amap_map/example/lib/widgets/toast.dart

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import 'package:flutter/material.dart';
//Toast 显示位置控制
enum ToastPostion {
top,
center,
bottom,
}
class Toast {
// toast靠它加到屏幕上
static OverlayEntry? _overlayEntry;
// toast是否正在showing
static bool _showing = false;
// 开启一个新toast的当前时间用于对比是否已经展示了足够时间
static DateTime? _startedTime;
// 提示内容
static String? _msg;
// toast显示时间
static int _showTime = 10;
// 背景颜色
static Color? _bgColor;
// 文本颜色
static Color? _textColor;
// 文字大小
static double? _textSize;
// 显示位置
static ToastPostion? _toastPosition;
// 左右边距
static double? _pdHorizontal;
// 上下边距
static double? _pdVertical;
static void toast(
BuildContext context, {
//显示的文本
String? msg,
//显示的时间 单位毫秒
int showTime = 1000,
//显示的背景
Color bgColor = Colors.black,
//显示的文本颜色
Color textColor = Colors.white,
//显示的文字大小
double textSize = 14.0,
//显示的位置
ToastPostion position = ToastPostion.center,
//文字水平方向的内边距
double pdHorizontal = 20.0,
//文字垂直方向的内边距
double pdVertical = 10.0,
}) async {
assert(msg != null);
_msg = msg;
_startedTime = DateTime.now();
_showTime = showTime;
_bgColor = bgColor;
_textColor = textColor;
_textSize = textSize;
_toastPosition = position;
_pdHorizontal = pdHorizontal;
_pdVertical = pdVertical;
//获取OverlayState
OverlayState overlayState = Overlay.of(context)!;
_showing = true;
if (_overlayEntry == null) {
//OverlayEntry负责构建布局
//通过OverlayEntry将构建的布局插入到整个布局的最上层
_overlayEntry = OverlayEntry(
builder: (BuildContext context) => Positioned(
//top值可以改变这个值来改变toast在屏幕中的位置
top: buildToastPosition(context),
child: Container(
alignment: Alignment.center,
width: MediaQuery.of(context).size.width,
child: Padding(
padding: EdgeInsets.symmetric(horizontal: 40.0),
child: AnimatedOpacity(
opacity: _showing ? 1.0 : 0.0, //目标透明度
duration: _showing
? Duration(milliseconds: 100)
: Duration(milliseconds: 400),
child: _buildToastWidget(),
),
)),
));
//插入到整个布局的最上层
overlayState.insert(_overlayEntry!);
} else {
//重新绘制UI类似setState
_overlayEntry!.markNeedsBuild();
}
// 等待时间
await Future.delayed(Duration(milliseconds: _showTime));
//2秒后 到底消失不消失
if (DateTime.now().difference(_startedTime!).inMilliseconds >= _showTime) {
_showing = false;
_overlayEntry!.markNeedsBuild();
await Future.delayed(Duration(milliseconds: 400));
_overlayEntry!.remove();
_overlayEntry = null;
}
}
//toast绘制
static _buildToastWidget() {
return Center(
child: Card(
color: _bgColor,
child: Padding(
padding: EdgeInsets.symmetric(
horizontal: _pdHorizontal!, vertical: _pdVertical!),
child: Text(
_msg!,
style: TextStyle(
fontSize: _textSize,
color: _textColor,
),
),
),
),
);
}
// 设置toast位置
static buildToastPosition(context) {
var backResult;
if (_toastPosition == ToastPostion.top) {
backResult = MediaQuery.of(context).size.height * 1 / 4;
} else if (_toastPosition == ToastPostion.center) {
backResult = MediaQuery.of(context).size.height * 2 / 5;
} else {
backResult = MediaQuery.of(context).size.height * 3 / 4;
}
return backResult;
}
}