Widget _buildImageMiddleOnlyImage(BuildContext context) {
    return TDButton(
      text: '图片居中-纯图片',
      size: TDButtonSize.large,
      type: TDButtonType.outline,
      theme: TDButtonTheme.primary,
      onTap: () {
        showGeneralDialog(
          context: context,
          pageBuilder: (BuildContext buildContext, Animation<double> animation,
              Animation<double> secondaryAnimation) {
            return TDImageDialog(
              image: _demoImage,
              imagePosition: TDDialogImagePosition.middle,
            );
          },
        );
      },
    );
  }