svg lettericons

Makefile

@@ -7,6 +7,7 @@ test_all: build test test_bench
 test:
 	go test -v github.com/mat/besticon/ico
 	go test -v github.com/mat/besticon/besticon
+	go test -v github.com/mat/besticon/besticon/iconserver
 	go test -v github.com/mat/besticon/lettericon
 	go test -v github.com/mat/besticon/colorfinder
 

besticon/iconserver/server.go

@@ -104,7 +104,12 @@ func iconHandler(w http.ResponseWriter, r *http.Request) {
 		}
 	}
 
-	redirectPath := lettericon.IconPath(letter, fmt.Sprintf("%d", sizeRange.Perfect), iconColor)
+	// We support both PNG and SVG fallback. Only return SVG if requested.
+	format := "png"
+	if includesString(finder.FormatsAllowed, "svg") {
+		format = "svg"
+	}
+	redirectPath := lettericon.IconPath(letter, fmt.Sprintf("%d", sizeRange.Perfect), iconColor, format)
 	redirectWithCacheControl(w, r, redirectPath)
 }
 
@@ -155,15 +160,20 @@ func alliconsHandler(w http.ResponseWriter, r *http.Request) {
 }
 
 func lettericonHandler(w http.ResponseWriter, r *http.Request) {
-	charParam, col, size := lettericon.ParseIconPath(r.URL.Path)
-	if charParam == "" || col == nil || size <= 0 {
+	charParam, col, size, format := lettericon.ParseIconPath(r.URL.Path)
+	if charParam == "" || col == nil || size <= 0 || format == "" {
 		writeAPIError(w, 400, errors.New("wrong format for lettericons/ path, must look like lettericons/M-144-EFC25D.png"))
 		return
 	}
 
-	w.Header().Add(contentType, imagePNG)
+	if format == "svg" {
+		w.Header().Add(contentType, imageSVG)
+		lettericon.RenderSVG(charParam, col, w)
+	} else {
+		w.Header().Add(contentType, imagePNG)
+		lettericon.RenderPNG(charParam, col, size, w)
+	}
 	addCacheControl(w, oneYear)
-	lettericon.Render(charParam, col, size, w)
 }
 
 func writeAPIError(w http.ResponseWriter, httpStatus int, e error) {
@@ -198,6 +208,7 @@ const (
 	contentType     = "Content-Type"
 	applicationJSON = "application/json"
 	imagePNG        = "image/png"
+	imageSVG        = "image/svg+xml"
 )
 
 func renderJSONResponse(w http.ResponseWriter, httpStatus int, data interface{}) {
@@ -431,3 +442,12 @@ func getenvOrFallback(key string, fallbackValue string) string {
 	}
 	return fallbackValue
 }
+
+func includesString(arr []string, str string) bool {
+	for _, e := range arr {
+		if e == str {
+			return true
+		}
+	}
+	return false
+}

besticon/iconserver/server_test.go

@@ -136,6 +136,19 @@ func TestGet404IconWithInvalidFallbackColor(t *testing.T) {
 	assertStringEquals(t, "/lettericons/H-32.png", w.Header().Get("Location"))
 }
 
+func TestGetIconWithSVG(t *testing.T) {
+	req, err := http.NewRequest("GET", "/icons?size=32&url=httpbin.org/status/404&formats=svg", nil)
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	w := httptest.NewRecorder()
+	iconHandler(w, req)
+
+	assertStringEquals(t, "302", fmt.Sprintf("%d", w.Code))
+	assertStringEquals(t, "/lettericons/H.svg", w.Header().Get("Location"))
+}
+
 func TestGetAllIcons(t *testing.T) {
 	req, err := http.NewRequest("GET", "/allicons.json?url=apple.com", nil)
 	if err != nil {
@@ -173,7 +186,7 @@ func TestGetPopular(t *testing.T) {
 	assertStringContains(t, w.Body.String(), `github.com`)
 }
 
-func TestGetLetterIcon(t *testing.T) {
+func TestGetLetterIconPNG(t *testing.T) {
 	req, err := http.NewRequest("GET", "/lettericons/M-144-EFC25D.png", nil)
 	if err != nil {
 		t.Fatal(err)
@@ -188,6 +201,21 @@ func TestGetLetterIcon(t *testing.T) {
 	assertIntegerInInterval(t, 1500, 1800, w.Body.Len())
 }
 
+func TestGetLetterIconSVG(t *testing.T) {
+	req, err := http.NewRequest("GET", "/lettericons/M-144-EFC25D.svg", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	w := httptest.NewRecorder()
+	lettericonHandler(w, req)
+
+	assertStringEquals(t, "200", fmt.Sprintf("%d", w.Code))
+	assertStringEquals(t, "image/svg+xml", w.Header().Get("Content-Type"))
+	assertStringEquals(t, "max-age=31536000", w.Header().Get("Cache-Control"))
+	assertStringContains(t, w.Body.String(), `<svg`)
+}
+
 func TestGetBadLetterIconPath(t *testing.T) {
 	req, err := http.NewRequest("GET", "/lettericons/--120.png", nil)
 	if err != nil {

lettericon/lettericon.go

@@ -2,6 +2,8 @@ package lettericon
 
 import (
 	"bufio"
+	"bytes"
+	"encoding/xml"
 	"errors"
 	"fmt"
 	"image"
@@ -13,6 +15,7 @@ import (
 	"math"
 	"net/url"
 	"path"
+	"path/filepath"
 	"strconv"
 	"strings"
 
@@ -30,7 +33,7 @@ const dpi = 72
 const fontSizeFactor = 0.6180340     // (by taste)
 const yOffsetFactor = 102.0 / 1024.0 // (by trial and error) :-)
 
-func Render(letter string, bgColor color.Color, width int, out io.Writer) error {
+func RenderPNG(letter string, bgColor color.Color, width int, out io.Writer) error {
 	fg := pickForegroundColor(bgColor)
 
 	rgba := image.NewRGBA(image.Rect(0, 0, width, width))
@@ -179,32 +182,52 @@ func ColorFromHex(hex string) (*color.RGBA, error) {
 	return &col, nil
 }
 
-func IconPath(letter string, size string, colr *color.RGBA) string {
+func IconPath(letter string, size string, colr *color.RGBA, format string) string {
+	var parts []string
+
+	// letter
 	if letter == "" {
 		letter = " "
 	} else {
 		letter = strings.ToUpper(letter)
 	}
+	parts = append(parts, letter)
+
+	// size (maybe)
+	if format == "png" {
+		parts = append(parts, size)
+	}
 
+	// colr (maybe)
 	if colr != nil {
-		return fmt.Sprintf("/lettericons/%s-%s-%s.png", letter, size, colorfinder.ColorToHex(*colr))
+		parts = append(parts, colorfinder.ColorToHex(*colr))
 	}
-	return fmt.Sprintf("/lettericons/%s-%s.png", letter, size)
+
+	return fmt.Sprintf("/lettericons/%s.%s", strings.Join(parts, "-"), format)
 }
 
 const defaultIconSize = 144
+
 // TODO: Sync with besticon.MaxIconSize ?
 const maxIconSize = 256
 
 // path is like: lettericons/M-144-EFC25D.png
-func ParseIconPath(fullpath string) (string, *color.RGBA, int) {
+func ParseIconPath(fullpath string) (string, *color.RGBA, int, string) {
 	fullpath = percentDecode(fullpath)
 
 	_, filename := path.Split(fullpath)
-	filename = strings.TrimSuffix(filename, ".png")
+
+	// what is the format?
+	format := filepath.Ext(filename)
+	if !(format == ".png" || format == ".svg") {
+		return "", nil, -1, ""
+	}
+	filename = strings.TrimSuffix(filename, format)
+	format = format[1:] // remove period
+
 	params := strings.Split(filename, "-")
 	if len(params) < 1 || len(params[0]) < 1 {
-		return "", nil, -1
+		return "", nil, -1, ""
 	}
 
 	charParam := firstRune(params[0])
@@ -230,7 +253,7 @@ func ParseIconPath(fullpath string) (string, *color.RGBA, int) {
 		col = DefaultBackgroundColor
 	}
 
-	return charParam, col, size
+	return charParam, col, size, format
 }
 
 func MainLetterFromURL(URL string) string {
@@ -281,6 +304,45 @@ func percentDecode(p string) string {
 	return u.Path
 }
 
+const svgTemplate = `
+<svg width="100" height="100" xmlns="http://www.w3.org/2000/svg">
+  <rect x="0" y="0" width="100" height="100" fill="$BG_COLOR"/>
+  <text x="50%" y="50%" dy="0.10em" font-family="Helvetica Neue, Helvetica, sans-serif" font-size="75" dominant-baseline="middle" text-anchor="middle" fill="$FG_COLOR">$LETTER</text>
+</svg>
+`
+
+// RenderSVG writes an SVG lettericon for this letter and color
+func RenderSVG(letter string, bgColor color.Color, out io.Writer) error {
+	// xml escape letter
+	var buf bytes.Buffer
+	err := xml.EscapeText(&buf, []byte(letter))
+	if err != nil {
+		return err
+	}
+
+	// vars
+	vars := map[string]string{
+		"$BG_COLOR": ColorToHex(bgColor),
+		"$FG_COLOR": ColorToHex(pickForegroundColor(bgColor)),
+		"$LETTER":   buf.String(),
+	}
+
+	// render SVG by replacing vars in template
+	svg := strings.TrimSpace(svgTemplate) + "\n"
+	for k, v := range vars {
+		svg = strings.ReplaceAll(svg, k, v)
+	}
+
+	_, err = io.WriteString(out, svg)
+	return err
+}
+
+// ColorToHex returns the #rrggbb hex string for a color
+func ColorToHex(c color.Color) string {
+	r, g, b, _ := c.RGBA()
+	return fmt.Sprintf("#%02x%02x%02x", r&0xff, g&0xff, b&0xff)
+}
+
 var fnt *truetype.Font
 
 var DefaultBackgroundColor *color.RGBA

lettericon/lettericon/cmd.go

@@ -31,7 +31,7 @@ func main() {
 		os.Exit(1)
 	}
 
-	err = lettericon.Render(*letter, col, *width, f)
+	err = lettericon.RenderPNG(*letter, col, *width, f)
 	if err != nil {
 		os.Exit(1)
 	}