HarmonyOS 顶部安全区域和底部安全区域的高度是多少，对应的单位是什么？

windowStage.loadContent('pages/Index', (err, data) => {  
  if (err.code) {  
    hilog.error(0x0000, 'testTag', 'Failed to load the content. Cause: %{public}s', JSON.stringify(err) ?? '');  
    return;  
  }  
  let windowClass: window.Window = windowStage.getMainWindowSync(); // 获取应用主窗口  
  let topAvoidArea = windowClass.getWindowAvoidArea(window.AvoidAreaType.TYPE_SYSTEM)  
  let bottomAvoidArea = windowClass.getWindowAvoidArea(window.AvoidAreaType.TYPE_NAVIGATION_INDICATOR)  
  let bottomRectHeight = px2vp(bottomAvoidArea.bottomRect.height)  
  let topRectHeight = px2vp(topAvoidArea.topRect.height)  
  AppStorage.setOrCreate('bottomRectHeight',bottomRectHeight)  
  AppStorage.setOrCreate('topRectHeight',topRectHeight)  
  let isLayoutFullScreen = true;  
  windowClass.setWindowLayoutFullScreen(isLayoutFullScreen)  
    .then(() => {  
      console.info('Succeeded in setting the window layout to full-screen mode.');  
    })  
    .catch((err: BusinessError) => {  
      console.error('Failed to set the window layout to full-screen mode. Cause:' + JSON.stringify(err));  
    });  
  hilog.info(0x0000, 'testTag', 'Succeeded in loading the content. Data: %{public}s', JSON.stringify(data) ?? '');  
});