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Differences Between: [Versions 39 and 401] [Versions 39 and 402] [Versions 39 and 403]

   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]), $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  }