mirror of
https://github.com/xiaoqidun/ofdgo.git
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321 lines
11 KiB
Go
321 lines
11 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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"context"
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"fmt"
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"image"
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"image/color"
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"strconv"
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"github.com/tdewolff/canvas"
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cimage "github.com/tdewolff/canvas/image"
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"github.com/tdewolff/canvas/renderers/pdf"
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"github.com/xiaoqidun/pdfgo"
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)
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// pdfRenderer PDF渲染器
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type pdfRenderer struct {
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*pdf.PDF
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glyphPaths map[*canvas.Path]*canvas.Path
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images [][]image.Image
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exactImages bool
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imageError error
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navigation *pdfNavigation
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}
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// pdfNavigation PDF导航信息
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type pdfNavigation struct {
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Link map[int][]pdfLink
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Outline []pdfOutline
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exactLinks bool
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}
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// pdfLink PDF链接
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type pdfLink struct {
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Rect canvas.Rect
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Region *pdfgo.LinkRegion
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Actions []pdfNavigationAction
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}
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// pdfTarget 保存输出页索引及默认用户空间中的跳转参数
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type pdfTarget struct {
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Page int
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Destination pdfgo.Destination
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}
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// pdfOutline PDF大纲
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type pdfOutline struct {
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Name string
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Level int
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Actions []pdfNavigationAction
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}
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// pdfNavigationAction 保存链接或目录的导航动作，输出时关联实际页面引用
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type pdfNavigationAction struct {
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URI string
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Target *pdfTarget
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}
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// RenderImage 校验惰性图片并同步不透明画笔，保留解码错误及后端透明度状态
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// 入参: img 图像, matrix 图像变换
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func (r *pdfRenderer) RenderImage(img image.Image, matrix canvas.Matrix) {
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if r.imageError != nil {
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return
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}
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if source, ok := img.(interface{ Image() (image.Image, error) }); ok {
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pixels, err := source.Image()
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if err != nil {
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r.imageError = err
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return
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}
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if pixels == nil || pixels.Bounds() != img.Bounds() {
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r.imageError = fmt.Errorf("PDF output image pixel bounds differ")
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return
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}
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}
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if len(r.images) != 0 {
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var original image.Image
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opaque := false
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if source, ok := img.(interface{ Opaque() bool }); ok {
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opaque = source.Opaque()
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}
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switch img.ColorModel() {
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case color.GrayModel, color.CMYKModel:
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case color.RGBAModel, color.NRGBAModel, color.AlphaModel:
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if !opaque {
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original = img
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}
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default:
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if source, ok := img.(*cimage.Image); !ok || source.Mimetype != "image/jpeg" || source.Mask != nil {
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original = img
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}
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}
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r.exactImages = r.exactImages || original != nil
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last := len(r.images) - 1
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r.images[last] = append(r.images[last], original)
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}
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style := canvas.DefaultStyle
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style.Fill = canvas.Paint{Color: canvas.White}
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style.Stroke = canvas.Paint{Color: canvas.Black}
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r.PDF.RenderPath(&canvas.Path{}, style, canvas.Identity)
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r.PDF.RenderImage(img, matrix)
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}
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// glyphPath 复用相似变换下的PDF字形圆弧转换
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// 入参: path 缓存字形路径, matrix 字形变换
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// 返回: *canvas.Path PDF字形路径
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func (r *pdfRenderer) glyphPath(path *canvas.Path, matrix canvas.Matrix) *canvas.Path {
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if !matrix.IsSimilarity() {
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return path
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}
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if cached, ok := r.glyphPaths[path]; ok {
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return cached
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}
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converted := path.ReplaceArcs()
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r.glyphPaths[path] = converted
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return converted
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}
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// newPDFNavigation 创建PDF导航信息
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// 入参: renderer 渲染器, doc 文档结构, pages 页面数据
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// 返回: *pdfNavigation PDF导航信息, error 区域或目标错误
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func newPDFNavigation(renderer *Renderer, doc *Document, pages []RenderDocumentPage) (*pdfNavigation, error) {
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navigation := &pdfNavigation{
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Link: make(map[int][]pdfLink),
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}
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pageIndex := make(map[string]int, len(pages))
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for i, page := range pages {
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pageIndex[page.Content.ID] = i
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}
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bookmarks := make(map[string]Dest)
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if doc != nil {
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for _, bookmark := range doc.Bookmarks.Bookmark {
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bookmarks[bookmark.Name] = bookmark.Dest
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}
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}
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for i, page := range pages {
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sources := renderer.pageActionSources(page.Content, page.Box)
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if renderer.RenderAnnotations {
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sources = append(sources, renderer.annotationActionSources(renderer.Reader.Annots[page.Content.ID])...)
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}
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for _, source := range sources {
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if err := navigation.addActions(renderer, i, source, bookmarks, pageIndex, pages); err != nil {
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return nil, err
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}
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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, bookmarks, pageIndex, pages); err != nil {
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return nil, err
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}
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}
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return navigation, nil
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}
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// pdfNavigationTarget 转换导航动作，选页未包含的目标不写入
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// 入参: action 动作, bookmarks 书签, pageIndex 页面索引表, pages 页面数据
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// 返回: *pdfNavigationAction 导航动作，nil表示无输出动作, error 目标参数错误
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func pdfNavigationTarget(action Action, bookmarks map[string]Dest, pageIndex map[string]int, pages []RenderDocumentPage) (*pdfNavigationAction, error) {
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if action.Goto != nil {
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dest := gotoDest(action.Goto, bookmarks)
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if dest == nil {
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return nil, nil
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}
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target, ok := pageIndex[dest.PageID]
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if !ok {
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return nil, nil
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}
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destination, err := pdfDestination(*dest, pages[target].Box.H)
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if err != nil {
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return nil, err
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}
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return &pdfNavigationAction{Target: &pdfTarget{Page: target, Destination: destination}}, nil
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}
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if action.URI != nil && action.URI.URI != "" {
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return &pdfNavigationAction{URI: resolveActionURI(*action.URI)}, nil
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}
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return nil, nil
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}
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// addOutlines 保留目录层级及节点自身的导航动作，选页时移除无保留子项的失效跳转节点
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// 入参: outlines 大纲节点, level 节点层级, bookmarks 书签, pageIndex 页面索引表, pages 页面数据
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// 返回: error 目标参数错误
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func (n *pdfNavigation) addOutlines(outlines []OutlineElem, level int, bookmarks map[string]Dest, pageIndex map[string]int, pages []RenderDocumentPage) error {
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for _, outline := range outlines {
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entry := pdfOutline{Name: outline.Title, Level: level}
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onlyMissingTargets := len(outline.Actions) != 0
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for _, action := range outline.Actions {
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if action.Goto == nil {
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onlyMissingTargets = false
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}
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value, err := pdfNavigationTarget(action, bookmarks, pageIndex, pages)
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if err != nil {
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return err
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}
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if value != nil {
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entry.Actions = append(entry.Actions, *value)
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}
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}
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index := len(n.Outline)
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n.Outline = append(n.Outline, entry)
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if err := n.addOutlines(outline.OutlineElem, level+1, bookmarks, pageIndex, pages); err != nil {
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return err
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}
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if onlyMissingTargets && len(entry.Actions) == 0 && len(n.Outline) == index+1 {
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n.Outline = n.Outline[:index]
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}
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}
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n.exactLinks = n.exactLinks || len(n.Outline) != 0
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return nil
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}
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// apply 生成链接及大纲结构，内部目标在原生写入时关联
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// 入参: renderer PDF渲染器, page 页面索引
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func (n *pdfNavigation) apply(renderer *pdf.PDF, page int) {
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for _, link := range n.Link[page] {
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renderer.AddLink("", link.Rect)
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}
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if page == 0 {
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for index, outline := range n.Outline {
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renderer.AddOutline(strconv.Itoa(index), outline.Level, 0)
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}
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}
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}
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// destinations 将输出页引用关联到原有链接和先序大纲，不按目标页重新排序
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// 入参: ctx 取消上下文, reader 输出PDF, pages 输出页引用, options 替换配置
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// 返回: error 目录结构或取消错误
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func (n *pdfNavigation) destinations(ctx context.Context, reader *pdfgo.Reader, pages []pdfgo.Reference, options *pdfgo.RewriteOptions) error {
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options.LinkDestinations = make(map[pdfgo.AnnotationLocation]pdfgo.Destination)
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options.LinkActions = make(map[pdfgo.AnnotationLocation][]pdfgo.NavigationAction)
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for page, links := range n.Link {
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for index, link := range links {
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if err := ctx.Err(); err != nil {
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return err
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}
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if len(link.Actions) == 1 && link.Actions[0].Target != nil {
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target := link.Actions[0].Target
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dest := target.Destination
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dest.Page = pages[target.Page]
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options.LinkDestinations[pdfgo.AnnotationLocation{Page: pages[page], Index: index}] = dest
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} else {
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options.LinkActions[pdfgo.AnnotationLocation{Page: pages[page], Index: index}] = pdfNavigationValues(link.Actions, pages)
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}
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}
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}
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if len(n.Outline) == 0 {
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return nil
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}
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options.OutlineDestinations = make(map[pdfgo.Reference]pdfgo.Destination, len(n.Outline))
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options.OutlineTitles = make(map[pdfgo.Reference]string, len(n.Outline))
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options.OutlineActions = make(map[pdfgo.Reference][]pdfgo.NavigationAction)
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count := 0
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if err := reader.WalkOutlines(ctx, func(level int, item pdfgo.OutlineItem) error {
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if count >= len(n.Outline) || n.Outline[count].Level != level || strconv.Itoa(count) != item.Title {
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return fmt.Errorf("PDF output outline differs")
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}
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actions := n.Outline[count].Actions
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if len(actions) == 1 && actions[0].Target != nil {
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target := actions[0].Target
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dest := target.Destination
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dest.Page = pages[target.Page]
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options.OutlineDestinations[item.Reference] = dest
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} else {
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options.OutlineActions[item.Reference] = pdfNavigationValues(actions, pages)
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}
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options.OutlineTitles[item.Reference] = n.Outline[count].Name
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count++
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return nil
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}); err != nil {
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return err
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}
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if count != len(n.Outline) {
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return fmt.Errorf("PDF output outline missing")
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}
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return nil
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}
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// pdfSourceRect 转换PDF动作区域
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// 入参: box OFD区域, pageH 页面高度
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// 返回: canvas.Rect PDF区域
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func pdfSourceRect(box Box, pageH float64) canvas.Rect {
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return canvas.RectFromSize(box.X, pageH-box.Y-box.H, box.W, box.H)
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}
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// pdfDestination 按OFD目标语义转换PDF坐标、显示模式及缩放比例
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// 入参: dest OFD跳转目标, pageH 页面高度
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// 返回: pdfgo.Destination 待关联输出页的目标, error 目标参数错误
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func pdfDestination(dest Dest, pageH float64) (pdfgo.Destination, error) {
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dest = dest.effective()
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if _, err := dest.attributes(); err != nil {
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return pdfgo.Destination{}, err
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}
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const scale = 72.0 / 25.4
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result := pdfgo.Destination{Mode: pdfgo.Name(dest.Type)}
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switch dest.Type {
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case "XYZ":
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result.Parameters = pdfgo.Array{pdfgo.Real(dest.Left * scale), pdfgo.Real((pageH - dest.Top) * scale), pdfgo.Real(dest.Zoom)}
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case "FitH":
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result.Parameters = pdfgo.Array{pdfgo.Real((pageH - dest.Top) * scale)}
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case "FitV":
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result.Parameters = pdfgo.Array{pdfgo.Real(dest.Left * scale)}
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case "FitR":
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result.Parameters = pdfgo.Array{pdfgo.Real(dest.Left * scale), pdfgo.Real((pageH - dest.Bottom) * scale), pdfgo.Real(dest.Right * scale), pdfgo.Real((pageH - dest.Top) * scale)}
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}
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return result, nil
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}
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