feat(媒体支持): 完善媒体播放与资源释放

ofdgo_media.go

@@ -0,0 +1,45 @@
+// 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 (
+	"fmt"
+	"io"
+)
+
+// Media 获取已加载的音视频资源，页面资源须先读取所属页面
+// 入参: id 资源标识
+// 返回: MultiMedia 资源信息, error 资源缺失或类型错误
+func (r *Reader) Media(id string) (MultiMedia, error) {
+	if _, err := r.Doc(); err != nil {
+		return MultiMedia{}, err
+	}
+	media, ok := r.mediaCache[id]
+	if !ok || media.Type != "Audio" && media.Type != "Video" {
+		return MultiMedia{}, fmt.Errorf("audio or video resource %q is unavailable", id)
+	}
+	return media, nil
+}
+
+// OpenMedia 打开文档内音视频原始数据，不解码或执行播放
+// 入参: id 资源标识
+// 返回: io.ReadCloser 数据流，由调用方关闭, error 资源或文件读取错误
+func (r *Reader) OpenMedia(id string) (io.ReadCloser, error) {
+	media, err := r.Media(id)
+	if err != nil {
+		return nil, err
+	}
+	return r.openFile(media.MediaFile)
+}