HarmonyOS 鸿蒙Next文件中数学符号丢失不显示

开发者您好， 使用文件管理自带预览和文件预览服务打开类似数学试卷，都未复现问题。请说明您的具体使用场景，DevEco Studio版本和手机版本，并提供docx文件，方便问题分析复现。用于复现问题的文件预览服务demo如下：

// Index.ets
import { filePreview } from '@kit.PreviewKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { fileIo as fs } from '@kit.CoreFileKit';
import { common } from '@kit.AbilityKit';
import fileUri from '@ohos.file.fileuri';

function myRawfileCopy(filetype: string, context: common.UIAbilityContext) {
  context.resourceManager.getRawFileContent(filetype, (err: BusinessError, data: Uint8Array) => {
    if (err != null) {
      console.info('open file failed: ' + err.message);
    } else {
      let buffer = data.buffer;
      console.info('size = ' + buffer.byteLength);
      let sandboxPath = context.cacheDir;
      console.info('myRawfileCopy path' + sandboxPath);
      let file: fs.File = null!;
      try {
        file = fs.openSync(context.cacheDir + '/' + filetype, fs.OpenMode.CREATE | fs.OpenMode.READ_WRITE);
        // 拷贝文件到沙箱
        fs.writeSync(file.fd, buffer);
        console.info('myRawfileCopy success');
      } catch (err) {
        console.info('myRawfileCopy error');
      } finally {
        fs.close(file.fd);
      }
    }
  });
}

export function viewFile(fileName: string, filePath: string, uiContext: UIContext) {
  let context = uiContext.getHostContext() as common.UIAbilityContext;
  let promptAction = uiContext.getPromptAction();
  // 将沙箱路径转换为uri
  let uri = fileUri.getUriFromPath(filePath);
  // 根据文件的uri判断文件是否可预览 传入支持的文件类型且项目存在时会返回true
  filePreview.canPreview(context, uri).then((result) => {
    // true:可以预览
    if (result === true) {
      let fileNames: string[] = fileName.split('.');
      let type = fileNames[fileNames.length-1];
      let mType: string = '';
      switch (type) {
        case 'pdf': {
          mType = 'application/pdf';
          break;
        }
        case 'txt': {
          mType = 'text/plain';
          break;
        }
        case 'png': {
          mType = 'image/png';
          break;
        }
        case 'jpg': {
          mType = 'image/jpeg';
          break;
        }
        case 'docx': {
          mType = 'application/vnd.openxmlformats-officedocument.wordprocessingml.document';
          break;
        }
        case 'xlsx': {
          mType = 'application/vnd.ms-excel';
          break;
        }
        default: {
          console.error('Type Is Not Support');
          promptAction.showToast({
            message: '不支持类型'
          });
          return;
        }
      }
      let fileInfo: filePreview.PreviewInfo = {
        // 文件预览信息，包含了文件标题名、uri以及文件类型（mimeType）
        title: fileName,
        uri: uri,
        mimeType: mType // 文件(夹)的媒体资源类型，如text/plain
      };
      filePreview.openPreview(context, fileInfo).then(() => {
        console.info('openPreview success');
      }).catch((err: BusinessError) => {
        console.error('openPreview failed, err = %s', err.message);
      });
    } else {
      promptAction.showToast({
        // 不可预览
        message: '不可预览'
      });
      console.info('openPreview failed, err = canPreview false');
    }
  }).catch((err: BusinessError) => {
    console.error('canPreview failed, err = %s', err.message);
  });
}

function viewTXT(uiContext: UIContext) {
  let context = uiContext.getHostContext() as common.UIAbilityContext;
  try {
    // 文件名称、文件所在的沙箱路径
    let fileName = 'sample.docx'; // sample.docx在rawfile路径下
    let filePath = context.cacheDir + '/' + fileName;
    myRawfileCopy(fileName, context as common.UIAbilityContext);
    viewFile(fileName, filePath, uiContext);
  } catch (error) {
    let err: BusinessError = error as BusinessError;
    console.error(`Invoke downloadTask failed-----, code is ${err.code}, message is ${err.message}`);
  }
}

@Entry
@Component
struct Index {
  build() {
    Column() {
      Button('预览DOCX文件') // docx文件存放在rawfile路径下，首先将docx拷贝进沙箱目录，再预览沙箱文件
        .onClick(() => {
          viewTXT(this.getUIContext());
        });
    };
  }
}