embed_extender hooks demo

embedextender_hookdemo.php

<?php

function au_landing_init(){
  // provide custom video handling for au.teacherstv and slideshare
  // these hooks are provided by my latest pull request
  // custom_patterns gathers regex patterns to select urls
  // custom_embed provides the embed code if a pattern is matched
  elgg_register_plugin_hook_handler('embed_extender', 'custom_patterns', 'au_landing_embed_patterns');
  elgg_register_plugin_hook_handler('embed_extender', 'custom_embed', 'au_landing_embed');
}

//
// called on the 'embed_extender', 'custom_patterns' hook
// $returnvalue is an array containing currently registered custom patterns
// here we can modify, add, or remove patterns
// for our purposes we're just adding patterns for teacherstv and slideshare
function au_landing_embed_patterns($hook, $type, $returnvalue, $params){
  $returnvalue[] = '/(http:\/\/)(au\.teacherstv\.ca\/)(.*)/';
  $returnvalue[] = '/(http:\/\/)(www\.slideshare\.net\/)(.*)/';
  
  return $returnvalue;
}

//
// this is the hook for the embed code, this is called when a match has been found
// for one of the patterns.  Check if it's one of our patterns and return the correct
// embed code.  If there's no match, 
function au_landing_embed($hook, $type, $returnvalue, $params){

  // get our variables from $params
  $url = $params['url'];
  $guid = $params['guid'];
  $videowidth = $params['videowidth'];
  
  // check if it's a teacherstv url
  $domain = au_landing_parse_teacherstv_url($url);
  if($domain){
    // it is teacherstv, so create the embed code
    videoembed_calc_size($videowidth, $videoheight, 425/320, 24);

	$embed_object = videoembed_add_css($guid, $videowidth, $videoheight);

	$embed_object .= "<div id=\"{$guid}\">";
	$embed_object .= "<object width=\"$videowidth\" height=\"$videoheight\"><param name=\"movie\" value=\"{$domain}\"></param><param name=\"allowFullScreen\" value=\"true\"></param><embed src=\"{$domain}\" type=\"application/x-shockwave-flash\" allowfullscreen=\"true\" width=\"$videowidth\" height=\"$videoheight\"></embed></object>";
	$embed_object .= "</div>";
                      
	return $embed_object;
  }
  
  // not teacherstv, try slideshare
  if(strpos($url, 'slideshare.net')){
    // it is a slideshare url
    videoembed_calc_size($videowidth, $videoheight, 425/320, 24);

	$embed_object = videoembed_add_css($guid, $videowidth, $videoheight);
	
	// get embed code
	// see http://www.slideshare.net/developers/oembed
        // note that slideshare is a special case - we can't tell if the link is a static page or an embed
        // as they don't have a standard url format (or it changed at some point)
        // but they do provide us with an API to check against
	$jsonurl = "http://www.slideshare.net/api/oembed/2?url={$url}&format=json&maxwidth={$videowidth}&maxheight={$videoheight}";
    $json = file_get_contents($jsonurl);
    $json_output = json_decode($json);
    
    if(!empty($json_output->html)){
	  $embed_object .= "<div id=\"{$guid}\">";
      $embed_object .= $json_output->html;
      $embed_object .= "</div>";
      
      return $embed_object;
    }
    
    // if we can't get embed data just output a link, as slideshare has weird urls
    // that don't distinguish well, we can't tell if it's an embed until we check
    // with their api.  If we got this far, it's been checked and found not to be an embed
	return "<a href=\"$url\">$url</a>";
  }
  
  // we got this far, it's nothing that concerns us
  // return the default value
  return $returnvalue;
}

//
// convenience function for creating the embed url from the teacherstv page url
function au_landing_parse_teacherstv_url($url){

	// This provides some security against inserting bad content.
	// Divides url into http://, www or localization, domain name, path.
	if (!preg_match('/(http:\/\/)(au\.teacherstv\.ca\/)(video\/watch\/)(.*)/', $url, $matches)) {
		return FALSE;
	}

	$domain = $matches[1].$matches[2] . 'v/' . $matches[4];

	return $domain;
}


elgg_register_event_handler('init', 'system', 'au_landing_init');