Commit c4d19c5a authored by David Mudrák's avatar David Mudrák
Browse files

MDL-32471 introducing file_storage::get_file_preview() method

parent f0a23f53
......@@ -152,6 +152,113 @@ class file_storage {
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.
*
......
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