<?php
/*
This script is developed by Arturs Sosins aka ar2rsawseen, http://code-snippets.co.cc
Fee free to distribute and modify code, but keep reference to its creator

This class can generate CSS sprite image from multiple provided images
Generated image can be outputted to browser, saved to specified location, etc.
This class also generates CSS code for sprite image, using element ID's provided with image.
It facilitates CSS sprite implementations to existing website structures
*/
class spritify
{
	//image type to save as (for possible future modifications)
	private $image_type = "png";
	//array to contain images and image informations
	private $images = array();
	//array for errors
	private $errors = array();
	
	//gets errors
	public function get_errors(){
		return $this->errors;
	}
	
	/*
	 * adds new image
	 * first parameter - path to image file like ./images/image.png
	 * second parameter (optiona) - ID of element fro css code generation
	 */
	public function add_image($image_path, $id="elem"){
		if(file_exists($image_path))
		{
			$info = getimagesize($image_path);
			if(is_array($info))
			{
				$new = sizeof($this->images);
				$this->images[$new]["path"] = $image_path;
				$this->images[$new]["width"] = $info[0];
				$this->images[$new]["height"] = $info[1];
				$this->images[$new]["mime"] = $info["mime"];
				$type = explode("/", $info['mime']);
				$this->images[$new]["type"] = $type[1];
				$this->images[$new]["id"] = $id;
			}
			else
			{
				$this->errors[] = "Provided file \"".$image_path."\" isn't correct image format";
			}
		}
		else
		{
			$this->errors[] = "Provided file \"".$image_path."\" doesn't exist";
		}
	}
	
	//calculates width and height needed for sprite image
	private function total_size(){
		$arr = array("width" => 0, "height" => 0);
		foreach($this->images as $image)
		{
			if($arr["width"] < $image["width"])
			{
				$arr["width"] = $image["width"];
			}
			$arr["height"] += $image["height"];
		}
		return $arr;
	}
	
	//creates sprite image resource
	private function create_image(){
		$total = $this->total_size();
		$sprite = imagecreatetruecolor($total["width"], $total["height"]);
		imagesavealpha($sprite, true);
		$transparent = imagecolorallocatealpha($sprite, 0, 0, 0, 127);
		imagefill($sprite, 0, 0, $transparent);
		$top = 0;
		foreach($this->images as $image)
		{
			$func = "imagecreatefrom".$image['type'];
			$img = $func($image["path"]);
			imagecopy( $sprite, $img, ($total["width"] - $image["width"]), $top, 0, 0,  $image["width"], $image["height"]);
			$top += $image["height"];
		}
		return $sprite;
	}
	
	//outputs image to browser (makes php file behave like image)
	public function output_image(){
		$sprite = $this->create_image();
		header('Content-Type: image/'.$this->image_type);
		$func = "image".$this->image_type;
		$func($sprite); 
		ImageDestroy($sprite);
	}
	
	/*
	 * generates css code using ID provided when adding images or pseido ID "elem"
	 * $path parameter (optional) - takes path to already generated css_sprite file or uses default file for pseudo code generation
	 */
	public function generate_css($path = "/css_sprite.png"){
		$total = $this->total_size();
		$top = $total["height"];
		$css = "";
		foreach($this->images as $image)
		{
			if(strpos($image["id"],"#") === false)
			{
				$css .= "#".$image["id"]." { ";
			}
			else
			{
				$css .= $image["id"]." { ";
			}
			$css .= "background-image: url(".$path."); ";
			$css .= "background-position: ".($image["width"] - $total["width"])."px ".($top - $total["height"])."px; ";
			$css .= "width: ".$image['width']."px; ";
			$css .= "height: ".$image['height']."px; ";
			$css .= "}\n";
			$top -= $image["height"];
		}
		return $css;
	}
	
	/*
	 * if $path provided, than saves image to path
	 * else forces image download
	 */
	public function safe_image($path = ""){
		$sprite = $this->create_image();
		$func = "image".$this->image_type;
		if(trim($path) == "")
		{
			header('Content-Description: File Transfer');
			header('Content-Type: image/'.$this->image_type);
			header('Content-Disposition: attachment; filename=css_sprite.'.$this->image_type);
			header('Content-Transfer-Encoding: binary');
			header('Expires: 0');
			header('Cache-Control: must-revalidate, post-check=0, pre-check=0');
			header('Pragma: public');
			header('Content-Length: ' . filesize($sprite));
			ob_clean();
			flush();
			$func($sprite); 
		}
		else
		{
			$func($sprite, $path); 
		}
		ImageDestroy($sprite);
	}
	
	//return image resource
	public function get_resource(){
		$sprite = $this->create_image();
		return $sprite;
	}
}
?>