From 70368abb7d2a848c7af3f24e10fecad1a9dc6773 Mon Sep 17 00:00:00 2001
From: mpl <mathieu.lonjaret@gmail.com>
Date: Sun, 4 Nov 2012 14:08:11 +0100
Subject: [PATCH] rotate thumbnails

Change-Id: I87dd3008facc5e9c8007fc8ebcba13e98f4a2175
---
 pkg/server/image.go | 40 +++++++++++++++++++++++++++++++++++++++-
 pkg/server/ui.go    | 20 ++++++++++++++++++--
 2 files changed, 57 insertions(+), 3 deletions(-)

diff --git a/pkg/server/image.go b/pkg/server/image.go
index 88c102782..c242cd4a8 100644
--- a/pkg/server/image.go
+++ b/pkg/server/image.go
@@ -41,6 +41,7 @@ type ImageHandler struct {
 	Fetcher             blobref.StreamingFetcher
 	Cache               blobserver.Storage // optional
 	MaxWidth, MaxHeight int
+	Rotate              int // degrees to rotate counter-clockwise: 0, ±90, ±180
 	Square              bool
 	sc                  ScaledImage // optional cache for scaled images
 }
@@ -143,6 +144,43 @@ func (ih *ImageHandler) scaledCached(buf *bytes.Buffer, file *blobref.BlobRef) (
 	return pieces[1], nil
 }
 
+// rotate returns the given image rotated by ih.Rotate degrees if it is
+// ±90 or ±180, or the source image otherwise.
+func (ih *ImageHandler) rotate(im image.Image) image.Image {
+	if ih.Rotate == 0 {
+		return im
+	}
+	var rotated *image.NRGBA
+	// trigonometric (i.e counter clock-wise)
+	switch ih.Rotate {
+	case 90:
+		newH, newW := im.Bounds().Dx(), im.Bounds().Dy()
+		rotated = image.NewNRGBA(image.Rect(0, 0, newW, newH))
+		for y := 0; y < newH; y++ {
+			for x := 0; x < newW; x++ {
+				rotated.Set(x, y, im.At(newH-1-y, x))
+			}
+		}
+	case -90:
+		newH, newW := im.Bounds().Dx(), im.Bounds().Dy()
+		rotated = image.NewNRGBA(image.Rect(0, 0, newW, newH))
+		for y := 0; y < newH; y++ {
+			for x := 0; x < newW; x++ {
+				rotated.Set(x, y, im.At(y, newW-1-x))
+			}
+		}
+	case 180, -180:
+		newW, newH := im.Bounds().Dx(), im.Bounds().Dy()
+		rotated = image.NewNRGBA(image.Rect(0, 0, newW, newH))
+		for y := 0; y < newH; y++ {
+			for x := 0; x < newW; x++ {
+				rotated.Set(x, y, im.At(newW-1-x, newH-1-y))
+			}
+		}
+	}
+	return rotated
+}
+
 func (ih *ImageHandler) scaleImage(buf *bytes.Buffer, file *blobref.BlobRef) (format string, err error) {
 	mw, mh := ih.MaxWidth, ih.MaxHeight
 
@@ -202,7 +240,7 @@ func (ih *ImageHandler) scaleImage(buf *bytes.Buffer, file *blobref.BlobRef) (fo
 	}
 
 	if !useBytesUnchanged {
-		i = resize.Resize(i, b, mw, mh)
+		i = ih.rotate(resize.Resize(i, b, mw, mh))
 		// Encode as a new image
 		buf.Reset()
 		switch format {
diff --git a/pkg/server/ui.go b/pkg/server/ui.go
index 52518d8b1..d5fa5cf27 100644
--- a/pkg/server/ui.go
+++ b/pkg/server/ui.go
@@ -309,15 +309,30 @@ func (ui *UIHandler) serveThumbnail(rw http.ResponseWriter, req *http.Request) {
 	query := req.URL.Query()
 	width, err := strconv.Atoi(query.Get("mw"))
 	if err != nil {
-		http.Error(rw, "Invalid specified max width 'mw': "+err.Error(), 500)
+		http.Error(rw, "Invalid specified max width 'mw'", 500)
 		return
 	}
 	height, err := strconv.Atoi(query.Get("mh"))
 	if err != nil {
-		http.Error(rw, "Invalid specified height 'mh': "+err.Error(), 500)
+		http.Error(rw, "Invalid specified height 'mh'", 500)
 		return
 	}
 
+	// TODO(mpl): delete this; just temporary assistance before EXIF is done
+	rot := query.Get("rot")
+	rotateAngle := 0
+	if rot != "" {
+		rotateAngle, err = strconv.Atoi(rot)
+		if err != nil {
+			http.Error(rw, "Invalid 'rot' param", 500)
+			return
+		}
+		if rotateAngle%90 != 0 {
+			http.Error(rw, "Invalid rotate angle", 500)
+			return
+		}
+	}
+
 	blobref := blobref.Parse(m[1])
 	if blobref == nil {
 		http.Error(rw, "Invalid blobref", 400)
@@ -329,6 +344,7 @@ func (ui *UIHandler) serveThumbnail(rw http.ResponseWriter, req *http.Request) {
 		Cache:     ui.Cache,
 		MaxWidth:  width,
 		MaxHeight: height,
+		Rotate:    rotateAngle,
 		sc:        ui.sc,
 	}
 	th.ServeHTTP(rw, req, blobref)