golang-image/colornames/gen.go
Nigel Tao 51ddfee6f3 colornames: export variables such as Darkred.
Change-Id: I1507d510ffa0ee3c899af652e0d1ab9d42a650d3
Reviewed-on: https://go-review.googlesource.com/23463
Reviewed-by: David Crawshaw <crawshaw@golang.org>
2016-05-27 00:36:51 +00:00

198 lines
5.7 KiB
Go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
// This program generates table.go from
// http://www.w3.org/TR/SVG/types.html#ColorKeywords
package main
import (
"bytes"
"fmt"
"go/format"
"image/color"
"io"
"io/ioutil"
"log"
"net/http"
"regexp"
"sort"
"strconv"
"strings"
"golang.org/x/net/html"
"golang.org/x/net/html/atom"
)
// matchFunc matches HTML nodes.
type matchFunc func(*html.Node) bool
// appendAll recursively traverses the parse tree rooted under the provided
// node and appends all nodes matched by the matchFunc to dst.
func appendAll(dst []*html.Node, n *html.Node, mf matchFunc) []*html.Node {
if mf(n) {
dst = append(dst, n)
}
for c := n.FirstChild; c != nil; c = c.NextSibling {
dst = appendAll(dst, c, mf)
}
return dst
}
// matchAtom returns a matchFunc that matches a Node with the specified Atom.
func matchAtom(a atom.Atom) matchFunc {
return func(n *html.Node) bool {
return n.DataAtom == a
}
}
// matchAtomAttr returns a matchFunc that matches a Node with the specified
// Atom and a html.Attribute's namespace, key and value.
func matchAtomAttr(a atom.Atom, namespace, key, value string) matchFunc {
return func(n *html.Node) bool {
return n.DataAtom == a && getAttr(n, namespace, key) == value
}
}
// getAttr fetches the value of a html.Attribute for a given namespace and key.
func getAttr(n *html.Node, namespace, key string) string {
for _, attr := range n.Attr {
if attr.Namespace == namespace && attr.Key == key {
return attr.Val
}
}
return ""
}
// re extracts RGB values from strings like "rgb( 0, 223, 128)".
var re = regexp.MustCompile(`rgb\(\s*([0-9]+),\s*([0-9]+),\s*([0-9]+)\)`)
// parseRGB parses a color from a string like "rgb( 0, 233, 128)". It sets
// the alpha value of the color to full opacity.
func parseRGB(s string) (color.RGBA, error) {
m := re.FindStringSubmatch(s)
if m == nil {
return color.RGBA{}, fmt.Errorf("malformed color: %q", s)
}
var rgb [3]uint8
for i, t := range m[1:] {
num, err := strconv.ParseUint(t, 10, 8)
if err != nil {
return color.RGBA{}, fmt.Errorf("malformed value %q in %q: %s", t, s, err)
}
rgb[i] = uint8(num)
}
return color.RGBA{rgb[0], rgb[1], rgb[2], 0xFF}, nil
}
// extractSVGColors extracts named colors from the parse tree of the SVG 1.1
// spec HTML document "Chapter 4: Basic data types and interfaces".
func extractSVGColors(tree *html.Node) (map[string]color.RGBA, error) {
ret := make(map[string]color.RGBA)
// Find the tables which store the color keywords in the parse tree.
colorTables := appendAll(nil, tree, func(n *html.Node) bool {
return n.DataAtom == atom.Table && strings.Contains(getAttr(n, "", "summary"), "color keywords part")
})
for _, table := range colorTables {
// Color names and values are stored in TextNodes within spans in each row.
for _, tr := range appendAll(nil, table, matchAtom(atom.Tr)) {
nameSpan := appendAll(nil, tr, matchAtomAttr(atom.Span, "", "class", "prop-value"))
valueSpan := appendAll(nil, tr, matchAtomAttr(atom.Span, "", "class", "color-keyword-value"))
// Since SVG 1.1 defines an odd number of colors, the last row
// in the second table does not have contents. We skip it.
if len(nameSpan) != 1 || len(valueSpan) != 1 {
continue
}
n, v := nameSpan[0].FirstChild, valueSpan[0].FirstChild
// This sanity checks for the existence of TextNodes under spans.
if n == nil || n.Type != html.TextNode || v == nil || v.Type != html.TextNode {
return nil, fmt.Errorf("extractSVGColors: couldn't find name/value text nodes")
}
val, err := parseRGB(v.Data)
if err != nil {
return nil, fmt.Errorf("extractSVGColors: couldn't parse name/value %q/%q: %s", n.Data, v.Data, err)
}
ret[n.Data] = val
}
}
return ret, nil
}
const preamble = `// generated by go generate; DO NOT EDIT.
package colornames
import "image/color"
`
// WriteColorNames writes table.go.
func writeColorNames(w io.Writer, m map[string]color.RGBA) {
keys := make([]string, 0, len(m))
for k := range m {
keys = append(keys, k)
}
sort.Strings(keys)
fmt.Fprintln(w, preamble)
fmt.Fprintln(w, "// Map contains named colors defined in the SVG 1.1 spec.")
fmt.Fprintln(w, "var Map = map[string]color.RGBA{")
for _, k := range keys {
c := m[k]
fmt.Fprintf(w, "%q:color.RGBA{%#02x, %#02x, %#02x, %#02x}, // rgb(%d, %d, %d)\n",
k, c.R, c.G, c.B, c.A, c.R, c.G, c.B)
}
fmt.Fprintln(w, "}\n")
fmt.Fprintln(w, "// Names contains the color names defined in the SVG 1.1 spec.")
fmt.Fprintln(w, "var Names = []string{")
for _, k := range keys {
fmt.Fprintf(w, "%q,\n", k)
}
fmt.Fprintln(w, "}\n")
fmt.Fprintln(w, "var (")
for _, k := range keys {
c := m[k]
// Make the upper case version of k: "Darkred" instead of "darkred".
k = string(k[0]-0x20) + k[1:]
fmt.Fprintf(w, "%s=color.RGBA{%#02x, %#02x, %#02x, %#02x} // rgb(%d, %d, %d)\n",
k, c.R, c.G, c.B, c.A, c.R, c.G, c.B)
}
fmt.Fprintln(w, ")")
}
const url = "http://www.w3.org/TR/SVG/types.html"
func main() {
res, err := http.Get(url)
if err != nil {
log.Fatalf("Couldn't read from %s: %s\n", url, err)
}
defer res.Body.Close()
tree, err := html.Parse(res.Body)
if err != nil {
log.Fatalf("Couldn't parse %s: %s\n", url, err)
}
colors, err := extractSVGColors(tree)
if err != nil {
log.Fatalf("Couldn't extract colors: %s\n", err)
}
buf := &bytes.Buffer{}
writeColorNames(buf, colors)
fmted, err := format.Source(buf.Bytes())
if err != nil {
log.Fatalf("Error while formatting code: %s\n", err)
}
if err := ioutil.WriteFile("table.go", fmted, 0644); err != nil {
log.Fatalf("Error writing table.go: %s\n", err)
}
}