feat(能力完善): 完善转换保真，修复交互缺陷

ofdgo_renderer_pdf_media.go

@@ -0,0 +1,69 @@
+// 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 (
+	"context"
+	"io"
+	"maps"
+	"path"
+	"slices"
+
+	"github.com/xiaoqidun/pdfgo"
+)
+
+// mediaFile 复用同一包内文件的输出说明，不合并播放资源及窗口
+// 入参: media 音视频资源
+// 返回: *pdfgo.FileSpecification 待读取的共享文件
+func (n *pdfNavigation) mediaFile(media MultiMedia) *pdfgo.FileSpecification {
+	name := n.source.ResPath(media.MediaFile)
+	if file := n.mediaFiles[name]; file != nil {
+		return file
+	}
+	file := &pdfgo.FileSpecification{Name: path.Base(name)}
+	if n.mediaFiles == nil {
+		n.mediaFiles = make(map[string]*pdfgo.FileSpecification)
+	}
+	n.mediaFiles[name] = file
+	return file
+}
+
+// loadMediaFiles 按需读取原始媒体，独立播放资源共用的文件只读取一次
+// 入参: ctx 取消上下文, files 媒体资源及输出文件
+// 返回: error 资源读取或取消错误
+func (n *pdfNavigation) loadMediaFiles(ctx context.Context, files map[string]*pdfgo.FileSpecification) error {
+	for _, id := range slices.Sorted(maps.Keys(files)) {
+		if err := ctx.Err(); err != nil {
+			return err
+		}
+		if files[id].Embedded != nil {
+			continue
+		}
+		input, err := n.source.OpenMedia(id)
+		if err != nil {
+			return err
+		}
+		data, err := io.ReadAll(imageInput{ReadCloser: input, context: ctx})
+		closeErr := input.Close()
+		if err != nil {
+			return err
+		}
+		if closeErr != nil {
+			return closeErr
+		}
+		files[id].Embedded = &pdfgo.Stream{Data: data}
+	}
+	return ctx.Err()
+}