mirror of
https://github.com/xiaoqidun/ofdgo.git
synced 2026-10-29 08:46:55 +08:00
106 lines
3.5 KiB
Go
106 lines
3.5 KiB
Go
// 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
|
|
}
|