ThumbGenerator.php: add thumb generation service interface

inc/Service/Media/ThumbGenerator.php

@@ -0,0 +1,20 @@
+<?php
+namespace Vichan\Service\Media;
+
+use Vichan\Data\ThumbGenerationResult;
+
+
+interface ThumbGenerator {
+	public function supportsMime(string $mime): bool;
+
+	/**
+	 * Generates a thumbnail from the given file.
+	 *
+	 * @param string $source_file_path
+	 * @param string $preferred_out_file_path
+	 * @param int $max_width
+	 * @param int $max_height
+	 * @return ThumbGenerationResult
+	 */
+	public function generateThumb(string $source_file_path, string $preferred_out_file_path, int $max_width, int $max_height): ThumbGenerationResult;
+}