mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 17:27:08 +08:00
243 lines
7.4 KiB
Go
243 lines
7.4 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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"bufio"
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"bytes"
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"fmt"
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"image"
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"io"
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"strconv"
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"github.com/tdewolff/canvas"
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"github.com/tdewolff/canvas/renderers/pdf"
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"github.com/tdewolff/canvas/renderers/ps"
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"github.com/tdewolff/canvas/renderers/svg"
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"github.com/xiaoqidun/pdfgo"
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)
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// canvasEPSWriter 在EPS头部写入本库制作软件，不改动绘图内容
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type canvasEPSWriter struct {
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io.Writer
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}
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// RenderSVG 使用canvas输出SVG，按模式保留资源和对象分组
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// 入参: r 渲染器, page 页面内容, writer 输出流, mode 资源模式
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// 返回: SVGResources 外部资源, error 错误信息
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func (CanvasBackend) RenderSVG(r *Renderer, page *PageContent, writer io.Writer, mode SVGMode) (SVGResources, error) {
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switch mode {
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case SVGExternalFonts:
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return r.renderSVGResources(page, writer, false, false)
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case SVGExternalResources:
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return r.renderSVGResources(page, writer, true, false)
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case SVGObjects:
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return r.renderSVGResources(page, writer, true, true)
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case SVGEmbedded:
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c, err := r.renderCanvasPage(page)
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if err != nil {
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return SVGResources{}, err
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}
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buffer := bufio.NewWriter(writer)
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renderer := &svgResourceRenderer{SVG: svg.New(buffer, c.W, c.H, nil), renderer: r, writer: buffer, embeddedFonts: true}
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io.WriteString(buffer, svgCreatorMetadata)
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io.WriteString(buffer, `<g style="image-orientation:none">`)
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c.RenderTo(renderer)
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if renderer.err != nil {
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return SVGResources{}, renderer.err
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}
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io.WriteString(buffer, `</g>`)
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if err := renderer.Close(); err != nil {
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return SVGResources{}, err
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}
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return SVGResources{}, buffer.Flush()
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default:
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return SVGResources{}, fmt.Errorf("unsupported SVG mode %d", mode)
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}
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}
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// RenderEPS 使用canvas输出单页EPS
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// 入参: r 渲染器, page 页面内容, writer 输出流
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// 返回: error 错误信息
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func (CanvasBackend) RenderEPS(r *Renderer, page *PageContent, writer io.Writer) error {
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c, err := r.renderCanvasPage(page)
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if err != nil {
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return err
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}
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options := ps.DefaultOptions
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options.Format = ps.EncapsulatedPostScript
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buffer := bufio.NewWriter(writer)
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renderer := ps.New(canvasEPSWriter{buffer}, c.W, c.H, &options)
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if r.Compression.Mode == CompressionUnchanged {
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c.RenderTo(renderer)
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} else {
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optimized := &epsImageRenderer{PS: renderer, writer: buffer, options: r.Compression, ctx: r.outputContext()}
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c.RenderTo(optimized)
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if optimized.err != nil {
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return optimized.err
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}
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}
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if err := renderer.Close(); err != nil {
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return err
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}
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return buffer.Flush()
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}
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// Write 写入EPS片段并替换独立的制作软件声明
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// 入参: data EPS片段
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// 返回: int 已处理字节数, error 写入错误
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func (w canvasEPSWriter) Write(data []byte) (int, error) {
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if bytes.Equal(data, []byte("%%Creator: tdewolff/canvas\n")) {
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if _, err := io.WriteString(w.Writer, "%%Creator: "+ofdCreator+"\n"); err != nil {
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return 0, err
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}
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return len(data), nil
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}
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return w.Writer.Write(data)
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}
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// RenderPDF 使用canvas输出PDF，保留导航与文字并复用输出缓冲
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// 入参: r 渲染器, pages 页面列表, writer 输出流, progress 页面处理进度
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// 返回: error 错误信息
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func (CanvasBackend) RenderPDF(r *Renderer, pages []RenderDocumentPage, writer io.Writer, progress func(int, int) error) error {
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ctx := r.outputContext()
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if err := ctx.Err(); err != nil {
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return err
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}
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view := *r
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view.pageContext = ctx
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r = &view
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if len(pages) == 0 {
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return fmt.Errorf("no pages found")
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}
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doc := r.Reader.doc
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navigation, err := newPDFNavigation(r, doc, pages)
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if err != nil {
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return err
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}
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buf, direct := writer.(*bytes.Buffer)
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if r.Compression.Mode != CompressionUnchanged {
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direct = false
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}
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if !direct {
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buf = &bytes.Buffer{}
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}
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start := buf.Len()
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p := pdf.New(buf, pages[0].Box.W, pages[0].Box.H, nil)
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renderer := &pdfRenderer{PDF: p, glyphPaths: make(map[*canvas.Path]*canvas.Path), images: make([][]image.Image, 1), text: make([]pdfPageText, 1), navigation: navigation}
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defer func() {
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if renderer.imageError != nil {
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r.canvasState().images = renderCache[*EncodedImage, image.Image]{limit: imageCacheLimit}
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}
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}()
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var info DocInfo
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if docInfo, err := r.Reader.DocInfo(); err == nil {
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info = *docInfo
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}
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p.SetInfo(info.Title, info.Subject, "", info.Author, ofdCreator)
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for i, page := range pages {
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content, err := page.ReadContent(ctx, r.Reader)
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if err != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to read page %d: %w", i+1, err)
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}
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if err := navigation.addPage(r, i, content, pages); err != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to read page %d navigation: %w", i+1, err)
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}
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if i > 0 {
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p.NewPage(page.Box.W, page.Box.H)
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renderer.images = append(renderer.images, nil)
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renderer.text = append(renderer.text, pdfPageText{})
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}
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navigation.apply(p, i)
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if err := r.renderCanvasPageToContext(canvas.NewContext(renderer), content, !r.TransparentBackground); err != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to render page %d: %w", i+1, err)
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}
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if renderer.imageError != nil {
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buf.Truncate(start)
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return fmt.Errorf("failed to render page %d: %w", i+1, renderer.imageError)
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}
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pages[i].Content = nil
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if err := ctx.Err(); err != nil {
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buf.Truncate(start)
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return err
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}
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if progress != nil {
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if err := progress(i+1, len(pages)); err != nil {
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buf.Truncate(start)
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return err
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}
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}
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if err := ctx.Err(); err != nil {
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buf.Truncate(start)
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return err
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}
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}
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if doc != nil {
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if err := navigation.addOutlines(doc.Outlines.OutlineElem, 0, navigation.bookmarks, navigation.pageIndex, pages); err != nil {
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buf.Truncate(start)
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return err
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}
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}
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for index, outline := range navigation.Outline {
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p.AddOutline(strconv.Itoa(index), outline.Level, 0)
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}
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if err := p.Close(); err != nil {
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buf.Truncate(start)
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return err
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}
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data := replacePDFProducer(buf.Bytes()[start:])
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options := pdfgo.OptimizeOptions{Compression: r.Compression}
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if r.Compression.Mode != CompressionUnchanged && progress != nil {
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options.OnProgress = func(_ string, _, _ int) error {
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return progress(len(pages), len(pages))
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}
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}
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if direct {
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if !renderer.exactImages && !renderer.exactText && !navigation.nativeWrite {
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if err := r.outputContext().Err(); err != nil {
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buf.Truncate(start)
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return err
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}
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return nil
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}
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var result bytes.Buffer
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err := renderer.writePDF(r.outputContext(), data, &result, options)
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buf.Truncate(start)
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if err != nil {
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return err
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}
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_, err = buf.Write(result.Bytes())
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return err
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}
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return renderer.writePDF(r.outputContext(), data, writer, options)
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}
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// replacePDFProducer 替换PDF的Producer属性
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// 入参: data PDF字节数据
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// 返回: []byte 替换后的PDF字节数据
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func replacePDFProducer(data []byte) []byte {
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old := []byte("/Producer(tdewolff/canvas)")
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idx := bytes.LastIndex(data, old)
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if idx < 0 {
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return data
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}
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dst := []byte("/Producer(" + ofdCreator + ")")
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copy(data[idx:idx+len(old)], dst)
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return data
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}
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