Program _php base for PNG format images without the GD library to generate the current time

The program is not the GD library can generate the current time of the PNG format image, to the people's eyes, very valuable reference. Teaman Finishing

<?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 ($b);
}
Functions for generating digital images
function Draw2digits ($x, $y, $number)
{
Draw_digit ($x, $y, (int) ($number/10));
Draw_digit ($x + one, $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;
$x 0 = $lines [$j] * $m + $x;
$y 0 = $lines [$j + 1] * $m + $y;
$x 1 = $lines [$j + 2] * $m + $x;
$y 1 = $lines [$j + 3] * $m + $y;
if ($x 0 = $x 1) {
$ofs = 3 * ($SX * $y 0 + $x 0);
for ($h = $y 0; $h <= $y 1; $h + +, $ofs + + 3 * $sx) {
$pixels [$ofs] = chr (0);
$pixels [$ofs + 1] = chr (0);
$pixels [$ofs + 2] = chr (0);
}
} else {
$ofs = 3 * ($SX * $y 0 + $x 0);
for ($w = $x 0; $w <= $x 1; $w + +) {
$pixels [$ofs + +] = chr (0);
$pixels [$ofs + +] = chr (0);
$pixels [$ofs + +] = chr (0);
}
}
}
}
}

Add text to the image
function Add_chunk ($type)
{
Global $result, $data, $chunk, $CRC _table;

   //chunk: For layer
   //length:4 bytes: Used to compute chunk 
   //Chun K Type:4 byte
   //chunk data:length bytes
   //crc:4 byte:  cyclic redundancy code check

   //Copy data and create CRC checksum
    $len = strlen ($data);
    $chunk = Pack ("c*", ($len >>) & 255,
        ($len >>) & 255,
        ($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 + +) {
$c 8 = ($c >> 8) & 0xFFFFFF;
$c = $CRC _table[($c ^ ord ($chunk [$n])) & 0xFF] ^ $c 8;
}
$CRC = $c ^ $z;

$chunk. = Chr (($CRC >>) & 255);
$chunk. = Chr (($CRC >>) & 255);
$chunk. = Chr (($CRC >> 8) & 255);
$chunk. = Chr ($CRC & 255);

Add the results to the $result
$result. = $chunk;
}

Main program

$SX = 80;
$sy = 21;
$pixels = "";

Fill
for ($h = 0; $h < $sy; $h + +) {
for ($w = 0; $w < $sx; $w + +) {
$r = 100/$SX * $w + 155;
$g = 100/$sy * $h + 155;
$b = 255-($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 (2, $m);
Draw2digits (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 cyclic redundancy Code Check table
$z =-306674912; = 0xedb88320
for ($n = 0; $n < 256; $n + +) {
$c = $n;
for ($k = 0; $k < 8; $k + +) {
$c 2 = ($c >> 1) & 0x7fffffff;
if ($c & 1) $c = $z ^ ($c 2); else $c = $c 2;
}
$CRC _table[$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 >>) & 255,
($sx >>) & 255,
($SX >> 8) & 255,
$SX & 255,
($sy >>) & 255,
($sy >>) & 255,
($sy >> 8) & 255,
$sy & 255,
8,
2,
0,
0,
0);
Add_chunk ("IHDR");

The following do not dare to translate, please own reference
Scanline:
Filter byte:0 = None
RGB bytes for the line
The scanline is compressed with "zlib" and 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 i)
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);
$i 2 = 0;
for ($h = 0; $h < $sy; $h + +) {
$data. = chr (0);
for ($w = 0; $w < $SX * 3; $w + +) {
$data. = $pixels [$i 2++];
}
}

Calculate a Adler32 checksum with the bytes Data[start. LEN-1]
$s 1 = 1;
$s 2 = 0;
for ($n = $start; $n < strlen ($data); $n + +) {
$s 1 = ($s 1 + ord ($data [$n]))% 65521;
$s 2 = ($s 2 + $s 1)% 65521;
}
$adler = ($s 2 << 16) | $s 1;

$data. = Chr (($adler >>) & 255);
$data. = Chr (($adler >>) & 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 image

Echo ($result);
?>

How to call, in fact very simple, save the above as timeimg.php
Then create a new page as follows:

<title>test</title>
<meta http-equiv= "Content-type" content= "text/html" >
<body>
//Call PHP file in image connection mode
</body>