added flip method

README.md

@@ -57,6 +57,7 @@ Add the facade of this package to the `$aliases` array.
 * Image::pixelate - Pixelate current image
 * Image::greyscale - Turn current image into a greyscale version
 * Image::invert - Invert colors of current image
+* Image::flip - Mirror image horizontally or vertically
 * 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
@@ -186,6 +187,12 @@ $img->circle('ae051f', 400, 300, 100, false);
 
 // draw a red line from point 10,10 to point 300,300 pixel
 $img->line('ae051f', 10, 10, 300, 300);
+
+// flip image horizontally
+$img->flip('h');
+
+// flip image vertically
+$img->flip('v');
 ```
 
 #### Method chaining

src/Intervention/Image/Image.php

@@ -406,6 +406,31 @@ class Image
         return $this->grab($width, $height);
     }
 
+    public function flip($mode = null)
+    {
+        $x = 0;
+        $y = 0;
+        $width = $this->width;
+        $height = $this->height;
+
+        switch (strtolower($mode)) {
+            case 2:
+            case 'v':
+            case 'vert':
+            case 'vertical':
+                $y = $height - 1;
+                $height = $height * (-1);
+                break;
+            
+            default:
+                $x = $width - 1;
+                $width = $width * (-1);
+                break;
+        }
+
+        return $this->modify(0, 0, $x, $y, $this->width, $this->height, $width, $height);
+    }
+
     /**
      * Insert another image on top of the current image
      *

tests/ImageTest.php

@@ -183,6 +183,19 @@ class ImageTest extends PHPUnit_Framework_Testcase
         $this->assertEquals($img->height, 200);
     }
 
+    public function testFlipImage()
+    {
+        $img = $this->getTestImage();
+        $img->flip('h');
+        $this->assertInstanceOf('Intervention\Image\Image', $img);
+        $this->assertEquals('#ffbf47', $img->pickColor(0, 0, 'hex'));
+        
+        $img = $this->getTestImage();
+        $img->flip('v');
+        $this->assertInstanceOf('Intervention\Image\Image', $img);
+        $this->assertEquals('#fed78c', $img->pickColor(0, 0, 'hex'));
+    }
+
     public function testInsertImage()
     {
         $img = $this->getTestImage();