Show part preview image in part tables.

src/Services/Attachments/PartPreviewGenerator.php

@@ -0,0 +1,88 @@
+<?php
+/**
+ *
+ * part-db version 0.1
+ * Copyright (C) 2005 Christoph Lechner
+ * http://www.cl-projects.de/
+ *
+ * part-db version 0.2+
+ * Copyright (C) 2009 K. Jacobs and others (see authors.php)
+ * http://code.google.com/p/part-db/
+ *
+ * Part-DB Version 0.4+
+ * Copyright (C) 2016 - 2019 Jan Böhmer
+ * https://github.com/jbtronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ *
+ */
+
+namespace App\Services\Attachments;
+
+
+use App\Entity\Attachments\Attachment;
+use App\Entity\Parts\Part;
+use App\Services\AttachmentHelper;
+
+/**
+ * @package App\Services\Attachments
+ */
+class PartPreviewGenerator
+{
+    protected $attachmentHelper;
+
+    public function __construct(AttachmentHelper $attachmentHelper)
+    {
+        $this->attachmentHelper = $attachmentHelper;
+    }
+
+    /**
+     * Determines what attachment should be used for previewing a part (especially in part table).
+     * The returned attachment is guaranteed to be existing and be a picture.
+     * @param Part $part The part for which the attachment should be determined
+     * @return Attachment|null
+     */
+    public function previewAttachment(Part $part) : ?Attachment
+    {
+        //First of all we check if the master attachment of the part is set (and a picture)
+        $attachment = $part->getMasterPictureAttachment();
+        if ($this->isAttachmentValidPicture($attachment)) {
+            return $attachment;
+        }
+
+        //Otherwise check if the part has a footprint with a valid masterattachment
+        if ($part->getFootprint() !== null) {
+            $attachment = $part->getFootprint()->getMasterPictureAttachment();
+            if ($this->isAttachmentValidPicture($attachment)) {
+                return $attachment;
+            }
+        }
+
+        //If nothing is available return null
+        return null;
+    }
+
+    /**
+     * Checks if a attachment is exising and a valid picture.
+     * @param Attachment|null $attachment The attachment that should be checked.
+     * @return bool True if the attachment is valid.
+     */
+    protected function isAttachmentValidPicture(?Attachment $attachment) : bool
+    {
+        return $attachment !== null
+            && $attachment->isPicture()
+            && $this->attachmentHelper->isFileExisting($attachment);
+    }
+}