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


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：







//以图象连接方式调用PHP文件