Initial version

.gitignore

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+badge-gen
+gin-bin

assets/badgeTemplate.tpl

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+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" width="{{ .Width }}" height="20">
+   <linearGradient id="b" x2="0" y2="100%">
+      <stop offset="0" stop-color="#bbb" stop-opacity=".1" />
+      <stop offset="1" stop-opacity=".1" />
+   </linearGradient>
+   <mask id="a">
+      <rect width="{{ .Width }}" height="20" rx="3" fill="#fff" />
+   </mask>
+   <g mask="url(#a)">
+      <path fill="#555"    d="M0  0 h{{ .TitleWidth }}  v20 H0  z" />
+      <path fill="#4c1"    d="M{{ .TitleWidth }} 0 H{{ .Width }}  v20 H{{ .TitleWidth }} z" />
+      <path fill="url(#b)" d="M0  0 h{{ .Width }} v20 H0  z" />
+   </g>
+   <g fill="#fff" text-anchor="middle" font-family="DejaVu Sans,Verdana,Geneva,sans-serif" font-size="11">
+      <text x="{{ .TitleAnchor }}" y="15" fill="#010101" fill-opacity=".3">{{ .Title }}</text>
+      <text x="{{ .TitleAnchor }}" y="14">{{ .Title }}</text>
+      <text x="{{ .TextAnchor }}" y="15" fill="#010101" fill-opacity=".3">{{ .Text }}</text>
+      <text x="{{ .TextAnchor }}" y="14">{{ .Text }}</text>
+   </g>
+</svg>

font.go

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+// Some of this code (namely the code for computing the
+// width of a string in a given font) was copied from
+// code.google.com/p/freetype-go/freetype/ which includes
+// the following copyright notice:
+// Copyright 2010 The Freetype-Go Authors. All rights reserved.
+package main
+
+import "code.google.com/p/freetype-go/freetype/truetype"
+
+const (
+	fontSize = 11
+)
+
+func calculateTextWidth(text string) (int, error) {
+	binFont, _ := Asset("assets/DejaVuSans.ttf")
+	font, err := truetype.Parse(binFont)
+	if err != nil {
+		return 0, err
+	}
+
+	scale := fontSize / float64(font.FUnitsPerEm())
+
+	width := 0
+	prev, hasPrev := truetype.Index(0), false
+	for _, rune := range text {
+		index := font.Index(rune)
+		if hasPrev {
+			width += int(font.Kerning(font.FUnitsPerEm(), prev, index))
+		}
+		width += int(font.HMetric(font.FUnitsPerEm(), index).AdvanceWidth)
+		prev, hasPrev = index, true
+	}
+
+	return int(float64(width) * scale), nil
+}

main.go

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+package main
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/alecthomas/template"
+	"github.com/gorilla/mux"
+)
+
+const (
+	xSpacing = 8
+)
+
+func main() {
+	port := fmt.Sprintf(":%s", os.Getenv("PORT"))
+	if port == ":" {
+		port = ":3000"
+	}
+
+	r := mux.NewRouter()
+	r.HandleFunc("/v1/badge", generateBadge).Methods("GET")
+
+	http.Handle("/", r)
+	http.ListenAndServe(port, nil)
+}
+
+func generateBadge(res http.ResponseWriter, r *http.Request) {
+	title := r.URL.Query().Get("title")
+	text := r.URL.Query().Get("text")
+
+	if title == "" || text == "" {
+		http.Error(res, "You must specify parameters 'title' and 'text'.", http.StatusInternalServerError)
+		return
+	}
+
+	badge := createBadge(title, text)
+
+	res.Header().Add("Content-Type", "image/svg+xml")
+	res.Header().Add("Cache-Control", "public, max-age=31536000")
+	res.Write(badge)
+}
+
+func createBadge(title, text string) []byte {
+	var buf bytes.Buffer
+	bufw := bufio.NewWriter(&buf)
+
+	titleW, _ := calculateTextWidth(title)
+	textW, _ := calculateTextWidth(text)
+
+	width := titleW + textW + 4*xSpacing
+
+	t, _ := Asset("assets/badgeTemplate.tpl")
+	tpl, _ := template.New("svg").Parse(string(t))
+
+	tpl.Execute(bufw, map[string]interface{}{
+		"Width":       width,
+		"TitleWidth":  titleW + 2*xSpacing,
+		"Title":       title,
+		"Text":        text,
+		"TitleAnchor": titleW/2 + xSpacing,
+		"TextAnchor":  titleW + textW/2 + 3*xSpacing,
+	})
+
+	bufw.Flush()
+	return buf.Bytes()
+}