mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
584 lines
18 KiB
Go
584 lines
18 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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"archive/zip"
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"bufio"
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"bytes"
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"compress/flate"
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"context"
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"encoding/binary"
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"encoding/xml"
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"hash/crc32"
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"image"
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"io"
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"maps"
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"path"
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"slices"
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"strings"
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"unicode/utf8"
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"github.com/xiaoqidun/pdfgo"
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)
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// 与PDFGo共用输出压缩模式和有损压缩等级
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const (
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CompressionUnchanged = pdfgo.CompressionUnchanged
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CompressionLossless = pdfgo.CompressionLossless
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CompressionLossy = pdfgo.CompressionLossy
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CompressionLight = pdfgo.CompressionLight
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CompressionMedium = pdfgo.CompressionMedium
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CompressionStrong = pdfgo.CompressionStrong
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)
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// outputOptimizationBufferLimit 限制压缩时的单个输出缓冲，单位为字节
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const outputOptimizationBufferLimit = 64 << 20
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// CompressionMode 选择原始、无损或有损输出策略
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type CompressionMode = pdfgo.CompressionMode
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// CompressionLevel 选择轻压、均衡或强压，仅用于有损模式
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type CompressionLevel = pdfgo.CompressionLevel
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// CompressionOptions 配置输出压缩，原始模式沿用现有输出策略，不额外优化
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// Quality和MaxDPI为零时按Level使用预设，不改变页面尺寸或整页导出精度
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// 无损表示不引入额外损失，不保证跨格式转换可逆；有损不栅格化文字和矢量
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type CompressionOptions = pdfgo.CompressionOptions
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// WriteOptions 配置OFD输出副本，不修改编辑资源和撤销记录
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type WriteOptions struct{ Compression CompressionOptions }
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// outputOptimization 保存单次写出的配置、图片路径及压缩进度，复用压缩器
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type outputOptimization struct {
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ctx context.Context
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options CompressionOptions
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images map[string]bool
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sizes map[string]image.Point
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protected bool
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completed int
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deflater *flate.Writer
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}
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// outputCompressionBuffer 限制候选ZIP编码，不能缩小时终止本次压缩
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type outputCompressionBuffer struct {
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buffer *bytes.Buffer
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limit int
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exceeded bool
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}
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// Write 写入有界候选编码，超过体积上限时返回短缓冲错误
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// 入参: data 编码数据
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// 返回: int 写入字节数, error 容量错误
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func (b *outputCompressionBuffer) Write(data []byte) (int, error) {
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if len(data) > b.limit-b.buffer.Len() {
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b.exceeded = true
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return 0, io.ErrShortBuffer
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}
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return b.buffer.Write(data)
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}
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// WriteToWithOptions 按压缩策略写出OFD，签名文档不额外改写资源内容
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// 入参: ctx 取消上下文, writer 输出流, options 输出配置
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// 返回: int64 已写入字节数, error 错误信息
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func (e *Editor) WriteToWithOptions(ctx context.Context, writer io.Writer, options WriteOptions) (int64, error) {
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snapshot, err := e.outputSnapshot(ctx, options)
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if err != nil {
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return 0, err
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}
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var count int64
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return snapshot.WriteTo(convertWriter{ctx: ctx, writer: writer, count: &count})
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}
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// WritePagesTo 按指定顺序另存页面，仅为所选页面准备资源和压缩计划
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// 保留关联资源、目录、注释和签章外观，生成新文档标识，不改变原文档和撤销记录
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// 签章外观不代表原签名在导出文档中仍有效，页码不可重复或为空
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// 入参: ctx 取消上下文, writer 输出流, indexes 零基页码, options 输出配置
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// 返回: int64 已写入字节数, error 错误信息
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func (e *Editor) WritePagesTo(ctx context.Context, writer io.Writer, indexes []int, options WriteOptions) (int64, error) {
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if err := ctx.Err(); err != nil {
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return 0, err
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}
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if err := options.Compression.Validate(); err != nil {
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return 0, err
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}
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snapshot := *e
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snapshot.OnWriteProgress = editorProgress(e.OnWriteProgress).withContext(ctx)
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snapshot.output = &outputOptimization{ctx: ctx, options: options.Compression}
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var count int64
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return snapshot.writePagesTo(convertWriter{ctx: ctx, writer: writer, count: &count}, indexes)
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}
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// outputSnapshot 创建只读输出配置，原签名存在时仅调整ZIP封装
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// 入参: ctx 取消上下文, options 输出配置
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// 返回: *Editor 输出快照, error 配置或资源错误
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func (e *Editor) outputSnapshot(ctx context.Context, options WriteOptions) (*Editor, error) {
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if err := ctx.Err(); err != nil {
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return nil, err
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}
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if err := options.Compression.Validate(); err != nil {
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return nil, err
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}
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snapshot := *e
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snapshot.OnWriteProgress = editorProgress(e.OnWriteProgress).withContext(ctx)
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snapshot.output = &outputOptimization{ctx: ctx, options: options.Compression}
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if options.Compression.Mode == CompressionUnchanged {
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return &snapshot, nil
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}
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if e.source != nil {
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protected, err := e.source.reader.hasOutputSignatures(ctx)
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if err != nil {
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return nil, err
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}
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snapshot.output.protected = protected
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if protected {
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return &snapshot, nil
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}
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}
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if options.Compression.Mode == CompressionLossy {
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reader, err := e.readerContext(ctx, editorProgress(snapshot.OnWriteProgress))
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if err != nil {
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return nil, err
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}
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defer reader.Close()
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snapshot.output.images, snapshot.output.sizes, err = reader.compressionImagePlan(ctx, options.Compression)
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if err != nil {
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return nil, err
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}
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}
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if err := snapshot.compressPatternPaints(); err != nil {
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return nil, err
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}
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return &snapshot, nil
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}
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// compressionImageSafety 按当前入口保护蒙版及其原图和替换图像，不完整的文档结构不参与降采样
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// 入参: ctx 取消上下文, images 图片资源
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// 返回: map[string]bool 只能无损处理的资源路径, bool 是否可分析尺寸, error 读取或取消错误
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func (r *Reader) compressionImageSafety(ctx context.Context, images []ImageInfo) (map[string]bool, bool, error) {
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names := make(map[string]bool)
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safe := true
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structured := len(r.OFD.DocBody) != 0
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if structured {
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entry, err := r.DocumentRootContext(ctx)
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if err != nil {
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return nil, false, err
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}
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dependencies, structures, err := r.versionDependencies(ctx, entry, nil, nil)
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if err != nil {
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if ctx.Err() != nil {
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return nil, false, ctx.Err()
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}
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safe = false
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}
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for name := range dependencies {
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if !r.fileNames[name] {
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safe = false
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break
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}
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}
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names = structures
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} else {
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for name := range r.fileIndex {
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names[name] = true
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}
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for name := range r.files {
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names[name] = true
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}
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}
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masks := make(map[string]bool)
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for _, name := range slices.Sorted(maps.Keys(names)) {
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if !safe {
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break
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}
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if err := ctx.Err(); err != nil {
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return nil, false, err
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}
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if strings.HasSuffix(name, "/") {
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continue
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}
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input, err := r.openFile(name)
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if err != nil {
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return nil, false, err
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}
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buffer := bufio.NewReader(imageInput{ReadCloser: input, ctx: ctx})
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found, err := editorXMLPrefix(buffer)
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if err != nil || !found && (structured || strings.EqualFold(path.Ext(name), ".xml")) {
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safe = false
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}
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if safe && found {
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decoder := xml.NewDecoder(buffer)
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var stack []xml.Name
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seen := false
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for {
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token, err := decoder.Token()
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if err == io.EOF {
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safe = seen && len(stack) == 0
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break
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}
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if err != nil {
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safe = false
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break
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}
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switch element := token.(type) {
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case xml.StartElement:
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if len(stack) == 0 && seen {
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safe = false
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break
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}
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seen = true
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if len(stack) != 0 && classifyOFDNamespace(element.Name.Space) == ofdXMLUnknown && element.Name.Space != stack[len(stack)-1].Space {
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safe = false
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break
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}
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if len(stack) != 0 && stack[len(stack)-1].Local == "Extension" && element.Name.Local == "Data" {
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if err := decoder.Skip(); err != nil {
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safe = false
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}
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break
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}
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stack = append(stack, element.Name)
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resource, substitution, masked := "", "", false
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for _, attr := range element.Attr {
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if attr.Name.Space != "" {
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continue
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}
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if attr.Name.Local == "ResourceID" {
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resource = editorResourceID(attr.Value)
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}
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if attr.Name.Local == "Substitution" {
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substitution = editorResourceID(attr.Value)
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}
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if attr.Name.Local == "ImageMask" {
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masks[editorResourceID(attr.Value)] = true
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masked = true
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}
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}
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if masked {
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masks[resource] = true
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if substitution != "" {
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masks[substitution] = true
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}
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}
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case xml.EndElement:
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stack = stack[:len(stack)-1]
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case xml.CharData:
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if len(stack) == 0 && len(bytes.Trim(element, " \t\r\n")) != 0 {
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safe = false
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}
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case xml.Directive:
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safe = false
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}
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if !safe {
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break
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}
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}
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}
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input.Close()
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if !safe {
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break
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}
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}
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paths := make(map[string]bool)
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for _, img := range images {
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if !safe || masks[editorResourceID(img.ID)] {
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paths[cleanPackagePath(img.Location)] = true
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}
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}
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return paths, safe, ctx.Err()
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}
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// hasOutputSignatures 检查全部文档的签名入口，不受当前文档或版本选择影响
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// 入参: ctx 取消上下文
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// 返回: bool 是否声明签名入口, error 取消错误
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func (r *Reader) hasOutputSignatures(ctx context.Context) (bool, error) {
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for _, body := range r.OFD.DocBody {
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if err := ctx.Err(); err != nil {
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return false, err
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}
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if body.Signatures != "" {
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return true, nil
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}
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}
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return false, ctx.Err()
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}
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// writeOutputEntry 优化ZIP编码，保留资源名称及条目的未压缩字节
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// 入参: archive 归档写入器, header 条目属性, data 原始数据
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// 返回: error 优化或写入错误
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func (e *Editor) writeOutputEntry(archive *zip.Writer, header zip.FileHeader, data []byte) error {
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if e.output == nil || e.output.options.Mode == CompressionUnchanged || len(data) > outputOptimizationBufferLimit {
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entry, err := archive.CreateHeader(&header)
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if err != nil {
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return err
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}
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if e.output != nil {
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return e.writeOutputBytes(entry, data)
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}
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_, err = entry.Write(data)
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return err
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}
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if err := editorProgress(e.OnWriteProgress).report("compress", e.output.completed, 0); err != nil {
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return err
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}
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compressed, err := e.compressOutputBytes(data, len(data))
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if err != nil {
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return err
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}
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payload := data
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header.Method = zip.Store
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if compressed != nil {
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payload = compressed
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header.Method = zip.Deflate
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}
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prepareOutputHeader(&header, header.Method, uint64(len(data)), uint64(len(payload)), crc32.ChecksumIEEE(data))
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entry, err := archive.CreateRaw(&header)
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if err != nil {
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return err
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}
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if err = e.writeOutputBytes(entry, payload); err != nil {
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return err
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}
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e.output.completed++
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return editorProgress(e.OnWriteProgress).report("compress", e.output.completed, 0)
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}
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// writeOutputBytes 分块写出已编码数据，不额外分配复制缓冲
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// 入参: writer 输出流, data 已编码字节
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// 返回: error 写入或取消错误
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func (e *Editor) writeOutputBytes(writer io.Writer, data []byte) error {
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for offset := 0; offset < len(data); {
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if err := e.output.ctx.Err(); err != nil {
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return err
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}
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end := min(offset+64<<10, len(data))
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n, err := writer.Write(data[offset:end])
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if err != nil {
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return err
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}
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if n != end-offset {
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return io.ErrShortWrite
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}
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offset = end
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}
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return e.output.ctx.Err()
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}
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// compressOutputBytes 复用压缩器并限制候选体积，无收益时返回空值
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// 入参: data 未压缩数据, limit 候选体积上限
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// 返回: []byte 更小的DEFLATE编码, error 取消或编码错误
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func (e *Editor) compressOutputBytes(data []byte, limit int) ([]byte, error) {
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var compressed bytes.Buffer
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output := &outputCompressionBuffer{buffer: &compressed, limit: min(limit, outputOptimizationBufferLimit)}
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deflater := e.output.deflater
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if deflater == nil {
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deflater, _ = flate.NewWriter(output, flate.BestCompression)
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e.output.deflater = deflater
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} else {
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deflater.Reset(output)
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}
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defer deflater.Close()
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for offset := 0; offset < len(data); {
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if err := e.output.ctx.Err(); err != nil {
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return nil, err
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}
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end := min(offset+64<<10, len(data))
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if _, err := deflater.Write(data[offset:end]); err != nil {
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if err == io.ErrShortBuffer {
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return nil, e.output.ctx.Err()
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}
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return nil, err
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}
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offset = end
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}
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if err := deflater.Close(); err != nil {
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if err == io.ErrShortBuffer {
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return nil, e.output.ctx.Err()
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}
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return nil, err
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}
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if compressed.Len() >= limit {
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return nil, e.output.ctx.Err()
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}
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return compressed.Bytes(), e.output.ctx.Err()
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}
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// compressOutputFile 分块重压缩ZIP条目，无收益时仍读完原数据并校验长度及校验和
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// 入参: file 原始条目, buffer 读取缓冲, limit 候选体积上限
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// 返回: []byte 更小的DEFLATE编码, error 读取、编码或取消错误
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func (e *Editor) compressOutputFile(file *zip.File, buffer []byte, limit int) ([]byte, error) {
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input, err := file.Open()
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if err != nil {
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return nil, err
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}
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defer input.Close()
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var compressed bytes.Buffer
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output := &outputCompressionBuffer{buffer: &compressed, limit: min(limit, outputOptimizationBufferLimit)}
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deflater := e.output.deflater
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if deflater == nil {
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deflater, _ = flate.NewWriter(output, flate.BestCompression)
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e.output.deflater = deflater
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} else {
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deflater.Reset(output)
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}
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defer deflater.Close()
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source := imageInput{ReadCloser: input, ctx: e.output.ctx}
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_, err = io.CopyBuffer(deflater, source, buffer)
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if output.exceeded {
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_, err = io.CopyBuffer(io.Discard, source, buffer)
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}
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closeErr := deflater.Close()
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if e.output.ctx.Err() != nil {
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return nil, e.output.ctx.Err()
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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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if output.exceeded {
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return nil, nil
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}
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if closeErr != nil {
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return nil, closeErr
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}
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if compressed.Len() >= limit {
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return nil, nil
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}
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return compressed.Bytes(), nil
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}
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// prepareOutputHeader 更新原始ZIP编码属性，保留名称、备注和字符集标记
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// 入参: header 条目属性, method 编码方法, size 原始尺寸, packed 编码尺寸, checksum 校验值
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func prepareOutputHeader(header *zip.FileHeader, method uint16, size, packed uint64, checksum uint32) {
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header.Method, header.ReaderVersion = method, 20
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header.CreatorVersion = header.CreatorVersion&0xff00 | 20
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header.CRC32, header.UncompressedSize64, header.CompressedSize64 = checksum, size, packed
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header.Flags &^= 8
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|
header.Extra = outputZIPExtra(header.Extra)
|
|
if header.NonUTF8 {
|
|
header.Flags &^= 0x800
|
|
} else if utf8.ValidString(header.Name) && utf8.ValidString(header.Comment) {
|
|
for _, value := range header.Name + header.Comment {
|
|
if value < 0x20 || value > 0x7d || value == 0x5c {
|
|
header.Flags |= 0x800
|
|
break
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// outputZIPExtra 保留扩展属性，移除由新归档重新生成的ZIP64尺寸及偏移
|
|
// 入参: extra 原始扩展属性
|
|
// 返回: []byte 输出扩展属性，不修改原始缓冲
|
|
func outputZIPExtra(extra []byte) []byte {
|
|
var output []byte
|
|
start := 0
|
|
for offset := 0; offset+4 <= len(extra); {
|
|
size := 4 + int(binary.LittleEndian.Uint16(extra[offset+2:]))
|
|
if size > len(extra)-offset {
|
|
break
|
|
}
|
|
if binary.LittleEndian.Uint16(extra[offset:]) == 1 {
|
|
if output == nil {
|
|
output = make([]byte, 0, len(extra))
|
|
}
|
|
output = append(output, extra[start:offset]...)
|
|
start = offset + size
|
|
}
|
|
offset += size
|
|
}
|
|
if output == nil {
|
|
return extra
|
|
}
|
|
return append(output, extra[start:]...)
|
|
}
|
|
|
|
// writeOutputFile 重压缩未修改条目，只采用优于原ZIP编码的结果
|
|
// 入参: archive 输出归档, file 原始条目, buffer 流式复制缓冲
|
|
// 返回: error 读取、写入或取消错误
|
|
func (e *Editor) writeOutputFile(archive *zip.Writer, file *zip.File, buffer []byte) error {
|
|
if err := editorProgress(e.OnWriteProgress).report("compress", e.output.completed, 0); err != nil {
|
|
return err
|
|
}
|
|
header := file.FileHeader
|
|
header.Extra = outputZIPExtra(header.Extra)
|
|
var payload io.Reader
|
|
if file.UncompressedSize64 <= outputOptimizationBufferLimit {
|
|
limit := min(file.CompressedSize64, file.UncompressedSize64)
|
|
compressed, err := e.compressOutputFile(file, buffer, int(limit))
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if compressed != nil {
|
|
prepareOutputHeader(&header, zip.Deflate, file.UncompressedSize64, uint64(len(compressed)), file.CRC32)
|
|
payload = bytes.NewReader(compressed)
|
|
} else if file.UncompressedSize64 < file.CompressedSize64 {
|
|
input, err := file.Open()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
defer input.Close()
|
|
prepareOutputHeader(&header, zip.Store, file.UncompressedSize64, file.UncompressedSize64, file.CRC32)
|
|
payload = input
|
|
}
|
|
}
|
|
if payload == nil {
|
|
var err error
|
|
payload, err = file.OpenRaw()
|
|
if err != nil {
|
|
return err
|
|
}
|
|
}
|
|
entry, err := archive.CreateRaw(&header)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
if _, err := io.CopyBuffer(entry, imageInput{ReadCloser: io.NopCloser(payload), ctx: e.output.ctx}, buffer); err != nil {
|
|
return err
|
|
}
|
|
e.output.completed++
|
|
return editorProgress(e.OnWriteProgress).report("compress", e.output.completed, 0)
|
|
}
|
|
|
|
// WithCompression 设置导出策略，不修改文档资源和渲染缓存
|
|
// 入参: options 压缩配置，写出时校验
|
|
// 返回: RendererOption 渲染器配置
|
|
func WithCompression(options CompressionOptions) RendererOption {
|
|
return func(r *Renderer) { r.Compression = options }
|
|
}
|
|
|
|
// writeCompressedImage 优化已经编码的图片，再交付调用方输出流
|
|
// 入参: writer 输出流, data 图片数据
|
|
// 返回: error 优化或写入错误
|
|
func (r *Renderer) writeCompressedImage(writer io.Writer, data []byte) error {
|
|
optimized, err := pdfgo.OptimizeImage(r.outputContext(), data, r.Compression)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
_, err = io.Copy(writer, bytes.NewReader(optimized))
|
|
return err
|
|
}
|
|
|
|
// outputContext 优先使用当前页面上下文，否则使用输出上下文
|
|
// 返回: context.Context 取消上下文
|
|
func (r *Renderer) outputContext() context.Context {
|
|
if r.pageContext != nil {
|
|
return r.pageContext
|
|
}
|
|
if r.OutputContext != nil {
|
|
return r.OutputContext
|
|
}
|
|
return context.Background()
|
|
}
|