// Show is the handler for showing a stored QR code.
func Show(w http.ResponseWriter, req *http.Request) {
ctxt := fs.NewContext(req)
tag := req.URL.Path[len("/qr/show/"):]
png := strings.HasSuffix(tag, ".png")
if png {
tag = tag[:len(tag)-len(".png")]
}
if !isTagName(tag) {
fmt.Fprintf(w, "Sorry, QR code not found\n")
return
}
if req.FormValue("flag") == "1" {
flag(w, req, tag, ctxt)
return
}
data, _, err := ctxt.Read("qrsave/" + tag)
if err != nil {
fmt.Fprintf(w, "Sorry, QR code not found.\n")
return
}
var m Image
if err := json.Unmarshal(data, &m); err != nil {
panic(err)
}
m.Tag = tag
switch req.FormValue("size") {
case "big":
m.Scale *= 2
case "small":
m.Scale /= 2
}
if png {
if err := m.Encode(req); err != nil {
panic(err)
return
}
w.Header().Set("Cache-Control", "public, max-age=3600")
w.Write(m.Code.PNG())
return
}
w.Header().Set("Cache-Control", "public, max-age=300")
runTemplate(ctxt, w, "qr/permalink.html", &m)
}
func upload(w http.ResponseWriter, req *http.Request, link string) {
// Upload of a new image.
// Copied from Moustachio demo.
f, _, err := req.FormFile("image")
if err != nil {
fmt.Fprintf(w, "You need to select an image to upload.\n")
return
}
defer f.Close()
i, _, err := image.Decode(f)
if err != nil {
panic(err)
}
// Convert image to 128x128 gray+alpha.
b := i.Bounds()
const max = 128
// If it's gigantic, it's more efficient to downsample first
// and then resize; resizing will smooth out the roughness.
var i1 *image.RGBA
if b.Dx() > 4*max || b.Dy() > 4*max {
w, h := 2*max, 2*max
if b.Dx() > b.Dy() {
h = b.Dy() * h / b.Dx()
} else {
w = b.Dx() * w / b.Dy()
}
i1 = resize.Resample(i, b, w, h)
} else {
// "Resample" to same size, just to convert to RGBA.
i1 = resize.Resample(i, b, b.Dx(), b.Dy())
}
b = i1.Bounds()
// Encode to PNG.
dx, dy := 128, 128
if b.Dx() > b.Dy() {
dy = b.Dy() * dx / b.Dx()
} else {
dx = b.Dx() * dy / b.Dy()
}
i128 := resize.ResizeRGBA(i1, i1.Bounds(), dx, dy)
var buf bytes.Buffer
if err := png.Encode(&buf, i128); err != nil {
panic(err)
}
h := md5.New()
h.Write(buf.Bytes())
tag := fmt.Sprintf("%x", h.Sum(nil))[:32]
ctxt := fs.NewContext(req)
if err := ctxt.Write("qr/upload/"+tag+".png", buf.Bytes()); err != nil {
panic(err)
}
// Redirect with new image tag.
// Redirect to draw with new image tag.
http.Redirect(w, req, req.URL.Path+"?"+url.Values{"i": {tag}, "url": {link}}.Encode(), 302)
}
// Draw is the handler for drawing a QR code.
func Draw(w http.ResponseWriter, req *http.Request) {
ctxt := fs.NewContext(req)
url := req.FormValue("url")
if url == "" {
url = "http://swtch.com/qr"
}
if req.FormValue("upload") == "1" {
upload(w, req, url)
return
}
t0 := time.Now()
img := req.FormValue("i")
if !isImgName(img) {
img = "pjw"
}
if req.FormValue("show") == "png" {
i := loadSize(ctxt, img, 48)
var buf bytes.Buffer
png.Encode(&buf, i)
w.Write(buf.Bytes())
return
}
if req.FormValue("flag") == "1" {
flag(w, req, img, ctxt)
return
}
if req.FormValue("x") == "" {
var data = struct {
Name string
URL string
}{
Name: img,
URL: url,
}
runTemplate(ctxt, w, "qr/main.html", &data)
return
}
arg := func(s string) int { x, _ := strconv.Atoi(req.FormValue(s)); return x }
targ := makeTarg(ctxt, img, 17+4*arg("v")+arg("z"))
m := &Image{
Name: img,
Dx: arg("x"),
Dy: arg("y"),
URL: req.FormValue("u"),
Version: arg("v"),
Mask: arg("m"),
RandControl: arg("r") > 0,
Dither: arg("i") > 0,
OnlyDataBits: arg("d") > 0,
SaveControl: arg("c") > 0,
Scale: arg("scale"),
Target: targ,
Seed: int64(arg("s")),
Rotation: arg("o"),
Size: arg("z"),
}
if m.Version > 8 {
m.Version = 8
}
if m.Scale == 0 {
if arg("l") > 1 {
m.Scale = 8
} else {
m.Scale = 4
}
}
if m.Version >= 12 && m.Scale >= 4 {
m.Scale /= 2
}
if arg("l") == 1 {
data, err := json.Marshal(m)
if err != nil {
panic(err)
}
h := md5.New()
h.Write(data)
tag := fmt.Sprintf("%x", h.Sum(nil))[:16]
if err := ctxt.Write("qrsave/"+tag, data); err != nil {
panic(err)
}
http.Redirect(w, req, "/qr/show/"+tag, http.StatusTemporaryRedirect)
return
}
if err := m.Encode(req); err != nil {
fmt.Fprintf(w, "%s\n", err)
return
}
var dat []byte
switch {
case m.SaveControl:
dat = m.Control
default:
dat = m.Code.PNG()
}
if arg("l") > 0 {
w.Header().Set("Content-Type", "image/png")
w.Write(dat)
return
}
w.Header().Set("Content-Type", "text/html; charset=utf-8")
fmt.Fprint(w, "<center><img src=\"data:image/png;base64,")
io.WriteString(w, base64.StdEncoding.EncodeToString(dat))
fmt.Fprint(w, "\" /><br>")
fmt.Fprintf(w, "<form method=\"POST\" action=\"%s&l=1\"><input type=\"submit\" value=\"Save this QR code\"></form>\n", m.Link())
fmt.Fprintf(w, "</center>\n")
fmt.Fprintf(w, "<br><center><font size=-1>%v</font></center>\n", time.Now().Sub(t0))
}
func makeImage(req *http.Request, caption, font string, pt, size, border, scale int, f func(x, y int) uint32) *image.RGBA {
d := (size + 2*border) * scale
csize := 0
if caption != "" {
if pt == 0 {
pt = 11
}
csize = pt * 2
}
c := image.NewRGBA(image.Rect(0, 0, d, d+csize))
// white
u := &image.Uniform{C: color.White}
draw.Draw(c, c.Bounds(), u, image.ZP, draw.Src)
for y := 0; y < size; y++ {
for x := 0; x < size; x++ {
r := image.Rect((x+border)*scale, (y+border)*scale, (x+border+1)*scale, (y+border+1)*scale)
rgba := f(x, y)
u.C = color.RGBA{byte(rgba >> 24), byte(rgba >> 16), byte(rgba >> 8), byte(rgba)}
draw.Draw(c, r, u, image.ZP, draw.Src)
}
}
if csize != 0 {
if font == "" {
font = "data/luxisr.ttf"
}
ctxt := fs.NewContext(req)
dat, _, err := ctxt.Read(font)
if err != nil {
panic(err)
}
tfont, err := freetype.ParseFont(dat)
if err != nil {
panic(err)
}
ft := freetype.NewContext()
ft.SetDst(c)
ft.SetDPI(100)
ft.SetFont(tfont)
ft.SetFontSize(float64(pt))
ft.SetSrc(image.NewUniform(color.Black))
ft.SetClip(image.Rect(0, 0, 0, 0))
wid, err := ft.DrawString(caption, freetype.Pt(0, 0))
if err != nil {
panic(err)
}
p := freetype.Pt(d, d+3*pt/2)
p.X -= wid.X
p.X /= 2
ft.SetClip(c.Bounds())
ft.DrawString(caption, p)
}
return c
}