List of photos in a folder

gistfile1.js

new Ajax.Updater('list_area','comics/list.php',{method: 'get'});
document.observe('click', function(evt){
  var elm;
  if(elm = evt.findElement('a.ajax')){
    evt.stop();
    var link = elm.href;
    $('photo_goes_here').update('<img src="' + link + '" alt="" />');
  }
});

list.php

<?php
//CONFIGURATION:
$limit = 20; //only 20 photos
date_default_timezone_set ( 'America/New_York' );

/**
* Place this file in a folder full of images to publish a list of the photos.
* 
*  -  Files are sorted latest-first by modification date.
* 
*  -  If present, IPTC comments will be used for the captions. If not, 
*     file names are used, (underscore is replaced with a space, extension
*     is removed).
*
*  -  JPEG, GIF, and PNG images are supported
*
*  -  Requires PHP5
*
* LICENSE (BSD License)
* 
* Copyright (c) 2012, Walter Lee Davis <waltd@wdstudio.com>
* All rights reserved.
* 
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 
*  - Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
*
*  - Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in
*    the documentation and/or other materials provided with the
*    distribution. 
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
* TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
* THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/

//FUNCTIONS
/**
* recursive variable replacement
*
* @param string $strText Input text including {{variable}} placeholders
* @return string with all templates replaced with existing global vars
* @author Walter Lee Davis
*/
function replace_vars($strText){
  $out = preg_replace_callback('/\{\{(.+?)\}\}/im','replace_vars_callback',$strText);
  if(strpos($out,'{{') !== false) {
    return replace_vars($out);
  }
  return $out;
}

function replace_vars_callback($arrMatches){
  $match = $arrMatches[1];
  if(isset($GLOBALS[$match])) return $GLOBALS[$match];
  //the spaces between the brackets here are Unicode Word Joiner characters (U+2060) 
  //not actual spaces. This keeps away the infinite loop.
  return '{⁠{' . $match . '}⁠}'; 
}

/**
 * test for variable present and not empty
 *
 * @param string $var Variable name
 * @return void
 * @author Walter Lee Davis
 */
function present($var){
  return (isset($var) && !empty($var));
}

/**
 * IPTC caption reader
 *
 * @param string $path path to file
 * @return string
 * @author Tim Plumb
 */
function readCaption($path){
  $IPTC_Caption = ""; 
  $size = getimagesize( $path, $info ); 
  if (isset($info["APP13"])) { 
    if($iptc = iptcparse( $info["APP13"] ) ) { 
      $IPTC_Caption = present($iptc["2#005"][0]) ? $iptc["2#005"][0] : $iptc["2#120"][0]; 
    } 
  }
  return( $IPTC_Caption );
}

/**
 * file extension from filename
 *
 * @param string $path 
 * @return string
 * @author Walter Lee Davis
 */
function extension($path){
  return strtolower(array_pop(explode('.',$path)));
}

/**
 * read the current request and return the full external URL
 *
 * @return string
 * @author Walter Lee Davis
 */
function absolute_url() {
  $out = 'http' . (($_SERVER['HTTPS'] == 'on') ? 's' : '') . '://';
  $out .= $_SERVER['SERVER_NAME'] . (($_SERVER['SERVER_PORT'] != '80') ? $_SERVER['SERVER_PORT'] : '');
  return $out . $_SERVER['PHP_SELF'];
}

function h($key){
  return htmlentities($key,ENT_COMPAT,'UTF-8');
}


//CONSTANTS

$url = dirname(absolute_url()) . '/';
$mimes = array('jpeg' => 'photo/jpeg', 'jpg' => 'photo/jpeg', 'png' => 'photo/png', 'gif' => 'photo/gif');
$dir = dirname(__FILE__);
$me = basename(__FILE__);
$files = $photos = $times = $entries = $figures = array();
$latest = $i = 0;

//MAIN LOOP
//read the directory
foreach(scandir($dir) as $file){
  if(preg_match('/^[^\.].+?\.(jpe?g|png|gif)$/i', $file)){
    $timestamp = filemtime($dir . '/' . $file);
    $latest = ($timestamp > $latest) ? $timestamp : $latest;
    $files[] = $file;
    $times[] = $timestamp;
  }
}
$page_updated = date('F j, Y, g:i a', $latest);
$pubdate = date('Y-m-d H:i\Z', $latest);
$latest = gmdate('Y-m-d\TH:i:s\Z',$latest);

//sort by date descending
arsort($times);
foreach($times as $k => $v){
  $photos[] = array($files[$k], $times[$k]);
}

$fragment = '<ul>
{{figures}}
</ul>
';
$figure = '  <li>
    <a href="{{link}}" class="ajax">
      {{figure_title}} — Posted <time datetime="{{datetime}}">{{posted}}</time>
    </a>
   </li>
';


//build the current set of entries as an array of strings
foreach($photos as $photo){
  if($i < $limit){
    $datetime = date('Y-m-d H:i\Z', $photo[1]);
    $posted = date('F j, Y, g:i a', $photo[1]);
    $link = $url . $photo[0];
    $item_title = readCaption($dir . '/' . $photo[0]);
    if ($item_title === ""){
      $item_title = preg_replace('/_/', ' ', preg_replace('/\.[a-zA-Z]{3,4}$/','',$photo[0]));
    }
    $figure_title = $item_title;
    $figures[] = replace_vars($figure);
    $i++;
  }else{
    break;
  }
}
//concatenate into a single string
$figures = implode("\n",$figures);
//build the outer shell
$fragment = replace_vars($fragment);
//send the result
 header('Content-type: text/html; charset=utf-8');
 print $fragment;
?>