MDL-67547 dataformat_pdf: method to convert images to supported format.
[moodle.git] / lib / classes / dataformat / base.php
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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 dataformat.
19 *
20 * @package core
21 * @subpackage dataformat
22 * @copyright 2016 Brendan Heywood (brendan@catalyst-au.net)
23 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
24 */
25
26namespace core\dataformat;
27
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28use coding_exception;
29
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30/**
31 * Base class for dataformat.
32 *
33 * @package core
34 * @subpackage dataformat
35 * @copyright 2016 Brendan Heywood (brendan@catalyst-au.net)
36 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
37 */
38abstract class base {
39
40 /** @var $mimetype */
41 protected $mimetype = "text/plain";
42
43 /** @var $extension */
44 protected $extension = ".txt";
45
46 /** @var $filename */
47 protected $filename = '';
48
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49 /** @var string The location to store the output content */
50 protected $filepath = '';
51
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52 /**
53 * Get the file extension
54 *
55 * @return string file extension
56 */
57 public function get_extension() {
58 return $this->extension;
59 }
60
61 /**
62 * Set download filename base
63 *
64 * @param string $filename
65 */
66 public function set_filename($filename) {
67 $this->filename = $filename;
68 }
69
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70 /**
71 * Set file path when writing to file
72 *
73 * @param string $filepath
74 * @throws coding_exception
75 */
76 public function set_filepath(string $filepath): void {
77 $filedir = dirname($filepath);
78 if (!is_writable($filedir)) {
79 throw new coding_exception('File path is not writable');
80 }
81
82 $this->filepath = $filepath;
83
84 // Some dataformat writers may expect filename to be set too.
85 $this->set_filename(pathinfo($this->filepath, PATHINFO_FILENAME));
86 }
87
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88 /**
89 * Set the title of the worksheet inside a spreadsheet
90 *
91 * For some formats this will be ignored.
92 *
93 * @param string $title
94 */
95 public function set_sheettitle($title) {
96 }
97
98 /**
99 * Output file headers to initialise the download of the file.
100 */
101 public function send_http_headers() {
40a6b502 102 if (defined('BEHAT_SITE_RUNNING') || PHPUNIT_TEST) {
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103 // For text based formats - we cannot test the output with behat if we force a file download.
104 return;
105 }
106 if (is_https()) {
107 // HTTPS sites - watch out for IE! KB812935 and KB316431.
108 header('Cache-Control: max-age=10');
109 header('Pragma: ');
110 } else {
111 // Normal http - prevent caching at all cost.
112 header('Cache-Control: private, must-revalidate, pre-check=0, post-check=0, max-age=0');
113 header('Pragma: no-cache');
114 }
115 header('Expires: '. gmdate('D, d M Y H:i:s', 0) .' GMT');
116 header("Content-Type: $this->mimetype\n");
117 $filename = $this->filename . $this->get_extension();
118 header("Content-Disposition: attachment; filename=\"$filename\"");
119 }
120
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121 /**
122 * Set the dataformat to be output to current file. Calling code must call {@see base::close_output_to_file()} when finished
123 */
124 public function start_output_to_file(): void {
125 // Raise memory limit to ensure we can store the entire content. Start collecting output.
126 raise_memory_limit(MEMORY_EXTRA);
127
128 ob_start();
129 $this->start_output();
130 }
131
bff1edbe 132 /**
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133 * Write the start of the file.
134 */
135 public function start_output() {
136 // Override me if needed.
137 }
138
139 /**
140 * Write the start of the sheet we will be adding data to.
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141 *
142 * @param array $columns
143 */
b62b5879 144 public function start_sheet($columns) {
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145 // Override me if needed.
146 }
147
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148 /**
149 * Method to define whether the dataformat supports export of HTML
150 *
151 * @return bool
152 */
153 public function supports_html(): bool {
154 return false;
155 }
156
157 /**
158 * Apply formatting to the cells of a given record
159 *
160 * @param array|\stdClass $record
161 * @return array
162 */
163 protected function format_record($record): array {
164 $record = (array)$record;
165
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166 // If the dataformat supports export of HTML, we need to allow them to manage embedded images.
167 if ($this->supports_html()) {
168 $record = array_map([$this, 'replace_pluginfile_images'], $record);
169 }
170
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171 return $record;
172 }
173
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174 /**
175 * Given a stored_file, return a suitable source attribute for an img element in the export (or null to use the original)
176 *
177 * @param \stored_file $file
178 * @return string|null
179 */
180 protected function export_html_image_source(\stored_file $file): ?string {
181 return null;
182 }
183
184 /**
185 * We need to locate all img tags within a given cell that match pluginfile URL's. Partly so the exported file will show
186 * the image without requiring the user is logged in; and also to prevent some of the dataformats requesting the file
187 * themselves, which is likely to fail due to them not having an active session
188 *
189 * @param string|null $content
190 * @return string
191 */
192 protected function replace_pluginfile_images(?string $content): string {
193 $content = (string)$content;
194
195 // Examine content to see if it contains any HTML image tags.
196 return preg_replace_callback('/(?<pre><img[^>]+src=")(?<source>[^"]*)(?<post>".*>)/i', function(array $matches) {
197 $source = $matches['source'];
198
199 // Now check if the image source looks like a pluginfile URL.
200 if (preg_match('/pluginfile.php\/(?<context>\d+)\/(?<component>[^\/]+)\/(?<filearea>[^\/]+)\/(?:(?<itemid>\d+)\/)?' .
201 '(?<path>.*)/u', $source, $args)) {
202
203 $context = $args['context'];
204 $component = clean_param($args['component'], PARAM_COMPONENT);
205 $filearea = clean_param($args['filearea'], PARAM_AREA);
206 $itemid = $args['itemid'] ?: 0;
207 $path = clean_param(urldecode($args['path']), PARAM_PATH);
208
209 // Try and get the matching file from storage, allow the dataformat to define the replacement source.
210 $fullpath = "/{$context}/{$component}/{$filearea}/{$itemid}/{$path}";
211 if ($file = get_file_storage()->get_file_by_hash(sha1($fullpath))) {
212 $exportsource = $this->export_html_image_source($file);
213
214 if ($exportsource) {
215 $source = $exportsource;
216 }
217 }
218 }
219
220 return $matches['pre'] . $source . $matches['post'];
221 }, $content);
222 }
223
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224 /**
225 * Write a single record
226 *
227 * @param array $record
228 * @param int $rownum
229 */
230 abstract public function write_record($record, $rownum);
231
232 /**
b62b5879 233 * Write the end of the sheet containing the data.
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234 *
235 * @param array $columns
236 */
b62b5879 237 public function close_sheet($columns) {
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238 // Override me if needed.
239 }
240
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241 /**
242 * Write the end of the file.
243 */
244 public function close_output() {
245 // Override me if needed.
246 }
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247
248 /**
249 * Write the data to disk. Calling code should have previously called {@see base::start_output_to_file()}
250 *
251 * @return bool Whether the write succeeded
252 */
253 public function close_output_to_file(): bool {
254 $this->close_output();
255
256 $filecontent = ob_get_contents();
257 ob_end_clean();
258
259 return file_put_contents($this->filepath, $filecontent) !== false;
260 }
bff1edbe 261}