From b61c3ac8c3916fb4452107d7fbd939ef09a50b1b Mon Sep 17 00:00:00 2001
From: Sander Hagenaars <sanderhagenaars@Sanders-MacBook-Pro.local>
Date: Wed, 14 Jun 2017 15:54:21 +0200
Subject: [PATCH] keep PNG transparancy on GDBackend::rotatePixelByPixel

---
 filesystem/GD.php | 1 +
 1 file changed, 1 insertion(+)

diff --git a/filesystem/GD.php b/filesystem/GD.php
index 7cd4c3aad..fe613d533 100644
--- a/filesystem/GD.php
+++ b/filesystem/GD.php
@@ -321,6 +321,7 @@ class GDBackend extends Object implements Image_Backend {
 		}
 		$rotate=imagecreatetruecolor($destWidth,$destHeight);
 		imagealphablending($rotate, false);
+		imagesavealpha($rotate, true); // to maintain PNG transparency
 		for ($x = 0; $x < ($sourceWidth); $x++) {
 			for ($y = 0; $y < ($sourceHeight); $y++) {
 				$color = imagecolorat($this->gd, $x, $y);