Import existing source code

idicon.go

@@ -0,0 +1,138 @@
+package main
+
+import (
+	"crypto/md5"
+	"encoding/hex"
+	"github.com/gorilla/mux"
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"log"
+	"net/http"
+	"os"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+func colorV1(hash [16]byte) color.RGBA {
+	r := 32 + (hash[0]%16)/2<<4
+	g := 32 + (hash[2]%16)/2<<4
+	b := 32 + (hash[len(hash)-1]%16)/2<<4
+
+	if r > g && r > b {
+		r += 48
+	} else if g > r && g > b {
+		g += 48
+	} else if b > r && b > g {
+		b += 48
+	}
+	return color.RGBA{r, g, b, 255}
+}
+
+func colorV2(hash [16]byte) color.RGBA {
+	var palette = []color.RGBA{
+		{0x3c, 0x38, 0x36, 0xff},
+		{0xcc, 0x24, 0x1d, 0xff},
+		{0x98, 0x97, 0x1a, 0xff},
+		{0xd7, 0x99, 0x21, 0xff},
+		{0x45, 0x85, 0x88, 0xff},
+		{0xb1, 0x62, 0x86, 0xff},
+		{0x68, 0x9d, 0x6a, 0xff},
+		{0xa8, 0x99, 0x84, 0xff},
+	}
+	return palette[hash[15]%8]
+}
+
+func genIdIcon(id string, size int, f func([16]byte) color.RGBA) *image.NRGBA {
+	id = strings.ToLower(id)
+	blocks := 5
+	if size > 512 {
+		size = 512
+	}
+
+	hash := hashBytes(id)
+	data := make([]bool, blocks*blocks)
+	for i := 0; i < len(hash)-1; i++ {
+		data[i] = hash[i]%2 != hash[i+1]%2
+	}
+	return drawImage(mirrorData(data, blocks), blocks, size, f(hash))
+}
+
+func hashBytes(id string) [16]byte {
+	hash := [16]byte{}
+	md5RegExp := regexp.MustCompile("[a-f0-9]{32}")
+	if !md5RegExp.Match([]byte(id)) {
+		hash = md5.Sum([]byte(id))
+	} else {
+		dec, _ := hex.DecodeString(id)
+		for idx, b := range dec {
+			hash[idx] = b
+		}
+	}
+	return hash
+}
+
+func mirrorData(data []bool, blocks int) []bool {
+	for x := 0; x < blocks; x++ {
+		min := x*blocks + 1
+		for y := 0; y < blocks; y++ {
+			a := ((blocks - x - 1) * blocks) + y
+			b := min + y - 1
+			if data[a] {
+				data[b] = true
+			}
+		}
+	}
+	return data
+}
+
+func drawImage(data []bool, blocks int, size int, c color.Color) *image.NRGBA {
+	img := image.NewNRGBA(image.Rect(0, 0, size, size))
+
+	draw.Draw(img, img.Bounds(), &image.Uniform{color.Gray{240}}, image.Point{0, 0}, draw.Src)
+
+	blockSize := size / (blocks + 1)
+	border := (size - (blocks * blockSize)) / 2
+
+	for x := border; x < blockSize*blocks+border; x++ {
+		bx := (x - border) / blockSize
+		for y := border; y < blockSize*blocks+border; y++ {
+			by := (y - border) / blockSize
+			idx := bx*blocks + by
+			if data[idx] && (bx < blocks || by < blocks) {
+				img.Set(x, y, c)
+			}
+		}
+	}
+
+	return img
+}
+
+func RequestHandler(w http.ResponseWriter, r *http.Request) {
+	id := mux.Vars(r)["id"]
+
+	size, err := strconv.Atoi(r.URL.Query().Get("s"))
+	if err != nil {
+		size = 80
+	}
+
+	colorScheme := r.URL.Query().Get("c")
+	if colorScheme == "" {
+		colorScheme = os.Getenv("COLORSCHEME")
+	}
+
+	w.Header().Add("Content-Type", "image/png")
+	if colorScheme == "v1" {
+		err = png.Encode(w, genIdIcon(id, size, colorV1))
+	} else {
+		err = png.Encode(w, genIdIcon(id, size, colorV2))
+	}
+}
+
+func main() {
+	router := mux.NewRouter()
+	router.HandleFunc("/avatar/{id}", RequestHandler)
+	log.Fatal(http.ListenAndServe(":8000", router))
+}