 0;
            return 1;
        }

        if ($this->Fresh)
        {
            $this->Fresh = 0;
            do
            {
                $this->FirstCode = $this->GetCode($data, $bInit);
                $this->OldCode = $this->FirstCode;
            }
            while ($this->FirstCode == $this->ClearCode);

            return $this->FirstCode;
        }

        if ($this->sp > 0)
        {
            $this->sp--;
            return $this->Stack[$this->sp];
        }

        while (($Code = $this->GetCode($data, $bInit)) >= 0)
        {
            if ($Code == $this->ClearCode)
            {
                for ($i = 0; $i < $this->ClearCode; $i++)
                {
                    $this->Next[$i] = 0;
                    $this->Vals[$i] = $i;
                }

                for (; $i < (1 << $this->MAX_LZW_BITS); $i++)
                {
                    $this->Next[$i] = 0;
                    $this->Vals[$i] = 0;
                }

                $this->CodeSize = $this->SetCodeSize + 1;
                $this->MaxCodeSize = $this->ClearCode << 1;
                $this->MaxCode = $this->ClearCode + 2;
                $this->sp = 0;
                $this->FirstCode = $this->GetCode($data, $bInit);
                $this->OldCode = $this->FirstCode;

                return $this->FirstCode;
            }

            if ($Code == $this->EndCode)
                return -2;

            $InCode = $Code;
            if ($Code >= $this->MaxCode)
            {
                $this->Stack[$this->sp] = $this->FirstCode;
                $this->sp++;
                $Code = $this->OldCode;
            }

            while ($Code >= $this->ClearCode)
            {
                $this->Stack[$this->sp] = $this->Vals[$Code];
                $this->sp++;

                if ($Code == $this->Next[$Code]) // Circular table entry, big GIF Error!
                    return -1;

                $Code = $this->Next[$Code];
            }

            $this->FirstCode = $this->Vals[$Code];
            $this->Stack[$this->sp] = $this->FirstCode;
            $this->sp++;

            if (($Code = $this->MaxCode) < (1 << $this->MAX_LZW_BITS))
            {
                $this->Next[$Code] = $this->OldCode;
                $this->Vals[$Code] = $this->FirstCode;
                $this->MaxCode++;

                if (($this->MaxCode >= $this->MaxCodeSize) && ($this->MaxCodeSize < (1 << $this->MAX_LZW_BITS)))
                {
                    $this->MaxCodeSize *= 2;
                    $this->CodeSize++;
                }
            }

            $this->OldCode = $InCode;
            if ($this->sp > 0)
            {
                $this->sp--;
                return $this->Stack[$this->sp];
            }
        }

        return $Code;
    }

    public function GetCode(&$data, $bInit)
    {
        if ($bInit)
        {
            $this->CurBit = 0;
            $this->LastBit = 0;
            $this->Done = 0;
            $this->LastByte = 2;

            return 1;
        }

        if (($this->CurBit + $this->CodeSize) >= $this->LastBit)
        {
            if ($this->Done)
            {
                // Ran off the end of my bits...
                if ($this->CurBit >= $this->LastBit)
                    return 0;

                return -1;
            }

            $this->Buf[0] = $this->Buf[$this->LastByte - 2];
            $this->Buf[1] = $this->Buf[$this->LastByte - 1];

            $count = ord($data[0]);
            $data = substr($data, 1);

            if ($count)
            {
                for ($i = 0; $i < $count; $i++)
                    $this->Buf[2 + $i] = ord($data{$i});

                $data = substr($data, $count);
            }
            else
                $this->Done = 1;

            $this->LastByte = 2 + $count;
            $this->CurBit = ($this->CurBit - $this->LastBit) + 16;
            $this->LastBit = (2 + $count) << 3;
        }

        $iRet = 0;
        for ($i = $this->CurBit, $j = 0; $j < $this->CodeSize; $i++, $j++)
            $iRet |= (($this->Buf[intval($i / 8)] & (1 << ($i % 8))) != 0) << $j;

        $this->CurBit += $this->CodeSize;
        return $iRet;
    }
}

class gif_color_table
{
    public $m_nColors;
    public $m_arColors;

    public function __construct()
    {
        unset($this->m_nColors, $this->m_arColors);
    }

    public function load($lpData, $num)
    {
        $this->m_nColors = 0;
        $this->m_arColors = array();

        for ($i = 0; $i < $num; $i++)
        {
            $rgb = substr($lpData, $i * 3, 3);
            if (strlen($rgb) < 3)
                return false;

            $this->m_arColors[] = (ord($rgb[2]) << 16) + (ord($rgb[1]) << 8) + ord($rgb[0]);
            $this->m_nColors++;
        }

        return true;
    }

    public function toString()
    {
        $ret = '';

        for ($i = 0; $i < $this->m_nColors; $i++)
        {
            $ret .=
                chr(($this->m_arColors[$i] & 0x000000FF)) . // R
                chr(($this->m_arColors[$i] & 0x0000FF00) >> 8) . // G
                chr(($this->m_arColors[$i] & 0x00FF0000) >> 16);  // B
        }

        return $ret;
    }

    public function colorIndex($rgb)
    {
        $dif = 0;
        $rgb = intval($rgb) & 0xFFFFFF;
        $r1 = ($rgb & 0x0000FF);
        $g1 = ($rgb & 0x00FF00) >> 8;
        $b1 = ($rgb & 0xFF0000) >> 16;
        $idx = -1;

        for ($i = 0; $i < $this->m_nColors; $i++)
        {
            $r2 = ($this->m_arColors[$i] & 0x000000FF);
            $g2 = ($this->m_arColors[$i] & 0x0000FF00) >> 8;
            $b2 = ($this->m_arColors[$i] & 0x00FF0000) >> 16;
            $d = abs($r2 - $r1) + abs($g2 - $g1) + abs($b2 - $b1);

            if (($idx == -1) || ($d < $dif))
            {
                $idx = $i;
                $dif = $d;
            }
        }

        return $idx;
    }
}

class gif_file_header
{
    public $m_lpVer, $m_nWidth, $m_nHeight, $m_bGlobalClr, $m_nColorRes;
    public $m_bSorted, $m_nTableSize, $m_nBgColor, $m_nPixelRatio;
    public $m_colorTable;

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

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

        $this->m_lpVer = substr($lpData, 0, 6);
        if (($this->m_lpVer != 'GIF87a') && ($this->m_lpVer != 'GIF89a'))
            return false;

        list ($this->m_nWidth, $this->m_nHeight) = array_values(unpack('v2', substr($lpData, 6, 4)));

        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)
        {
            $this->m_colorTable = new gif_color_table();
            if (!$this->m_colorTable->load(substr($lpData, $hdrLen), $this->m_nTableSize))
                return false;

            $hdrLen += 3 * $this->m_nTableSize;
        }

        return true;
    }
}

class gif_image_header
{
    public $m_nLeft, $m_nTop, $m_nWidth, $m_nHeight, $m_bLocalClr;
    public $m_bInterlace, $m_bSorted, $m_nTableSize, $m_colorTable;

    public function __construct()
    {
        unset($this->m_nLeft, $this->m_nTop, $this->m_nWidth, $this->m_nHeight, $this->m_bLocalClr);
        unset($this->m_bInterlace, $this->m_bSorted, $this->m_nTableSize, $this->m_colorTable);
    }

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

        // Get the width/height/etc. from the header.
        list ($this->m_nLeft, $this->m_nTop, $this->m_nWidth, $this->m_nHeight) = array_values(unpack('v4', substr($lpData, 0, 8)));

        if (!$this->m_nWidth || !$this->m_nHeight)
            return false;

        $b = ord($lpData[8]);
        $this->m_bLocalClr = ($b & 0x80) ? true : false;
        $this->m_bInterlace = ($b & 0x40) ? true : false;
        $this->m_bSorted = ($b & 0x20) ? true : false;
        $this->m_nTableSize = 2 << ($b & 0x07);
        $hdrLen = 9;

        if ($this->m_bLocalClr)
        {
            $this->m_colorTable = new gif_color_table();
            if (!$this->m_colorTable->load(substr($lpData, $hdrLen), $this->m_nTableSize))
                return false;

            $hdrLen += 3 * $this->m_nTableSize;
        }

        return true;
    }
}

class gif_image
{
    public $m_disp, $m_bUser, $m_bTrans, $m_nDelay, $m_nTrans, $m_lpComm;
    public $m_gih, $m_data, $m_lzw;

    public function __construct()
    {
        unset($this->m_disp, $this->m_bUser, $this->m_nDelay, $this->m_nTrans, $this->m_lpComm, $this->m_data);
        $this->m_gih = new gif_image_header();
        $this->m_lzw = new gif_lzw_compression();
    }

    public function load($data, &$datLen)
    {
        $datLen = 0;

        while (true)
        {
            $b = ord($data[0]);
            $data = substr($data, 1);
            $datLen++;

            switch ($b)
            {
                // Extension...
                case 0x21:
                    $len = 0;
                    if (!$this->skipExt($data, $len))
                        return false;

                    $datLen += $len;
                    break;

                // Image...
                case 0x2C:
                    // Load the header and color table.
                    $len = 0;
                    if (!$this->m_gih->load($data, $len))
                        return false;

                    $data = substr($data, $len);
                    $datLen += $len;

                    // Decompress the data, and ride on home ;).
                    $len = 0;
                    if (!($this->m_data = $this->m_lzw->decompress($data, $len)))
                        return false;

                    $datLen += $len;

                    if ($this->m_gih->m_bInterlace)
                        $this->deInterlace();

                    return true;

                case 0x3B: // EOF
                default:
                    return false;
            }
        }
        return false;
    }

    public function skipExt(&$data, &$extLen)
    {
        $extLen = 0;

        $b = ord($data[0]);
        $data = substr($data, 1);
        $extLen++;

        switch ($b)
        {
            // Graphic Control...
            case 0xF9:
                $b = ord($data[1]);
                $this->m_disp = ($b & 0x1C) >> 2;
                $this->m_bUser = ($b & 0x02) ? true : false;
                $this->m_bTrans = ($b & 0x01) ? true : false;
                list ($this->m_nDelay) = array_values(unpack('v', substr($data, 2, 2)));
                $this->m_nTrans = ord($data[4]);
                break;

            // Comment...
            case 0xFE:
                $this->m_lpComm = substr($data, 1, ord($data[0]));
                break;

            // Plain text...
            case 0x01:
                break;

            // Application...
            case 0xFF:
                break;
        }

        // Skip default as defs may change.
        $b = ord($data[0]);
        $data = substr($data, 1);
        $extLen++;
        while ($b > 0)
        {
            $data = substr($data, $b);
            $extLen += $b;
            $b = ord($data[0]);
            $data = substr($data, 1);
            $extLen++;
        }
        return true;
    }

    public function deInterlace()
    {
        $data = $this->m_data;

        for ($i = 0; $i < 4; $i++)
        {
            switch ($i)
            {
                case 0:
                    $s = 8;
                    $y = 0;
                    break;

                case 1:
                    $s = 8;
                    $y = 4;
                    break;

                case 2:
                    $s = 4;
                    $y = 2;
                    break;

                case 3:
                    $s = 2;
                    $y = 1;
                    break;
            }

            for (; $y < $this->m_gih->m_nHeight; $y += $s)
            {
                $lne = substr($this->m_data, 0, $this->m_gih->m_nWidth);
                $this->m_data = substr($this->m_data, $this->m_gih->m_nWidth);

                $data =
                    substr($data, 0, $y * $this->m_gih->m_nWidth) .
                    $lne .
                    substr($data, ($y + 1) * $this->m_gih->m_nWidth);
            }
        }

        $this->m_data = $data;
    }
}

class gif_file
{
    public $header, $image, $data, $loaded;

    public function __construct()
    {
        $this->data = '';
        $this->loaded = false;
        $this->header = new gif_file_header();
        $this->image = new gif_image();
    }

    public function loadFile($filename, $iIndex)
    {
        if ($iIndex < 0)
            return false;

        $this->data = @file_get_contents($filename);
        if ($this->data === false)
            return false;

        // Tell the header to load up....
        $len = 0;
        if (!$this->header->load($this->data, $len))
            return false;

        $this->data = substr($this->data, $len);

        // Keep reading (at least once) so we get to the actual image we're looking for.
        for ($j = 0; $j <= $iIndex; $j++)
        {
            $imgLen = 0;
            if (!$this->image->load($this->data, $imgLen))
                return false;

            $this->data = substr($this->data, $imgLen);
        }

        $this->loaded = true;
        return true;
    }

    public function get_png_data($background_color)
    {
        if (!$this->loaded)
            return false;

        // Prepare the color table.
        if ($this->image->m_gih->m_bLocalClr)
        {
            $colors = $this->image->m_gih->m_nTableSize;
            $pal = $this->image->m_gih->m_colorTable->toString();

            if ($background_color != -1)
                $background_color = $this->image->m_gih->m_colorTable->colorIndex($background_color);
        }
        elseif ($this->header->m_bGlobalClr)
        {
            $colors = $this->header->m_nTableSize;
            $pal = $this->header->m_colorTable->toString();

            if ($background_color != -1)
                $background_color = $this->header->m_colorTable->colorIndex($background_color);
        }
        else
        {
            $colors = 0;
            $background_color = -1;
        }

        if ($background_color == -1)
            $background_color = $this->header->m_nBgColor;

        $data = &$this->image->m_data;
        $header = &$this->image->m_gih;

        $i = 0;
        $bmp = '';

        // Prepare the bitmap itself.
        for ($y = 0; $y < $this->header->m_nHeight; $y++)
        {
            $bmp .= "\x00";

            for ($x = 0; $x < $this->header->m_nWidth; $x++, $i++)
            {
                // Is this in the proper range?  If so, get the specific pixel data...
                if ($x >= $header->m_nLeft && $y >= $header->m_nTop && $x < ($header->m_nLeft + $header->m_nWidth) && $y < ($header->m_nTop + $header->m_nHeight))
                    $bmp .= $data{$i};
                // Otherwise, this is background...
                else
                    $bmp .= chr($background_color);
            }
        }

        $bmp = gzcompress($bmp, 9);

        // Output the basic signature first of all.
        $out = "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A";

        // Now, we want the header...
        $out .= "\x00\x00\x00\x0D";
        $tmp = 'IHDR' . pack('N', (int) $this->header->m_nWidth) . pack('N', (int) $this->header->m_nHeight) . "\x08\x03\x00\x00\x00";
        $out .= $tmp . pack('N', smf_crc32($tmp));

        // The palette, assuming we have one to speak of...
        if ($colors > 0)
        {
            $out .= pack('N', (int) $colors * 3);
            $tmp = 'PLTE' . $pal;
            $out .= $tmp . pack('N', smf_crc32($tmp));
        }

        // Do we have any transparency we want to make available?
        if ($this->image->m_bTrans && $colors > 0)
        {
            $out .= pack('N', (int) $colors);
            $tmp = 'tRNS';

            // Stick each color on - full transparency or none.
            for ($i = 0; $i < $colors; $i++)
                $tmp .= $i == $this->image->m_nTrans ? "\x00" : "\xFF";

            $out .= $tmp . pack('N', smf_crc32($tmp));
        }

        // Here's the data itself!
        $out .= pack('N', strlen($bmp));
        $tmp = 'IDAT' . $bmp;
        $out .= $tmp . pack('N', smf_crc32($tmp));

        // EOF marker...
        $out .= "\x00\x00\x00\x00" . 'IEND' . "\xAE\x42\x60\x82";

        return $out;
    }
}

// 64-bit only functions?
if (!function_exists('smf_crc32'))
{
    require_once $sourcedir . '/Subs-Compat.php';
}

?>