1// Copyright 2017 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package opentype
6
7import (
8	"image"
9
10	"golang.org/x/image/font"
11	"golang.org/x/image/font/sfnt"
12	"golang.org/x/image/math/fixed"
13)
14
15// FaceOptions describes the possible options given to NewFace when
16// creating a new font.Face from a sfnt.Font.
17type FaceOptions struct {
18	Size    float64      // Size is the font size in points
19	DPI     float64      // DPI is the dots per inch resolution
20	Hinting font.Hinting // Hinting selects how to quantize a vector font's glyph nodes
21}
22
23func defaultFaceOptions() *FaceOptions {
24	return &FaceOptions{
25		Size:    12,
26		DPI:     72,
27		Hinting: font.HintingNone,
28	}
29}
30
31// Face implements the font.Face interface for sfnt.Font values.
32type Face struct {
33	f       *sfnt.Font
34	hinting font.Hinting
35	scale   fixed.Int26_6
36
37	buf sfnt.Buffer
38}
39
40// NewFace returns a new font.Face for the given sfnt.Font.
41// if opts is nil, sensible defaults will be used.
42func NewFace(f *sfnt.Font, opts *FaceOptions) (font.Face, error) {
43	if opts == nil {
44		opts = defaultFaceOptions()
45	}
46	face := &Face{
47		f:       f,
48		hinting: opts.Hinting,
49		scale:   fixed.Int26_6(0.5 + (opts.Size * opts.DPI * 64 / 72)),
50	}
51	return face, nil
52}
53
54// Close satisfies the font.Face interface.
55func (f *Face) Close() error {
56	return nil
57}
58
59// Metrics satisfies the font.Face interface.
60func (f *Face) Metrics() font.Metrics {
61	m, err := f.f.Metrics(&f.buf, f.scale, f.hinting)
62	if err != nil {
63		return font.Metrics{}
64	}
65	return m
66}
67
68// Kern satisfies the font.Face interface.
69func (f *Face) Kern(r0, r1 rune) fixed.Int26_6 {
70	x0 := f.index(r0)
71	x1 := f.index(r1)
72	k, err := f.f.Kern(&f.buf, x0, x1, fixed.Int26_6(f.f.UnitsPerEm()), f.hinting)
73	if err != nil {
74		return 0
75	}
76	return k
77}
78
79// Glyph satisfies the font.Face interface.
80func (f *Face) Glyph(dot fixed.Point26_6, r rune) (dr image.Rectangle, mask image.Image, maskp image.Point, advance fixed.Int26_6, ok bool) {
81	panic("not implemented")
82}
83
84// GlyphBounds satisfies the font.Face interface.
85func (f *Face) GlyphBounds(r rune) (bounds fixed.Rectangle26_6, advance fixed.Int26_6, ok bool) {
86	advance, ok = f.GlyphAdvance(r)
87	if !ok {
88		return bounds, advance, ok
89	}
90	panic("not implemented")
91}
92
93// GlyphAdvance satisfies the font.Face interface.
94func (f *Face) GlyphAdvance(r rune) (advance fixed.Int26_6, ok bool) {
95	idx := f.index(r)
96	advance, err := f.f.GlyphAdvance(&f.buf, idx, f.scale, f.hinting)
97	return advance, err == nil
98}
99
100func (f *Face) index(r rune) sfnt.GlyphIndex {
101	x, _ := f.f.GlyphIndex(&f.buf, r)
102	return x
103}
104