jlcyr.com

<?php
/*
* Title: PNG Image Generation
* Author: Jean-Luc Cyr
* Date: 2008-09-17
* License: GNU GPL2
* Description: Generate a simple PNG image
* directly in PHP without using external libs
* like GD.
*/
 
header("content-type: image/png");
 
function long2string($long)
{
$string = chr(($long&0xFF000000)>>24).
chr(($long&0xFF0000)>>16).
chr(($long&0xFF00)>>8).
chr(($long&0xFF)>>0);
return $string;
} // long2string()
function build_png($matrix, $w, $h)
{
////////////////////////////////////////////////////////////////
//PNG Header
$image = chr(0x89).chr(0x50).chr(0x4E).chr(0x47);
$image .= chr(0x0D).chr(0x0A).chr(0x1A).chr(0x0A);
 
////////////////////////////////////////////////////////////////
//Header Chunk
 
//Chunk type
$chunk = "IHDR";
//Chunk data
//Width
$data = long2string($w);
//Height
$data .= long2string($h);
//Depth
$data .= chr(8); //Bits per sample
//Color Type
$data .= chr(2); //RGB
//Compression method
$data .= chr(0);
//Filter method
$data .= chr(0);
//Interlaced method
$data .= chr(0);
 
$crc = crc32($chunk.$data);
//Add length at start
$chunk = long2string(strlen($data)).$chunk.$data;
//Add CRC at the end
//Dump chunk
$chunk = $chunk.long2string($crc);
$image .= $chunk;
 
////////////////////////////////////////////////////////////////
//Data Chunk
 
//Chunk type
$chunk = "IDAT";
//Data (2x2 rgb 8bits)
$s = 3; //samples per pixels
#$matrix  ="\0\0\0\0\0\0\0\0\0";
#$matrix .="\0\0\0\0\0\0\0\0\0";
#$matrix .="\0\0\0\0\0\0\0\0\0";
// No filter so add 0 to beginning of each scan line
$datas = '';
for($c=0; $c<$h; $c++)
$datas .= "\0". substr($matrix,$c*($w*$s),($w*$s));
// Compress Data
#$zdata = gzencode($data,9,FORCE_DEFLATE);
#$zdata = gzdeflate($data,0);
$zdata = gzcompress($datas,0);
// Calculate CRC
$crc = crc32($chunk.$zdata);
// Add length at start
$l = strlen($zdata);
$chunk = long2string($l).$chunk.$zdata;
// Add CRC at the end
$chunk = $chunk.long2string($crc);
$image .= $chunk;
 
////////////////////////////////////////////////////////////////
//End Chunk
 
// Chunk type
$chunk = "IEND";
// Data
$data = "";
// Calculate CRC
$crc = crc32($chunk);
// Add length at start
$chunk = long2string(strlen($data)).$chunk.$data;
// Add CRC at the end
$chunk = $chunk.long2string($crc);
$image .= $chunk;
 
// Send out the image
echo $image;die();
} // build_png()
////////////////////////////////////////////////////////////////
// Demo code
 
// Build a simple image matrix
// 256 x 256 x 8rgb
 
$w=256; // width
$h=256; // height
$s=3;   // 3 x 8 bits samples per pixel (8bits rgb)
for($x=0; $x<$h; $x++)
for($y=0; $y<$w; $y++)
//    for($z=0; $z<$s; $z++) //Ordered R G B
$matrix .=
chr( ( (($y/64)<1) && (($y/64)>0) )?$x:0 ). // R
chr( ( (($y/64)<2) && (($y/64)>1) )?$x:0 ). // G
chr( ( (($y/64)<3) && (($y/64)>2) )?$x:0 ); // B
 
build_png($matrix,$w,$h);
die();
 
////////////////////////////////////////////////////////////////
// Hex dump image for debugging
 
for ($x=0; $x<strlen($image); $x++) {
printf("%02X ",ord($image[$x]));
if ((($x+1)%16)==0)
printf("<br/>");
}