add UploadFormField that supports strings and instances of UploadFile for getting the file's location

see also https://community.woltlab.com/thread/288853-uploadformfield-bild-vorschau-ohne-darstellbares-bild/?postID=1841066#post1841066

Author: mutec

files/lib/system/form/builder/field/PreviewedUploadFormField.class.php

@@ -0,0 +1,80 @@
+<?php
+
+namespace wcf\system\form\builder\field;
+
+use wcf\data\IStorableObject;
+use wcf\system\file\upload\UploadFile;
+use wcf\util\ImageUtil;
+
+/**
+ * Implementation of a form field for to uploads.
+ * This extension supports UploadFile-objects and strings for file-locations.
+ *
+ * @author  Joshua Ruesweg, Florian Gail
+ * @copyright   2001-2019 WoltLab GmbH
+ * @license GNU Lesser General Public License <http://opensource.org/licenses/lgpl-license.php>
+ * @package WoltLabSuite\Core\System\Form\Builder\Field
+ * @since   5.2
+ */
+class PreviewedUploadFormField extends UploadFormField {
+	/**
+	 * @inheritDoc
+	 *
+	 * @throws \InvalidArgumentException    if the getter for the value provides invalid values
+	 */
+	public function updatedObject(array $data, IStorableObject $object, $loadValues = true) {
+		if ($loadValues) {
+			// first check, whether an getter for the field exists
+			if (\method_exists($object, 'get' . \ucfirst($this->getObjectProperty()) . 'UploadFileLocations')) {
+				$value = \call_user_func([
+					$object,
+					'get' . \ucfirst($this->getObjectProperty()) . 'UploadFileLocations',
+				]);
+				$method = "method '" . \get_class($object) . "::get" . \ucfirst($this->getObjectProperty()) . "UploadFileLocations()'";
+			}
+			elseif (\method_exists($object, 'get' . \ucfirst($this->getObjectProperty()))) {
+				$value = \call_user_func([
+					$object,
+					'get' . \ucfirst($this->getObjectProperty())
+				]);
+				$method = "method '" . \get_class($object) . "::get" . \ucfirst($this->getObjectProperty()) . "()'";
+			}
+			else {
+				$value = $data[$this->getObjectProperty()];
+				$method = "variable '" . \get_class($object) . "::$" . $this->getObjectProperty() . "'";
+			}
+			
+			if (\is_array($value)) {
+				$value = \array_map(function ($v) use ($method) {
+					if ($v instanceof UploadFile) {
+						if (!file_exists($v->getLocation())) {
+							throw new \InvalidArgumentException("The " . $method . " must return an array of strings or object of class '" . UploadFile::class . "' with the valid file locations.");
+						}
+						
+						return $v;
+					}
+					else {
+						if (!\is_string($v) || !\file_exists($v)) {
+							throw new \InvalidArgumentException("The " . $method . " must return an array of strings or object of class '" . UploadFile::class . "' with the valid file locations.");
+						}
+						
+						return new UploadFile(
+							$v,
+							\basename($v),
+							ImageUtil::isImage($v, \basename($v), $this->svgImageAllowed()),
+							true,
+							$this->svgImageAllowed()
+						);
+					}
+				}, $value);
+				
+				$this->value($value);
+			}
+			else {
+				throw new \InvalidArgumentException("The " . $method . " must return an array of strings with the file locations.");
+			}
+		}
+		
+		return $this;
+	}
+}