// Package svg contains an SVG formatter.
package svg
import (
"encoding/base64"
"errors"
"fmt"
"io"
"io/ioutil"
"path"
"strings"
"github.com/alecthomas/chroma"
)
// Option sets an option of the SVG formatter.
type Option func(f *Formatter)
// FontFamily sets the font-family.
func FontFamily(fontFamily string) Option { return func(f *Formatter) { f.fontFamily = fontFamily } }
// EmbedFontFile embeds given font file
func EmbedFontFile(fontFamily string, fileName string) (option Option, err error) {
var format FontFormat
switch path.Ext(fileName) {
case ".woff":
format = WOFF
case ".woff2":
format = WOFF2
case ".ttf":
format = TRUETYPE
default:
return nil, errors.New("unexpected font file suffix")
}
var content []byte
if content, err = ioutil.ReadFile(fileName); err == nil {
option = EmbedFont(fontFamily, base64.StdEncoding.EncodeToString(content), format)
}
return
}
// EmbedFont embeds given base64 encoded font
func EmbedFont(fontFamily string, font string, format FontFormat) Option {
return func(f *Formatter) { f.fontFamily = fontFamily; f.embeddedFont = font; f.fontFormat = format }
}
// New SVG formatter.
func New(options ...Option) *Formatter {
f := &Formatter{fontFamily: "Consolas, Monaco, Lucida Console, Liberation Mono, DejaVu Sans Mono, Bitstream Vera Sans Mono, Courier New, monospace"}
for _, option := range options {
option(f)
}
return f
}
// Formatter that generates SVG.
type Formatter struct {
fontFamily string
embeddedFont string
fontFormat FontFormat
}
func (f *Formatter) Format(w io.Writer, style *chroma.Style, iterator chroma.Iterator) (err error) {
f.writeSVG(w, style, iterator.Tokens())
return err
}
var svgEscaper = strings.NewReplacer(
`&`, "&",
`<`, "<",
`>`, ">",
`"`, """,
` `, " ",
` `, " ",
)
// EscapeString escapes special characters.
func escapeString(s string) string {
return svgEscaper.Replace(s)
}
func (f *Formatter) writeSVG(w io.Writer, style *chroma.Style, tokens []chroma.Token) { // nolint: gocyclo
svgStyles := f.styleToSVG(style)
lines := chroma.SplitTokensIntoLines(tokens)
fmt.Fprint(w, "\n")
fmt.Fprint(w, "\n")
fmt.Fprintf(w, "\n")
}
func maxLineWidth(lines [][]chroma.Token) int {
maxWidth := 0
for _, tokens := range lines {
length := 0
for _, token := range tokens {
length += len(strings.Replace(token.String(), ` `, " ", -1))
}
if length > maxWidth {
maxWidth = length
}
}
return maxWidth
}
// There is no background attribute for text in SVG so simply calculate the position and text
// of tokens with a background color that differs from the default and add a rectangle for each before
// adding the token.
func (f *Formatter) writeTokenBackgrounds(w io.Writer, lines [][]chroma.Token, style *chroma.Style) {
for index, tokens := range lines {
lineLength := 0
for _, token := range tokens {
length := len(strings.Replace(token.String(), ` `, " ", -1))
tokenBackground := style.Get(token.Type).Background
if tokenBackground.IsSet() && tokenBackground != style.Get(chroma.Background).Background {
fmt.Fprintf(w, "\n", escapeString(token.String()), lineLength, 1.2*float64(index)+0.25, length, style.Get(token.Type).Background.String())
}
lineLength += length
}
}
}
type FontFormat int
// https://transfonter.org/formats
const (
WOFF FontFormat = iota
WOFF2
TRUETYPE
)
var fontFormats = [...]string{
"woff",
"woff2",
"truetype",
}
func (f *Formatter) writeFontStyle(w io.Writer) {
fmt.Fprintf(w, ``, f.fontFamily, fontFormats[f.fontFormat], f.embeddedFont, fontFormats[f.fontFormat])
}
func (f *Formatter) styleAttr(styles map[chroma.TokenType]string, tt chroma.TokenType) string {
if _, ok := styles[tt]; !ok {
tt = tt.SubCategory()
if _, ok := styles[tt]; !ok {
tt = tt.Category()
if _, ok := styles[tt]; !ok {
return ""
}
}
}
return styles[tt]
}
func (f *Formatter) styleToSVG(style *chroma.Style) map[chroma.TokenType]string {
converted := map[chroma.TokenType]string{}
bg := style.Get(chroma.Background)
// Convert the style.
for t := range chroma.StandardTypes {
entry := style.Get(t)
if t != chroma.Background {
entry = entry.Sub(bg)
}
if entry.IsZero() {
continue
}
converted[t] = StyleEntryToSVG(entry)
}
return converted
}
// StyleEntryToSVG converts a chroma.StyleEntry to SVG attributes.
func StyleEntryToSVG(e chroma.StyleEntry) string {
var styles []string
if e.Colour.IsSet() {
styles = append(styles, "fill=\""+e.Colour.String()+"\"")
}
if e.Bold == chroma.Yes {
styles = append(styles, "font-weight=\"bold\"")
}
if e.Italic == chroma.Yes {
styles = append(styles, "font-style=\"italic\"")
}
if e.Underline == chroma.Yes {
styles = append(styles, "text-decoration=\"underline\"")
}
return strings.Join(styles, " ")
}