feat(字体处理): 修复符号字体缺字错字

ofdgo_font_symbol.go

@@ -0,0 +1,134 @@
+// 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 (
+	"context"
+	"encoding/binary"
+	"fmt"
+	"unicode/utf8"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// symbolFontProgram 为标准符号字体补齐Unicode映射，保留字形编号和轮廓
+// 入参: ctx 取消上下文, data 独立字体数据, name 标准字体名，为空时从字体名称表识别
+// 返回: []byte 字体数据, map[string]uint16 标准字形编号，不适用时为空, error 映射或取消错误
+func symbolFontProgram(ctx context.Context, data []byte, name string) ([]byte, map[string]uint16, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, nil, err
+	}
+	tables, err := fontFileTables(data, 0)
+	if err != nil {
+		return data, nil, nil
+	}
+	legacy := symbolFontCmap(tables["cmap"])
+	if name == "" && !legacy {
+		return data, nil, nil
+	}
+	actual := symbolFontName(tables["name"])
+	if name == "" {
+		name = actual
+	}
+	if name != "Symbol" && name != "ZapfDingbats" || !legacy && actual != name {
+		return data, nil, nil
+	}
+	standard, err := new(pdfgo.Reader).ReadFontContext(ctx, pdfgo.Dictionary{"Type": pdfgo.Name("Font"), "Subtype": pdfgo.Name("Type1"), "BaseFont": pdfgo.Name(name)})
+	if err != nil {
+		return nil, nil, err
+	}
+	codes := make([]byte, 256)
+	for index := range codes {
+		codes[index] = byte(index)
+	}
+	glyphs, err := standard.DecodeContext(ctx, codes)
+	if err != nil {
+		return nil, nil, err
+	}
+	original := parseCmapMappings(tables["cmap"])
+	mapping := make(map[rune]uint16)
+	names := make(map[string]uint16)
+	for _, glyph := range glyphs {
+		if glyph.Name == ".notdef" || glyph.Name == "" {
+			continue
+		}
+		char, size := utf8.DecodeRuneInString(glyph.Text)
+		var id uint16
+		if legacy {
+			id = original[rune(glyph.Code)]
+			for _, base := range [...]rune{0xf000, 0xf100, 0xf200} {
+				if candidate := original[base+rune(glyph.Code)]; candidate != 0 {
+					if id != 0 && id != candidate {
+						return nil, nil, fmt.Errorf("ambiguous symbol font mapping")
+					}
+					id = candidate
+				}
+			}
+		} else if size != 0 && size == len(glyph.Text) {
+			id = original[char]
+		}
+		if id == 0 {
+			continue
+		}
+		names[glyph.Name] = id
+		if size != 0 && size == len(glyph.Text) {
+			mapping[char] = id
+		}
+	}
+	if !legacy || len(mapping) == 0 {
+		return data, names, nil
+	}
+	tables["cmap"] = buildCmapTable(0, mapping)
+	program, err := serializeOTF(tables)
+	return program, names, err
+}
+
+// symbolFontName 从字体名称表识别标准符号字体，不依据文件名推断编码
+// 入参: data 名称表数据
+// 返回: string 标准字体名，无法识别时为空
+func symbolFontName(data []byte) string {
+	for _, name := range fontNamesFromTable(data) {
+		switch fontNormalizeName(name) {
+		case "symbol", "symbolmt", "symbolregular":
+			return "Symbol"
+		case "zapfdingbats", "zapfdingbatsregular", "itczapfdingbats":
+			return "ZapfDingbats"
+		}
+	}
+	return ""
+}
+
+// symbolFontCmap 识别不含Unicode字符表的Windows符号字体
+// 入参: data 字符映射表
+// 返回: bool 是否为旧式符号字体
+func symbolFontCmap(data []byte) bool {
+	if len(data) < 4 {
+		return false
+	}
+	count := int(binary.BigEndian.Uint16(data[2:]))
+	if count > (len(data)-4)/8 {
+		return false
+	}
+	symbol := false
+	for i := range count {
+		pos := 4 + i*8
+		platform, encoding := binary.BigEndian.Uint16(data[pos:]), binary.BigEndian.Uint16(data[pos+2:])
+		if platform == 0 || platform == 3 && (encoding == 1 || encoding == 10) {
+			return false
+		}
+		symbol = symbol || platform == 3 && encoding == 0
+	}
+	return symbol
+}