Intial implementation of class

Gantt.php

@@ -25,11 +25,147 @@ class Gantt {
 	 **/
 	private $events		= array();
 
+	/**
+	 * HTML render of our chart
+	 * @access private
+	 * @var string
+	 **/
+	private $html 		= '';
+
+	/**
+	 * List of colors to use for events
+	 * @access private
+	 * @var array
+	 **/
+	 private $colors	= array();
+
+	 /**
+	  * Track the number of times we've retrieved colors
+	  * @access private
+	  * @var integer
+	  **/
+	 private $color_count = 0;
+
 	/**
 	 * Constructor
 	 **/
 	function __construct() {
-		
+		//add a default set of colors
+		$this->add_color('#FF8080');
+		$this->add_color('#99CCFF');
+		$this->add_color('#00FF00');
+		$this->add_color('#FF9900');
+		$this->add_color('#800080');
+	}
+
+	/**
+	 * Add an event to be processed
+	 * @param string name of the event
+	 * @param integer the week to start this event
+	 * @param integer duration
+	 * @return bool whether or not the event was added successfully
+	 **/
+	 public function add_event($event, $start, $duration) {
+	 	// return false if we do not have valid data
+	 	if(!is_int($start)) return false;
+	 	if(!is_int($duration)) return false;
+
+	 	// add the event
+	 	$this->events[] = (object)array(
+	 		'event'		=> $event,
+		 	'start'		=> $start,
+		 	'duration'	=> $duration,
+		);
+
+		// reset the HTML so it is re-rendered next attempt
+		$this->html = '';
+
+	 	return true;
+	 }
+
+	 /**
+	  * Create an HTML Gantt chart from the current events
+	  * @return string html for our gantt chart
+	  **/
+	public function render_html() {
+		// if we have previously rendered this gantt and have not added 
+		// new events, we don't need to do it again and can returned the 
+		// cached html
+		if($this->html != '') {
+			return $this->html;
+		}
+		$columns = $this->find_last();
+
+		$this->html = '<table id="gantt">' . "\n";
+
+		// create the header
+		$this->html .= '	<tr>' . "\n";
+		$this->html .= '		<th>Task</th>' . "\n";
+		$this->html .= '		<th>Weeks</th>' . "\n";
+		for($i = 1; $i <= $columns; $i++) {
+			$this->html .= '		<th>' . $i . '</th>' . "\n";
+		}
+		$this->html .= '	</tr>' . "\n";
+
+		// add all the rows
+		foreach($this->events as $event) {
+			$color = $this->get_color();
+			$this->html .= '	<tr>' . "\n";
+			$this->html .= '		<td>' . $event->event . '</td>' . "\n";
+			$this->html .= '		<td>' . $event->duration . '</td>' . "\n";
+			for($i = 1; $i <= $columns; $i++) {
+				if($i >= $event->start && $i < ($event->start + $event->duration)) {
+					$style = ' style="background-color:' . $color . '"';
+				} else {
+					$style = ' style="background-color:#fff"';
+				}
+				$this->html .= '		<td class="colored"'. $style .'>&nbsp;</td>' . "\n";
+			}
+			$this->html .= '	</tr>' . "\n";
+		}
+		$this->html .= '</table>' . "\n";
+
+		return $this->html;
+	}
+
+	/**
+	 * Find the last column in our Gantt chart
+	 * @return integer last column
+	 **/
+	private function find_last() {
+		$last = 0;
+
+		foreach($this->events as $event) {
+			$end = $event->start + $event->duration - 1;
+			$last = ($end > $last) ? $end : $last;
+		}
+
+		return $last;
+	}
+
+	/**
+	 * Add a color to our list
+	 * @param string hexadecimal color code
+	 * @return bool whether or not the color was added
+	 **/
+	public function add_color($color) {
+		// the color was not properly formatted
+		if(preg_match('/^#(?:[0-9a-fA-F]{3}){1,2}$/',$color) == 0) return false;
+		// color is already in the list
+		if(in_array($color,$this->colors)) return false;
+
+		$this->colors[] = $color;
+
+		return true;
+	}
+
+	/**
+	 * Get a color to use
+	 * @param integer the number of times this function has been called
+	 * @return string color code
+	 **/
+	private function get_color() {
+		return $this->colors[++$this->color_count % count($this->colors)];
 	}
 }
 ?>