Hide FAB when onscreen keyboard appear

You can achieve it by checking for keyboard visibility using viewInsets and hide fab based on it.

Example:

import 'package:flutter/material.dart';void main() {  runApp(new MaterialApp(    title: "Example",    home: new FabHideOnKeyboard(),  ));}class FabHideOnKeyboard extends StatefulWidget {  @override  _FabHideOnKeyboardState createState() => new _FabHideOnKeyboardState();}class _FabHideOnKeyboardState extends State<FabHideOnKeyboard> {  @override  Widget build(BuildContext context) {    final bool showFab = MediaQuery.of(context).viewInsets.bottom==0.0;    return Scaffold(      resizeToAvoidBottomPadding: true,      body:Container(        alignment: Alignment.center,        child: Column(          mainAxisAlignment: MainAxisAlignment.center,          children: <Widget>[            Text("TextField:"),            TextField()          ],        ),      ),      floatingActionButton: showFab?Icon(Icons.add):null,    );  }}

Hope that helped!

Wrap your FloatingActionButton with a Visibility widget and control the visibility with a bool value.

Widget build(context) {  bool keyboardIsOpen = MediaQuery.of(context).viewInsets.bottom != 0;  return Scaffold(    body: // ...    floatingActionButton: Visibility(      visible: !keyboardIsOpen,      child: // your FloatingActionButton    ),  );}

This solution also gets rid of the animation when the button disappears and appears.

Be sure that the class extends StatefulWidget and you have created a state for it

For future reference, this is an implementation following the basic idea from https://github.com/flutter/flutter/issues/26100 but using already existing mixins to reduce quirks and code:

class FixedCenterDockedFabLocation extends StandardFabLocation    with FabCenterOffsetX, FabDockedOffsetY {  const FixedCenterDockedFabLocation();  @override  String toString() => 'FloatingActionButtonLocation.fixedCenterDocked';  @override  double getOffsetY(      ScaffoldPrelayoutGeometry scaffoldGeometry, double adjustment) {    final double contentBottom = scaffoldGeometry.contentBottom;    final double bottomMinInset = scaffoldGeometry.minInsets.bottom;    if (bottomMinInset > 0) {      // Hide if there's a keyboard      return contentBottom;    }    return super.getOffsetY(scaffoldGeometry, adjustment);  }}

You can then use it as simple as floatingActionButtonLocation: const FixedCenterDockedFabLocation(), (don't forget the const ;)).

Feel free to use this code without limitations or attribution.