不用GD库生成当前时间的PNG格式图象的程序

= 255 << 24;
    $c = $z;
    for ($n = 4; $n < strlen($chunk); $n++) {
        $c8 = ($c >> 8) & 0xffffff;
        $c = $crc_table[($c ^ ord($chunk][$n])) & 0xff] ^ $c8;
    }
    $crc = $c ^ $z;

    $chunk .= chr(($crc >> 24) & 255);
    $chunk .= chr(($crc >> 16) & 255);
    $chunk .= chr(($crc >> 8) & 255);
    $chunk .= chr($crc & 255);

    // 将结果加到$result中
    $result .= $chunk;
    }

    //主程序

    $sx = 80;
    $sy = 21;
    $pixels = "";
            
    // 填充
    for ($h = 0; $h < $sy; $h++) {
    for ($w = 0; $w < $sx; $w++) {
        $r = 100 / $sx * $w + 155;
        $g = 100 / $sy * $h + 155;
        $b = 255 - (100 / ($sx + $sy) * ($w + $h));
        $pixels .= chr($r);
        $pixels .= chr($g);
        $pixels .= chr($b);
    }
    }
        
    $date = getdate();
    $s = $date["seconds"];
    $m = $date["minutes"];
    $h = $date["hours"];
    $digits = array(95, 5, 118, 117, 45, 121, 123, 69, 127, 125);
    $lines = array(1, 1, 1, 2, 0, 1, 0, 2, 1, 0, 1, 1, 0, 0, 0, 1, 0, 2, 1, 2, 0, 1, 1, 1, 0, 0, 1, 0);
        
    draw2digits(4, 2, $h);
    draw2digits(30, 2, $m);
    draw2digits(56, 2, $s);
    set_4pixel(0, 0, 0, 26, 7);
    set_4pixel(0, 0, 0, 26, 13);
    set_4pixel(0, 0, 0, 52, 7);
    set_4pixel(0, 0, 0, 52, 13);

    // 创建循环冗余码校验表
    $z = -306674912;  // = 0xedb88320
    for ($n = 0; $n < 256; $n++) {
        $c = $n;
        for ($k = 0; $k < 8; $k++) {
            $c2 = ($c >> 1) & 0x7fffffff;
            if ($c & 1) $c = $z ^ ($c2); else $c = $c2;
        }
        $crc_table[$n] = $c;
    }

    // PNG file signature
    $result = pack("c*", 137,80,78,71,13,10,26,10);
        
    // IHDR chunk data:
    //   width:              4 bytes
    //   height:             4 bytes
    //   bit depth:          1 byte (8 bits per RGB value)
    //   color type:         1 byte (2 = RGB)
    //   compression method: 1 byte (0 = deflate/inflate)
    //   filter method:      1 byte (0 = adaptive filtering)
    //   interlace method:   1 byte (0 = no interlace)
    $data = pack("c*", ($sx >> 24) & 255,
    ($sx >> 16) & 255,
    ($sx >> 8) & 255,
    $sx & 255,
    ($sy >> 24) & 255,
    ($sy >> 16) & 255,
    ($sy >> 8) & 255,
    $sy & 255,
    8,
    2,
    0,
    0,
    0);
    add_chunk("IHDR");

    // 以下不敢乱翻译，请自行参考
    //    scanline:
    //        filter byte: 0 = none
    //        RGB bytes for the line
    //    the scanline is compressed with "zlib", method 8 (RFC-1950):
    //        compression method/flags code: 1 byte ($78 = method 8, 32k window)
    //        additional flags/check bits:   1 byte ($01: FCHECK = 1, FDICT = 0, FLEVEL = 0)
    //        compressed data blocks:        n bytes
    //            one block (RFC-1951):
    //                bit 0: BFINAL: 1 for the last block
    //                bit 1 and 2: BTYPE: 0 for no compression
    //                next 2 bytes: LEN (LSB first)
    //                next 2 bytes: one's complement of LEN
    //                LEN bytes uncompressed data
    //        check value:  4 bytes (Adler-32 checksum of the uncompressed data)
    //
    $len = ($sx * 3 + 1) * $sy;
    $data = pack("c*", 0x78, 0x01,
        1,
    $len & 255,
    ($len >> 8) & 255,
    255 - ($len & 255),
    255 - (($len >> 8) & 255));
    $start = strlen($data);
    $i2 = 0;
    for ($h = 0; $h < $sy; $h++) {
    $data .= chr(0);
    for ($w = 0; $w < $sx * 3; $w++) {
        $data .= $pixels[$i2++];
    }
    }

    // calculate a Adler32 checksum with the bytes data[start..len-1]
    $s1 = 1;
    $s2 = 0;
    for ($n = $start; $n < strlen($data); $n++) {
    $s1 = ($s1 + ord($data[$n])) % 65521;
    $s2 = ($s2 + $s1) % 65521;
    }
    $adler = ($s2 << 16)

关键词：不用GD库生成当前时间的PNG格式图象的程序