mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-30 01:27:26 +08:00
301 lines
11 KiB
Go
301 lines
11 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ofdgo
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import (
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"bytes"
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"cmp"
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"fmt"
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"math"
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"slices"
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"strconv"
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"strings"
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"sync"
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"unicode"
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"unicode/utf8"
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typefont "github.com/go-text/typesetting/font"
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"github.com/go-text/typesetting/harfbuzz"
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"github.com/go-text/typesetting/language"
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ggtext "github.com/gogpu/gg/text"
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xlanguage "golang.org/x/text/language"
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)
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// ggFontMetrics 适配GG设计单位度量与字形轮廓，按需缓存可配置塑形器
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type ggFontMetrics struct {
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font ggtext.ParsedFont
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data []byte
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source *ggtext.FontSource
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shaper *ggtext.OwnShaper
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shapeMu sync.Mutex
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shapeFont *harfbuzz.Font
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shapeBuffer *harfbuzz.Buffer
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}
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// ResolveFont 使用公共字体来源匹配，不创建Canvas字体
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// 入参: r 渲染器, id 字体ID, exact 是否禁止无关回退
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// 返回: ResolvedFont 字体及来源, error 解析错误
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func (b GGBackend) ResolveFont(r *Renderer, id string, exact bool) (ResolvedFont, error) {
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return r.resolveFontSource(b, id, exact)
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}
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// OpenFont 通过GG解析独立字体，保留原始SFNT编码
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// 入参: data 字体数据
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// 返回: FontMetrics 字体度量, error 解析错误
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func (GGBackend) OpenFont(data []byte) (FontMetrics, error) {
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data = bytes.Clone(data)
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source, err := ggtext.NewFontSource(data)
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if err != nil {
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return nil, err
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}
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return &ggFontMetrics{font: source.Parsed(), data: data, source: source, shaper: ggtext.NewOwnShaper()}, nil
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}
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// ShapeText 使用GG执行横向字偶距与连字塑形，不改动原文定位
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// 当前支持拉丁、希腊、西里尔和东亚文字，复杂文字可通过ShapeTextWithOptions指定脚本与方向
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// 入参: value 单行原文, size 毫米字号
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// 返回: []ShapedGlyph 定位字形, error 字符或能力错误
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func (f *ggFontMetrics) ShapeText(value string, size float64) ([]ShapedGlyph, error) {
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if !rasterPositive(size) || !utf8.ValidString(value) {
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return nil, fmt.Errorf("invalid shaping text or size")
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}
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for _, char := range value {
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if unicode.IsControl(char) || char == '\u2028' || char == '\u2029' {
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return nil, fmt.Errorf("shaping requires a single text line")
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}
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if !unicode.In(char, unicode.Latin, unicode.Greek, unicode.Cyrillic, unicode.Han, unicode.Hiragana, unicode.Katakana, unicode.Hangul, unicode.Common, unicode.Inherited) {
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return nil, fmt.Errorf("GG shaping for U+%04X: %w", char, ErrBackendUnavailable)
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}
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}
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glyphs := f.shaper.Shape(value, f.source.Face(size))
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result := make([]ShapedGlyph, len(glyphs))
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for i, glyph := range glyphs {
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result[i] = ShapedGlyph{Glyph: uint16(glyph.GID), Cluster: glyph.Cluster, X: glyph.X, Y: -glyph.Y, Advance: glyph.XAdvance}
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}
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return result, nil
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}
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// ShapeTextWithOptions 使用现有纯Go塑形引擎处理单一方向原文，保留逻辑簇和视觉位置
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// 不执行混合方向分段，调用方应将双向段落拆为单向文字对象
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// 入参: value 单行原文, size 毫米字号, options 塑形选项
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// 返回: []ShapedGlyph 定位字形, error 字符或选项错误
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func (f *ggFontMetrics) ShapeTextWithOptions(value string, size float64, options TextShapeOptions) ([]ShapedGlyph, error) {
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if options == (TextShapeOptions{}) {
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return f.ShapeText(value, size)
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}
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if !rasterPositive(size) || !utf8.ValidString(value) {
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return nil, fmt.Errorf("invalid shaping text or size")
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}
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for _, char := range value {
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if unicode.IsControl(char) || char == '\u2028' || char == '\u2029' {
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return nil, fmt.Errorf("shaping requires a single text line")
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}
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}
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props := harfbuzz.SegmentProperties{Direction: harfbuzz.LeftToRight}
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switch options.Direction {
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case "", "ltr":
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case "rtl":
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props.Direction = harfbuzz.RightToLeft
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default:
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return nil, fmt.Errorf("shaping direction %q: %w", options.Direction, ErrBackendUnavailable)
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}
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if options.Script != "" {
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if len(options.Script) != 4 || strings.ContainsFunc(options.Script, func(c rune) bool { return c < 'A' || c > 'Z' && c < 'a' || c > 'z' }) {
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return nil, fmt.Errorf("invalid shaping script %q", options.Script)
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}
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props.Script, _ = language.ParseScript(options.Script)
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}
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if options.Language != "" {
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tag, err := xlanguage.Parse(options.Language)
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if err != nil {
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return nil, fmt.Errorf("shaping language: %w", err)
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}
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props.Language = language.NewLanguage(tag.String())
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}
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var features []harfbuzz.Feature
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if options.Features != "" {
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for _, setting := range strings.Split(options.Features, ",") {
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setting = strings.TrimSpace(setting)
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if strings.ContainsAny(setting, "[]") {
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return nil, fmt.Errorf("shaping feature ranges: %w", ErrBackendUnavailable)
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}
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tag, value, hasValue := strings.Cut(setting, "=")
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if len(tag) != 4 || strings.ContainsFunc(tag, func(c rune) bool { return c < '0' || c > '9' && c < 'A' || c > 'Z' && c < 'a' || c > 'z' }) {
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return nil, fmt.Errorf("invalid shaping feature %q", setting)
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}
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if hasValue {
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if _, err := strconv.ParseUint(value, 10, 32); err != nil {
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return nil, fmt.Errorf("shaping feature %q: %w", setting, err)
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}
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}
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feature, err := harfbuzz.ParseFeature(setting)
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if err != nil {
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return nil, fmt.Errorf("shaping feature %q: %w", setting, err)
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}
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if feature.Start != harfbuzz.FeatureGlobalStart || feature.End != harfbuzz.FeatureGlobalEnd {
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return nil, fmt.Errorf("shaping feature ranges: %w", ErrBackendUnavailable)
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}
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features = append(features, feature)
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}
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}
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f.shapeMu.Lock()
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defer f.shapeMu.Unlock()
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if f.shapeFont == nil {
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face, err := typefont.ParseTTF(bytes.NewReader(f.data))
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if err != nil {
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return nil, fmt.Errorf("shaping font: %w", err)
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}
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f.shapeFont = harfbuzz.NewFont(face)
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f.shapeBuffer = harfbuzz.NewBuffer()
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}
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buffer := f.shapeBuffer
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buffer.Clear()
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buffer.Props = props
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runes := []rune(value)
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buffer.AddRunes(runes, 0, len(runes))
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buffer.GuessSegmentProperties()
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buffer.Shape(f.shapeFont, features)
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unit := size / float64(f.UnitsPerEm())
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result := make([]ShapedGlyph, len(buffer.Info))
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var x, y float64
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for i, info := range buffer.Info {
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if info.Glyph >= typefont.GID(f.NumGlyphs()) {
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return nil, fmt.Errorf("invalid shaped glyph index %d", info.Glyph)
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}
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position := buffer.Pos[i]
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result[i] = ShapedGlyph{Glyph: uint16(info.Glyph), Cluster: info.Cluster,
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X: (x + float64(position.XOffset)) * unit, Y: -(y + float64(position.YOffset)) * unit,
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Advance: float64(position.XAdvance) * unit}
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if !finite(result[i].X) || !finite(result[i].Y) || !finite(result[i].Advance) {
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return nil, fmt.Errorf("shaped position exceeds finite range")
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}
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x += float64(position.XAdvance)
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y += float64(position.YAdvance)
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}
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slices.SortStableFunc(result, func(a, b ShapedGlyph) int { return cmp.Compare(a.Cluster, b.Cluster) })
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return result, nil
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}
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// UnitsPerEm 返回字体设计单位
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// 返回: uint16 每字单位数
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func (f *ggFontMetrics) UnitsPerEm() uint16 { return uint16(f.font.UnitsPerEm()) }
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// NumGlyphs 返回字形数量
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// 返回: uint16 字形数量
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func (f *ggFontMetrics) NumGlyphs() uint16 { return uint16(f.font.NumGlyphs()) }
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// GlyphIndex 返回字符对应的字形编号
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// 入参: character 字符
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// 返回: uint16 字形编号
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func (f *ggFontMetrics) GlyphIndex(character rune) uint16 { return f.font.GlyphIndex(character) }
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// GlyphAdvance 返回字形设计单位推进宽度
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// 入参: glyph 字形编号
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// 返回: uint16 推进宽度
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func (f *ggFontMetrics) GlyphAdvance(glyph uint16) uint16 {
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return uint16(math.Round(f.font.GlyphAdvance(glyph, float64(f.font.UnitsPerEm()))))
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}
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// VerticalMetrics 返回非负的上升、下降与行间隙
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// 返回: uint16 上升高度, uint16 下降高度, uint16 行间隙
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func (f *ggFontMetrics) VerticalMetrics() (uint16, uint16, uint16) {
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m := f.font.Metrics(float64(f.font.UnitsPerEm()))
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return uint16(math.Round(math.Max(0, m.Ascent))), uint16(math.Round(math.Max(0, -m.Descent))), uint16(math.Round(math.Max(0, m.LineGap)))
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}
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// Write 返回独立字体数据，不更新字体元信息
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// 返回: []byte SFNT数据
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func (f *ggFontMetrics) Write() []byte { return bytes.Clone(f.data) }
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// GlyphOutline 返回基线原点、纵轴向下的字形路径
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// 入参: glyph 字形编号, size 字号，单位为毫米
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// 返回: GeometryPath 字形路径, error 轮廓解析错误
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func (f *ggFontMetrics) GlyphOutline(glyph uint16, size float64) (GeometryPath, error) {
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if !rasterPositive(size) || int(glyph) >= f.font.NumGlyphs() {
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return nil, fmt.Errorf("invalid glyph or size")
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}
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outline, err := ggtext.NewOutlineExtractor().ExtractOutline(f.font, ggtext.GlyphID(glyph), size)
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if err != nil || outline == nil {
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return nil, err
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}
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return ggOutlinePath(outline)
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}
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// GlyphOutlines 按指定编号批量提取轮廓，重复字形只解析一次
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// 入参: glyphs 字形编号, size 毫米字号
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// 返回: []GeometryPath 同序只读轮廓, error 轮廓解析错误
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func (f *ggFontMetrics) GlyphOutlines(glyphs []uint16, size float64) ([]GeometryPath, error) {
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if !rasterPositive(size) {
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return nil, fmt.Errorf("invalid glyph size")
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}
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for _, glyph := range glyphs {
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if int(glyph) >= f.font.NumGlyphs() {
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return nil, fmt.Errorf("invalid glyph index %d", glyph)
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}
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}
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result := make([]GeometryPath, len(glyphs))
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paths := make(map[uint16]GeometryPath, len(glyphs))
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for i, glyph := range glyphs {
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path, ok := paths[glyph]
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if !ok {
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var err error
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path, err = f.GlyphOutline(glyph, size)
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if err != nil {
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return nil, err
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}
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paths[glyph] = path
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}
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result[i] = path
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}
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return result, nil
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}
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// ggOutlinePath 将GG轮廓转换为闭合的公共字形路径
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// 入参: outline GG字形轮廓
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// 返回: GeometryPath 公共路径, error 未知轮廓指令
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func ggOutlinePath(outline *ggtext.GlyphOutline) (GeometryPath, error) {
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capacity := len(outline.Segments)
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for _, segment := range outline.Segments {
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if segment.Op == ggtext.OutlineOpMoveTo {
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capacity++
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}
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}
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result := make(GeometryPath, 0, capacity)
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point := func(p ggtext.OutlinePoint) Point { return Point{X: float64(p.X), Y: float64(p.Y)} }
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for _, s := range outline.Segments {
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segment := GeometrySegment{End: point(s.Points[0])}
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switch s.Op {
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case ggtext.OutlineOpMoveTo:
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if len(result) > 0 {
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result = append(result, GeometrySegment{Verb: GeometryClose})
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}
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segment.Verb = GeometryMove
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case ggtext.OutlineOpLineTo:
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segment.Verb = GeometryLine
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case ggtext.OutlineOpQuadTo:
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segment.Verb, segment.Control1, segment.End = GeometryQuad, point(s.Points[0]), point(s.Points[1])
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case ggtext.OutlineOpCubicTo:
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segment.Verb, segment.Control1, segment.Control2, segment.End = GeometryCubic, point(s.Points[0]), point(s.Points[1]), point(s.Points[2])
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default:
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return nil, fmt.Errorf("unsupported GG outline command %d", s.Op)
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}
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result = append(result, segment)
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}
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if len(result) > 0 {
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result = append(result, GeometrySegment{Verb: GeometryClose})
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}
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return result, nil
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}
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