出现屏幕键盘时隐藏 FAB

Question

在Flutter中，如何让FAB button出现屏幕键盘时隐藏？

FAB 按钮在屏幕键盘上显示时会覆盖其他元素。

Answer 1

您可以通过使用 viewInsets 检查键盘可见性并根据它隐藏 fab 来实现它。

示例：

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,
    );
  }
}

Answer 2

用 Visibility 小部件包装您的 FloatingActionButton 并用 bool 值控制可见性。

片段：

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

此解决方案还消除了按钮消失和出现时的动画。

确保 class extends StatefulWidget 并且您已经为它创建了一个状态

Answer 3

为了将来参考，这是一个遵循 https://github.com/flutter/flutter/issues/26100 基本思想的实现，但使用现有的 mixin 来减少怪癖和代码：

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);
  }
}

然后您可以像 floatingActionButtonLocation: const FixedCenterDockedFabLocation(), 一样简单地使用它（不要忘记 const ;)）。

请随意使用此代码，不受限制或注明出处。

Answer 4

希望这就是您要找的

Scaffold(resizeToAvoidBottomInset: false)

Answer 5

Widget build(context) {
  return Scaffold(
    resizeToAvoidBottomInset: false,
    appBar: // ...
    body: // ...
    floatingActionButton: Visibility(
      child: // your FloatingActionButton
    ),
  );
}

出现屏幕键盘时隐藏 FAB

Hide FAB when onscreen keyboard appear

material-design

floating-action-button

flutter