feat(转换能力): 支持引用页面与代理转换

go.mod

@@ -10,7 +10,7 @@ require (
 	github.com/tdewolff/canvas v0.0.0-20260923214215-09804640d00c
 	github.com/tdewolff/font v0.0.0-20260913163313-54f98bb59ee6
 	github.com/xiaoqidun/jbig2 v1.1.1
-	github.com/xiaoqidun/pdfgo v0.0.0-20261002153346-125ae06f23bf
+	github.com/xiaoqidun/pdfgo v0.0.0-20261002164637-41541220b1c3
 	golang.org/x/crypto v0.57.0
 	golang.org/x/image v0.46.0
 	golang.org/x/text v0.42.0

go.sum

@@ -62,8 +62,8 @@ github.com/tdewolff/test v1.0.12 h1:7F21DqIajswxuche0geHdrUZRCWE4oko4b7bcmkkrxk=
 github.com/tdewolff/test v1.0.12/go.mod h1:XPuWBzvdUzhCuxWO1ojpXsyzsA5bFoS3tO/Q3kFuTG8=
 github.com/xiaoqidun/jbig2 v1.1.1 h1:SjliS9ZO0e9HX5oYUfBuXrfFsXhWricrSz+XY4zORDI=
 github.com/xiaoqidun/jbig2 v1.1.1/go.mod h1:8QonVWtENmh2kc6l+leqeGl7psb79DWlHDkCpdChjfQ=
-github.com/xiaoqidun/pdfgo v0.0.0-20261002153346-125ae06f23bf h1:AjfoqpGGjeyWFH1ikxmZJ9n+hG1Qaqolaqlv9kGX91w=
+github.com/xiaoqidun/pdfgo v0.0.0-20261002164637-41541220b1c3 h1:mrWCBsxLuBf1sjeEK9r+1KZa5WpER5J3sDPVicajM1E=
-github.com/xiaoqidun/pdfgo v0.0.0-20261002153346-125ae06f23bf/go.mod h1:4Pf0JO0BEf1uzRY+uZjlMjN/OPn3PYa0YMi6cqPPTLQ=
+github.com/xiaoqidun/pdfgo v0.0.0-20261002164637-41541220b1c3/go.mod h1:4Pf0JO0BEf1uzRY+uZjlMjN/OPn3PYa0YMi6cqPPTLQ=
 github.com/xyproto/randomstring v1.0.5 h1:YtlWPoRdgMu3NZtP45drfy1GKoojuR7hmRcnhZqKjWU=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
 github.com/yuin/goldmark v1.8.5 h1:r6N5afV5qj/5S4UTch8agZHJ8UxNCMwX7WjkkJam2NA=

ofdgo_pdf.go

@@ -35,7 +35,8 @@ var ErrPDFPassword = pdfgo.ErrPassword
 // RendererOptions复用渲染器字体来源和后端配置，Backends优先于其中的后端设置
 // RasterDPI指定局部透明效果合成精度，0沿用渲染器DPI，默认300dpi，Strict禁用局部合成
 // OnProgress按open、pages、convert及write.*阶段报告进度，total为0表示总量未知
-// ResolveFile读取PDF引用的外部媒体和附件，默认不访问网络或本地路径
+// ResolveFile读取PDF引用的外部媒体、附件和页面，默认不访问网络或本地路径
+// ResolveReference可提供已解密的引用页面，目标阅读器由调用方维护
 type PDFImportOptions struct {
 	Password         []byte
 	PasswordUTF8     bool
@@ -46,6 +47,7 @@ type PDFImportOptions struct {
 	Strict           bool
 	RasterDPI        float64
 	ResolveFile      pdfgo.FileResolver
+	ResolveReference pdfgo.ReferenceResolver
 }
 
 // PDFImportReport 汇总转换页数、对象数、链接数和转换警告
@@ -91,6 +93,10 @@ type pdfImporter struct {
 	compositeSpace   *pdfgo.ColorSpace
 	annotationData   []byte
 	resolveFile      pdfgo.FileResolver
+	resolveReference pdfgo.ReferenceResolver
+	referenceReaders map[[32]byte]*pdfgo.Reader
+	referenceStreams map[*pdfgo.Stream]*pdfgo.Reader
+	referencePages   map[pdfReferencePageKey]*pdfgo.Page
 	halftoneWarnings map[*pdfgo.Halftone]bool
 	transferBackdrop bool
 }
@@ -137,6 +143,11 @@ func ImportPDF(ctx context.Context, source io.ReaderAt, size int64, options PDFI
 	importer.report.Warnings = diagnostics
 	importer.pageIndexes = make(map[pdfgo.Reference]int)
 	importer.resolveFile = options.ResolveFile
+	importer.resolveReference = options.ResolveReference
+	importer.referenceReaders = make(map[[32]byte]*pdfgo.Reader)
+	importer.referenceStreams = make(map[*pdfgo.Stream]*pdfgo.Reader)
+	importer.referencePages = make(map[pdfReferencePageKey]*pdfgo.Page)
+	defer importer.closeReferenceReaders()
 	importer.halftoneWarnings = make(map[*pdfgo.Halftone]bool)
 	if security := reader.Encryption(); security != nil && !security.Owner && security.Permissions&0xf3c != 0xf3c {
 		if options.Strict {
@@ -657,7 +668,7 @@ func (p *pdfImporter) tilingPattern(source *pdfgo.TilingPattern, base pdfgo.Pain
 	cell.matrix = pdfgo.Matrix{unit, 0, 0, -unit, -box.XMin * unit, box.YMax * unit}
 	cell.pageWidth, cell.pageHeight = width*unit, height*unit
 	cell.objects, cell.pendingPath = nil, nil
-	visitor := pdfgo.Visitor{Path: cell.path, Text: cell.text, Image: cell.image}
+	visitor := pdfgo.Visitor{Path: cell.path, Text: cell.text, Image: cell.image, Reference: p.referencePage}
 	visitor.Group = func(mark pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error {
 		return cell.group(mark, walk, visitor)
 	}

ofdgo_pdf_composite.go

@@ -245,7 +245,7 @@ func (p *pdfImporter) collectCompositeNodes(walk func(pdfgo.Visitor) error) ([]p
 	var collect func(func(pdfgo.Visitor) error) ([]pdfCompositeNode, error)
 	collect = func(walk func(pdfgo.Visitor) error) ([]pdfCompositeNode, error) {
 		var nodes []pdfCompositeNode
-		v := pdfgo.Visitor{Warning: p.warning}
+		v := pdfgo.Visitor{Warning: p.warning, Reference: p.referencePage}
 		v.Path = func(mark pdfgo.PathMark) error {
 			if err := p.halftone(mark.Style); err != nil {
 				return err

ofdgo_pdf_group.go

@@ -93,6 +93,8 @@ func pdfOpaqueVisitor(visitor pdfgo.Visitor) pdfgo.Visitor {
 		return nil
 	}
 	v := pdfgo.Visitor{
+		Reference:       visitor.Reference,
+		OptionalContent: visitor.OptionalContent,
 		Path:            func(m pdfgo.PathMark) error { return check(m.Style, m.Fill, m.Stroke) },
 		Text: func(m pdfgo.TextMark) error {
 			return check(m.Style, m.Mode%4 == 0 || m.Mode%4 == 2, m.Mode%4 == 1 || m.Mode%4 == 2)
@@ -134,6 +136,8 @@ func (p *pdfImporter) groupPaths(mark pdfgo.GroupMark, walk func(pdfgo.Visitor)
 	opaque := true
 	scale := math.Hypot(p.matrix[0], p.matrix[1])
 	collect := pdfgo.Visitor{
+		Reference:       visitor.Reference,
+		OptionalContent: visitor.OptionalContent,
 		Warning:         visitor.Warning,
 		Text:            func(pdfgo.TextMark) error { return errPDFGroupRaster },
 		Image:           func(pdfgo.ImageMark) error { return errPDFGroupRaster },
@@ -297,7 +301,7 @@ func (p *pdfImporter) rasterGroup(mark pdfgo.GroupMark, walk func(pdfgo.Visitor)
 // visitor 绑定当前导入器的图元与透明组访问函数
 // 返回: pdfgo.Visitor 页面访问器
 func (p *pdfImporter) visitor() pdfgo.Visitor {
-	v := pdfgo.Visitor{Path: p.path, Text: p.text, Image: p.image, Warning: p.warning}
+	v := pdfgo.Visitor{Path: p.path, Text: p.text, Image: p.image, Warning: p.warning, Reference: p.referencePage}
 	v.Group = func(mark pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error { return p.group(mark, walk, v) }
 	return v
 }

ofdgo_pdf_object.go

@@ -188,7 +188,7 @@ func (p *pdfImporter) text(mark pdfgo.TextMark) error {
 		if err := p.flushPath(); err != nil {
 			return err
 		}
-		visitor := pdfgo.Visitor{Path: p.path, Image: p.image, Warning: p.warning}
+		visitor := pdfgo.Visitor{Path: p.path, Image: p.image, Warning: p.warning, Reference: p.referencePage}
 		visitor.Group = func(group pdfgo.GroupMark, walk func(pdfgo.Visitor) error) error {
 			return p.group(group, walk, visitor)
 		}

ofdgo_pdf_reference.go

@@ -0,0 +1,105 @@
+// Copyright 2025-2026 肖其顿 (XIAO QI DUN)
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ofdgo
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha256"
+	"errors"
+	"fmt"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// pdfReferencePageKey 区分目标文档、索引和文本标签，避免重复遍历页面树
+type pdfReferencePageKey struct {
+	reader  *pdfgo.Reader
+	index   int64
+	label   string
+	labeled bool
+}
+
+// referencePage 解析引用目标，目标不可用时按PDF标准保留代理内容
+// 入参: ctx 取消上下文, source 来源文档, reference 引用目标
+// 返回: *pdfgo.Page 目标页面，不可用时为空, error 取消或调用方解析错误
+func (p *pdfImporter) referencePage(ctx context.Context, source *pdfgo.Reader, reference pdfgo.ReferenceXObject) (*pdfgo.Page, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	if p.resolveReference != nil {
+		return p.resolveReference(ctx, source, reference)
+	}
+	reader := p.referenceStreams[reference.File.Embedded]
+	if reader == nil {
+		if reference.File.Embedded == nil && p.resolveFile == nil {
+			return p.referenceProxy(ctx, fmt.Errorf("external reference file unavailable"))
+		}
+		data, err := source.ReadFileData(ctx, reference.File, p.resolveFile)
+		if err != nil {
+			return p.referenceProxy(ctx, err)
+		}
+		key := sha256.Sum256(data)
+		reader = p.referenceReaders[key]
+		if reader == nil {
+			reader, err = pdfgo.NewReaderWithOptions(bytes.NewReader(data), int64(len(data)), pdfgo.ReaderOptions{Warning: p.warning})
+			if err != nil {
+				return p.referenceProxy(ctx, err)
+			}
+			p.referenceReaders[key] = reader
+		}
+		if reference.File.Embedded != nil {
+			p.referenceStreams[reference.File.Embedded] = reader
+		}
+	}
+	key := pdfReferencePageKey{reader: reader, index: reference.PageIndex}
+	if reference.PageLabel != nil {
+		key.index, key.label, key.labeled = 0, *reference.PageLabel, true
+	}
+	if page := p.referencePages[key]; page != nil {
+		return page, ctx.Err()
+	}
+	page, err := reader.ResolveReferencePage(ctx, reference)
+	if err != nil {
+		return p.referenceProxy(ctx, err)
+	}
+	p.referencePages[key] = page
+	return page, ctx.Err()
+}
+
+// referenceProxy 记录目标不可用原因，不将合法的代理绘制视为转换失败
+// 入参: ctx 取消上下文, cause 目标不可用原因
+// 返回: *pdfgo.Page 空目标, error 取消错误
+func (p *pdfImporter) referenceProxy(ctx context.Context, cause error) (*pdfgo.Page, error) {
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	if errors.Is(cause, context.Canceled) || errors.Is(cause, context.DeadlineExceeded) {
+		return nil, cause
+	}
+	if p.warning != nil {
+		p.warning(pdfgo.Diagnostic{Message: "reference XObject proxy retained: " + cause.Error()})
+	}
+	return nil, nil
+}
+
+// closeReferenceReaders 释放本次转换打开的引用文档，不关闭调用方提供的阅读器
+func (p *pdfImporter) closeReferenceReaders() {
+	for _, reader := range p.referenceReaders {
+		reader.Close()
+	}
+	p.referenceReaders, p.referenceStreams = nil, nil
+	p.referencePages = nil
+}