dynamic animated gif clock

gif.php

<?php

date_default_timezone_set('America/Halifax');
include 'GIFEncoder.class.php';


$time = $_GET['time'];
$future_date = new DateTime(date('r',strtotime($time)));
$time_now = time();
$now = new DateTime(date('r', $time_now));


$frames = array();
$delays = array();


$image = imagecreatefrompng('countdown.png');
$delay = 100; // milliseconds
$font = array(
	'size'=>40,
	'angle'=>0,
	'x-offset'=>10,
	'y-offset'=>70,
	'file'=>'DIGITALDREAM.ttf',
	'color'=>imagecolorallocate($image, 255, 255, 255),
);
for($i = 0; $i <= 60; $i++){
	$interval = date_diff($future_date, $now);
	if($future_date < $now){
		// Open the first source image and add the text.
		$image = imagecreatefrompng('countdown.png');;
		$text = $interval->format('00:00:00:00');
		imagettftext ($image , $font['size'] , $font['angle'] , $font['x-offset'] , $font['y-offset'] , $font['color'] , $font['file'], $text );
		ob_start();
		imagegif($image);
		$frames[]=ob_get_contents();
		$delays[]=$delay;
                $loops = 1;
		ob_end_clean();
		break;
	} else {
		// Open the first source image and add the text.
		$image = imagecreatefrompng('countdown.png');;
		$text = $interval->format('%a:%H:%I:%S');
		// %a is weird in that it doesn’t give you a two digit number
		// check if it starts with a single digit 0-9
		// and prepend a 0 if it does
		if(preg_match('/^[0-9]\:/', $text)){
			$text = '0'.$text;
		}
		imagettftext ($image , $font['size'] , $font['angle'] , $font['x-offset'] , $font['y-offset'] , $font['color'] , $font['file'], $text );
		ob_start();
		imagegif($image);
		$frames[]=ob_get_contents();
		$delays[]=$delay;
                $loops = 0;
		ob_end_clean();
	}
	$now->modify('+1 second');
}
//expire this image instantly
header( 'Expires: Sat, 26 Jul 1997 05:00:00 GMT' );
header( 'Last-Modified: ' . gmdate( 'D, d M Y H:i:s' ) . ' GMT' );
header( 'Cache-Control: no-store, no-cache, must-revalidate' );
header( 'Cache-Control: post-check=0, pre-check=0', false );
header( 'Pragma: no-cache' ); 
$gif = new AnimatedGif($frames,$delays,$loops);
$gif->display();

GIFEncoder.class.php

<?php

/*
  :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
  :: Formerly known as:::
  :: GIFEncoder Version 2.0 by László Zsidi, http://gifs.hu
  ::
  :: This class is a rewritten 'GifMerge.class.php' version.
  ::
  :: Modification:
  :: - Simplified and easy code,
  :: - Ultra fast encoding,
  :: - Built-in errors,
  :: - Stable working
  ::
  ::
  :: Updated at 2007. 02. 13. '00.05.AM'
  ::
  ::
  ::
  :: Try on-line GIFBuilder Form demo based on GIFEncoder.
  ::
  :: http://gifs.hu/phpclasses/demos/GifBuilder/
  ::
  :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
 */

/**
 * Encode animated gifs
 */
class AnimatedGif {

    /**
     * The built gif image
     * @var resource
     */
    private $image = '';

    /**
     * The array of images to stack
     * @var array
     */
    private $buffer = Array();

    /**
     * How many times to loop? 0 = infinite
     * @var int
     */
    private $number_of_loops = 0;

    /**
     * 
     * @var int 
     */
    private $DIS = 2;

    /**
     * Which colour is transparent
     * @var int
     */
    private $transparent_colour = -1;

    /**
     * Is this the first frame
     * @var int
     */
    private $first_frame = TRUE;

    /**
     * Encode an animated gif
     * @param array $source_images An array of binary source images
     * @param array $image_delays The delays associated with the source images
     * @param type $number_of_loops The number of times to loop
     * @param int $transparent_colour_red
     * @param int $transparent_colour_green
     * @param int $transparent_colour_blue 
     */
    function __construct(array $source_images, array $image_delays, $number_of_loops, $transparent_colour_red = -1, $transparent_colour_green = -1, $transparent_colour_blue = -1) {
        /**
         * I have no idea what these even do, they appear to do nothing to the image so far 
         */
        $transparent_colour_red = 0;
        $transparent_colour_green = 0;
        $transparent_colour_blue = 0;

        $this->number_of_loops = ( $number_of_loops > -1 ) ? $number_of_loops : 0;
        $this->set_transparent_colour($transparent_colour_red, $transparent_colour_green, $transparent_colour_blue);
        $this->buffer_images($source_images);

        $this->addHeader();
        for ($i = 0; $i < count($this->buffer); $i++) {
            $this->addFrame($i, $image_delays [$i]);
        }
    }
    
    /**
     * Set the transparent colour
     * @param int $red
     * @param int $green
     * @param int $blue 
     */
    private function set_transparent_colour($red, $green, $blue){
        $this->transparent_colour = ( $red > -1 && $green > -1 && $blue > -1 ) ?
                ( $red | ( $green << 8 ) | ( $blue << 16 ) ) : -1;
    }

    /**
     * Buffer the images and check to make sure they are vaild
     * @param array $source_images the array of source images
     * @throws Exception 
     */
    private function buffer_images($source_images) {
        for ($i = 0; $i < count($source_images); $i++) {
            $this->buffer [] = $source_images [$i];
            if (substr($this->buffer [$i], 0, 6) != "GIF87a" && substr($this->buffer [$i], 0, 6) != "GIF89a") {
                throw new Exception('Image at position ' . $i. ' is not a gif');
            }
            for ($j = ( 13 + 3 * ( 2 << ( ord($this->buffer [$i] { 10 }) & 0x07 ) ) ), $k = TRUE; $k; $j++) {
                switch ($this->buffer [$i] { $j }) {
                    case "!":
                        if (( substr($this->buffer [$i], ( $j + 3), 8) ) == "NETSCAPE") {
                            throw new Exception('You cannot make an animation from an animated gif.');
                        }
                        break;
                    case ";":
                        $k = FALSE;
                        break;
                }
            }
        }
    }

    /**
     * Add the gif header to the image
     */
    private function addHeader() {
        $cmap = 0;
        $this->image = 'GIF89a';
        if (ord($this->buffer [0] { 10 }) & 0x80) {
            $cmap = 3 * ( 2 << ( ord($this->buffer [0] { 10 }) & 0x07 ) );
            $this->image .= substr($this->buffer [0], 6, 7);
            $this->image .= substr($this->buffer [0], 13, $cmap);
            $this->image .= "!\377\13NETSCAPE2.0\3\1" . $this->word($this->number_of_loops) . "\0";
        }
    }

    /**
     * Add a frame to the animation
     * @param int $frame The frame to be added
     * @param int $delay The delay associated with the frame
     */
    private function addFrame($frame, $delay) {
        $Locals_str = 13 + 3 * ( 2 << ( ord($this->buffer [$frame] { 10 }) & 0x07 ) );

        $Locals_end = strlen($this->buffer [$frame]) - $Locals_str - 1;
        $Locals_tmp = substr($this->buffer [$frame], $Locals_str, $Locals_end);

        $Global_len = 2 << ( ord($this->buffer [0] { 10 }) & 0x07 );
        $Locals_len = 2 << ( ord($this->buffer [$frame] { 10 }) & 0x07 );

        $Global_rgb = substr($this->buffer [0], 13, 3 * ( 2 << ( ord($this->buffer [0] { 10 }) & 0x07 ) ));
        $Locals_rgb = substr($this->buffer [$frame], 13, 3 * ( 2 << ( ord($this->buffer [$frame] { 10 }) & 0x07 ) ));

        $Locals_ext = "!\xF9\x04" . chr(( $this->DIS << 2 ) + 0) .
                chr(( $delay >> 0 ) & 0xFF) . chr(( $delay >> 8 ) & 0xFF) . "\x0\x0";

        if ($this->transparent_colour > -1 && ord($this->buffer [$frame] { 10 }) & 0x80) {
            for ($j = 0; $j < ( 2 << ( ord($this->buffer [$frame] { 10 }) & 0x07 ) ); $j++) {
                if (
                        ord($Locals_rgb { 3 * $j + 0 }) == ( ( $this->transparent_colour >> 16 ) & 0xFF ) &&
                        ord($Locals_rgb { 3 * $j + 1 }) == ( ( $this->transparent_colour >> 8 ) & 0xFF ) &&
                        ord($Locals_rgb { 3 * $j + 2 }) == ( ( $this->transparent_colour >> 0 ) & 0xFF )
                ) {
                    $Locals_ext = "!\xF9\x04" . chr(( $this->DIS << 2 ) + 1) .
                            chr(( $delay >> 0 ) & 0xFF) . chr(( $delay >> 8 ) & 0xFF) . chr($j) . "\x0";
                    break;
                }
            }
        }
        switch ($Locals_tmp { 0 }) {
            case "!":
                $Locals_img = substr($Locals_tmp, 8, 10);
                $Locals_tmp = substr($Locals_tmp, 18, strlen($Locals_tmp) - 18);
                break;
            case ",":
                $Locals_img = substr($Locals_tmp, 0, 10);
                $Locals_tmp = substr($Locals_tmp, 10, strlen($Locals_tmp) - 10);
                break;
        }
        if (ord($this->buffer [$frame] { 10 }) & 0x80 && $this->first_frame === FALSE) {
            if ($Global_len == $Locals_len) {
                if ($this->blockCompare($Global_rgb, $Locals_rgb, $Global_len)) {
                    $this->image .= ( $Locals_ext . $Locals_img . $Locals_tmp );
                } else {
                    $byte = ord($Locals_img { 9 });
                    $byte |= 0x80;
                    $byte &= 0xF8;
                    $byte |= ( ord($this->buffer [0] { 10 }) & 0x07 );
                    $Locals_img { 9 } = chr($byte);
                    $this->image .= ( $Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp );
                }
            } else {
                $byte = ord($Locals_img { 9 });
                $byte |= 0x80;
                $byte &= 0xF8;
                $byte |= ( ord($this->buffer [$frame] { 10 }) & 0x07 );
                $Locals_img { 9 } = chr($byte);
                $this->image .= ( $Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp );
            }
        } else {
            $this->image .= ( $Locals_ext . $Locals_img . $Locals_tmp );
        }
        $this->first_frame = FALSE;
    }

    /**
     * Add the gif footer 
     */
    private function addFooter() {
        $this->image .= ";";
    }

    /**
     * Compare gif blocks? What is a block?
     * @param type $GlobalBlock
     * @param type $LocalBlock
     * @param type $Len
     * @return type 
     */
    private function blockCompare($GlobalBlock, $LocalBlock, $Len) {
        for ($i = 0; $i < $Len; $i++) {
            if (
                    $GlobalBlock { 3 * $i + 0 } != $LocalBlock { 3 * $i + 0 } ||
                    $GlobalBlock { 3 * $i + 1 } != $LocalBlock { 3 * $i + 1 } ||
                    $GlobalBlock { 3 * $i + 2 } != $LocalBlock { 3 * $i + 2 }
            ) {
                return ( 0 );
            }
        }

        return ( 1 );
    }

    /**
     * No clue
     * @param int $int
     * @return string the char you meant? 
     */
    private function word($int) {
        return ( chr($int & 0xFF) . chr(( $int >> 8 ) & 0xFF) );
    }

    /**
     * Return the animated gif
     * @return type 
     */
    function getAnimation() {
        return $this->image;
    }

    /**
     * Return the animated gif
     * @return type 
     */
    function display() {
        //late footer add
        $this->addFooter();
        header('Content-type:image/gif');
        echo $this->image;
    }

}