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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 players which return native HTML5 <video> or <audio> tags
*
* @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 players which return native HTML5 <video> or <audio> tags
*
* @package core_media
* @copyright 2016 Marina Glancy
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class core_media_player_native extends core_media_player {
/**
* Extracts a value for an attribute
*
* @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
* @param string $attrname name of the attribute we are looking for
* @param string $type one of PARAM_* constants to clean the attribute value
* @return string|null
*/
public static function get_attribute($tag, $attrname, $type = PARAM_RAW) {
if (preg_match('/^<[^>]*\b' . $attrname . '="(.*?)"/is', $tag, $matches)) {
return clean_param(htmlspecialchars_decode($matches[1]), $type);
} else if (preg_match('~^<[^>]*\b' . $attrname . '[ />]"~is', $tag, $matches)) {
// Some attributes may not have value, for example this is valid: <video controls>.
return clean_param("true", $type);
}
return null;
}
/**
* Removes an attribute from the media tags
*
* @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
* @param string|array $attrname
* @return string
*/
public static function remove_attributes($tag, $attrname) {
if (is_array($attrname)) {
$attrname = join('|', $attrname);
}
while (preg_match('/^(<[^>]*\b)(' . $attrname . ')=".*?"(.*)$/is', $tag, $matches)) {
$tag = $matches[1] . $matches[3];
}
while (preg_match('~^(<[^>]*\b)(' . $attrname . ')([ />].*)$~is', $tag, $matches)) {
// Some attributes may not have value, for example: <video controls>.
$tag = $matches[1] . $matches[3];
}
return $tag;
}
/**
* Adds attributes to the media tags
*
* @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
* @param array $attributes key-value pairs of attributes to be added
* @return string
*/
public static function add_attributes($tag, $attributes) {
$tag = self::remove_attributes($tag, array_keys($attributes));
if (!preg_match('/^(<.*?)(>.*)$/s', $tag, $matches)) {
return $tag;
}
$rv = $matches[1];
foreach ($attributes as $name => $value) {
$rv .= " $name=\"".s($value).'"';
}
$rv .= $matches[2];
return $rv;
}
/**
* Replaces all embedded <source> tags and src attribute
*
* @param string $tag html tag which properties are extracted, for example "<video ...>....</video>"
* @param string $sources replacement string (expected to contain <source> tags)
* @return string
*/
public static function replace_sources($tag, $sources) {
$tag = self::remove_attributes($tag, 'src');
$tag = preg_replace(['~</?source\b[^>]*>~i'], '', $tag);
if (preg_match('/^(<.*?>)([^\0]*)$/ms', $tag, $matches)) {
$tag = $matches[1].$sources.$matches[2];
}
return $tag;
}
public function get_supported_extensions() {
global $CFG;
require_once($CFG->libdir . '/filelib.php');
return file_get_typegroup('extension', ['html_video', 'html_audio']);
}
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, $extensions) && core_useragent::supports_html5($ext)) {
// Unfortunately html5 video does not handle fallback properly.
// https://www.w3.org/Bugs/Public/show_bug.cgi?id=10975
// That means we need to do browser detect and not use html5 on
// browsers which do not support the given type, otherwise users
// will not even see the fallback link.
$result[] = $url;
}
}
return $result;
}
}