flutter 底部弹窗

                  showModalBottomSheet(
                      context: context,
                      builder: (BuildContext context) {
                        return Container(
                          color: Colors.transparent,
//                          height: 120,
                          child: new Column(
                            crossAxisAlignment: CrossAxisAlignment.center,
                            children: <Widget>[
                              Expanded(child:
                              Markdown(data: _markdownData))
                            ],
                          ),
                        );
                      });

调用上面方法即可