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248 lines
8.3 KiB
248 lines
8.3 KiB
<?php
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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Moodle is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* Class for converting files between different file formats using unoconv.
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*
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* @package core_files
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* @copyright 2017 Damyon Wiese
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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namespace core_files;
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defined('MOODLE_INTERNAL') || die();
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use stored_file;
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/**
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* Class for converting files between different formats using unoconv.
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*
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* @package core_files
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* @copyright 2017 Damyon Wiese
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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class converter {
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/**
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* Get a list of enabled plugins and classes.
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*
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* @return array List of enabled plugins
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*/
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protected function get_enabled_plugins() {
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$plugins = \core\plugininfo\fileconverter::get_enabled_plugins();
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$pluginclasses = [];
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foreach ($plugins as $plugin) {
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$pluginclasses[$plugin] = \core\plugininfo\fileconverter::get_classname($plugin);
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}
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return $pluginclasses;
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}
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/**
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* Return the file_storage API.
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*
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* This allows for mocking of the file_storage API.
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*
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* @return \file_storage
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*/
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protected function get_file_storage() {
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return get_file_storage();
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}
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/**
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* Start the conversion for a stored_file into a new format.
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*
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* @param stored_file $file The file to convert
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* @param string $format The desired target file format (file extension)
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* @param boolean $forcerefresh If true, the file will be converted every time (not cached).
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* @return conversion conversion object
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*/
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public function start_conversion(stored_file $file, $format, $forcerefresh = false) {
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$conversions = conversion::get_conversions_for_file($file, $format);
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if ($forcerefresh || count($conversions) > 1) {
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while ($conversion = array_shift($conversions)) {
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if ($conversion->get('id')) {
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$conversion->delete();
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}
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}
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}
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if (empty($conversions)) {
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$conversion = new conversion(0, (object) [
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'sourcefileid' => $file->get_id(),
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'targetformat' => $format,
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]);
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$conversion->create();
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} else {
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$conversion = array_shift($conversions);
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}
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if ($conversion->get('status') !== conversion::STATUS_COMPLETE) {
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$this->poll_conversion($conversion);
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}
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return $conversion;
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}
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/**
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* Poll for updates to the supplied conversion.
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*
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* @param conversion $conversion The conversion in progress
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* @return $this
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*/
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public function poll_conversion(conversion $conversion) {
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$format = $conversion->get('targetformat');
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$file = $conversion->get_sourcefile();
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if ($conversion->get('status') == conversion::STATUS_IN_PROGRESS) {
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// The current conversion is in progress.
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// Check for updates.
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if ($instance = $conversion->get_converter_instance()) {
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$instance->poll_conversion_status($conversion);
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} else {
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// Unable to fetch the converter instance.
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// Reset the status back to PENDING so that it may be picked up again.
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$conversion->set('status', conversion::STATUS_PENDING);
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}
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$conversion->update();
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}
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// Refresh the status.
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$status = $conversion->get('status');
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if ($status === conversion::STATUS_PENDING || $status === conversion::STATUS_FAILED) {
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// The current status is either pending or failed.
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// Attempt to pick up a new converter and convert the document.
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$from = pathinfo($file->get_filename(), PATHINFO_EXTENSION);
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$converters = $this->get_document_converter_classes($from, $format);
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$currentconverter = $this->get_next_converter($converters, $conversion->get('converter'));
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if (!$currentconverter) {
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// No more converters available.
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$conversion->set('status', conversion::STATUS_FAILED);
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$conversion->update();
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return $this;
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}
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do {
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$conversion
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->set('converter', $currentconverter)
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->set('status', conversion::STATUS_IN_PROGRESS)
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->update();
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$instance = $conversion->get_converter_instance();
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$instance->start_document_conversion($conversion);
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$failed = $conversion->get('status') === conversion::STATUS_FAILED;
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$currentconverter = $this->get_next_converter($converters, $currentconverter);
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} while ($failed && $currentconverter);
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$conversion->update();
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}
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return $this;
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}
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/**
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* Fetch the next converter to try.
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*
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* @param array $converters The list of converters to try
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* @param string|null $currentconverter The converter currently in use
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* @return string|false Name of next converter if present
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*/
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protected function get_next_converter($converters, $currentconverter = null) {
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if ($currentconverter) {
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$keys = array_keys($converters, $currentconverter);
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$key = $keys[0];
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if (isset($converters[$key + 1])) {
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return $converters[$key + 1];
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} else {
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return false;
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}
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} else if (!empty($converters)) {
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return $converters[0];
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} else {
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return false;
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}
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}
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/**
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* Fetch the class for the preferred document converter.
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*
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* @param string $from The source target file (file extension)
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* @param string $to The desired target file format (file extension)
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* @return string The class for document conversion
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*/
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protected function get_document_converter_classes($from, $to) {
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$classes = [];
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$converters = $this->get_enabled_plugins();
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foreach ($converters as $plugin => $classname) {
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if (!class_exists($classname)) {
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continue;
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}
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if (!$classname::are_requirements_met()) {
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continue;
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}
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if ($classname::supports($from, $to)) {
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$classes[] = $classname;
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}
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}
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return $classes;
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}
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/**
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* Check whether document conversion is supported for this file and target format.
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*
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* @param stored_file $file The file to convert
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* @param string $to The desired target file format (file extension)
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* @return bool Whether the target type can be converted
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*/
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public function can_convert_storedfile_to(stored_file $file, $to) {
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if ($file->is_directory()) {
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// Directories cannot be converted.
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return false;
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}
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if (!$file->get_filesize()) {
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// Empty files cannot be converted.
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return false;
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}
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$from = pathinfo($file->get_filename(), PATHINFO_EXTENSION);
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if (!$from) {
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// No file extension could be found. Unable to determine converter.
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return false;
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}
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return $this->can_convert_format_to($from, $to);
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}
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/**
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* Check whether document conversion is supported for this file and target format.
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*
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* @param string $from The source target file (file extension)
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* @param string $to The desired target file format (file extension)
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* @return bool Whether the target type can be converted
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*/
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public function can_convert_format_to($from, $to) {
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return !empty($this->get_document_converter_classes($from, $to));
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}
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}
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