flutter Toast工具类

在项目中有这么个需求，在设置页中会有清理缓存功能，有缓存时显示清理缓存，清理完成后显示清理完成，直接上代码 

import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'dart:async';
import 'package:back_button_interceptor/back_button_interceptor.dart';
import 'package:funya/util/size_util.dart';const Color _bgColor = Color.fromRGBO(51, 51, 51, 0.8);
const Color _contentColor = Color.fromRGBO(255, 255, 255, 1);
const double _textFontSize = 14.0;
const double _radius = 12.0;
const double _imgWH = 30.0;
const int _time = 1;
enum _Orientation { horizontal, vertical }class ToastUtil {static Future showText(BuildContext context, {@required String msg,int closeTime = _time,}) {return _showToast(context: context, msg: msg, stopEvent: true, closeTime: closeTime);}static Future showSuccess(BuildContext context, {@required String msg,int closeTime = _time,}) {Widget img = Image.asset("assets/toast_sccuess.png", width: _imgWH);return _showToast(context: context,msg: msg,image: img,stopEvent: true,closeTime: closeTime);}static _HideCallback showLoadingText_iOS(BuildContext context, {String msg = "加载中...",}) {Widget img = Image.asset("assets/loading.gif", width: _imgWH);return _showJhToast(context: context,msg: msg,image: img,isLoading: false,stopEvent: true);}
}Future _showToast({@required BuildContext context,String msg,stopEvent = false,Widget image,int closeTime,_Orientation orientation = _Orientation.vertical}) {msg = msg;var hide = _showJhToast(context: context,msg: msg,isLoading: false,stopEvent: stopEvent,image: image,orientation: orientation);return Future.delayed(Duration(seconds: closeTime), () {hide();});
}typedef _HideCallback = Future Function();class JhToastWidget extends StatelessWidget {const JhToastWidget({Key key,@required this.msg,this.image,@required this.isLoading,@required this.stopEvent,@required this.orientation,}) : super(key: key);final bool stopEvent;final Widget image;final String msg;final bool isLoading;final _Orientation orientation;@overrideWidget build(BuildContext context) {SizeUtil.init(context, width: 375, height: 812, allowFontScaling: false);Widget topW;bool isHidden;if (this.isLoading == true) {isHidden = false;topW = CircularProgressIndicator(strokeWidth: 3.0,valueColor: AlwaysStoppedAnimation<Color>(_contentColor),);} else {isHidden = image == null ? true : false;topW = image;}var widget = Material(
//        color: Colors.yellow,color: Colors.transparent,child: Align(
//            alignment: Alignment.center,alignment: Alignment(0.0, -0.2), //中间往上一点child: Container(margin: const EdgeInsets.all(50.0),padding:EdgeInsets.symmetric(horizontal: 24.0.w, vertical: 16.0.w),decoration: BoxDecoration(color: _bgColor,borderRadius: BorderRadius.circular(_radius),),child: ClipRect(child: orientation == _Orientation.vertical? Column(mainAxisSize: MainAxisSize.min,children: <Widget>[Offstage(offstage: isHidden,child: Container(width: 40.0.w,height: 40.0.w,margin: EdgeInsets.only(bottom: 8.0.w),padding: EdgeInsets.all(4.0),child: topW,),),Text(msg,style: TextStyle(fontSize: _textFontSize,color: _contentColor),textAlign: TextAlign.center),],): Row(mainAxisSize: MainAxisSize.min,mainAxisAlignment: MainAxisAlignment.center,children: <Widget>[Offstage(offstage: isHidden,child: Container(width: 36.0.w,height: 36.0.w,margin: EdgeInsets.only(right: 8.0.w),padding: EdgeInsets.all(4.0),child: topW,),),Text(msg,style: TextStyle(fontSize: _textFontSize,color: _contentColor),textAlign: TextAlign.center),],),),)));return IgnorePointer(ignoring: !stopEvent,child: widget,);}
}int backButtonIndex = 2;_HideCallback _showJhToast({@required BuildContext context,@required String msg,Widget image,@required bool isLoading,bool stopEvent = false,_Orientation orientation = _Orientation.vertical,
}) {Completer<VoidCallback> result = Completer<VoidCallback>();var backButtonName = 'funya$backButtonIndex';BackButtonInterceptor.add((stopDefaultButtonEvent) {result.future.then((hide) {hide();});return true;}, zIndex: backButtonIndex, name: backButtonName);backButtonIndex++;var overlay = OverlayEntry(maintainState: true,builder: (_) => WillPopScope(onWillPop: () async {var hide = await result.future;hide();return false;},child: JhToastWidget(image: image,msg: msg,stopEvent: stopEvent,isLoading: isLoading,orientation: orientation,),));result.complete(() {if (overlay == null) {return;}overlay.remove();overlay = null;BackButtonInterceptor.removeByName(backButtonName);});Overlay.of(context).insert(overlay);return () async {var hide = await result.future;hide();};
}

使用方法：

 var hide = ToastUtil.showLoadingText_iOS(context, msg: "正在清理中...");Future.delayed(Duration(seconds: 2), () {ToastUtil.showSuccess(context, msg: '清理完成');hide();});