From c77ddc29f598b6823448e5178bd1092a11e4fe46 Mon Sep 17 00:00:00 2001
From: Oliver Vogel <oliver@olivervogel.net>
Date: Thu, 26 Jun 2014 16:58:34 +0200
Subject: [PATCH] fixed gif encoding looses transparency

---
 src/Intervention/Image/Gd/Decoder.php |  1 +
 tests/GdSystemTest.php                | 14 ++++++++++++++
 tests/ImagickSystemTest.php           | 14 ++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/src/Intervention/Image/Gd/Decoder.php b/src/Intervention/Image/Gd/Decoder.php
index 536200f0..5f0cbda6 100644
--- a/src/Intervention/Image/Gd/Decoder.php
+++ b/src/Intervention/Image/Gd/Decoder.php
@@ -120,6 +120,7 @@ class Decoder extends \Intervention\Image\AbstractDecoder
         imagealphablending($canvas, false);
         $transparent = imagecolorallocatealpha($canvas, 255, 255, 255, 127);
         imagefilledrectangle($canvas, 0, 0, $width, $height, $transparent);
+        imagecolortransparent($canvas, $transparent);
         imagealphablending($canvas, true);
 
         // copy original
diff --git a/tests/GdSystemTest.php b/tests/GdSystemTest.php
index 8ec310f8..4440ab3e 100644
--- a/tests/GdSystemTest.php
+++ b/tests/GdSystemTest.php
@@ -1506,6 +1506,20 @@ class GdSystemTest extends PHPUnit_Framework_TestCase
         $this->assertInternalType('resource', $cln->getCore());
     }
 
+    public function testGifConversionKeepsTransparency()
+    {
+        $save_as = 'tests/tmp/foo.gif';
+
+        // create gif image from transparent png
+        $img = $this->manager()->make('tests/images/star.png');
+        $img->save($save_as);
+
+        // new gif image should be transparent
+        $img = $this->manager()->make($save_as);
+        $this->assertTransparentPosition($img, 0, 0);
+        @unlink($save_as);
+    }
+
     private function assertColorAtPosition($color, $img, $x, $y)
     {
         $pick = $img->pickColor($x, $y, 'hex');
diff --git a/tests/ImagickSystemTest.php b/tests/ImagickSystemTest.php
index 0ec1db41..944c8fe6 100644
--- a/tests/ImagickSystemTest.php
+++ b/tests/ImagickSystemTest.php
@@ -1487,6 +1487,20 @@ class ImagickSystemTest extends PHPUnit_Framework_TestCase
         $this->assertInstanceOf('Imagick', $cln->getCore());
     }
 
+    public function testGifConversionKeepsTransparency()
+    {
+        $save_as = 'tests/tmp/foo.gif';
+
+        // create gif image from transparent png
+        $img = $this->manager()->make('tests/images/star.png');
+        $img->save($save_as);
+
+        // new gif image should be transparent
+        $img = $this->manager()->make($save_as);
+        $this->assertTransparentPosition($img, 0, 0);
+        @unlink($save_as);
+    }
+
     private function assertColorAtPosition($color, $img, $x, $y)
     {
         $pick = $img->pickColor($x, $y, 'hex');