mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
206 lines
7.2 KiB
Go
206 lines
7.2 KiB
Go
// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
|
|
//
|
|
// Licensed under the Apache License, Version 2.0 (the "License");
|
|
// you may not use this file except in compliance with the License.
|
|
// You may obtain a copy of the License at
|
|
//
|
|
// http://www.apache.org/licenses/LICENSE-2.0
|
|
//
|
|
// Unless required by applicable law or agreed to in writing, software
|
|
// distributed under the License is distributed on an "AS IS" BASIS,
|
|
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
// See the License for the specific language governing permissions and
|
|
// limitations under the License.
|
|
|
|
package ofdgo
|
|
|
|
import (
|
|
"bytes"
|
|
"encoding/binary"
|
|
"fmt"
|
|
"math"
|
|
|
|
"github.com/go-text/typesetting/font/cff"
|
|
"github.com/go-text/typesetting/font/opentype"
|
|
"github.com/go-text/typesetting/font/opentype/tables"
|
|
)
|
|
|
|
// defaultCFF2Font 将CFF2默认实例转换为静态OpenType字体，保留字形编号和三次轮廓
|
|
// 入参: data 独立字体数据
|
|
// 返回: []byte 字体数据，非CFF2原样返回, error 解析或编码错误
|
|
func defaultCFF2Font(data []byte) (result []byte, err error) {
|
|
if len(data) < 12 || string(data[:4]) != "OTTO" {
|
|
return data, nil
|
|
}
|
|
found := false
|
|
for i, count := 0, int(binary.BigEndian.Uint16(data[4:])); i < count && i < (len(data)-12)/16; i++ {
|
|
if string(data[12+i*16:16+i*16]) == "CFF2" {
|
|
found = true
|
|
break
|
|
}
|
|
}
|
|
if !found {
|
|
return data, nil
|
|
}
|
|
table, err := fontFileTables(data, 0)
|
|
if err != nil || table["CFF2"] == nil {
|
|
return data, err
|
|
}
|
|
if table["CFF "] != nil || table["glyf"] != nil || len(table["head"]) < 54 || len(table["maxp"]) < 6 || len(table["hhea"]) < 36 {
|
|
return nil, fmt.Errorf("invalid CFF2 font tables")
|
|
}
|
|
defer func() {
|
|
if failure := recover(); failure != nil {
|
|
result, err = nil, fmt.Errorf("invalid CFF2 font: %v", failure)
|
|
}
|
|
}()
|
|
cffData := table["CFF2"]
|
|
if len(cffData) < 5 || cffData[0] != 2 || cffData[1] != 0 || cffData[2] < 5 || binary.BigEndian.Uint32(table["maxp"]) != 0x5000 {
|
|
return nil, fmt.Errorf("invalid CFF2 header")
|
|
}
|
|
start := int(cffData[2])
|
|
end := start + int(binary.BigEndian.Uint16(cffData[3:]))
|
|
if end > len(cffData) {
|
|
return nil, fmt.Errorf("invalid CFF2 dictionary length")
|
|
}
|
|
dict, err := readCFFDictionary(cffData[start:end], true)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
matrix, err := readCFFMatrix(dict, [6]float64{.001, 0, 0, .001, 0, 0})
|
|
units := binary.BigEndian.Uint16(table["head"][18:])
|
|
if err != nil || units < 16 || units > 16384 || matrix[0] != matrix[3] || matrix[1] != 0 || matrix[2] != 0 || matrix[4] != 0 || matrix[5] != 0 || math.Abs(matrix[0]*float64(units)-1) > 1e-6 {
|
|
return nil, fmt.Errorf("CFF2 FontMatrix does not match design units")
|
|
}
|
|
program, err := cff.ParseCFF2(table["CFF2"])
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
if len(dict[24]) != 0 {
|
|
fvar := table["fvar"]
|
|
if len(fvar) < 16 || binary.BigEndian.Uint32(fvar) != 0x10000 || int(binary.BigEndian.Uint16(fvar[8:])) != program.VarStore.AxisCount() {
|
|
return nil, fmt.Errorf("CFF2 variation axis count mismatch")
|
|
}
|
|
}
|
|
count := int(binary.BigEndian.Uint16(table["maxp"][4:]))
|
|
metrics := int(binary.BigEndian.Uint16(table["hhea"][34:]))
|
|
if count == 0 || len(program.Charstrings) != count || metrics == 0 || metrics > count || len(table["hmtx"]) < metrics*4+(count-metrics)*2 {
|
|
return nil, fmt.Errorf("invalid CFF2 glyph metrics")
|
|
}
|
|
chars := make([][]byte, count)
|
|
for gid := range chars {
|
|
segments, _, err := program.LoadGlyph(tables.GlyphID(gid), nil)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("CFF2 glyph %d: %w", gid, err)
|
|
}
|
|
width := binary.BigEndian.Uint16(table["hmtx"][min(gid, metrics-1)*4:])
|
|
chars[gid], err = cffOutlineProgram(segments, width)
|
|
if err != nil {
|
|
return nil, fmt.Errorf("CFF2 glyph %d: %w", gid, err)
|
|
}
|
|
}
|
|
table["CFF "], err = staticCIDFont(table, chars)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
for _, tag := range []string{"CFF2", "fvar", "avar", "STAT", "HVAR", "VVAR", "MVAR", "DSIG"} {
|
|
delete(table, tag)
|
|
}
|
|
return serializeOTF(table)
|
|
}
|
|
|
|
// cffOutlineProgram 将默认设计轮廓编码为无子程序的Type2字形
|
|
// 入参: segments 字体设计坐标路径, width 水平字宽
|
|
// 返回: []byte 字形程序, error 坐标超出编码范围
|
|
func cffOutlineProgram(segments []opentype.Segment, width uint16) ([]byte, error) {
|
|
var output bytes.Buffer
|
|
if width < 32768 {
|
|
if err := encodeType2Number(&output, float64(width)); err != nil {
|
|
return nil, err
|
|
}
|
|
} else {
|
|
for range 2 {
|
|
if err := encodeType2Number(&output, float64(width)/2); err != nil {
|
|
return nil, err
|
|
}
|
|
}
|
|
output.Write([]byte{12, 10})
|
|
}
|
|
var x, y float64
|
|
for _, segment := range segments {
|
|
count, op := 1, byte(21)
|
|
switch segment.Op {
|
|
case opentype.SegmentOpMoveTo:
|
|
case opentype.SegmentOpLineTo:
|
|
op = 5
|
|
case opentype.SegmentOpCubeTo:
|
|
count, op = 3, 8
|
|
default:
|
|
return nil, fmt.Errorf("invalid CFF2 path operation")
|
|
}
|
|
for _, point := range segment.Args[:count] {
|
|
nx, ny := float64(point.X), float64(point.Y)
|
|
if err := encodeType2Number(&output, nx-x); err != nil {
|
|
return nil, err
|
|
}
|
|
if err := encodeType2Number(&output, ny-y); err != nil {
|
|
return nil, err
|
|
}
|
|
x, y = nx, ny
|
|
}
|
|
output.WriteByte(op)
|
|
}
|
|
output.WriteByte(14)
|
|
return output.Bytes(), nil
|
|
}
|
|
|
|
// staticCIDFont 封装独立Type2字形，CID与字形编号一致，不依赖字形名称
|
|
// 入参: table OpenType表, chars 字形程序
|
|
// 返回: []byte CFF字体, error 字体结构错误
|
|
func staticCIDFont(table map[string][]byte, chars [][]byte) ([]byte, error) {
|
|
if len(chars) == 0 || len(chars) > 65535 || len(table["head"]) < 54 {
|
|
return nil, fmt.Errorf("invalid static CFF glyph count")
|
|
}
|
|
units := binary.BigEndian.Uint16(table["head"][18:])
|
|
if units < 16 || units > 16384 {
|
|
return nil, fmt.Errorf("invalid CFF design units")
|
|
}
|
|
name := fontFaceInfo(table["name"], 0).PostScriptName
|
|
if name == "" {
|
|
name = "OpenTypeInstance"
|
|
}
|
|
names := encodeCFFIndex([][]byte{[]byte(name)})
|
|
strings := encodeCFFIndex([][]byte{[]byte("Adobe"), []byte("Identity")})
|
|
cids := make([]int, len(chars))
|
|
for gid := 1; gid < len(chars); gid++ {
|
|
cids[gid] = gid
|
|
}
|
|
charset := encodeCFFSubsetCharset(cids)
|
|
selects := []byte{3, 0, 1, 0, 0, 0}
|
|
selects = binary.BigEndian.AppendUint16(selects, uint16(len(chars)))
|
|
fonts := encodeCFFIndex([][]byte{encodeCFFDict(cffDict{18: {0, 0}})})
|
|
charIndex := encodeCFFIndex(chars)
|
|
scale := 1 / float64(units)
|
|
dict := cffDict{1230: {391, 392, 0}, 1234: {float64(len(chars))}, 1207: {scale, 0, 0, scale, 0, 0}, 15: {0}, 17: {0}, 1236: {0}, 1237: {0}}
|
|
for i := 0; i < 4; i++ {
|
|
dict[5] = append(dict[5], float64(int16(binary.BigEndian.Uint16(table["head"][36+2*i:]))))
|
|
}
|
|
var top []byte
|
|
for range 16 {
|
|
top = encodeCFFIndex([][]byte{encodeCFFDict(dict)})
|
|
offset := 4 + len(names) + len(top) + len(strings) + 2
|
|
if dict[15][0] == float64(offset) {
|
|
var output bytes.Buffer
|
|
for _, part := range [][]byte{{1, 0, 4, 4}, names, top, strings, {0, 0}, charset, selects, fonts, charIndex} {
|
|
output.Write(part)
|
|
}
|
|
return output.Bytes(), nil
|
|
}
|
|
dict[15][0] = float64(offset)
|
|
dict[1237][0] = float64(offset + len(charset))
|
|
dict[1236][0] = float64(offset + len(charset) + len(selects))
|
|
dict[17][0] = float64(offset + len(charset) + len(selects) + len(fonts))
|
|
}
|
|
return nil, fmt.Errorf("CFF offsets did not converge")
|
|
}
|