import 'dart:ui';

MediaQueryData.fromWindow(window).padding.top

Scaffold(

        appBar: PreferredSize(

        child: AppBar(

        ),

        preferredSize: Size.fromHeight(screenSize.height * 0.07))

);

/// The height of the toolbar component of the [AppBar].

const double kToolbarHeight = 56.0;

/// The height of the bottom navigation bar.

const double kBottomNavigationBarHeight = 56.0;

/// The height of a tab bar containing text.

const double kTextTabBarHeight = 48.0;

/// The amount of time theme change animations should last.

const Duration kThemeChangeDuration = Duration(milliseconds: );

/// The radius of a circular material ink response in logical pixels.

const double kRadialReactionRadius = 20.0;

/// The amount of time a circular material ink response should take to expand to its full size.

const Duration kRadialReactionDuration = Duration(milliseconds: );

/// The value of the alpha channel to use when drawing a circular material ink response.

const int kRadialReactionAlpha = 0x1F;

/// The duration of the horizontal scroll animation that occurs when a tab is tapped.

const Duration kTabScrollDuration = Duration(milliseconds: );

/// The horizontal padding included by [Tab]s.

const EdgeInsets kTabLabelPadding = EdgeInsets.symmetric(horizontal: 16.0);

/// The padding added around material list items.

const EdgeInsets kMaterialListPadding = EdgeInsets.symmetric(vertical: 8.0);

var now = new DateTime.now();

print(now.millisecondsSinceEpoch); //单位毫秒，13位时间戳

/** 或者 */

/** 返回当前时间戳 */

  static int currentTimeMillis() {

    return new DateTime.now().millisecondsSinceEpoch;

  }

var now = new DateTime.now();

var a=now.millisecondsSinceEpoch;  //时间戳

print(DateTime.fromMillisecondsSinceEpoch(a));

.首先先需要对控件进行渲染

初始化GlobalKey ：GlobalKey anchorKey = GlobalKey();

.在需要测量的控件的下面添加key：

child: Text("点击弹出悬浮窗",

  style: TextStyle(fontSize: ),

  key: anchorKey

),

.获取控件的坐标：

RenderBox renderBox = anchorKey.currentContext.findRenderObject();

var offset =  renderBox.localToGlobal(Offset.zero);

控件的横坐标：offset.dx

控件的纵坐标：offset.dy

如果想获得控件正下方的坐标：

 RenderBox renderBox = anchorKey.currentContext.findRenderObject();

 var offset =  renderBox.localToGlobal(Offset(0.0, renderBox.size.height));

   控件下方的横坐标：offset.dx

   控件下方的纵坐标：offset.dy

.获取控件的大小：

RenderBox renderBox = anchorKey.currentContext.findRenderObject();

final size = renderBox.size;

import 'dart:convert';

import 'package:convert/convert.dart';

import 'package:crypto/crypto.dart';

// md5 加密

String generateMd5(String data) {

  var content = new Utf8Encoder().convert(data);

  var digest = md5.convert(content);

  // 这里其实就是 digest.toString()

  return hex.encode(digest.bytes);

}