<?PHP 
    // 
    // clock.php3 -- shows the current time as a PNG-image 
    FUNCTION set_4pixel($r, $g, $b, $x, $y) 
    { 
    GLOBAL $sx, $sy, $pixels; 
 
    $ofs = 3 * ($sx * $y + $x); 
    $pixels[$ofs] = CHR($r); 
    $pixels[$ofs + 1] = CHR($g); 
    $pixels[$ofs + 2] = CHR($b); 
    $pixels[$ofs + 3] = CHR($r); 
    $pixels[$ofs + 4] = CHR($g); 
    $pixels[$ofs + 5] = CHR($b); 
    $ofs += 3 * $sx; 
    $pixels[$ofs] = CHR($r); 
    $pixels[$ofs + 1] = CHR($g); 
    $pixels[$ofs + 2] = CHR($b); 
    $pixels[$ofs + 3] = CHR($r); 
    $pixels[$ofs + 4] = CHR($g); 
    $pixels[$ofs + 5] = CHR($b); 
    } 
 
    FUNCTION draw2digits($x, $y, $number) 
    { 
    draw_digit($x, $y, (int) ($number / 10)); 
    draw_digit($x + 11, $y, $number % 10); 
    } 
 
    FUNCTION draw_digit($x, $y, $digit) 
    { 
    GLOBAL $sx, $sy, $pixels, $digits, $lines; 
 
    $digit = $digits[$digit]; 
    $m = 8; 
    FOR ($b = 1, $i = 0; $i < 7; $i++, $b *= 2) { 
        IF (($b & $digit) == $b) { 
        $j = $i * 4; 
        $x0 = $lines[$j] * $m + $x; 
        $y0 = $lines[$j + 1] * $m + $y; 
        $x1 = $lines[$j + 2] * $m + $x; 
        $y1 = $lines[$j + 3] * $m + $y; 
        IF ($x0 == $x1) { 
            $ofs = 3 * ($sx * $y0 + $x0); 
            FOR ($h = $y0; $h <= $y1; $h++, $ofs += 3 * $sx) { 
            $pixels[$ofs] = CHR(0); 
            $pixels[$ofs + 1] = CHR(0); 
            $pixels[$ofs + 2] = CHR(0); 
            } 
        } ELSE { 
            $ofs = 3 * ($sx * $y0 + $x0); 
            FOR ($w = $x0; $w <= $x1; $w++) { 
            $pixels[$ofs++] = CHR(0); 
            $pixels[$ofs++] = CHR(0); 
            $pixels[$ofs++] = CHR(0); 
            } 
        } 
        } 
    } 
    } 
 
    // create a chunk with the bytes in $data and the specified 
    // type and add it to $result 
    FUNCTION add_chunk($type) 
    { 
    GLOBAL $result, $data, $chunk, $crc_table; 
 
    // chunk layout: 
    // length: 4 bytes: counting chunk data only 
    // chunk type: 4 bytes 
    // chunk data: length bytes 
    // CRC: 4 bytes: CRC-32 checksum of the type and the data 
 
    // copy data and create CRC checksum 
    $len = STRLEN($data); 
    $chunk = PACK("c*", ($len >> 24) & 255, 
        ($len >> 16) & 255, 
        ($len >> 8) & 255, 
        $len & 255); 
    $chunk .= $type; 
    $chunk .= $data; 
 
    // calculate a CRC checksum with the bytes chunk[4..len-1] 
    $z = 16777215; 
    $z |= 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); 
 
    // add it to the result 
    $result .= $chunk; 
    } 
 
 
    // ============ 
    // main program 
    // ============ 
 
    $sx = 80; 
    $sy = 21; 
    $pixels = ""; 
 
    // create filling 
    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); 
 
    // create crc-table 
    $z = -306674912;  // = 0xedb88320 
    FOR ($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"); 
 
    // IDAT: image data: 
    //    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) | $s1; 
 
    $data .= CHR(($adler >> 24) & 255); 
    $data .= CHR(($adler >> 16) & 255); 
    $data .= CHR(($adler >> 8) & 255); 
    $data .= CHR($adler & 255); 
    add_chunk("IDAT"); 
 
    // IEND: marks the end of the PNG-file 
    $data = ""; 
    add_chunk("IEND"); 
 
    // print the image 
    HEADER("Content-type: image/png"); 
    PRINT($result); 
?>