mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 16:25:49 +08:00
512 lines
15 KiB
Go
512 lines
15 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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"encoding/binary"
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"errors"
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"fmt"
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"math"
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"sync"
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"github.com/tdewolff/font"
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)
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// sfntOutliner 缓存字体程序并提取独立字形轮廓
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type sfntOutliner struct {
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font *font.SFNT
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once sync.Once
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program *ttInterpreter
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err error
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mu sync.Mutex
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warnings map[uint16]error
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}
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// ttGlyph 保存字形轮廓及四个度量虚拟点
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type ttGlyph struct {
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points []ttPoint
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ends []uint16
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metrics *[4]ttPoint
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warning error
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}
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// path 按TrueType指令和隐含点规则生成闭合轮廓，CFF保留原有解析
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// 入参: path 路径接收器, glyph 字形编号, scale 字体单位缩放
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// 返回: error 字形解析错误
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func (f *sfntOutliner) path(path font.Pather, glyph uint16, scale float64) error {
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if !f.font.IsTrueType {
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return f.font.GlyphPath(path, glyph, 0, 0, 0, scale, font.NoHinting)
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}
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contour, err := f.glyph(glyph, make(map[uint16]bool))
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if err != nil {
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return err
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}
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points := contour.points
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first := 0
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for _, endpoint := range contour.ends {
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last := int(endpoint)
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if last < first || last >= len(points)-4 {
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return fmt.Errorf("invalid TrueType contour endpoints")
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}
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if last == first {
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first = last + 1
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continue
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}
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point := func(i int) Point {
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return Point{X: float64(points[i].x) * scale / 64, Y: float64(points[i].y) * scale / 64}
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}
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start, end := point(first), point(last)
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begin, stop := first, last
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if points[first].on {
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begin++
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} else if points[last].on {
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start, stop = end, last-1
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} else {
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start = Point{X: (start.X + end.X) / 2, Y: (start.Y + end.Y) / 2}
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}
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path.MoveTo(start.X, start.Y)
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var control Point
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pending := false
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for i := begin; i <= stop; i++ {
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p := point(i)
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if points[i].on {
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if pending {
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path.QuadTo(control.X, control.Y, p.X, p.Y)
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} else {
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path.LineTo(p.X, p.Y)
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}
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pending = false
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} else {
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if pending {
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path.QuadTo(control.X, control.Y, (control.X+p.X)/2, (control.Y+p.Y)/2)
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}
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control, pending = p, true
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}
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}
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if pending {
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path.QuadTo(control.X, control.Y, start.X, start.Y)
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}
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path.Close()
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first = last + 1
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}
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return nil
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}
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// glyph 解码简单或复合字形并执行对应字节码，不改写字体资源
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// 入参: id 字形编号, active 递归访问集合
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// 返回: ttGlyph 字形轮廓, error 字形错误
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func (f *sfntOutliner) glyph(id uint16, active map[uint16]bool) (ttGlyph, error) {
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var result ttGlyph
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if id >= f.font.NumGlyphs() || active[id] {
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return result, fmt.Errorf("invalid TrueType component reference %d", id)
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}
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active[id] = true
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defer delete(active, id)
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data, err := trueTypeGlyphData(f.font.Tables, id)
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if err != nil {
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return result, err
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}
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if len(data) == 0 {
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data = make([]byte, 12)
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}
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if len(data) < 10 {
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return result, fmt.Errorf("truncated TrueType glyph %d", id)
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}
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n := int(int16(binary.BigEndian.Uint16(data)))
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phantoms := f.phantomPoints(id, data)
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var program []byte
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if n >= 0 {
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result, program, err = readTTSimple(data, n)
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} else {
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result, program, err = f.composite(id, data, phantoms, active)
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}
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if err != nil {
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return result, err
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}
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if result.warning != nil {
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f.recordGlyphWarning(id, result.warning)
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}
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if result.metrics != nil {
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result.points = append(result.points, result.metrics[:]...)
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} else {
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result.points = append(result.points, phantoms[:]...)
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}
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if len(program) == 0 {
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return result, nil
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}
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outlineOnly, err := ttOutlineOnly(f.font.Tables, program)
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if err != nil {
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return result, err
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}
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if outlineOnly {
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return result, nil
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}
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f.once.Do(func() { f.program, f.err = newTTInterpreter(f.font.Tables, f.font.UnitsPerEm()) })
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if f.err != nil {
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if ttRecoverableHint(f.err) {
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result.warning = f.err
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f.recordGlyphWarning(id, f.err)
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return result, nil
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}
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return result, f.err
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}
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if f.program.graphics.inhibit {
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return result, nil
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}
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vm := f.program.clone()
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vm.zones[1], vm.ends = append([]ttPoint(nil), result.points...), result.ends
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if err := vm.run(program); err != nil {
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if ttRecoverableHint(err) {
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result.warning = err
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f.recordGlyphWarning(id, err)
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return result, nil
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}
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return result, fmt.Errorf("TrueType glyph %d: %w", id, err)
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}
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result.points = vm.zones[1]
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return result, nil
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}
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// phantomPoints 按水平和垂直度量生成字形末尾的四个虚拟点
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// 入参: id 字形编号, data 完整字形头
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// 返回: [4]ttPoint 左右边距与上下原点
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func (f *sfntOutliner) phantomPoints(id uint16, data []byte) [4]ttPoint {
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left := int32(int16(binary.BigEndian.Uint16(data[2:]))) - int32(f.font.Hmtx.LeftSideBearing(id))
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top := int32(int16(binary.BigEndian.Uint16(data[8:])))
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if f.font.Vmtx != nil {
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top += int32(f.font.Vmtx.TopSideBearing(id))
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}
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return [4]ttPoint{{x: left * 64, ox: left * 64}, {x: (left + int32(f.font.GlyphAdvance(id))) * 64, ox: (left + int32(f.font.GlyphAdvance(id))) * 64}, {y: top * 64, oy: top * 64}, {y: (top - int32(f.font.GlyphVerticalAdvance(id))) * 64, oy: (top - int32(f.font.GlyphVerticalAdvance(id))) * 64}}
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}
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// ttRecoverableHint 判断栈参数、指令引用或控制流错误是否允许保留执行前轮廓
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// 入参: err 指令错误
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// 返回: bool 是否可恢复
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func ttRecoverableHint(err error) bool {
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return errors.Is(err, errTTStackUnderflow) || errors.Is(err, errTTInvalidReference) || errors.Is(err, errTTInvalidControlFlow)
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}
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// trueTypeGlyphData 按loca索引读取字形，拒绝倒序或越界的数据范围
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// 入参: tables 字体表, id 字形编号
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// 返回: []byte 字形数据, error 索引错误
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func trueTypeGlyphData(tables map[string][]byte, id uint16) ([]byte, error) {
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head, loca, glyf := tables["head"], tables["loca"], tables["glyf"]
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if len(head) < 52 {
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return nil, fmt.Errorf("truncated TrueType head")
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}
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var start, end uint64
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switch binary.BigEndian.Uint16(head[50:]) {
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case 0:
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offset := int(id) * 2
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if offset+4 > len(loca) {
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return nil, fmt.Errorf("truncated TrueType loca")
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}
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start, end = uint64(binary.BigEndian.Uint16(loca[offset:]))*2, uint64(binary.BigEndian.Uint16(loca[offset+2:]))*2
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case 1:
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offset := int(id) * 4
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if offset+8 > len(loca) {
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return nil, fmt.Errorf("truncated TrueType loca")
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}
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start, end = uint64(binary.BigEndian.Uint32(loca[offset:])), uint64(binary.BigEndian.Uint32(loca[offset+4:]))
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default:
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return nil, fmt.Errorf("invalid TrueType loca format")
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}
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if start > end || end > uint64(len(glyf)) {
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return nil, fmt.Errorf("invalid TrueType glyph %d range", id)
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}
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return glyf[start:end], nil
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}
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// recordGlyphWarning 记录字形恢复提示，允许并发提取轮廓
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// 入参: id 字形编号, warning 恢复原因
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func (f *sfntOutliner) recordGlyphWarning(id uint16, warning error) {
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f.mu.Lock()
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defer f.mu.Unlock()
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if f.warnings == nil {
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f.warnings = make(map[uint16]error)
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}
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f.warnings[id] = warning
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}
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// glyphWarning 返回字形恢复为执行前轮廓的原因
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// 入参: id 字形编号
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// 返回: error 恢复原因，无恢复时为空
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func (f *sfntOutliner) glyphWarning(id uint16) error {
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f.mu.Lock()
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defer f.mu.Unlock()
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return f.warnings[id]
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}
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// readTTSimple 读取简单字形的重复标志、差分坐标和字节码
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// 入参: data 字形数据, count 轮廓数
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// 返回: ttGlyph 字形轮廓, []byte 字节码, error 数据错误
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func readTTSimple(data []byte, count int) (ttGlyph, []byte, error) {
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var result ttGlyph
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if count == 0 && len(data) == 10 {
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return result, nil, nil
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}
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if len(data) < 12+2*count {
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return result, nil, fmt.Errorf("truncated TrueType contour endpoints")
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}
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pos := 10
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for i := 0; i < count; i++ {
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end := binary.BigEndian.Uint16(data[pos:])
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pos += 2
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if i > 0 && end <= result.ends[i-1] {
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return result, nil, fmt.Errorf("unordered TrueType contour endpoints")
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}
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result.ends = append(result.ends, end)
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}
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length := int(binary.BigEndian.Uint16(data[pos:]))
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pos += 2
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if length > len(data)-pos {
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return result, nil, fmt.Errorf("truncated TrueType glyph instructions")
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}
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program := data[pos : pos+length]
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pos += length
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points := 0
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if count > 0 {
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points = int(result.ends[count-1]) + 1
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}
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flags := make([]byte, 0, points)
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for len(flags) < points {
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if pos >= len(data) {
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return result, nil, fmt.Errorf("truncated TrueType point flags")
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}
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flag := data[pos]
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pos++
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repeat := 1
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if flag&8 != 0 {
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if pos >= len(data) {
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return result, nil, fmt.Errorf("truncated TrueType flag repeat")
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}
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repeat += int(data[pos])
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pos++
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}
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if repeat > points-len(flags) {
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return result, nil, fmt.Errorf("excessive TrueType flag repeat")
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}
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for i := 0; i < repeat; i++ {
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flags = append(flags, flag)
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}
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}
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result.points = make([]ttPoint, points)
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for axis := 0; axis < 2; axis++ {
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coordinate := int32(0)
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short, same := byte(2<<axis), byte(16<<axis)
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for i, flag := range flags {
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if flag&short != 0 {
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if pos >= len(data) {
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return result, nil, fmt.Errorf("truncated TrueType short coordinate")
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}
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delta := int32(data[pos])
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pos++
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if flag&same == 0 {
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delta = -delta
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}
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coordinate += delta
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} else if flag&same == 0 {
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if len(data)-pos < 2 {
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return result, nil, fmt.Errorf("truncated TrueType coordinate")
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}
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coordinate += int32(int16(binary.BigEndian.Uint16(data[pos:])))
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pos += 2
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}
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p := &result.points[i]
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p.on = flag&1 != 0
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if axis == 0 {
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p.x, p.ox = coordinate*64, coordinate*64
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} else {
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p.y, p.oy = coordinate*64, coordinate*64
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}
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}
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}
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return result, program, nil
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}
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// composite 合成分量变换和点匹配，保留分量顺序及父级字节码
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// 入参: glyph 父字形编号, data 复合字形数据, phantoms 父字形虚拟点, active 递归访问集合
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// 返回: ttGlyph 字形轮廓, []byte 字节码, error 数据错误
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func (f *sfntOutliner) composite(glyph uint16, data []byte, phantoms [4]ttPoint, active map[uint16]bool) (ttGlyph, []byte, error) {
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var result ttGlyph
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pos := 10
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total := -1
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first := true
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hasInstructions := false
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for {
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if len(data)-pos < 6 {
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return result, nil, fmt.Errorf("truncated TrueType component")
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}
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flags, id := binary.BigEndian.Uint16(data[pos:]), binary.BigEndian.Uint16(data[pos+2:])
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if first && flags&2 == 0 {
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return result, nil, fmt.Errorf("first TrueType component requires coordinate offsets")
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}
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first = false
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pos += 4
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a, b := int32(data[pos]), int32(data[pos+1])
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pos += 2
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if flags&1 != 0 {
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pos -= 2
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if len(data)-pos < 4 {
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return result, nil, fmt.Errorf("truncated TrueType component arguments")
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}
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a, b = int32(binary.BigEndian.Uint16(data[pos:])), int32(binary.BigEndian.Uint16(data[pos+2:]))
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pos += 4
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}
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if flags&2 != 0 {
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if flags&1 != 0 {
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a, b = int32(int16(a)), int32(int16(b))
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} else {
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a, b = int32(int8(a)), int32(int8(b))
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}
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}
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matrix := [4]float64{1, 0, 0, 1}
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indices := []int(nil)
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switch flags & 0xc8 {
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case 8:
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indices = []int{0}
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case 0x40:
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indices = []int{0, 3}
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case 0x80:
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indices = []int{0, 1, 2, 3}
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case 0:
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default:
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return result, nil, fmt.Errorf("conflicting TrueType component transforms")
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}
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for _, index := range indices {
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if len(data)-pos < 2 {
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return result, nil, fmt.Errorf("truncated TrueType component transform")
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}
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matrix[index] = float64(int16(binary.BigEndian.Uint16(data[pos:]))) / 16384
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pos += 2
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}
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if flags&8 != 0 {
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matrix[3] = matrix[0]
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}
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part, err := f.glyph(id, active)
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if err != nil {
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return result, nil, err
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}
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if part.warning != nil {
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result.warning = fmt.Errorf("TrueType component %d: %w", id, part.warning)
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}
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if flags&0x200 != 0 {
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if result.metrics == nil {
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result.metrics = new([4]ttPoint)
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}
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copy(result.metrics[:], part.points[len(part.points)-4:])
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}
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pointCount := len(part.points) - 4
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for i := range pointCount {
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p := &part.points[i]
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x, y := float64(p.x), float64(p.y)
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p.x = int32(math.Round(matrix[0]*x + matrix[2]*y))
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p.y = int32(math.Round(matrix[1]*x + matrix[3]*y))
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}
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dx, dy := a*64, b*64
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if flags&2 == 0 {
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if b < 0 || int64(b) >= int64(len(part.points)) {
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return result, nil, fmt.Errorf("invalid TrueType component point matching")
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}
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child := part.points[b]
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if int64(b) >= int64(pointCount) {
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x, y := float64(child.x), float64(child.y)
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child.x = int32(math.Round(matrix[0]*x + matrix[2]*y))
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child.y = int32(math.Round(matrix[1]*x + matrix[3]*y))
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}
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var parent ttPoint
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if a >= 0 && int64(a) < int64(len(result.points)) {
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parent = result.points[a]
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} else {
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if total < 0 {
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var err error
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total, err = trueTypePointCount(f.font.Tables, glyph, map[uint16]int{}, map[uint16]bool{})
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if err != nil {
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return result, nil, err
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}
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}
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if a < int32(total) || a >= int32(total)+4 {
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return result, nil, fmt.Errorf("invalid TrueType component point matching")
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}
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metrics := &phantoms
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if result.metrics != nil {
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metrics = result.metrics
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}
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parent = metrics[a-int32(total)]
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}
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dx, dy = parent.x-child.x, parent.y-child.y
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} else if flags&0x1800 == 0x800 {
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x, y := float64(dx), float64(dy)
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dx, dy = int32(math.Round(matrix[0]*x+matrix[2]*y)), int32(math.Round(matrix[1]*x+matrix[3]*y))
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}
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if flags&6 == 6 {
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dx, dy = int32(math.Round(float64(dx)/64))*64, int32(math.Round(float64(dy)/64))*64
|
|
}
|
|
part.points = part.points[:pointCount]
|
|
if len(result.points)+len(part.points) > 65536 {
|
|
return result, nil, fmt.Errorf("excessive TrueType component points")
|
|
}
|
|
for _, end := range part.ends {
|
|
result.ends = append(result.ends, uint16(len(result.points)+int(end)))
|
|
}
|
|
for i := range part.points {
|
|
p := &part.points[i]
|
|
p.x += dx
|
|
p.y += dy
|
|
p.ox, p.oy = p.x, p.y
|
|
p.tx, p.ty = false, false
|
|
}
|
|
result.points = append(result.points, part.points...)
|
|
hasInstructions = hasInstructions || flags&0x100 != 0
|
|
if flags&0x20 == 0 {
|
|
break
|
|
}
|
|
}
|
|
var program []byte
|
|
if hasInstructions {
|
|
if len(data)-pos < 2 {
|
|
return result, nil, fmt.Errorf("truncated TrueType composite instructions")
|
|
}
|
|
n := int(binary.BigEndian.Uint16(data[pos:]))
|
|
pos += 2
|
|
if n > len(data)-pos {
|
|
return result, nil, fmt.Errorf("truncated TrueType composite instructions")
|
|
}
|
|
program = data[pos : pos+n]
|
|
}
|
|
return result, program, nil
|
|
}
|
|
|
|
// ttOutlineOnly 识别已剥离提示表但仍引用字体函数或控制值的子集字形，使用设计轮廓
|
|
// 入参: tables 字体表, code 字形程序
|
|
// 返回: bool 是否只提取轮廓, error 字节码错误
|
|
func ttOutlineOnly(tables map[string][]byte, code []byte) (bool, error) {
|
|
if len(tables["fpgm"])+len(tables["prep"])+len(tables["cvt "]) != 0 {
|
|
return false, nil
|
|
}
|
|
for pc := 0; pc < len(code); {
|
|
op := code[pc]
|
|
if op == 0x2a || op == 0x2b || op == 0x3e || op == 0x3f || op == 0x44 || op == 0x45 || op == 0x70 || op >= 0x73 && op <= 0x75 || op >= 0xe0 {
|
|
return true, nil
|
|
}
|
|
var err error
|
|
pc, err = ttInstructionEnd(code, pc)
|
|
if err != nil {
|
|
return false, err
|
|
}
|
|
}
|
|
return false, nil
|
|
}
|