Add the genbasicfont program.
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Nigel Tao
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// Copyright 2016 The Freetype-Go Authors. All rights reserved.
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// Use of this source code is governed by your choice of either the
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// FreeType License or the GNU General Public License version 2 (or
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// any later version), both of which can be found in the LICENSE file.
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// +build example
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//
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// This build tag means that "go install github.com/golang/freetype/..."
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// doesn't install this example program. Use "go run main.go" to run it or "go
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// install -tags=example" to install it.
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// Program genbasicfont generates Go source code that imports
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// golang.org/x/image/font/basicfont to provide a fixed width font face.
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package main
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import (
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"bytes"
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"flag"
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"fmt"
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"go/format"
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"image"
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"image/draw"
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"io/ioutil"
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"log"
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"net/http"
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"strings"
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"unicode"
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"github.com/golang/freetype/truetype"
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"golang.org/x/image/font"
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"golang.org/x/image/math/fixed"
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)
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var (
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fontfile = flag.String("fontfile", "../../testdata/luxisr.ttf", "filename or URL of the TTF font")
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hinting = flag.String("hinting", "none", "none, vertical or full")
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pkg = flag.String("pkg", "example", "the package name for the generated code")
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size = flag.Float64("size", 12, "the number of pixels in 1 em")
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vr = flag.String("var", "example", "the variable name for the generated code")
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)
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func loadFontFile() ([]byte, error) {
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if strings.HasPrefix(*fontfile, "http://") || strings.HasPrefix(*fontfile, "https://") {
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resp, err := http.Get(*fontfile)
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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return ioutil.ReadAll(resp.Body)
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}
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return ioutil.ReadFile(*fontfile)
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}
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func parseHinting(h string) font.Hinting {
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switch h {
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case "full":
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return font.HintingFull
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case "vertical":
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log.Fatal("TODO: have package truetype implement vertical hinting")
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return font.HintingVertical
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}
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return font.HintingNone
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}
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func privateUseArea(r rune) bool {
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return 0xe000 <= r && r <= 0xf8ff ||
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0xf0000 <= r && r <= 0xffffd ||
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0x100000 <= r && r <= 0x10fffd
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}
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func loadRanges(f *truetype.Font) (ret [][2]rune) {
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rr := [2]rune{-1, -1}
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for r := rune(0); r <= unicode.MaxRune; r++ {
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if privateUseArea(r) {
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continue
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}
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if f.Index(r) == 0 {
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continue
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}
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if rr[1] == r {
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rr[1] = r + 1
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continue
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}
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if rr[0] != -1 {
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ret = append(ret, rr)
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}
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rr = [2]rune{r, r + 1}
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}
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if rr[0] != -1 {
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ret = append(ret, rr)
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}
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return ret
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}
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func emptyCol(m *image.Gray, r image.Rectangle, x int) bool {
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for y := r.Min.Y; y < r.Max.Y; y++ {
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if m.GrayAt(x, y).Y > 0 {
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return false
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}
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}
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return true
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}
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func emptyRow(m *image.Gray, r image.Rectangle, y int) bool {
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for x := r.Min.X; x < r.Max.X; x++ {
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if m.GrayAt(x, y).Y > 0 {
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return false
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}
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}
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return true
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}
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func tightBounds(m *image.Gray) (r image.Rectangle) {
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r = m.Bounds()
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for ; r.Min.Y < r.Max.Y && emptyRow(m, r, r.Min.Y+0); r.Min.Y++ {
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}
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for ; r.Min.Y < r.Max.Y && emptyRow(m, r, r.Max.Y-1); r.Max.Y-- {
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}
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for ; r.Min.X < r.Max.X && emptyCol(m, r, r.Min.X+0); r.Min.X++ {
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}
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for ; r.Min.X < r.Max.X && emptyCol(m, r, r.Max.X-1); r.Max.X-- {
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}
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return r
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}
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func printPix(ranges [][2]rune, glyphs map[rune]*image.Gray, b image.Rectangle) []byte {
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buf := new(bytes.Buffer)
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for _, rr := range ranges {
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for r := rr[0]; r < rr[1]; r++ {
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m := glyphs[r]
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fmt.Fprintf(buf, "// U+%08x '%c'\n", r, r)
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for y := b.Min.Y; y < b.Max.Y; y++ {
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for x := b.Min.X; x < b.Max.X; x++ {
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fmt.Fprintf(buf, "%#02x, ", m.GrayAt(x, y).Y)
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}
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fmt.Fprintln(buf)
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}
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fmt.Fprintln(buf)
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}
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}
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return buf.Bytes()
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}
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func printRanges(ranges [][2]rune) []byte {
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buf := new(bytes.Buffer)
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offset := 0
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for _, rr := range ranges {
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fmt.Fprintf(buf, "{'\\U%08x', '\\U%08x', %d},\n", rr[0], rr[1], offset)
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offset += int(rr[1] - rr[0])
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}
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return buf.Bytes()
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}
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func main() {
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flag.Parse()
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b, err := loadFontFile()
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if err != nil {
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log.Fatal(err)
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}
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f, err := truetype.Parse(b)
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if err != nil {
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log.Fatal(err)
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}
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face := truetype.NewFace(f, &truetype.Options{
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Size: *size,
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Hinting: parseHinting(*hinting),
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})
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defer face.Close()
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fBounds := f.Bounds(fixed.Int26_6(*size * 64))
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iBounds := image.Rect(
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+fBounds.Min.X.Floor(),
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-fBounds.Max.Y.Ceil(),
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+fBounds.Max.X.Ceil(),
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-fBounds.Min.Y.Floor(),
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)
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tBounds := image.Rectangle{}
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glyphs := map[rune]*image.Gray{}
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advance := fixed.Int26_6(-1)
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ranges := loadRanges(f)
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for _, rr := range ranges {
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for r := rr[0]; r < rr[1]; r++ {
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dr, mask, maskp, adv, ok := face.Glyph(fixed.Point26_6{}, r)
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if !ok {
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log.Fatalf("could not load glyph for %U", r)
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}
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if advance < 0 {
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advance = adv
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} else if advance != adv {
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log.Fatalf("advance was not constant: got %v and %v", advance, adv)
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}
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dst := image.NewGray(iBounds)
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draw.DrawMask(dst, dr, image.White, image.Point{}, mask, maskp, draw.Src)
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glyphs[r] = dst
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tBounds = tBounds.Union(tightBounds(dst))
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}
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}
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// height is the glyph image height, not the inter-line spacing.
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width, height := tBounds.Dx(), tBounds.Dy()
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buf := new(bytes.Buffer)
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fmt.Fprintf(buf, "// generated by go generate; DO NOT EDIT.\n\npackage %s\n\n", *pkg)
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fmt.Fprintf(buf, "import (\n\"image\"\n\n\"golang.org/x/image/font/basicfont\"\n)\n\n")
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fmt.Fprintf(buf, "// %s contains %d %d×%d glyphs in %d Pix bytes.\n",
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*vr, len(glyphs), width, height, len(glyphs)*width*height)
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fmt.Fprintf(buf, `var %s = basicfont.Face{
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Advance: %d,
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Width: %d,
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Height: %d,
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Ascent: %d,
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Descent: %d,
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Left: %d,
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Mask: &image.Alpha{
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Stride: %d,
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Rect: image.Rectangle{Max: image.Point{%d, %d*%d}},
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Pix: []byte{
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%s
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},
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},
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Ranges: []basicfont.Range{
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%s
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},
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}`, *vr, advance.Ceil(), width, face.Metrics().Height.Ceil(), -tBounds.Min.Y, +tBounds.Max.Y, tBounds.Min.X,
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width, width, len(glyphs), height,
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printPix(ranges, glyphs, tBounds), printRanges(ranges))
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fmted, err := format.Source(buf.Bytes())
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if err != nil {
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log.Fatalf("format.Source: %v", err)
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}
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if err := ioutil.WriteFile(*vr+".go", fmted, 0644); err != nil {
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log.Fatalf("ioutil.WriteFile: %v", err)
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}
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}
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