mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
98 lines
3.0 KiB
Go
98 lines
3.0 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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"fmt"
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"slices"
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"github.com/tdewolff/font"
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)
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// subsetFonts 收集新增字体实际使用的字形，仅裁剪保存结果，不修改编辑资源或原文档字体。
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// 返回: map[string][]byte 包内字体子集, error 错误信息
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func (e *Editor) subsetFonts() (map[string][]byte, error) {
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used := make(map[string]map[uint16]bool)
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for _, resource := range e.resources {
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if resource.font == nil {
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continue
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}
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sfnt := e.fonts[resource.font.ID]
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if sfnt.IsTrueType && !slices.ContainsFunc([]string{"fvar", "COLR", "CBDT", "sbix", "SVG "}, func(tag string) bool { return sfnt.Tables[tag] != nil }) {
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used[resource.font.ID] = make(map[uint16]bool)
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}
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}
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for _, page := range e.pages {
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for _, layer := range page.Content.Layer {
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for _, object := range layer.Objects {
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if object.Type != "TextObject" {
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continue
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}
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obj := object.TextObject
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glyphs := used[obj.Font]
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if glyphs == nil {
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continue
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}
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for _, code := range obj.TextCode {
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for _, char := range textCodeRunes(code.Value) {
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glyphs[e.fonts[obj.Font].GlyphIndex(char)] = true
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}
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}
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}
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}
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}
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result := make(map[string][]byte)
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for _, resource := range e.resources {
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if resource.font == nil || len(used[resource.font.ID]) == 0 {
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continue
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}
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glyphs := used[resource.font.ID]
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glyphs[0] = true
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ids := make([]uint16, 0, len(glyphs))
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for id := range glyphs {
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ids = append(ids, id)
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}
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slices.Sort(ids)
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data, err := subsetEditorFont(resource.data, ids)
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if err != nil {
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return nil, fmt.Errorf("subset font %s: %w", resource.font.FontName, err)
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}
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if len(data) < len(resource.data) {
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result[resource.name] = data
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}
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}
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return result, nil
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}
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// subsetEditorFont 裁剪TrueType字形及复合依赖，保留字符映射、名称、度量和提示指令。
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// 入参: data 字体数据, glyphs 已排序的字形编号，包含0
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// 返回: []byte 字体子集, error 错误信息
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func subsetEditorFont(data []byte, glyphs []uint16) ([]byte, error) {
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sfnt, err := font.ParseSFNT(bytes.Clone(data), 0)
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if err != nil {
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return nil, err
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}
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subset, err := sfnt.Subset(glyphs, font.SubsetOptions{Tables: []string{
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"cmap", "head", "hhea", "hmtx", "maxp", "OS/2", "post", "glyf", "loca", "cvt ", "fpgm", "prep", "gasp",
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}})
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if err != nil {
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return nil, err
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}
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subset.Tables["name"] = sfnt.Tables["name"]
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clear(subset.Tables["head"][8:12])
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return serializeOTF(subset.Tables)
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}
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