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font.go
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font.go
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package util
import (
"image"
"io/ioutil"
"os"
"strconv"
"strings"
"github.com/aarzilli/yacco/otat"
"github.com/golang/freetype"
"github.com/golang/freetype/truetype"
"golang.org/x/image/font"
"golang.org/x/image/math/fixed"
)
type Multiface struct {
faces []font.Face
lineextra float64
// cache for Kern
r0, r1 rune
idxr0, idxr1 int
Otatm *otat.Machine
}
func parseFontConfig(fontConfig string, defaultSize, defaultLineSpacing float64, defaultFullHinting, defaultAutoligatures bool) (fontv []string, size, lineSpacing float64, fullHinting, autoligatures bool) {
size = defaultSize
lineSpacing = defaultLineSpacing
fullHinting = defaultFullHinting
autoligatures = defaultAutoligatures
v := strings.Split(fontConfig, "@")
for _, param := range v[1:] {
vv := strings.SplitN(param, "=", 2)
if len(vv) != 2 {
continue
}
switch vv[0] {
case "Pixel":
x, err := strconv.ParseFloat(vv[1], 64)
if err == nil {
size = x
}
case "LineSpacing":
x, err := strconv.ParseFloat(vv[1], 64)
if err == nil {
lineSpacing = x
}
case "FullHinting":
switch vv[1] {
case "true":
fullHinting = true
case "false":
fullHinting = false
}
case "Autoligatures":
switch vv[1] {
case "true":
autoligatures = true
case "false":
autoligatures = false
}
}
}
fontv = strings.Split(v[0], ":")
return
}
// Reads a Font: fontPath is a ':' separated list of ttf or pcf font files (they will be used to search characters)
func NewFont(dpi, size, lineSpacing float64, fullHinting, autoligatures bool, fontPath string) (font.Face, error) {
fontPathV, size, lineSpacing, fullHinting, autoligatures := parseFontConfig(fontPath, size, lineSpacing, fullHinting, autoligatures)
fbs := make([][]byte, len(fontPathV))
for i, fontfile := range fontPathV {
fontBytes, err := ioutil.ReadFile(os.ExpandEnv(fontfile))
if err != nil {
return nil, err
}
fbs[i] = fontBytes
}
return NewFontFromBytes(dpi, size, lineSpacing, fullHinting, autoligatures, fbs)
}
func MustNewFont(dpi, size, lineSpacing float64, fullHinting, autoligatures bool, fontPath string) font.Face {
r, err := NewFont(dpi, size, lineSpacing, fullHinting, autoligatures, fontPath)
if err != nil {
panic(err)
}
return r
}
func NewFontFromBytes(dpi, size, lineSpacing float64, fullHinting, autoligatures bool, fontBytes [][]byte) (font.Face, error) {
rf := &Multiface{make([]font.Face, 0, len(fontBytes)), lineSpacing, 0, 0, -1, -1, nil}
for i, aFontBytes := range fontBytes {
parsedfont, err := freetype.ParseFont(aFontBytes)
if err != nil {
return nil, err
}
hinting := font.HintingNone
if fullHinting {
hinting = font.HintingFull
}
rf.faces = append(rf.faces, truetype.NewFace(parsedfont, &truetype.Options{Size: size, DPI: dpi, Hinting: hinting}))
if i == 0 {
rf.Otatm, _, err = otat.New(aFontBytes, "", "calt", autoligatures)
if err != nil {
return nil, err
}
}
}
return rf, nil
}
func MustNewFontFromBytes(dpi, size, lineSpacing float64, fullHinting, autoligatures bool, fontBytes [][]byte) font.Face {
f, err := NewFontFromBytes(dpi, size, lineSpacing, fullHinting, autoligatures, fontBytes)
if err != nil {
panic(err)
}
return f
}
func (f *Multiface) Close() error {
for i := range f.faces {
if err := f.faces[i].Close(); err != nil {
return err
}
}
return nil
}
func (f *Multiface) Glyph(dot fixed.Point26_6, r rune) (dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool) {
for i := range f.faces {
dr, mask, maskp, advance, ok = f.faces[i].Glyph(dot, r)
if ok {
return
}
}
return
}
func (f *Multiface) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
for i := range f.faces {
advance, ok = f.faces[i].GlyphAdvance(r)
if ok {
f.idxr0 = f.idxr1
f.r0 = f.r1
f.idxr1 = i
f.r1 = r
return
}
}
return
}
func (f *Multiface) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) {
for i := range f.faces {
bounds, advance, ok = f.faces[i].GlyphBounds(r)
if ok {
return
}
}
return
}
func (f *Multiface) findIndex(r rune) int {
for i := range f.faces {
_, ok := f.faces[i].GlyphAdvance(r)
if ok {
return i
}
}
return -1
}
func (f *Multiface) Kern(r0, r1 rune) fixed.Int26_6 {
idxr0 := -1
if r0 == f.r0 && f.idxr0 >= 0 {
idxr0 = f.idxr0
} else if r0 == f.r1 && f.idxr1 >= 0 {
idxr0 = f.idxr1
} else {
idxr0 = f.findIndex(r0)
}
idxr1 := -1
if r1 == f.r0 && f.idxr0 >= 0 {
idxr1 = f.idxr0
} else if r1 == f.r1 && f.idxr1 >= 0 {
idxr1 = f.idxr1
} else {
idxr1 = f.findIndex(r1)
}
if idxr0 < 0 || idxr1 < 0 || idxr0 != idxr1 {
return 0
}
return f.faces[idxr0].Kern(r0, r1)
}
func (f *Multiface) Metrics() font.Metrics {
m := f.faces[0].Metrics()
m.Height += FloatToFixed(f.lineextra)
return m
}
func FloatToFixed(x float64) fixed.Int26_6 {
n := int(x)
frac := int(0x3f * (x - float64(n)))
return fixed.Int26_6(n<<6 + frac)
}
// Mesures the length of the string
func MeasureString(face font.Face, in string) int {
d := font.Drawer{Face: face}
return d.MeasureString(in).Floor()
}