s[$ofs++] = chr(0); $pixels[$ofs++] = chr(0); $pixels[$ofs++] = chr(0); } } } } } //将文字加入到图象中 function add_chunk($type) { global $result, $data, $chunk, $crc_table;
// chunk :为层 // length: 4 字节: 用来计算 chunk // chunk type: 4 字节 // chunk data: length bytes // CRC: 4 字节: 循环冗余码校验 // 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);
// 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); } } & |