onwillpop

@override
  Widget build(BuildContext context) {
    return WillPopScope(
      child: Container(
        child: Row(
          mainAxisAlignment: MainAxisAlignment.end,
          children: <Widget>[
            isWIllPop
                ? Material(
                    child: new Container(
                      margin: new EdgeInsets.symmetric(horizontal: 1.0),
                      child: FadeInImage.assetNetwork(
                        placeholder: 'animation/loading.gif',
                        image: 'BASE_URL/pictureUrl',
                        width: 50,
                        height: 200,
                      ),
                    ),
                    color: Colors.white,
                  )
                : Material(
                    child: new Container(
                      margin: new EdgeInsets.symmetric(horizontal: 1.0),
                      child: FadeInImage.assetNetwork(
                        placeholder: 'animation/loading.gif',
                        image: 'BASE_URL/pictureUrl',
                        width: 50,
                        height: 50,
                      ),
                    ),
                    color: Colors.white,
                  ),
            Material(
              child: new Container(
                margin: new EdgeInsets.symmetric(horizontal: 1.0),
                child: new IconButton(
                  icon: new Icon(Icons.add_circle),
                  onPressed: () {},
                ),
              ),
              color: Colors.white,
            ),
            // Edit text
            Flexible(
              child: Container(
                child: TextField(
                  style: TextStyle(color: Colors.blue, fontSize: 15.0),
                  decoration: InputDecoration.collapsed(
                    hintText: 'Type your message...',
                    hintStyle: TextStyle(color: Colors.green),
                  ),
                ),
              ),
            ),

            // Button send message
            Material(
              child: new Container(
                margin: new EdgeInsets.symmetric(horizontal: 8.0),
                child: new IconButton(
                  icon: new Icon(Icons.send),
                  onPressed: () {},
                  color: Colors.blue,
                ),
              ),
              color: Colors.white,
            ),
          ],
        ),
        width: double.infinity,
        height: 50.0,
        decoration: new BoxDecoration(
            border: new Border(
                top: new BorderSide(color: Colors.green, width: 0.5)),
            color: Colors.white),
      ),
      onWillPop: onBackPress,
    );
  }

  Future<bool> onBackPress() {
    setState(() {
      isWIllPop = true;
    });
    return Future.value(true);
  }