Visibility 显隐组件

控制一个组件显示或隐藏 可设置隐藏后的占位组件。与其功能相似的由OffStage组件。

相关组件

Offstage

根据visible控制内部子组件的显隐情况

【visible】 : 是否显示 【bool】
【child】: 孩子 【Widget】
默认孩子隐藏时会失去原来所在区域。

import 'package:flutter/material.dart';
class CustomVisibility extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Wrap(
      spacing: 10,
      children: <Widget>[
        _buildVisibility(true),
        _buildVisibility(false),
      ],
    );
  }
  _buildVisibility(bool visible) {
    var box = Container(
      height: 30,
      width: 30,
      color: Colors.blue,
    );
    return Container(
      width: 150,
      height: 150 * 0.618,
      color: Colors.cyanAccent.withAlpha(33),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          box,
          Visibility(
              visible: visible,
              child: Container(
                alignment: Alignment.center,
                height: 80 * 0.618,
                width: 80,
                color: Colors.red,
                child: Text(
                  "visible\ntrue",
                  style: TextStyle(fontSize: 20),
                ),
              )),
          box,
        ],
      ),
    );
  }
}

replacement可在隐藏时进行占位

【replacement】 : 隐藏时的占位组件 【Widget】

import 'package:flutter/material.dart';
class ReplacementVisibility extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Wrap(
      spacing: 10,
      children: <Widget>[
        _buildVisibility(true),
        _buildVisibility(false),
      ],
    );
  }

  _buildVisibility(bool visible) {
    var box = Container(
      height: 30,
      width: 30,
      color: Colors.blue,
    );
    return Container(
      width: 150,
      height: 150 * 0.618,
      color: Colors.cyanAccent.withAlpha(33),
      child: Row(
        mainAxisAlignment: MainAxisAlignment.center,
        children: <Widget>[
          box,
          Visibility(
              visible: visible,
              replacement: Container(
                alignment: Alignment.center,
                height: 80 * 0.618,
                width: 80,
              ),
              child: Container(
                alignment: Alignment.center,
                height: 80 * 0.618,
                width: 80,
                color: Colors.red,
                child: Text(
                  "visible\ntrue",
                  style: TextStyle(fontSize: 20),
                ),
              )),
          box,
        ],
      ),
    );
  }
}