media/classes/player_external.php

   1 <?php
   2 // This file is part of Moodle - http://moodle.org/
   3 //
   4 // Moodle is free software: you can redistribute it and/or modify
   5 // it under the terms of the GNU General Public License as published by
   6 // the Free Software Foundation, either version 3 of the License, or
   7 // (at your option) any later version.
   8 //
   9 // Moodle is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13 //
  14 // You should have received a copy of the GNU General Public License
  15 // along with Moodle.  If not, see <http://www.gnu.org/licenses/>.
  16
  17 /**
  18  * Base class for players which handle external links
  19  *
  20  * @package   core_media
  21  * @copyright 2016 Marina Glancy
  22  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  23  */
  24
  25 defined('MOODLE_INTERNAL') || die();
  26
  27 /**
  28  * Base class for players which handle external links (YouTube etc).
  29  *
  30  * As opposed to media files.
  31  *
  32  * @package   core_media
  33  * @copyright 2016 Marina Glancy
  34  * @author    2011 The Open University
  35  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  36  */
  37 abstract class core_media_player_external extends core_media_player {
  38     /**
  39      * Array of matches from regular expression - subclass can assume these
  40      * will be valid when the embed function is called, to save it rerunning
  41      * the regex.
  42      * @var array
  43      */
  44     protected $matches;
  45
  46     /**
  47      * Part of a regular expression, including ending ~ symbol (note: these
  48      * regexes use ~ instead of / because URLs and HTML code typically include
  49      * / symbol and makes harder to read if you have to escape it).
  50      * Matches the end part of a link after you have read the 'important' data
  51      * including optional #d=400x300 at end of url, plus content of <a> tag,
  52      * up to </a>.
  53      * @var string
  54      */
  55     const END_LINK_REGEX_PART = '[^#]*(#d=([\d]{1,4})x([\d]{1,4}))?~si';
  56
  57     public function embed($urls, $name, $width, $height, $options) {
  58         return $this->embed_external(reset($urls), $name, $width, $height, $options);
  59     }
  60
  61     /**
  62      * Obtains HTML code to embed the link.
  63      * @param moodle_url $url Single URL to embed
  64      * @param string $name Display name; '' to use default
  65      * @param int $width Optional width; 0 to use default
  66      * @param int $height Optional height; 0 to use default
  67      * @param array $options Options array
  68      * @return string HTML code for embed
  69      */
  70     protected abstract function embed_external(moodle_url $url, $name, $width, $height, $options);
  71
  72     public function list_supported_urls(array $urls, array $options = array()) {
  73         // These only work with a SINGLE url (there is no fallback).
  74         if (count($urls) != 1) {
  75             return array();
  76         }
  77         $url = reset($urls);
  78
  79         // Check against regex.
  80         if (preg_match($this->get_regex(), $url->out(false), $this->matches)) {
  81             return array($url);
  82         }
  83
  84         return array();
  85     }
  86
  87     /**
  88      * Returns regular expression used to match URLs that this player handles
  89      * @return string PHP regular expression e.g. '~^https?://example.org/~'
  90      */
  91     protected function get_regex() {
  92         return '~^unsupported~';
  93     }
  94
  95     /**
  96      * Annoyingly, preg_match $matches result does not always have the same
  97      * number of parameters - it leaves out optional ones at the end. WHAT.
  98      * Anyway, this function can be used to fix it.
  99      * @param array $matches Array that should be adjusted
 100      * @param int $count Number of capturing groups (=6 to make $matches[6] work)
 101      */
 102     protected static function fix_match_count(&$matches, $count) {
 103         for ($i = count($matches); $i <= $count; $i++) {
 104             $matches[$i] = false;
 105         }
 106     }
 107 }