wpf Expander 动画效果

WPF实现Expander折叠展开动画,从写Expander，改变样式，不再是默认样式。从写后样式华丽，也可以根据个人爱好，再从新看代码修改样式！

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Threading.Tasks;
using System.Windows;

namespace ExpanderTest
{
    /// 

    /// App.xaml 的交互逻辑
    /// 

    public partial class App : Application
    {
    }
}

 属性            大小     日期    时间   名称
----------- ---------  ---------- -----  ----
     目录           0  2016-01-12 21:34  ExpanderTest\
     目录           0  2016-01-12 21:34  ExpanderTest\.vs\
     目录           0  2017-12-09 10:41  ExpanderTest\.vs\ExpanderTest\
     目录           0  2016-01-12 21:34  ExpanderTest\.vs\ExpanderTest\v14\
     文件       49664  2016-01-12 21:47  ExpanderTest\.vs\ExpanderTest\v14\.suo
     目录           0  2017-12-09 10:41  ExpanderTest\.vs\ExpanderTest\v15\
     文件       58880  2017-12-09 13:01  ExpanderTest\.vs\ExpanderTest\v15\.suo
     目录           0  2017-12-09 13:02  ExpanderTest\.vs\ExpanderTest\v15\sqlite3\
     目录           0  2017-12-09 13:01  ExpanderTest\ExpanderTest\
     文件        1003  2016-01-12 21:34  ExpanderTest\ExpanderTest.sln
     文件         189  2016-01-12 21:34  ExpanderTest\ExpanderTest\App.config
     文件         378  2016-01-12 21:34  ExpanderTest\ExpanderTest\App.xaml
     文件         339  2016-01-12 21:34  ExpanderTest\ExpanderTest\App.xaml.cs
     目录           0  2017-12-09 12:55  ExpanderTest\ExpanderTest\bin\
     目录           0  2016-01-12 21:47  ExpanderTest\ExpanderTest\bin\Debug\
     文件       22016  2017-12-09 13:01  ExpanderTest\ExpanderTest\bin\Debug\ExpanderTest.exe
     文件         189  2016-01-12 21:34  ExpanderTest\ExpanderTest\bin\Debug\ExpanderTest.exe.config
     文件       26112  2017-12-09 13:01  ExpanderTest\ExpanderTest\bin\Debug\ExpanderTest.pdb
     文件       22696  2016-01-12 21:47  ExpanderTest\ExpanderTest\bin\Debug\ExpanderTest.vshost.exe
     文件         189  2016-01-12 21:34  ExpanderTest\ExpanderTest\bin\Debug\ExpanderTest.vshost.exe.config
     文件         490  2015-07-10 19:01  ExpanderTest\ExpanderTest\bin\Debug\ExpanderTest.vshost.exe.manifest
     目录           0  2017-12-09 12:55  ExpanderTest\ExpanderTest\bin\Release\
     文件        4656  2017-12-09 12:57  ExpanderTest\ExpanderTest\ExpanderTest.csproj
     文件        2892  2017-12-09 12:55  ExpanderTest\ExpanderTest\icon.png
     文件       18706  2017-12-09 13:01  ExpanderTest\ExpanderTest\MainWindow.xaml
     文件         658  2016-01-12 21:34  ExpanderTest\ExpanderTest\MainWindow.xaml.cs
     文件         656  2017-12-09 10:49  ExpanderTest\ExpanderTest\MultiplyConverter.cs
     目录           0  2016-01-12 21:34  ExpanderTest\ExpanderTest\obj\
     目录           0  2017-12-09 13:01  ExpanderTest\ExpanderTest\obj\Debug\
     文件        2337  2017-12-09 12:52  ExpanderTest\ExpanderTest\obj\Debug\App.g.cs
     文件        2337  2017-12-09 12:52  ExpanderTest\ExpanderTest\obj\Debug\App.g.i.cs
............此处省略30个文件信息