func (ui *UIHandler) serveThumbnail(rw http.ResponseWriter, req *http.Request) {
if ui.Storage == nil {
http.Error(rw, "No BlobRoot configured", 500)
return
}
fetchSeeker, err := ui.storageSeekFetcher()
if err != nil {
http.Error(rw, err.String(), 500)
return
}
suffix := req.Header.Get("X-PrefixHandler-PathSuffix")
m := thumbnailPattern.FindStringSubmatch(suffix)
if m == nil {
httputil.ErrorRouting(rw, req)
return
}
query := req.URL.Query()
width, err := strconv.Atoi(query.Get("mw"))
if err != nil {
http.Error(rw, "Invalid specified max width 'mw': "+err.String(), 500)
return
}
height, err := strconv.Atoi(query.Get("mh"))
if err != nil {
http.Error(rw, "Invalid specified height 'mh': "+err.String(), 500)
return
}
blobref := blobref.Parse(m[1])
if blobref == nil {
http.Error(rw, "Invalid blobref", 400)
return
}
filename := m[2]
if len(filename) > 0 {
filename = filename[1:] // remove leading slash
}
fr, err := schema.NewFileReader(fetchSeeker, blobref)
if err != nil {
http.Error(rw, "Can't serve file: "+err.String(), 500)
return
}
var buf bytes.Buffer
n, err := io.Copy(&buf, fr)
i, format, err := image.Decode(&buf)
if err != nil {
http.Error(rw, "Can't serve file: "+err.String(), 500)
return
}
b := i.Bounds()
// only do downscaling, otherwise just serve the original image
if width < b.Dx() || height < b.Dy() {
const huge = 2400
// If it's gigantic, it's more efficient to downsample first
// and then resize; resizing will smooth out the roughness.
// (trusting the moustachio guys on that one).
if b.Dx() > huge || b.Dy() > huge {
w, h := width*2, height*2
if b.Dx() > b.Dy() {
w = b.Dx() * h / b.Dy()
} else {
h = b.Dy() * w / b.Dx()
}
i = resize.Resample(i, i.Bounds(), w, h)
b = i.Bounds()
}
// conserve proportions. use the smallest of the two as the decisive one.
if width > height {
width = b.Dx() * height / b.Dy()
} else {
height = b.Dy() * width / b.Dx()
}
i = resize.Resize(i, b, width, height)
// Encode as a new image
buf.Reset()
switch format {
case "jpeg":
err = jpeg.Encode(&buf, i, nil)
default:
err = png.Encode(&buf, i)
}
if err != nil {
http.Error(rw, "Can't serve file: "+err.String(), 500)
return
}
}
ct := ""
switch format {
case "jpeg":
ct = "image/jpeg"
default:
ct = "image/png"
}
rw.Header().Set("Content-Type", ct)
size := buf.Len()
rw.Header().Set("Content-Length", fmt.Sprintf("%d", size))
n, err = io.Copy(rw, &buf)
if err != nil {
log.Printf("error serving thumbnail of file schema %s: %v", blobref, err)
return
}
if n != int64(size) {
log.Printf("error serving thumbnail of file schema %s: sent %d, expected size of %d",
blobref, n, size)
return
}
}
func (ih *ImageHandler) ServeHTTP(rw http.ResponseWriter, req *http.Request, file *blobref.BlobRef) {
if req.Method != "GET" && req.Method != "HEAD" {
http.Error(rw, "Invalid method", 400)
return
}
mw, mh := ih.MaxWidth, ih.MaxHeight
if mw == 0 || mh == 0 || mw > 2000 || mh > 2000 {
http.Error(rw, "bogus dimensions", 400)
return
}
fetchSeeker, err := ih.storageSeekFetcher()
if err != nil {
http.Error(rw, err.String(), 500)
return
}
fr, err := schema.NewFileReader(fetchSeeker, file)
if err != nil {
http.Error(rw, "Can't serve file: "+err.String(), 500)
return
}
var buf bytes.Buffer
n, err := io.Copy(&buf, fr)
if err != nil {
log.Printf("image resize: error reading image %s: %v", file, err)
return
}
i, format, err := image.Decode(bytes.NewBuffer(buf.Bytes()))
if err != nil {
http.Error(rw, "Can't serve file: "+err.String(), 500)
return
}
b := i.Bounds()
useBytesUnchanged := true
isSquare := b.Dx() == b.Dy()
if ih.Square && !isSquare {
useBytesUnchanged = false
i = squareImage(i)
b = i.Bounds()
}
// only do downscaling, otherwise just serve the original image
if mw < b.Dx() || mh < b.Dy() {
useBytesUnchanged = false
const huge = 2400
// If it's gigantic, it's more efficient to downsample first
// and then resize; resizing will smooth out the roughness.
// (trusting the moustachio guys on that one).
if b.Dx() > huge || b.Dy() > huge {
w, h := mw*2, mh*2
if b.Dx() > b.Dy() {
w = b.Dx() * h / b.Dy()
} else {
h = b.Dy() * w / b.Dx()
}
i = resize.Resample(i, i.Bounds(), w, h)
b = i.Bounds()
}
// conserve proportions. use the smallest of the two as the decisive one.
if mw > mh {
mw = b.Dx() * mh / b.Dy()
} else {
mh = b.Dy() * mw / b.Dx()
}
}
if !useBytesUnchanged {
i = resize.Resize(i, b, mw, mh)
// Encode as a new image
buf.Reset()
switch format {
case "jpeg":
err = jpeg.Encode(&buf, i, nil)
default:
err = png.Encode(&buf, i)
}
if err != nil {
http.Error(rw, "Can't serve file: "+err.String(), 500)
return
}
}
rw.Header().Set("Content-Type", imageContentTypeOfFormat(format))
size := buf.Len()
rw.Header().Set("Content-Length", fmt.Sprintf("%d", size))
n, err = io.Copy(rw, &buf)
if err != nil {
log.Printf("error serving thumbnail of file schema %s: %v", file, err)
return
}
if n != int64(size) {
log.Printf("error serving thumbnail of file schema %s: sent %d, expected size of %d",
file, n, size)
return
}
}