MAGETWO-65006: [GitHub][PR] Keep transparency when resizing images #7307

 - fix is created based on public pull request #7307 by @kassner
 - closing #7307

Author: Oleksii Korshenko

lib/internal/Magento/Framework/Image/Adapter/Gd2.php

@@ -346,6 +346,10 @@ public function resize($frameWidth = null, $frameHeight = null)
             $newImage = imagecreate($dims['frame']['width'], $dims['frame']['height']);
         }
 
+        if ($isAlpha) {
+            $this->_saveAlpha($newImage);
+        }
+
         // fill new image with required color
         $this->_fillBackgroundColor($newImage);
 

lib/internal/Magento/Framework/Image/Adapter/ImageMagick.php

@@ -168,6 +168,13 @@ public function resize($frameWidth = null, $frameHeight = null)
             );
         }
 
+        $newImage->compositeImage(
+            $this->_imageHandler,
+            \Imagick::COMPOSITE_COPYOPACITY,
+            $dims['dst']['x'],
+            $dims['dst']['y']
+        );
+
         $newImage->compositeImage(
             $this->_imageHandler,
             \Imagick::COMPOSITE_OVER,