namespace PostViewer

{

    using System.Collections.ObjectModel;

    using System.ComponentModel;

    /// <summary>

    /// 数据类型ViewModel.

    /// </summary>

    public class VmTviDataType : ITreeItem

    {

        private bool mIsExpanded = true;

        private bool mIsSelected;

        /// <summary>

        /// Initializes a new instance of the <see cref="VmTviDataType"/> class.

        /// </summary>

        /// <param name="type">类型.</param>

        public VmTviDataType()

        {

            this.TviDataList = new ObservableCollection<VmTviData>();

        }

        /// <inheritdoc/>

        public event PropertyChangedEventHandler PropertyChanged;

        /// <summary>

        /// Gets or sets 元素名称.

        /// </summary>

        public string Header { get; protected set; }

        /// <summary>

        /// Gets or sets a value indicating whether Treeviewitem 展开.

        /// </summary>

        public bool IsExpanded

        {

            get

            {

                return this.mIsExpanded;

            }

            set

            {

                if (value != this.mIsExpanded)

                {

                    this.mIsExpanded = value;

                    this.OnPropertyChanged("IsExpanded");

                }

            }

        }

        /// <summary>

        /// Gets or sets a value indicating whether Treeviewitem 选中.

        /// </summary>

        public bool IsSelected

        {

            get

            {

                return this.mIsSelected;

            }

            set

            {

                if (value != this.mIsSelected)

                {

                    this.mIsSelected = value;

                    this.OnPropertyChanged("IsSelected");

                }

            }

        }

        /// <summary>

        /// Gets or sets 数据集合.

        /// </summary>

        public ObservableCollection<VmTviData> TviDataList { get; set; }

        /// <summary>

        /// 属性变更事件处理.

        /// </summary>

        /// <param name="v">属性名称.</param>

        protected void OnPropertyChanged(string v)

        {

            this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(v));

        }

    }

}

// <copyright file="ITreeItem.cs" company="Xtech">

// Copyright (c) Xtech. All rights reserved.

// </copyright>

namespace PostViewer

{

    using System.ComponentModel;

    /// <summary>

    /// 树形控件接口.

    /// </summary>

    public interface ITreeItem : INotifyPropertyChanged

    {

        /// <summary>

        /// Gets or sets a value indicating whether 是否选中.

        /// </summary>

        bool IsSelected { get; set; }

        /// <summary>

        /// Gets or sets a value indicating whether 是否展开.

        /// </summary>

        bool IsExpanded { get; set; }

        /// <summary>

        /// Gets 元素显示名称.

        /// </summary>

        string Header { get; }

    }

}

<UserControl x:Class="PostViewer.UcProjectTree"

             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

             xmlns:local="clr-namespace:PostViewer"

             mc:Ignorable="d"

             d:DesignHeight="600" d:DesignWidth="300">

    <Grid>

        <TreeView ItemsSource="{Binding TviProjectTypes}">

            <TreeView.ItemContainerStyle>

                <Style TargetType="{x:Type TreeViewItem}">

                    <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />

                    <Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />

                    <Setter Property="HorizontalContentAlignment" Value="Center" />

                    <Setter Property="VerticalContentAlignment" Value="Center" />

                    <Setter Property="FontWeight" Value="Normal" />

                    <Style.Triggers>

                        <Trigger Property="IsSelected" Value="True" >

                            <Setter Property="FontWeight" Value="Bold" />

                        </Trigger>

                    </Style.Triggers>

                </Style>

            </TreeView.ItemContainerStyle>

            <TreeView.Resources>

                <HierarchicalDataTemplate DataType="{x:Type local:VmTviProjectType}" ItemsSource="{Binding TviDataTypes}">

                    <StackPanel Orientation="Horizontal" Margin="0 2 5 0">

                        <TextBlock Text="{Binding Header}"/>

                    </StackPanel>

                </HierarchicalDataTemplate>

                <HierarchicalDataTemplate DataType="{x:Type local:VmTviDataType}" ItemsSource="{Binding TviDataList}">

                    <StackPanel Orientation="Horizontal" Margin="0 2 5 0">

                        <TextBlock Text="{Binding Header}" />

                    </StackPanel>

                </HierarchicalDataTemplate>

                <HierarchicalDataTemplate DataType="{x:Type local:VmTviData}">

                    <StackPanel Orientation="Horizontal" Margin="0 2 5 0">

                        <Image Width="15" Height="15" Margin="0, 1, 0 ,0" Source="/PostViewer;component/Resources/tree_blue.png" />

                        <TextBlock Text="{Binding Header}" />

                    </StackPanel>

                </HierarchicalDataTemplate>

            </TreeView.Resources>

        </TreeView>

    </Grid>

</UserControl>