MultiSelectComboBox(一)

1. MultiSelectComboBox.xaml

<UserControl x:Class="MultiSelectComboBox.MultiSelectComboBox"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             >
    <ComboBox
        x:Name="MultiSelectCombo" 
        SnapsToDevicePixels="True"
        OverridesDefaultStyle="True"
        ScrollViewer.HorizontalScrollBarVisibility="Auto"
        ScrollViewer.VerticalScrollBarVisibility="Auto"
        ScrollViewer.CanContentScroll="True"
        IsSynchronizedWithCurrentItem="True"
                           >
        <ComboBox.ItemTemplate>
            <DataTemplate>
                <CheckBox Content="{Binding Title}"
                          IsChecked="{Binding Path=IsSelected, Mode=TwoWay}"
                          Tag="{RelativeSource FindAncestor, AncestorType={x:Type ComboBox}}"
                          Click="CheckBox_Click"           />
            </DataTemplate>
        </ComboBox.ItemTemplate>
        <ComboBox.Template>
            <ControlTemplate TargetType="ComboBox">
                <Grid >
                    <ToggleButton
                        x:Name="ToggleButton"
                        Grid.Column="2"
                        IsChecked="{Binding Path=IsDropDownOpen,Mode=TwoWay,
                        RelativeSource={RelativeSource TemplatedParent}}"
                        Focusable="false"                          
                        ClickMode="Press" HorizontalContentAlignment="Left" >
                        <ToggleButton.Template>
                            <ControlTemplate>
                                <Grid>
                                    <Grid.ColumnDefinitions>
                                        <ColumnDefinition Width="*"/>
                                        <ColumnDefinition Width="18"/>
                                    </Grid.ColumnDefinitions>
                                    <Border
                  x:Name="Border"
                  Grid.ColumnSpan="2"
                  CornerRadius="2"
                  Background="White"
                  BorderBrush="Black"
                  BorderThickness="1,1,1,1" />
                                    <Border
                    x:Name="BorderComp"
                  Grid.Column="0"
                  CornerRadius="2"
                  Margin="1"
                 Background="White"
                  BorderBrush="Black"
                  BorderThickness="0,0,0,0" >
                                        <TextBlock Text="{Binding Path=Text,RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=UserControl}}"
                                               Background="White" Padding="3" />
                                    </Border>
                                    <Path
                  x:Name="Arrow"
                  Grid.Column="1"    
                  Fill="Black"
                  HorizontalAlignment="Center"
                  VerticalAlignment="Center"
                  Data="M 0 0 L 4 4 L 8 0 Z"/>
                                </Grid>
                            </ControlTemplate>
                        </ToggleButton.Template>
                         </ToggleButton>
                        <Popup
                        Name="Popup"
                        Placement="Bottom"                       
                        AllowsTransparency="True"
                        Focusable="False"  IsOpen="{TemplateBinding IsDropDownOpen}"
                        PopupAnimation="Slide">
                        <Grid
                                  Name="DropDown"
                                  SnapsToDevicePixels="True" 
                            MinWidth="{TemplateBinding ActualWidth}"
                                  MaxHeight="{TemplateBinding MaxDropDownHeight}">
                            <Border
                                    x:Name="DropDownBorder"
                                   BorderThickness="1" Background="White"
                                    BorderBrush="Black"/>
                            <ScrollViewer Margin="4,6,4,6" SnapsToDevicePixels="True" DataContext="{Binding}">
                                <StackPanel IsItemsHost="True" KeyboardNavigation.DirectionalNavigation="Contained" />
                            </ScrollViewer>
                        </Grid>
                    </Popup>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="HasItems" Value="false">
                        <Setter TargetName="DropDownBorder" Property="MinHeight" Value="95"/>
                    </Trigger>
                    <Trigger SourceName="Popup" Property="Popup.AllowsTransparency" Value="true">
                        <Setter TargetName="DropDownBorder" Property="CornerRadius" Value="4"/>
                        <Setter TargetName="DropDownBorder" Property="Margin" Value="0,2,0,0"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </ComboBox.Template>
    </ComboBox>
</UserControl>

2. MultiSelectComboBox.xaml.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;
using System.ComponentModel;

namespace MultiSelectComboBox
{
    /// <summary>
    /// Interaction logic for MultiSelectComboBox.xaml
    /// </summary>
    public partial class MultiSelectComboBox : UserControl
    {
        private ObservableCollection<Node> _nodeList;
        public MultiSelectComboBox()
        {
            InitializeComponent();
            _nodeList = new ObservableCollection<Node>();
        }

        #region Dependency Properties

        public static readonly DependencyProperty ItemsSourceProperty =
             DependencyProperty.Register("ItemsSource", typeof(Dictionary<string, object>), typeof(MultiSelectComboBox), new FrameworkPropertyMetadata(null,
        new PropertyChangedCallback(MultiSelectComboBox.OnItemsSourceChanged)));

        public static readonly DependencyProperty SelectedItemsProperty =
         DependencyProperty.Register("SelectedItems", typeof(Dictionary<string, object>), typeof(MultiSelectComboBox), new FrameworkPropertyMetadata(null,
     new PropertyChangedCallback(MultiSelectComboBox.OnSelectedItemsChanged)));

        public static readonly DependencyProperty TextProperty =
           DependencyProperty.Register("Text", typeof(string), typeof(MultiSelectComboBox), new UIPropertyMetadata(string.Empty));

        public static readonly DependencyProperty DefaultTextProperty =
            DependencyProperty.Register("DefaultText", typeof(string), typeof(MultiSelectComboBox), new UIPropertyMetadata(string.Empty));

        public Dictionary<string, object> ItemsSource
        {
            get { return (Dictionary<string, object>)GetValue(ItemsSourceProperty); }
            set
            {
                SetValue(ItemsSourceProperty, value);
            }
        }

        public Dictionary<string, object> SelectedItems
        {
            get { return (Dictionary<string, object>)GetValue(SelectedItemsProperty); }
            set
            {
                SetValue(SelectedItemsProperty, value);
            }
        }

        public string Text
        {
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); }
        }

        public string DefaultText
        {
            get { return (string)GetValue(DefaultTextProperty); }
            set { SetValue(DefaultTextProperty, value); }
        }
        #endregion

        #region Events
        private static void OnItemsSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            MultiSelectComboBox control = (MultiSelectComboBox)d;
            control.DisplayInControl();
        }

        private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
        {
            MultiSelectComboBox control = (MultiSelectComboBox)d;
            control.SelectNodes();
            control.SetText();
        }

        private void CheckBox_Click(object sender, RoutedEventArgs e)
        {
            CheckBox clickedBox = (CheckBox)sender;

            if (clickedBox.Content == "All" )
            {
                if (clickedBox.IsChecked.Value)
                {
                    foreach (Node node in _nodeList)
                    {
                        node.IsSelected = true;
                    }
                }
                else
                {
                    foreach (Node node in _nodeList)
                    {
                        node.IsSelected = false;
                    }
                }

            }
            else
            {
                int _selectedCount = 0;
                foreach (Node s in _nodeList)
                {
                    if (s.IsSelected && s.Title != "All")
                        _selectedCount++;
                }
                if (_selectedCount == _nodeList.Count - 1)
                    _nodeList.FirstOrDefault(i => i.Title == "All").IsSelected = true;
                else
                    _nodeList.FirstOrDefault(i => i.Title == "All").IsSelected = false;
            }
            SetSelectedItems();
            SetText();

        }
        #endregion

        #region Methods
        private void SelectNodes()
        {
            foreach (KeyValuePair<string, object> keyValue in SelectedItems)
            {
                Node node = _nodeList.FirstOrDefault(i => i.Title == keyValue.Key);
                if (node != null)
                    node.IsSelected = true;
            }
        }

        private void SetSelectedItems()
        {
            if (SelectedItems == null)
                SelectedItems = new Dictionary<string, object>();
            SelectedItems.Clear();
            foreach (Node node in _nodeList)
            {
                if (node.IsSelected && node.Title != "All")
                {
                    if (this.ItemsSource.Count > 0)

                        SelectedItems.Add(node.Title, this.ItemsSource[node.Title]);
                }
            }
        }

        private void DisplayInControl()
        {
            _nodeList.Clear();
            if (this.ItemsSource.Count > 0)
                _nodeList.Add(new Node("All"));
            foreach (KeyValuePair<string, object> keyValue in this.ItemsSource)
            {
                Node node = new Node(keyValue.Key);
                _nodeList.Add(node);
            }
            MultiSelectCombo.ItemsSource = _nodeList;
        }

        private void SetText()
        {
            if (this.SelectedItems != null)
            {
                StringBuilder displayText = new StringBuilder();
                foreach (Node s in _nodeList)
                {
                    if (s.IsSelected == true && s.Title == "All")
                    {
                        displayText = new StringBuilder();
                        displayText.Append("All");
                        break;
                    }
                    else if (s.IsSelected == true && s.Title != "All")
                    {
                        displayText.Append(s.Title);
                        displayText.Append(',');
                    }
                }
                this.Text = displayText.ToString().TrimEnd(new char[] { ',' });
            }          
            // set DefaultText if nothing else selected
            if (string.IsNullOrEmpty(this.Text))
            {
                this.Text = this.DefaultText;
            }
        }

        #endregion
    }

    public class Node : INotifyPropertyChanged
    {

        private string _title;
        private bool _isSelected;
        #region ctor
        public Node(string title)
        {
            Title = title;
        }
        #endregion

        #region Properties
        public string Title
        {
            get
            {
                return _title;
            }
            set
            {
                _title = value;
                NotifyPropertyChanged("Title");
            }
        }
        public bool IsSelected
        {
            get
            {
                return _isSelected;
            }
            set
            {
                _isSelected = value;
                NotifyPropertyChanged("IsSelected");
            }
        }
        #endregion

        public event PropertyChangedEventHandler PropertyChanged;
        protected void NotifyPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }

    }
}