fis_lib_vid/lib/async_vid/shell/reader.dart

import 'dart:typed_data';

import 'package:fis_common/extensions/date.dart';
import 'package:fis_common/web/shell_api_hepler.dart';
import 'package:vid/us/vid_us_data_http_reader.dart';

import '../reader.dart';

class AsyncShellVidDataReader extends AsyncVidDataReaderBase {
  final int minChunkSize;
  late final String id =
      DateTime.now().format('MMddHHmmssSSS') + hashCode.toString();

  AsyncShellVidDataReader(
    String url, {
    DownloadCallback? downloadCallback,
    this.minChunkSize = 65536,
  }) : super(url, downloadCallback: downloadCallback);

  @override
  void close() {
    ShellApiHelper.call('cancelFetchVid', id);
  }

  @override
  void startDownload() async {
    final size = await getFileSize();
    // 获取到size即开始下载
    if (size == null) {
      setError(true, 'Get file size fail.');
    }
  }

  /// 接收分片数据
  void receiveChunk(Uint8List chunk) {
    appendChunk(chunk);
    final progress = downloadedSize / totalSize;
    updateProgress(progress);
  }

  Future<int?> getFileSize() async {
    final result = await ShellApiHelper.call(
      'fetchVid',
      {
        'Id': id,
        'Url': url,
        'MinChunkSize': minChunkSize,
      },
    );
    return result;
  }
}