media/classes/player_native.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 return native HTML5 <video> or <audio> tags
  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 return native HTML5 <video> or <audio> tags
  29  *
  30  * @package   core_media
  31  * @copyright 2016 Marina Glancy
  32  * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
  33  */
  34 abstract class core_media_player_native extends core_media_player {
  35     /**
  36      * Extracts a value for an attribute
  37      *
  38      * @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
  39      * @param string $attrname name of the attribute we are looking for
  40      * @param string $type one of PARAM_* constants to clean the attribute value
  41      * @return string|null
  42      */
  43     public static function get_attribute($tag, $attrname, $type = PARAM_RAW) {
  44         if (preg_match('/^<[^>]*\b' . $attrname . '="(.*?)"/is', $tag, $matches)) {
  45             return clean_param(htmlspecialchars_decode($matches[1], ENT_COMPAT), $type);
  46         } else if (preg_match('~^<[^>]*\b' . $attrname . '[ />]"~is', $tag, $matches)) {
  47             // Some attributes may not have value, for example this is valid: <video controls>.
  48             return clean_param("true", $type);
  49         }
  50         return null;
  51     }
  52
  53     /**
  54      * Removes an attribute from the media tags
  55      *
  56      * @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
  57      * @param string|array $attrname
  58      * @return string
  59      */
  60     public static function remove_attributes($tag, $attrname) {
  61         if (is_array($attrname)) {
  62             $attrname = join('|', $attrname);
  63         }
  64         while (preg_match('/^(<[^>]*\b)(' . $attrname . ')=".*?"(.*)$/is', $tag, $matches)) {
  65             $tag = $matches[1] . $matches[3];
  66         }
  67         while (preg_match('~^(<[^>]*\b)(' . $attrname . ')([ />].*)$~is', $tag, $matches)) {
  68             // Some attributes may not have value, for example: <video controls>.
  69             $tag = $matches[1] . $matches[3];
  70         }
  71         return $tag;
  72     }
  73
  74     /**
  75      * Adds attributes to the media tags
  76      *
  77      * @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
  78      * @param array $attributes key-value pairs of attributes to be added
  79      * @return string
  80      */
  81     public static function add_attributes($tag, $attributes) {
  82         $tag = self::remove_attributes($tag, array_keys($attributes));
  83         if (!preg_match('/^(<.*?)(>.*)$/s', $tag, $matches)) {
  84             return $tag;
  85         }
  86         $rv = $matches[1];
  87         foreach ($attributes as $name => $value) {
  88             $rv .= " $name=\"".s($value).'"';
  89         }
  90         $rv .= $matches[2];
  91         return $rv;
  92     }
  93
  94     /**
  95      * Replaces all embedded <source> tags and src attribute
  96      *
  97      * @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
  98      * @param string $sources replacement string (expected to contain <source> tags)
  99      * @return string
 100      */
 101     public static function replace_sources($tag, $sources) {
 102         $tag = self::remove_attributes($tag, 'src');
 103         $tag = preg_replace(['~</?source\b[^>]*>~i'], '', $tag);
 104         if (preg_match('/^(<.*?>)([^\0]*)$/ms', $tag, $matches)) {
 105             $tag = $matches[1].$sources.$matches[2];
 106         }
 107         return $tag;
 108     }
 109
 110     public function get_supported_extensions() {
 111         global $CFG;
 112         require_once($CFG->libdir . '/filelib.php');
 113         return file_get_typegroup('extension', ['html_video', 'html_audio']);
 114     }
 115
 116     public function list_supported_urls(array $urls, array $options = array()) {
 117         $extensions = $this->get_supported_extensions();
 118         $result = array();
 119         foreach ($urls as $url) {
 120             $ext = core_media_manager::instance()->get_extension($url);
 121             if (in_array('.' . $ext, $extensions) && core_useragent::supports_html5($ext)) {
 122                 // Unfortunately html5 video does not handle fallback properly.
 123                 // https://www.w3.org/Bugs/Public/show_bug.cgi?id=10975
 124                 // That means we need to do browser detect and not use html5 on
 125                 // browsers which do not support the given type, otherwise users
 126                 // will not even see the fallback link.
 127                 $result[] = $url;
 128             }
 129         }
 130         return $result;
 131     }
 132 }