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// 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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"crypto/rand"
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"crypto/sha256"
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"encoding/hex"
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"encoding/xml"
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"fmt"
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"image"
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"math"
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"strconv"
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"strings"
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"time"
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"unicode/utf8"
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"github.com/tdewolff/font"
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)
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// Editor 新建OFD文档，长度单位为毫米，页面索引从0开始，实例需串行使用
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// Info可修改文档元数据，页面和资源通过方法添加，不修改已有OFD文件
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type Editor struct {
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Info DocInfo
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pages []PageContent
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resources []editorResource
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fonts map[string]*font.SFNT
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images map[string]bool
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resourceID map[editorResourceKey]string
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maxID int
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}
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// editorResource 文档内嵌资源
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type editorResource struct {
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name string
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data []byte
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font *Font
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image *MultiMedia
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}
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// editorResourceKey 资源内容和字体集合索引
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type editorResourceKey struct {
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checksum [32]byte
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index int
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}
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// NewEditor 创建空白文档，保存前至少添加一页
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// 返回: *Editor 文档编辑器
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func NewEditor() *Editor {
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var id [16]byte
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rand.Read(id[:])
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id[6] = id[6]&0x0f | 0x40
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id[8] = id[8]&0x3f | 0x80
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return &Editor{
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Info: DocInfo{
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DocID: hex.EncodeToString(id[:]),
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CreationDate: time.Now().Format("2006-01-02"),
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},
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fonts: make(map[string]*font.SFNT),
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images: make(map[string]bool),
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resourceID: make(map[editorResourceKey]string),
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}
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}
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// AddPage 添加页面及默认正文图层
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// 入参: width 页面宽度, height 页面高度
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// 返回: int 页面索引, error 错误信息
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func (e *Editor) AddPage(width, height float64) (int, error) {
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if !finite(width) || !finite(height) || width <= 0 || height <= 0 {
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return 0, fmt.Errorf("page dimensions must be finite and positive")
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}
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e.pages = append(e.pages, PageContent{
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ID: e.nextID(),
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Area: PageArea{PhysicalBox: fmt.Sprintf("0 0 %s %s", ofdNumber(width), ofdNumber(height))},
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Content: Content{Layer: []Layer{{ID: e.nextID(), Type: "Body"}}},
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})
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return len(e.pages) - 1, nil
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}
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// nextID 分配文档内唯一标识
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// 返回: string 对象标识
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func (e *Editor) nextID() string {
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e.maxID++
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return strconv.Itoa(e.maxID)
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}
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// AddFont 嵌入OpenType字体，集合字体按索引提取，重复资源复用标识
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// 入参: file 字体文件, index 集合内字体索引，单字体为0
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// 返回: string 字体资源标识, error 错误信息
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func (e *Editor) AddFont(file FontFile, index int) (string, error) {
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if index < 0 {
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return "", fmt.Errorf("font index must not be negative")
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}
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data, err := font.ToSFNT(file.Data)
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if err != nil {
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return "", err
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}
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key := editorResourceKey{checksum: sha256.Sum256(data), index: index}
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if id, ok := e.resourceID[key]; ok {
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return id, nil
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}
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if bytes.HasPrefix(data, []byte("ttcf")) {
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data, err = extractCollectionFont(data, index)
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if err != nil {
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return "", err
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}
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index = 0
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} else {
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data = bytes.Clone(data)
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}
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sfnt, err := font.ParseSFNT(data, index)
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if err != nil {
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return "", err
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}
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name := editorFontName(sfnt, font.NamePostScript, font.NameFull, font.NameFontFamily)
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if name == "" {
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return "", fmt.Errorf("font has no name")
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}
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id := e.nextID()
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extension := ".ttf"
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if sfnt.IsCFF {
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extension = ".otf"
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}
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resource := editorResource{
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name: "Doc_0/Res/Font_" + id + extension,
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data: data,
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font: &Font{
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ID: id, FontName: name,
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FamilyName: editorFontName(sfnt, font.NamePreferredFamily, font.NameFontFamily),
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Charset: "unicode",
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Bold: sfnt.Head.MacStyle[0],
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Italic: sfnt.Head.MacStyle[1],
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FixedWidth: sfnt.Post.IsFixedPitch != 0,
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},
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}
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resource.font.FontFile = strings.TrimPrefix(resource.name, "Doc_0/Res/")
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e.resources = append(e.resources, resource)
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e.fonts[id] = sfnt
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e.resourceID[key] = id
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return id, nil
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}
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// editorFontName 获取字体中的名称
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// 入参: sfnt 字体, names 名称类型，按顺序查找
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// 返回: string 字体名称
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func editorFontName(sfnt *font.SFNT, names ...font.NameID) string {
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for _, name := range names {
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for _, record := range sfnt.Name.Get(name) {
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if value := record.String(); value != "" {
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return value
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}
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}
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}
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return ""
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}
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// AddImage 嵌入PNG或JPEG图片，保留原始编码，重复资源复用标识
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// 入参: data 图片数据
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// 返回: string 图片资源标识, error 错误信息
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func (e *Editor) AddImage(data []byte) (string, error) {
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config, format, err := image.DecodeConfig(bytes.NewReader(data))
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if err != nil {
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return "", err
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}
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if (format != "png" && format != "jpeg") || config.Width <= 0 || config.Height <= 0 {
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return "", fmt.Errorf("only PNG and JPEG images are supported")
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}
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key := editorResourceKey{checksum: sha256.Sum256(data), index: -1}
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if id, ok := e.resourceID[key]; ok {
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return id, nil
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}
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id := e.nextID()
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extension := format
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if extension == "jpeg" {
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extension = "jpg"
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}
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name := "Image_" + id + "." + extension
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e.resources = append(e.resources, editorResource{
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name: "Doc_0/Res/" + name,
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data: bytes.Clone(data),
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image: &MultiMedia{ID: id, Type: "Image", Format: strings.ToUpper(format), MediaFile: name},
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})
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e.images[id] = true
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e.resourceID[key] = id
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return id, nil
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}
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// AddObject 按添加顺序放入正文图层，支持文字、路径和图片，自动分配对象ID
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// 首版支持基本颜色和直接资源引用，不支持动作、裁剪、渐变及复合图元
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// 入参: page 页面索引, object 对象内容，添加后不再引用调用方的可变数据
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// 返回: string 对象标识, error 错误信息
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func (e *Editor) AddObject(page int, object GraphicObject) (string, error) {
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if page < 0 || page >= len(e.pages) {
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return "", fmt.Errorf("page index %d out of range", page)
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}
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id := strconv.Itoa(e.maxID + 1)
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var boundary, ctm, drawParam, join string
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var alpha *int
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var clips *Clips
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var actions []Action
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var fill, stroke *FillColor
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switch object.Type {
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case "TextObject":
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obj := &object.TextObject
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if err := e.prepareText(obj); err != nil {
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return "", err
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}
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obj.ID = id
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boundary, ctm, drawParam = obj.Boundary, obj.CTM, obj.DrawParam
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join = obj.Join
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alpha, clips, actions = obj.Alpha, obj.Clips, obj.Actions
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fill, stroke = obj.FillColor, (*FillColor)(obj.StrokeColor)
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case "PathObject":
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obj := &object.PathObject
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if err := creationPath(obj.AbbreviatedData); err != nil {
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return "", err
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}
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if obj.Rule != "" && obj.Rule != "NonZero" && obj.Rule != "Even-Odd" {
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return "", fmt.Errorf("invalid fill rule %q", obj.Rule)
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}
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if !finite(obj.LineWidth) || obj.LineWidth < 0 || !finite(obj.MiterLimit) || obj.MiterLimit < 0 {
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return "", fmt.Errorf("invalid path stroke dimensions")
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}
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if obj.Cap != "" && obj.Cap != "Butt" && obj.Cap != "Round" && obj.Cap != "Square" {
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return "", fmt.Errorf("invalid line cap %q", obj.Cap)
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}
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if obj.DashOffset != nil && !finite(*obj.DashOffset) {
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return "", fmt.Errorf("invalid dash offset")
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}
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if obj.DashPattern != "" {
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values, err := creationNumbers(obj.DashPattern, len(strings.Fields(obj.DashPattern)))
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if err != nil {
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return "", err
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}
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total := 0.0
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for _, value := range values {
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if value < 0 {
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return "", fmt.Errorf("dash lengths must not be negative")
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}
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total += value
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}
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if total == 0 {
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return "", fmt.Errorf("dash pattern must have a positive length")
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}
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}
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obj.ID = id
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boundary, ctm, drawParam = obj.Boundary, obj.CTM, obj.DrawParam
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join = obj.Join
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alpha, clips, actions = obj.Alpha, obj.Clips, obj.Actions
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fill, stroke = obj.FillColor, (*FillColor)(obj.StrokeColor)
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case "ImageObject":
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obj := &object.ImageObject
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if !e.images[obj.ResourceID] || (obj.ImageMask != "" && !e.images[obj.ImageMask]) {
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return "", fmt.Errorf("image resource not found")
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}
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if obj.Border != nil {
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return "", fmt.Errorf("image borders are not supported for creation")
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}
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obj.ID = id
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boundary, ctm = obj.Boundary, obj.CTM
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alpha, clips, actions = obj.Alpha, obj.Clips, obj.Actions
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default:
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return "", fmt.Errorf("unsupported object type %q", object.Type)
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}
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box, err := creationBox(boundary)
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if err != nil {
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return "", err
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}
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if ctm != "" {
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if _, err := creationNumbers(ctm, 6); err != nil {
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return "", fmt.Errorf("invalid CTM: %w", err)
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}
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} else if object.Type == "ImageObject" {
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object.ImageObject.CTM = fmt.Sprintf("%s 0 0 %s 0 0", ofdNumber(box.W), ofdNumber(box.H))
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}
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if drawParam != "" || clips != nil || len(actions) != 0 {
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return "", fmt.Errorf("draw parameter references, clips and actions are not supported for creation")
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}
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if alpha != nil && (*alpha < 0 || *alpha > 255) {
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return "", fmt.Errorf("alpha must be between 0 and 255")
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}
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for _, color := range []*FillColor{fill, stroke} {
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if err := creationColor(color); err != nil {
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return "", err
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}
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}
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if join != "" && join != "Miter" && join != "Round" && join != "Bevel" {
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return "", fmt.Errorf("invalid line join %q", join)
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}
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data, err := objectXML(object)
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if err != nil {
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return "", err
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}
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object = GraphicObject{Type: object.Type}
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var target any
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switch object.Type {
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case "TextObject":
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target = &object.TextObject
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case "PathObject":
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target = &object.PathObject
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case "ImageObject":
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target = &object.ImageObject
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}
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if err := xml.Unmarshal(data, target); err != nil {
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return "", err
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}
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e.maxID++
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e.pages[page].Content.Layer[0].Objects = append(e.pages[page].Content.Layer[0].Objects, object)
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return id, nil
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}
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// AddText 添加单行文字，使用嵌入字体的字宽定位，不进行段落排版和复杂文字塑形
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// 入参: page 页面索引, box 文字边界, value 原文, fontID 字体资源标识, size 字号
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// 返回: string 对象标识, error 错误信息
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func (e *Editor) AddText(page int, box Box, value, fontID string, size float64) (string, error) {
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sfnt, ok := e.fonts[fontID]
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if !ok {
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return "", fmt.Errorf("font resource %q not found", fontID)
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}
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if !utf8.ValidString(value) || strings.ContainsAny(value, "\r\n\t") || value == "" {
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return "", fmt.Errorf("text must be a nonempty UTF-8 line")
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}
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runes := []rune(value)
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deltas := make([]string, 0, len(runes)-1)
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for i, char := range runes {
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glyph := sfnt.GlyphIndex(char)
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if glyph == 0 {
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return "", fmt.Errorf("font does not contain U+%04X", char)
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}
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if i+1 < len(runes) {
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deltas = append(deltas, ofdNumber(float64(sfnt.GlyphAdvance(glyph))*size/float64(sfnt.UnitsPerEm())))
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}
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}
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ascender, _, _ := sfnt.VerticalMetrics()
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return e.AddObject(page, GraphicObject{Type: "TextObject", TextObject: TextObject{
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Boundary: fmt.Sprintf("%s %s %s %s", ofdNumber(box.X), ofdNumber(box.Y), ofdNumber(box.W), ofdNumber(box.H)),
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Font: fontID, Size: size,
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TextCode: []TextCode{{X: "0", Y: ofdNumber(float64(ascender) * size / float64(sfnt.UnitsPerEm())), DeltaX: strings.Join(deltas, " "), Value: escapeOFDText(value)}},
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}})
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}
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// prepareText 校验并补全标准文字定位，避免依赖阅读器的缺省字距补偿
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// 入参: obj 文字对象
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// 返回: error 错误信息
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func (e *Editor) prepareText(obj *TextObject) error {
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if e.fonts[obj.Font] == nil || !finite(obj.Size) || obj.Size <= 0 {
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return fmt.Errorf("text requires an embedded font and a positive finite size")
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}
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if len(obj.TextCode) == 0 {
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return fmt.Errorf("text codes are empty")
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}
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if obj.VScale != 0 || obj.Decoration != "" || len(obj.CGTransform) != 0 {
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return fmt.Errorf("text extensions and glyph transforms are not supported for creation")
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}
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if !finite(obj.HScale) || obj.HScale < 0 || !finite(obj.LineWidth) || obj.LineWidth < 0 || !finite(obj.MiterLimit) || obj.MiterLimit < 0 {
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return fmt.Errorf("invalid text dimensions")
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}
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if obj.Weight < 0 || obj.Weight > 900 || obj.Weight%100 != 0 {
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return fmt.Errorf("invalid text weight")
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}
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for _, direction := range []int{obj.ReadDirection, obj.CharDirection} {
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if direction != 0 && direction != 90 && direction != 180 && direction != 270 {
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||||
return fmt.Errorf("invalid text direction %d", direction)
|
||||
}
|
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}
|
||||
obj.TextCode = append([]TextCode(nil), obj.TextCode...)
|
||||
x, y := "", ""
|
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for i := range obj.TextCode {
|
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code := &obj.TextCode[i]
|
||||
if code.Index != "" || !utf8.ValidString(code.Value) {
|
||||
return fmt.Errorf("text requires Unicode character data")
|
||||
}
|
||||
if code.X != "" {
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x = code.X
|
||||
}
|
||||
if code.Y != "" {
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||||
y = code.Y
|
||||
}
|
||||
for _, coordinate := range []string{x, y} {
|
||||
if _, err := creationNumbers(coordinate, 1); err != nil {
|
||||
return fmt.Errorf("invalid text origin: %w", err)
|
||||
}
|
||||
}
|
||||
code.X, code.Y = x, y
|
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runes := textCodeRunes(code.Value)
|
||||
if len(runes) == 0 {
|
||||
return fmt.Errorf("text code is empty")
|
||||
}
|
||||
for _, char := range runes {
|
||||
if e.fonts[obj.Font].GlyphIndex(char) == 0 {
|
||||
return fmt.Errorf("font does not contain U+%04X", char)
|
||||
}
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||||
}
|
||||
for _, delta := range []string{code.DeltaX, code.DeltaY} {
|
||||
if delta != "" {
|
||||
if err := creationDeltas(delta, len(runes)-1); err != nil {
|
||||
return fmt.Errorf("invalid text delta: %w", err)
|
||||
}
|
||||
}
|
||||
}
|
||||
if len(runes) > 1 && code.DeltaX == "" && code.DeltaY == "" {
|
||||
code.DeltaX = strings.TrimSpace(strings.Repeat("0 ", len(runes)-1))
|
||||
}
|
||||
code.Value = escapeOFDText(string(runes))
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// creationDeltas 校验文字位移数组及g重复编码
|
||||
// 入参: value 位移数组, count 所需位移数量
|
||||
// 返回: error 错误信息
|
||||
func creationDeltas(value string, count int) error {
|
||||
fields := strings.Fields(value)
|
||||
numbers := 0
|
||||
for i := 0; i < len(fields); i++ {
|
||||
repeat := 1
|
||||
if fields[i] == "g" {
|
||||
if i+2 >= len(fields) {
|
||||
return fmt.Errorf("incomplete delta repetition")
|
||||
}
|
||||
var err error
|
||||
repeat, err = strconv.Atoi(fields[i+1])
|
||||
if err != nil || repeat <= 0 {
|
||||
return fmt.Errorf("invalid delta repetition")
|
||||
}
|
||||
i += 2
|
||||
}
|
||||
if _, err := creationNumbers(fields[i], 1); err != nil {
|
||||
return err
|
||||
}
|
||||
if repeat > count-numbers {
|
||||
return fmt.Errorf("too many text deltas")
|
||||
}
|
||||
numbers += repeat
|
||||
}
|
||||
if numbers != count {
|
||||
return fmt.Errorf("expected %d text deltas", count)
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// creationPath 校验紧缩路径的命令及有限数值参数
|
||||
// 入参: value 路径数据
|
||||
// 返回: error 错误信息
|
||||
func creationPath(value string) error {
|
||||
tokens := strings.Fields(value)
|
||||
if len(tokens) == 0 || (tokens[0] != "M" && tokens[0] != "S") {
|
||||
return fmt.Errorf("path must start with M or S")
|
||||
}
|
||||
for i := 0; i < len(tokens); {
|
||||
command := tokens[i]
|
||||
i++
|
||||
count := 0
|
||||
switch command {
|
||||
case "M", "S", "L":
|
||||
count = 2
|
||||
case "Q":
|
||||
count = 4
|
||||
case "B":
|
||||
count = 6
|
||||
case "A":
|
||||
count = 7
|
||||
case "C":
|
||||
default:
|
||||
return fmt.Errorf("invalid path command %q", command)
|
||||
}
|
||||
if len(tokens)-i < count {
|
||||
return fmt.Errorf("missing arguments for path command %s", command)
|
||||
}
|
||||
values, err := creationNumbers(strings.Join(tokens[i:i+count], " "), count)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
if command == "A" && (values[0] < 0 || values[1] < 0 || (values[3] != 0 && values[3] != 1) || (values[4] != 0 && values[4] != 1)) {
|
||||
return fmt.Errorf("invalid arc radii or flags")
|
||||
}
|
||||
i += count
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// creationNumbers 解析创建接口的有限十进制数值序列
|
||||
// 入参: value 数值序列, count 数值数量
|
||||
// 返回: []float64 数值, error 错误信息
|
||||
func creationNumbers(value string, count int) ([]float64, error) {
|
||||
fields := strings.Fields(value)
|
||||
if len(fields) != count {
|
||||
return nil, fmt.Errorf("expected %d numbers", count)
|
||||
}
|
||||
values := make([]float64, count)
|
||||
for i, field := range fields {
|
||||
number, err := strconv.ParseFloat(field, 64)
|
||||
if err != nil || !finite(number) || strings.ContainsAny(field, "xX_") {
|
||||
return nil, fmt.Errorf("invalid number %q", field)
|
||||
}
|
||||
values[i] = number
|
||||
}
|
||||
return values, nil
|
||||
}
|
||||
|
||||
// creationBox 校验对象边界
|
||||
// 入参: value 边界描述
|
||||
// 返回: Box 矩形, error 错误信息
|
||||
func creationBox(value string) (Box, error) {
|
||||
values, err := creationNumbers(value, 4)
|
||||
if err != nil {
|
||||
return Box{}, err
|
||||
}
|
||||
if values[2] <= 0 || values[3] <= 0 {
|
||||
return Box{}, fmt.Errorf("boundary dimensions must be positive")
|
||||
}
|
||||
return Box{X: values[0], Y: values[1], W: values[2], H: values[3]}, nil
|
||||
}
|
||||
|
||||
// creationColor 校验默认RGB颜色空间中的基本颜色
|
||||
// 入参: color 颜色
|
||||
// 返回: error 错误信息
|
||||
func creationColor(color *FillColor) error {
|
||||
if color == nil {
|
||||
return nil
|
||||
}
|
||||
if color.ColorSpace != "" || color.Index != nil || color.Pattern != nil || color.AxialShd != nil || color.RadialShd != nil || color.unsupported {
|
||||
return fmt.Errorf("only direct RGB colors are supported for creation")
|
||||
}
|
||||
values, err := creationNumbers(color.Value, 3)
|
||||
if err != nil {
|
||||
return err
|
||||
}
|
||||
for _, value := range values {
|
||||
if value < 0 || value > 255 || math.Trunc(value) != value {
|
||||
return fmt.Errorf("RGB channels must be integers between 0 and 255")
|
||||
}
|
||||
}
|
||||
if color.Alpha != nil && (*color.Alpha < 0 || *color.Alpha > 255) {
|
||||
return fmt.Errorf("color alpha must be between 0 and 255")
|
||||
}
|
||||
return nil
|
||||
}
|
||||
|
||||
// finite 判断数值是否有限
|
||||
// 入参: value 数值
|
||||
// 返回: bool 是否有限
|
||||
func finite(value float64) bool {
|
||||
return !math.IsNaN(value) && !math.IsInf(value, 0)
|
||||
}
|
||||
|
||||
// ofdNumber 格式化OFD数值
|
||||
// 入参: value 数值
|
||||
// 返回: string 数值文本
|
||||
func ofdNumber(value float64) string {
|
||||
return strconv.FormatFloat(value, 'f', -1, 64)
|
||||
}
|
||||
|
||||
// escapeOFDText 转义控制字符、反斜线和XML不允许的字符
|
||||
// 入参: value 原文
|
||||
// 返回: string OFD文字编码
|
||||
func escapeOFDText(value string) string {
|
||||
var text strings.Builder
|
||||
for _, char := range value {
|
||||
if char < ' ' || char == '\\' || char == '\ufffe' || char == '\uffff' {
|
||||
fmt.Fprintf(&text, "\\%04X", char)
|
||||
} else {
|
||||
text.WriteRune(char)
|
||||
}
|
||||
}
|
||||
return text.String()
|
||||
}
|
||||
Reference in new issue
Block a user