golang-image/font/opentype/face.go

104 lines
2.6 KiB
Go

// Copyright 2017 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.
package opentype
import (
"image"
"git.fireandbrimst.one/aw/golang-image/font"
"git.fireandbrimst.one/aw/golang-image/font/sfnt"
"git.fireandbrimst.one/aw/golang-image/math/fixed"
)
// FaceOptions describes the possible options given to NewFace when
// creating a new font.Face from a sfnt.Font.
type FaceOptions struct {
Size float64 // Size is the font size in points
DPI float64 // DPI is the dots per inch resolution
Hinting font.Hinting // Hinting selects how to quantize a vector font's glyph nodes
}
func defaultFaceOptions() *FaceOptions {
return &FaceOptions{
Size: 12,
DPI: 72,
Hinting: font.HintingNone,
}
}
// Face implements the font.Face interface for sfnt.Font values.
type Face struct {
f *sfnt.Font
hinting font.Hinting
scale fixed.Int26_6
buf sfnt.Buffer
}
// NewFace returns a new font.Face for the given sfnt.Font.
// if opts is nil, sensible defaults will be used.
func NewFace(f *sfnt.Font, opts *FaceOptions) (font.Face, error) {
if opts == nil {
opts = defaultFaceOptions()
}
face := &Face{
f: f,
hinting: opts.Hinting,
scale: fixed.Int26_6(0.5 + (opts.Size * opts.DPI * 64 / 72)),
}
return face, nil
}
// Close satisfies the font.Face interface.
func (f *Face) Close() error {
return nil
}
// Metrics satisfies the font.Face interface.
func (f *Face) Metrics() font.Metrics {
m, err := f.f.Metrics(&f.buf, f.scale, f.hinting)
if err != nil {
return font.Metrics{}
}
return m
}
// Kern satisfies the font.Face interface.
func (f *Face) Kern(r0, r1 rune) fixed.Int26_6 {
x0 := f.index(r0)
x1 := f.index(r1)
k, err := f.f.Kern(&f.buf, x0, x1, fixed.Int26_6(f.f.UnitsPerEm()), f.hinting)
if err != nil {
return 0
}
return k
}
// Glyph satisfies the font.Face interface.
func (f *Face) Glyph(dot fixed.Point26_6, r rune) (dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool) {
panic("not implemented")
}
// GlyphBounds satisfies the font.Face interface.
func (f *Face) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) {
advance, ok = f.GlyphAdvance(r)
if !ok {
return bounds, advance, ok
}
panic("not implemented")
}
// GlyphAdvance satisfies the font.Face interface.
func (f *Face) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
idx := f.index(r)
advance, err := f.f.GlyphAdvance(&f.buf, idx, f.scale, f.hinting)
return advance, err == nil
}
func (f *Face) index(r rune) sfnt.GlyphIndex {
x, _ := f.f.GlyphIndex(&f.buf, r)
return x
}