Change background color in PHP

<?php
	/*
		----------------------------------------------------------------
		Easy Reflections by Richard Davey, Core PHP (rich@corephp.co.uk)
		v2 - 2nd March 2007
        Updates include changes by Monte Ohrt (monte@ohrt.com)
		----------------------------------------------------------------
		You are free to use this in any product, or on any web site.
		Latest builds at: http://reflection.corephp.co.uk
		----------------------------------------------------------------
		
		This script accepts the following $_GET parameters:
		
		img		        required	The source image (to reflect)
		height	        optional	Height of the reflection (% or pixel value)
		bgc		        optional	Background colour to fade into, default = #000000
        fade_start      optional    Start the alpha fade from whch value? (% value)
        fade_end        optional    End the alpha fade from whch value? (% value)
		jpeg	        optional	Output will be JPEG at 'param' quality (default 80)
        cache           optional    Save reflection image to the cache? (boolean)
	*/
	
	// Replace special chars to be HTML-Code
	function stringToHTML($string)
	{
		$array_search = array('é', 'è', 'ë', 'ê', 'à', 'ä', 'Ä', 'â', 'ù', 'ü', 'Ü', 'û', 'ö', 'Ö', 'ô', 'ï', 'î');
		$array_replace = array('&eacute;', '&egrave;',	'&euml;', '&ecirc;', '&agrave;', '&auml;', '&Auml;', '&acirc;', '&ugrave;', '&uuml;', '&Uuml;', '&ucirc;', '&ouml;', '&Ouml;', '&ocirc;', '&iuml;', '&icirc;');
		$string_return = str_replace($array_search, $array_replace, $string);
		return $string_return;
	}
 
	// CACHE! EVERYTHING! 
	$_GET['cache'] = 1;
 
	//	PHP Version sanity check
	if (version_compare('4.3.2', phpversion()) == 1)
	{
		echo 'This version of PHP is not fully supported. You need 4.3.2 or above.';
		exit();
	}
	
	//	GD check
	if (extension_loaded('gd') == false && !dl('gd.so'))
	{
		echo 'You are missing the GD extension for PHP, sorry but I cannot continue.';
		exit();
	}
	
	//	Our allowed query string parameters
 
    //  To cache or not to cache? that is the question
    if (isset($_GET['cache']))
    {
        if ((int) $_GET['cache'] == 1)
        {
            $cache = true;
        }
        else
        {
            $cache = false;
        }
    }
    else
    {
        $cache = false;
    }
 
	//	img (the image to reflect)
	if (isset($_GET['img']))
	{
		$source_image = $_GET['img'];
 
		//$source_image = utf8_decode($source_image);
 
		$source_image = str_replace('://','',$source_image);
		//$source_image = $_SERVER['DOCUMENT_ROOT'] . DIRECTORY_SEPARATOR . $source_image;
        
        if (file_exists($source_image))
        {
            if ($cache)
            {
                $cache_dir = dirname($source_image);
                $cache_base = basename($source_image);
                $cache_file = 'refl_' . md5($_SERVER['REQUEST_URI']) . '_' . $cache_base;
                $cache_path = $cache_dir . DIRECTORY_SEPARATOR . $cache_file;
 
                if (file_exists($cache_path) && filemtime($cache_path) >= filemtime($source_image))
                {
                    // Use cached image
                    $image_info = getimagesize($cache_path);
                    header("Content-type: " . $image_info['mime']);
                    readfile($cache_path);
                    exit();
                }
            }
        }
        else
        {
          echo 'Cannot find or read source image';
          exit();
        }
	}
	else
	{
		echo 'No source image to reflect supplied';
		exit();
	}
 
	//	bgc (the background colour used, defaults to black if not given)
	if (isset($_GET['bgc']) == false)
	{
		$red = 0;
		$green = 0;
		$blue = 0;
	}
	else
	{
		//	Extract the hex colour
		$hex_bgc = $_GET['bgc'];
		
		//	Does it start with a hash? If so then strip it
		$hex_bgc = str_replace('#', '', $hex_bgc);
		
		switch (strlen($hex_bgc))
		{
			case 6:
				$red = hexdec(substr($hex_bgc, 0, 2));
				$green = hexdec(substr($hex_bgc, 2, 2));
				$blue = hexdec(substr($hex_bgc, 4, 2));
				break;
				
			case 3:
				$red = substr($hex_bgc, 0, 1);
				$green = substr($hex_bgc, 1, 1);
				$blue = substr($hex_bgc, 2, 1);
				$red = hexdec($red . $red);
				$green = hexdec($green . $green);
				$blue = hexdec($blue . $blue);
				break;
				
			default:
				//	Wrong values passed, default to black
				$red = 0;
				$green = 0;
				$blue = 0;
		}
	}
	
	//	height (how tall should the reflection be?)
	if (isset($_GET['height']))
	{
		$output_height = $_GET['height'];
		
		//	Have they given us a percentage?
		if (substr($output_height, -1) == '%')
		{
			//	Yes, remove the % sign
			$output_height = (int) substr($output_height, 0, -1);
 
			//	Gotta love auto type casting ;)
			if ($output_height < 10)
			{
				$output_height = "0.0$output_height";
			}
			else
			{
				$output_height = "0.$output_height";
			}
		}
		else
		{
			$output_height = (int) $output_height;
		}
	}
	else
	{
		//	No height was given, so default to 50% of the source images height
		$output_height = 0.50;
	}
	
	if (isset($_GET['fade_start']))
	{
		if (strpos($_GET['fade_start'], '%') !== false)
		{
			$alpha_start = str_replace('%', '', $_GET['fade_start']);
			$alpha_start = (int) (127 * $alpha_start / 100);
		}
		else
		{
			$alpha_start = (int) $_GET['fade_start'];
		
			if ($alpha_start < 1 || $alpha_start > 127)
			{
				$alpha_start = 80;
			}
		}
	}
	else
	{
		$alpha_start = 80;
	}
 
	if (isset($_GET['fade_end']))
	{
		if (strpos($_GET['fade_end'], '%') !== false)
		{
			$alpha_end = str_replace('%', '', $_GET['fade_end']);
			$alpha_end = (int) (127 * $alpha_end / 100);
		}
		else
		{
			$alpha_end = (int) $_GET['fade_end'];
		
			if ($alpha_end < 1 || $alpha_end > 0)
			{
				$alpha_end = 0;
			}
		}
	}
	else
	{
		$alpha_end = 0;
	}
 
	/*
		----------------------------------------------------------------
		Ok, let's do it ...
		----------------------------------------------------------------
	*/
	
	//	How big is the image?
	$image_details = getimagesize($source_image);
	
	if ($image_details === false)
	{
		echo 'Not a valid image supplied, or this script does not have permissions to access it.';
		exit();
	}
	else
	{
		$width = $image_details[0];
		$height = $image_details[1];
		$type = $image_details[2];
		$mime = $image_details['mime'];
	}
	
	//	Calculate the height of the output image
	if ($output_height < 1)
	{
		//	The output height is a percentage
		$new_height = $height * $output_height;
	}
	else
	{
		//	The output height is a fixed pixel value
		$new_height = $output_height;
	}
 
	//	Detect the source image format - only GIF, JPEG and PNG are supported. If you need more, extend this yourself.
	switch ($type)
	{
		case 1:
			//	GIF
			$source = imagecreatefromgif($source_image);
			break;
			
		case 2:
			//	JPG
			$source = imagecreatefromjpeg($source_image);
			break;
			
		case 3:
			//	PNG
			$source = imagecreatefrompng($source_image);
			break;
			
		default:
			echo 'Unsupported image file format.';
			exit();
	}
 
 
	/*
		----------------------------------------------------------------
		Build the reflection image
		----------------------------------------------------------------
	*/
 
	//	We'll store the final reflection in $output. $buffer is for internal use.
	$output = imagecreatetruecolor($width, $new_height);
	$buffer = imagecreatetruecolor($width, $new_height);
 
	//	Copy the bottom-most part of the source image into the output
	imagecopy($output, $source, 0, 0, 0, $height - $new_height, $width, $new_height);
	
	//	Rotate and flip it (strip flip method)
    for ($y = 0; $y < $new_height; $y++)
    {
       imagecopy($buffer, $output, 0, $y, 0, $new_height - $y - 1, $width, 1);
    }
 
	$output = $buffer;
	
	/*
		----------------------------------------------------------------
		Apply the fade effect
		----------------------------------------------------------------
	*/
	
	//	This is quite simple really. There are 127 available levels of alpha, so we just
	//	step-through the reflected image, drawing a box over the top, with a set alpha level.
	//	The end result? A cool fade into the background colour given.
 
	//	There are a maximum of 127 alpha fade steps we can use, so work out the alpha step rate
 
	$alpha_length = abs($alpha_start - $alpha_end);
 
	for ($y = 0; $y <= $new_height; $y++)
	{
		//  Get % of reflection height
		$pct = $y / $new_height;
 
		//  Get % of alpha
		if ($alpha_start > $alpha_end)
        {
            $alpha = (int) ($alpha_start - ($pct * $alpha_length));
        }
        else
        {
            $alpha = (int) ($alpha_start + ($pct * $alpha_length));
        }
 
		imagefilledrectangle($output, 0, $y, $width, $y, imagecolorallocatealpha($output, $red, $green, $blue, $alpha));
		
	}
 
		
	/*
		----------------------------------------------------------------
		HACK - Build the reflection image by combining the source 
		image AND the reflection in one new image!
		----------------------------------------------------------------
	*/
		$finaloutput = imagecreatetruecolor($width, $height+$new_height);
		imagecopy($finaloutput, $source, 0, 0, 0, 0, $width, $height);
		imagecopy($finaloutput, $output, 0, $height, 0, 0, $width, $new_height);
		$output = $finaloutput;
 
	/*
		----------------------------------------------------------------
		Output our final PNG
		----------------------------------------------------------------
	*/
 
	if (headers_sent())
	{
		echo 'Headers already sent, I cannot display an image now. Have you got an extra line-feed in this file somewhere?';
		exit();
	}
	else
	{
		//	If you'd rather output a JPEG instead of a PNG then pass the parameter 'jpeg' (no value needed) on the querystring
 
		if (isset($_GET['png']))
		{
			//	PNG
			header("Content-type: image/png");
			imagepng($output);
 
            // Save cached file
            if ($cache)
            {
                imagepng($output, $cache_path);
            }
			
		}
		else
		{
			if(!isset( $_GET['jpeg']))  $_GET['jpeg'] = 90;
			
			$quality = (int) $_GET['jpeg'];
			
			if ($quality < 1 || $quality > 100)
			{
				$quality = 90;
			}
			
			//	JPEG (the final parameter = the quality, 0 = terrible, 100 = pixel perfect)
			header("Content-type: image/jpeg");
			imagejpeg($output, '', $quality);
 
			// Save cached file
            if ($cache)
            {
                imagejpeg($output, $cache_path, $quality);
            }
			
           
		}
 
		imagedestroy($output);
		exit();
	}
?>