From 291a13927b45f41acc313c1eea9a1e0566c140ae Mon Sep 17 00:00:00 2001
From: Oliver Vogel <oliver@olivervogel.net>
Date: Fri, 1 Mar 2013 16:53:57 +0100
Subject: [PATCH] added invert method

---
 README.md                        |  1 +
 src/Intervention/Image/Image.php | 12 ++++++++++++
 tests/ImageTest.php              |  8 ++++++++
 3 files changed, 21 insertions(+)

diff --git a/README.md b/README.md
index cd39f658..cd7b7e0f 100644
--- a/README.md
+++ b/README.md
@@ -56,6 +56,7 @@ Add the facade of this package to the `$aliases` array.
 * Image::contrast - Changes contrast of current image (-100 = min contrast, 0 = no change, +100 = max contrast)
 * Image::pixelate - Pixelate current image
 * Image::greyscale - Turn current image into a greyscale version
+* Image::invert - Invert colors of current image
 * Image::text - Write text in current image
 * Image::fill - Fill image with given color at position x,y
 * Image::rectangle - Draw rectangle in current image starting at point 1 and ending at point 2
diff --git a/src/Intervention/Image/Image.php b/src/Intervention/Image/Image.php
index 9d7f467a..3336cfd3 100644
--- a/src/Intervention/Image/Image.php
+++ b/src/Intervention/Image/Image.php
@@ -626,6 +626,18 @@ class Image
         return $this;
     }
 
+    /**
+     * Invert colors of current image
+     * 
+     * @return Image
+     */
+    public function invert()
+    {
+        imagefilter($this->resource, IMG_FILTER_NEGATE);
+
+        return $this;
+    }
+
     /**
      * Reset to original image resource
      *
diff --git a/tests/ImageTest.php b/tests/ImageTest.php
index b6b25104..f35e42c2 100644
--- a/tests/ImageTest.php
+++ b/tests/ImageTest.php
@@ -205,6 +205,14 @@ class ImageTest extends PHPUnit_Framework_Testcase
         $this->assertInstanceOf('Intervention\Image\Image', $img);
     }
 
+    public function testInvertImage()
+    {
+        $img = $this->getTestImage();
+        $img->invert();
+        $this->assertInstanceOf('Intervention\Image\Image', $img);
+        $this->assertEquals('#000000', $img->pickColor(0, 0, 'hex'));
+    }
+
     public function testFillImage()
     {
         $img = $this->getTestImage();