php不用GD库生成当前时间的PNG格式图象的程序_php技巧

该程序是不用GD库可以生成当前时间的PNG格式图象，给人大开眼界，很有参考价值. teaman整理

<?php 
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($b); 
} 
//生成数字图象的函数 
function draw2digits($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); 
} 
} 
} 
} 
} 
//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); 
} 
} 
$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) | $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 
$data = ""; 
add_chunk("IEND"); 
// 列印图象 
echo($result); 
?> 
//如何调用，其实很简单，将上面存为Timeimg.php 
//然后新建一个页面如下： 
<html> 
<head> 
<title>test</title> 
<meta http-equiv="Content-Type" content="text/html"> 
</head> 
<body> 
<img src="Timeimg.php"> //以图象连接方式调用PHP文件 
</body> 
</html>