<?php
error_reporting(0);
/**
 * Get the width and height of the destination image
 * from the POST variables and convert them into
 * integer values
 */
$w = (int)$_POST['width'];
$h = (int)$_POST['height'];

// create the image with desired width and height

$img = imagecreatetruecolor($w, $h);

// now fill the image with blank color
// do you remember i wont pass the 0xFFFFFF pixels 
// from flash?
imagefill($img, 0, 0, 0xFFFFFF);

$rows = 0;
$cols = 0;

// now process every POST variable which
// contains a pixel color
for($rows = 0; $rows < $h; $rows++){
	// convert the string into an array of n elements
	$c_row = explode(",", $_POST['px' . $rows]);
	for($cols = 0; $cols < $w; $cols++){
		// get the single pixel color value
		$value = $c_row[$cols];
		// if value is not empty (empty values are the blank pixels)
		if($value != ""){
			// get the hexadecimal string (must be 6 chars length)
			// so add the missing chars if needed
			$hex = $value;
			while(strlen($hex) < 6){
				$hex = "0" . $hex;
			}
			// convert value from HEX to RGB
			$r = hexdec(substr($hex, 0, 2));
			$g = hexdec(substr($hex, 2, 2));
			$b = hexdec(substr($hex, 4, 2));
			// allocate the new color
			// N.B. teorically if a color was already allocated 
			// we dont need to allocate another time
			// but this is only an example
			$test = imagecolorallocate($img, $r, $g, $b);
			// and paste that color into the image
			// at the correct position
			imagesetpixel($img, $cols, $rows, $test);
		}
	}
}

// print out the correct header to the browser
header("Content-type:image/jpeg");
// display the image
imagejpeg($img, "pix/test.png", 90);
imagejpeg($img, "", 90);
?>