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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Base class for media players
*
* @package core_media
* @copyright 2016 Marina Glancy
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
defined('MOODLE_INTERNAL') || die();
/**
* Base class for media players.
*
* Media players return embed HTML for a particular way of playing back audio
* or video (or another file type).
*
* @package core_media
* @copyright 2016 Marina Glancy
* @author 2011 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class core_media_player {
/**
* Placeholder text used to indicate where the fallback content is placed
* within a result.
*/
const PLACEHOLDER = '<!--FALLBACK-->';
/**
* Placeholder text used to indicate where the link fallback is placed.
* No other players will apply to it but it will be converted to the link in the
* end (unless prevented by OPTION_NO_LINK).
*/
const LINKPLACEHOLDER = '<!--LINKFALLBACK-->';
/**
* Generates code required to embed the player.
*
* The returned code contains a placeholder comment '<!--FALLBACK-->'
* (constant core_media_player::PLACEHOLDER) which indicates the location
* where fallback content should be placed in the event that this type of
* player is not supported by user browser.
*
* The $urls parameter includes one or more alternative media formats that
* are supported by this player. It does not include formats that aren't
* supported (see list_supported_urls).
*
* The $options array contains key-value pairs. See OPTION_xx constants
* for documentation of standard option(s).
*
* @param array $urls URLs of media files
* @param string $name Display name; '' to use default
* @param int $width Optional width; 0 to use default
* @param int $height Optional height; 0 to use default
* @param array $options Options array
* @return string HTML code for embed
*/
public abstract function embed($urls, $name, $width, $height, $options);
/**
* Gets the list of file extensions supported by this media player.
*
* Note: This is only required for the default implementations of
* list_supported_urls(), get_embeddable_markers() and supports().
* If you override these functions to determine
* supported URLs in some way other than by extension, then this function
* is not necessary.
*
* @return array Array of strings (extension not including dot e.g. '.mp3')
*/
public function get_supported_extensions() {
return array();
}
/**
* Lists keywords that must be included in a url that can be embedded with
* this player. Any such keywords should be added to the array.
*
* For example if this player supports FLV and F4V files then it should add
* '.flv' and '.f4v' to the array. (The check is not case-sensitive.)
*
* Default handling calls the get_supported_extensions function, so players
* only need to override this if they don't implement get_supported_extensions.
*
* This is used to improve performance when matching links in the media filter.
*
* @return array Array of keywords to add to the embeddable markers list
*/
public function get_embeddable_markers() {
return $this->get_supported_extensions();
}
/**
* Returns human-readable string of supported file/link types for the "Manage media players" page
* @param array $usedextensions extensions that should NOT be highlighted
* @return string
*/
public function supports($usedextensions = []) {
$out = [];
if ($extensions = $this->get_supported_extensions()) {
$video = $audio = $other = [];
foreach ($extensions as $key => $extension) {
$displayextension = $extension;
if (!in_array($extension, $usedextensions)) {
$displayextension = '<strong>'.$extension.'</strong>';
}
if (file_extension_in_typegroup('file.'.$extension, 'audio')) {
$audio[] = $displayextension;
} else if (file_extension_in_typegroup('file.'.$extension, 'video')) {
$video[] = $displayextension;
} else {
$other[] = $displayextension;
}
}
if ($video) {
$out[] = get_string('videoextensions', 'core_media', join(', ', $video));
}
if ($audio) {
$out[] = get_string('audioextensions', 'core_media', join(', ', $audio));
}
if ($other) {
$out[] = get_string('extensions', 'core_media', join(', ', $other));
}
}
return join('<br>', $out);
}
/**
* Gets the ranking of this player. This is an integer used to decide which
* player to use (after applying other considerations such as which ones
* the user has disabled).
*
* This function returns the default rank that can be adjusted by the administrator
* on the Manage media players page.
*
* @return int Rank (higher is better)
*/
public abstract function get_rank();
/**
* @deprecated since Moodle 3.2
*/
public function is_enabled() {
throw new coding_exception('core_media_player::is_enabled() can not be used anymore.');
}
/**
* Given a list of URLs, returns a reduced array containing only those URLs
* which are supported by this player. (Empty if none.)
* @param array $urls Array of moodle_url
* @param array $options Options (same as will be passed to embed)
* @return array Array of supported moodle_url
*/
public function list_supported_urls(array $urls, array $options = array()) {
$extensions = $this->get_supported_extensions();
$result = array();
foreach ($urls as $url) {
$ext = core_media_manager::instance()->get_extension($url);
if (in_array('.' . $ext, $extensions) || in_array($ext, $extensions)) {
$result[] = $url;
}
}
return $result;
}
/**
* Obtains suitable name for media. Uses specified name if there is one,
* otherwise makes one up.
* @param string $name User-specified name ('' if none)
* @param array $urls Array of moodle_url used to make up name
* @return string Name
*/
protected function get_name($name, $urls) {
// If there is a specified name, use that.
if ($name) {
return $name;
}
// Get filename of first URL.
$url = reset($urls);
$name = core_media_manager::instance()->get_filename($url);
// If there is more than one url, strip the extension as we could be
// referring to a different one or several at once.
if (count($urls) > 1) {
$name = preg_replace('~\.[^.]*$~', '', $name);
}
return $name;
}
/**
* @deprecated since Moodle 3.2
*/
public static function compare_by_rank() {
throw new coding_exception('core_media_player::compare_by_rank() can not be used anymore.');
}
/**
* Utility function that sets width and height to defaults if not specified
* as a parameter to the function (will be specified either if, (a) the calling
* code passed it, or (b) the URL included it).
* @param int $width Width passed to function (updated with final value)
* @param int $height Height passed to function (updated with final value)
*/
protected static function pick_video_size(&$width, &$height) {
global $CFG;
if (!$width) {
$width = $CFG->media_default_width;
$height = $CFG->media_default_height;
}
}
/**
* Setup page requirements.
*
* The typical javascript requirements MUST not take action on the content
* directly. They are meant to load the required libraries and listen
* to events in order to know when to take action. The role of this method
* is not to provide a way for plugins to look for content to embed on the
* page. The {@link self::embed()} method is meant to be used for that.
*
* @param moodle_page $page The page we are going to add requirements to.
* @since Moodle 3.2
*/
public function setup($page) {
// Override is need be.
}
}