From a039c1bbca4a741fea8ca3cfcacd1b0e8f961f8d Mon Sep 17 00:00:00 2001
From: Will Norris <will@willnorris.com>
Date: Fri, 6 Dec 2013 22:18:44 -0800
Subject: [PATCH] add options to flip horizontally and vertically

---
 data/data.go           | 12 ++++++++++++
 proxy/proxy_test.go    | 20 ++++++++++----------
 readme.md              |  6 ++++++
 transform/transform.go |  8 ++++++++
 4 files changed, 36 insertions(+), 10 deletions(-)

diff --git a/data/data.go b/data/data.go
index 77fedb2..fb6f08c 100644
--- a/data/data.go
+++ b/data/data.go
@@ -35,6 +35,9 @@ type Options struct {
 
 	// Rotate image the specified degrees counter-clockwise.  Valid values are 90, 180, 270.
 	Rotate int
+
+	FlipVertical   bool
+	FlipHorizontal bool
 }
 
 func (o Options) String() string {
@@ -68,6 +71,15 @@ func ParseOptions(str string) *Options {
 			o.Fit = true
 			continue
 		}
+		if part == "fv" {
+			o.FlipVertical = true
+			continue
+		}
+		if part == "fh" {
+			o.FlipHorizontal = true
+			continue
+		}
+
 		if len(part) > 2 && strings.HasPrefix(part, "r=") {
 			o.Rotate, _ = strconv.Atoi(part[2:])
 			continue
diff --git a/proxy/proxy_test.go b/proxy/proxy_test.go
index 1115009..df46ea1 100644
--- a/proxy/proxy_test.go
+++ b/proxy/proxy_test.go
@@ -84,27 +84,27 @@ func TestNewRequest(t *testing.T) {
 		},
 		{
 			"http://localhost/1x/http://example.com/",
-			"http://example.com/", &data.Options{1, 0, false}, false,
+			"http://example.com/", &data.Options{1, 0, false, 0, false, false}, false,
 		},
 		{
 			"http://localhost/x1/http://example.com/",
-			"http://example.com/", &data.Options{0, 1, false}, false,
+			"http://example.com/", &data.Options{0, 1, false, 0, false, false}, false,
 		},
 		{
 			"http://localhost/1x2/http://example.com/",
-			"http://example.com/", &data.Options{1, 2, false}, false,
+			"http://example.com/", &data.Options{1, 2, false, 0, false, false}, false,
+		},
+		{
+			"http://localhost/0.1x0.2/http://example.com/",
+			"http://example.com/", &data.Options{0.1, 0.2, false, 0, false, false}, false,
 		},
 		{
 			"http://localhost/,fit/http://example.com/",
-			"http://example.com/", &data.Options{0, 0, true}, false,
+			"http://example.com/", &data.Options{0, 0, true, 0, false, false}, false,
 		},
 		{
-			"http://localhost/1x2,fit/http://example.com/",
-			"http://example.com/", &data.Options{1, 2, true}, false,
-		},
-		{
-			"http://localhost/0.1x0.2,fit/http://example.com/",
-			"http://example.com/", &data.Options{0.1, 0.2, true}, false,
+			"http://localhost/1x2,fit,r=90,fv,fh/http://example.com/",
+			"http://example.com/", &data.Options{1, 2, true, 90, true, true}, false,
 		},
 	}
 
diff --git a/readme.md b/readme.md
index 63f3ea6..973e30a 100644
--- a/readme.md
+++ b/readme.md
@@ -65,6 +65,11 @@ The `r={degrees}` option will rotate the image the specified number of degrees,
 counter-clockwise.  Valid degrees values are `90`, `180`, and `270`.  Images
 are rotated **after** being resized.
 
+#### Flip ####
+
+The `fv` option will flip the image vertically.  The `fh` option will flip the
+image horizontally.  Images are flipped **after** being resized and rotated.
+
 ### Remote URL ###
 
 The URL of the original image to load is specified as the remainder of the
@@ -92,6 +97,7 @@ x100    | 100px tall, proportional width           | ![x100](https://s.wjn.me/x1
 100     | 100px square, cropping as needed         | ![100](https://s.wjn.me/100/https://willnorris.com/content/uploads/2013/12/small-things.jpg)
 150,fit | fit to be no more than 150 by 150 pixels | ![150,fit](https://s.wjn.me/150,fit/https://willnorris.com/content/uploads/2013/12/small-things.jpg)
 100,r=90| 100px square, rotated 90 degrees         | ![100,r=90](https://s.wjn.me/100,r=90/https://willnorris.com/content/uploads/2013/12/small-things.jpg)
+100,fv,fh | 100px square, flipped horizontal and vertical | ![100,fv,fh](https://s.wjn.me/100,fv,fh/https://willnorris.com/content/uploads/2013/12/small-things.jpg)
 
 
 ## License ##
diff --git a/transform/transform.go b/transform/transform.go
index 9f40e4d..2782a8d 100644
--- a/transform/transform.go
+++ b/transform/transform.go
@@ -73,6 +73,14 @@ func Transform(img data.Image, opt *data.Options) (*data.Image, error) {
 		}
 	}
 
+	// flip
+	if opt.FlipVertical {
+		m = imaging.FlipV(m)
+	}
+	if opt.FlipHorizontal {
+		m = imaging.FlipH(m)
+	}
+
 	// rotate
 	switch opt.Rotate {
 	case 90: