Proyectos de Subversion Moodle

<?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], ENT_COMPAT), $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;

    }

}