mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
251 lines
7.5 KiB
Go
251 lines
7.5 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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"fmt"
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"image"
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"image/color"
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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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)
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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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}
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// pdfNavigation PDF导航信息
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type pdfNavigation struct {
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Anchor map[int][]pdfAnchor
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Link map[int][]pdfLink
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Outline map[int][]pdfOutline
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nextID int
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}
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// pdfAnchor PDF跳转目标
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type pdfAnchor struct {
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Name string
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Rect canvas.Rect
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}
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// pdfLink PDF链接
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type pdfLink struct {
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URI string
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Rect canvas.Rect
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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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Y float64
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}
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// RenderImage 在图像局部保存状态前同步不透明画笔，避免恢复后的透明度与后端缓存不一致
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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 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 几何错误
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func newPDFNavigation(renderer *Renderer, doc *Document, pages []RenderDocumentPage) (*pdfNavigation, error) {
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navigation := &pdfNavigation{
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Anchor: make(map[int][]pdfAnchor),
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Link: make(map[int][]pdfLink),
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Outline: make(map[int][]pdfOutline),
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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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for _, action := range source.Actions {
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if action.Event != "CLICK" {
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continue
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}
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box, _, err := renderer.actionLinkRegion(source, action)
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if err != nil {
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return nil, err
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}
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if box.W <= 0 || box.H <= 0 {
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continue
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}
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rect := pdfSourceRect(box, page.Box.H)
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navigation.addAction(i, rect, action, bookmarks, pageIndex, pages)
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}
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}
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}
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if doc != nil {
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navigation.addOutlines(doc.Outlines.OutlineElem, 0, bookmarks, pageIndex, pages)
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}
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return navigation, nil
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}
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// addAction 添加PDF动作
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// 入参: page 页面索引, rect 动作区域, action 动作, bookmarks 书签, pageIndex 页面索引表, pages 页面数据
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func (n *pdfNavigation) addAction(page int, rect canvas.Rect, action Action, bookmarks map[string]Dest, pageIndex map[string]int, pages []RenderDocumentPage) {
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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
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}
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target, ok := pageIndex[dest.PageID]
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if !ok {
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return
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}
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targetRect, ok := pdfDestRect(*dest, pages[target].Box.H)
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if !ok {
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return
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}
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name := fmt.Sprintf("ofdgo-dest-%d", n.nextID)
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n.nextID++
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n.Anchor[target] = append(n.Anchor[target], pdfAnchor{Name: name, Rect: targetRect})
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n.Link[page] = append(n.Link[page], pdfLink{URI: "#" + name, Rect: rect})
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return
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}
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if action.URI != nil && action.URI.URI != "" {
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n.Link[page] = append(n.Link[page], pdfLink{URI: resolveActionURI(*action.URI), Rect: rect})
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}
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}
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// addOutlines 添加PDF大纲
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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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func (n *pdfNavigation) addOutlines(outlines []OutlineElem, level int, bookmarks map[string]Dest, pageIndex map[string]int, pages []RenderDocumentPage) {
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for _, outline := range outlines {
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nextLevel := level
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if dest := outlineDest(outline, bookmarks); dest != nil {
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if page, ok := pageIndex[dest.PageID]; ok {
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n.Outline[page] = append(n.Outline[page], pdfOutline{
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Name: outline.Title,
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Level: level,
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Y: pdfDestY(*dest, pages[page].Box.H),
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})
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nextLevel++
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}
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}
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n.addOutlines(outline.OutlineElem, nextLevel, bookmarks, pageIndex, pages)
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}
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}
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// apply 应用PDF导航信息
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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 _, anchor := range n.Anchor[page] {
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renderer.AddAnchor(anchor.Name, anchor.Rect)
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}
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for _, link := range n.Link[page] {
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renderer.AddLink(link.URI, link.Rect)
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}
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for _, outline := range n.Outline[page] {
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renderer.AddOutline(outline.Name, outline.Level, outline.Y)
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}
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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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// pdfDestRect 转换PDF跳转目标
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// 入参: dest OFD跳转目标, pageH 页面高度
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// 返回: canvas.Rect PDF目标区域, bool 是否支持
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func pdfDestRect(dest Dest, pageH float64) (canvas.Rect, bool) {
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switch dest.Type {
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case "XYZ":
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return canvas.Rect{X0: dest.Left, Y0: pageH - dest.Top, X1: dest.Left, Y1: pageH - dest.Top}, true
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case "Fit":
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return canvas.Rect{}, true
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case "FitH":
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return canvas.Rect{Y0: pageH - dest.Top, Y1: pageH - dest.Top}, true
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case "FitV":
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return canvas.Rect{X0: dest.Left, X1: dest.Left}, true
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case "FitR":
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return canvas.Rect{X0: dest.Left, Y0: pageH - dest.Bottom, X1: dest.Right, Y1: pageH - dest.Top}, true
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}
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return canvas.Rect{}, false
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}
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// pdfDestY 获取PDF大纲目标位置
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// 入参: dest OFD跳转目标, pageH 页面高度
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// 返回: float64 PDF纵坐标
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func pdfDestY(dest Dest, pageH float64) float64 {
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switch dest.Type {
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case "XYZ", "FitH", "FitR":
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return pageH - dest.Top
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}
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return 0
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}
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