feat(#20): support flop operation (interface broken, sorry im still beta)

README.md

@@ -43,6 +43,7 @@ The [install script](https://github.com/lovell/sharp/blob/master/preinstall.sh)
 - Crop
 - Rotate
 - Flip
+- Flop
 - Thumbnail
 - Extract area
 - Format conversion
@@ -56,7 +57,7 @@ Here you can see some performance test comparisons for multiple scenarios:
 - [libvips speed and memory usage](http://www.vips.ecs.soton.ac.uk/index.php?title=Speed_and_Memory_Use)
 - [sharp performance tests](https://github.com/lovell/sharp#the-task) 
 
-#### bimg performance tests
+#### Benchmarks
 
 Tested using Go 1.4 and libvips-7.42.3 in OSX i7 2.7Ghz
 ```

image.go

@@ -82,13 +82,13 @@ func (i *Image) Rotate(a Angle) ([]byte, error) {
 
 // Flip the image about the vertical Y axis
 func (i *Image) Flip() ([]byte, error) {
-	options := Options{Flip: VERTICAL}
+	options := Options{Flip: true}
 	return i.Process(options)
 }
 
 // Flop the image about the horizontal X axis
 func (i *Image) Flop() ([]byte, error) {
-	options := Options{Flip: VERTICAL}
+	options := Options{Flop: true}
 	return i.Process(options)
 }
 

image_test.go

@@ -112,6 +112,14 @@ func TestImageFlip(t *testing.T) {
 	Write("fixtures/test_flip_out.jpg", buf)
 }
 
+func TestImageFlop(t *testing.T) {
+	buf, err := initImage("test.jpg").Flop()
+	if err != nil {
+		t.Errorf("Cannot process the image: %#v", err)
+	}
+	Write("fixtures/test_flop_out.jpg", buf)
+}
+
 func TestImageRotate(t *testing.T) {
 	buf, err := initImage("test_flip_out.jpg").Rotate(90)
 	if err != nil {

options.go

@@ -68,9 +68,10 @@ type Options struct {
 	Crop         bool
 	Enlarge      bool
 	Embed        bool
+	Flip         bool
+	Flop         bool
 	Type         ImageType
 	Rotate       Angle
-	Flip         Direction
 	Gravity      Gravity
 	Interpolator Interpolator
 }

resize.go

@@ -160,10 +160,11 @@ func extractImage(image *C.struct__VipsImage, o Options) (*C.struct__VipsImage,
 
 func rotateImage(image *C.struct__VipsImage, o Options) (*C.struct__VipsImage, error) {
 	var err error
+	var direction Direction = -1
 
 	rotation, flip := calculateRotationAndFlip(image, o.Rotate)
 	if flip {
-		o.Flip = HORIZONTAL
+		o.Flip = flip
 	}
 	if rotation > D0 && o.Rotate == 0 {
 		o.Rotate = rotation
@@ -172,8 +173,15 @@ func rotateImage(image *C.struct__VipsImage, o Options) (*C.struct__VipsImage, e
 	if o.Rotate > 0 {
 		image, err = vipsRotate(image, getAngle(o.Rotate))
 	}
-	if o.Flip > 0 {
+
-		image, err = vipsFlip(image, o.Flip)
+	if o.Flip {
+		direction = HORIZONTAL
+	} else if o.Flop {
+		direction = VERTICAL
+	}
+
+	if direction != -1 {
+		image, err = vipsFlip(image, direction)
 	}
 
 	return image, err