return new stored_file($this, $file_record, $this->filedir);
}
+ /**
+ * Returns an image file that represent the given stored file as a preview
+ *
+ * At the moment, only GIF, JPEG and PNG files are supported to have previews. In the
+ * future, the support for other mimetypes can be added, too (eg. generate an image
+ * preview of PDF, text documents etc).
+ *
+ * @param stored_file $file the file we want to preview
+ * @param string $mode preview mode, eg. 'thumb'
+ * @return stored_file|bool false if unable to create the preview, stored file otherwise
+ */
+ public function get_file_preview(stored_file $file, $mode) {
+
+ $context = context_system::instance();
+ $path = '/' . trim($mode, '/') . '/';
+ $preview = $this->get_file($context->id, 'core', 'preview', 0, $path, $file->get_contenthash());
+
+ if (!$preview) {
+ $preview = $this->create_file_preview($file, $mode);
+ if (!$preview) {
+ return false;
+ }
+ }
+
+ return $preview;
+ }
+
+ /**
+ * Generates a preview image for the stored file
+ *
+ * @param stored_file $file the file we want to preview
+ * @param string $mode preview mode, eg. 'thumb'
+ * @return stored_file|bool the newly created preview file or false
+ */
+ protected function create_file_preview(stored_file $file, $mode) {
+
+ $mimetype = $file->get_mimetype();
+
+ if ($mimetype == 'image/gif' or $mimetype == 'image/jpeg' or $mimetype == 'image/png') {
+ // make a preview of the image
+ $data = $this->create_imagefile_preview($file, $mode);
+
+ } else {
+ // unable to create the preview of this mimetype yet
+ return false;
+ }
+
+ if (empty($data)) {
+ return false;
+ }
+
+ // getimagesizefromstring() is available from PHP 5.4 but we need to support
+ // lower versions, so...
+ $tmproot = make_temp_directory('thumbnails');
+ $tmpfilepath = $tmproot.'/'.$file->get_contenthash().'_thumb';
+ file_put_contents($tmpfilepath, $data);
+ $imageinfo = getimagesize($tmpfilepath);
+ unlink($tmpfilepath);
+
+ $context = context_system::instance();
+
+ $record = array(
+ 'contextid' => $context->id,
+ 'component' => 'core',
+ 'filearea' => 'preview',
+ 'itemid' => 0,
+ 'filepath' => '/' . trim($mode, '/') . '/',
+ 'filename' => $file->get_contenthash(),
+ );
+
+ if ($imageinfo) {
+ $record['mimetype'] = $imageinfo['mime'];
+ }
+
+ return $this->create_file_from_string($record, $data);
+ }
+
+ /**
+ * Generates a preview for the stored image file
+ *
+ * @param stored_file $file the image we want to preview
+ * @param string $mode preview mode, eg. 'thumb'
+ * @return string|bool false if a problem occurs, the thumbnail image data otherwise
+ */
+ protected function create_imagefile_preview(stored_file $file, $mode) {
+ global $CFG;
+ require_once($CFG->libdir.'/gdlib.php');
+
+ $tmproot = make_temp_directory('thumbnails');
+ $tmpfilepath = $tmproot.'/'.$file->get_contenthash();
+ $file->copy_content_to($tmpfilepath);
+
+ if ($mode == 'tinyicon') {
+ $data = generate_image_thumbnail($tmpfilepath, 16, 16);
+
+ } else if ($mode == 'thumb') {
+ $data = generate_image_thumbnail($tmpfilepath, 90, 90);
+
+ } else {
+ throw new file_exception('storedfileproblem', 'Invalid preview mode requested');
+ }
+
+ unlink($tmpfilepath);
+
+ return $data;
+ }
+
/**
* Fetch file using local file id.
*
