TreeView无法绑定SelectedItem，而又想知道treeview的selecteditem的变化，当然目前有很多方法，我这里简单的提供一个。
目前主要思路就是通过处理xaml的TreeViewItem的IsSelected属性来进行绑定。
<TreeView
BorderThickness="0"
Width="220"
ItemsSource="{Binding Items, IsAsync=True}"
HorizontalAlignment="Left">
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="FontWeight" Value="Normal" />
<Setter Property="HorizontalAlignment" Value="Left" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Items, IsAsync=True}">
<Label Content="{Binding Name}" />
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
主要部分是
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
这里的意思就是绑定到集合泛型的IsSelected属性。
这里呢主要是通过抽象类去实现的也就是：
public abstract class TreeViewItemModel<T> : Notify
{
private bool _IsSelected;
public bool IsSelected
{
get { return _IsSelected; }
set
{
_IsSelected = value;
OnChanged();
if (value)
{
IChanged<T> changed = ModelChangedManger.Sub.Get<T>();
if (changed?.Accepted == true)
{
changed.OnModelChanged((T)Convert.ChangeType(this, typeof(T)));
}
}
}
}
}
具体的使用类再去继承即可，也就是
public class GroupModel : TreeViewItemModel<GroupModel>
{
public GroupModel()
{
Id = Guid.NewGuid();
}
private Guid _id;
public Guid Id
{
get { return _id; }
set
{
_id = value;
OnChanged();
}
}
private string _name;
public string Name
{
get { return _name; }
set
{
_name = value;
OnChanged();
}
}
private ObservableCollection<GroupModel> _Item = new ObservableCollection<GroupModel>();
public ObservableCollection<GroupModel> Items
{
get { return _Item; }
set
{
_Item = value;
OnChanged();
}
}
}
处理完这样，我们只是完成了一部分。这里这来说下
if (value)
{
IChanged<T> changed = ModelChangedManger.Sub.Get<T>();
if (changed?.Accepted == true)
{
changed.OnModelChanged((T)Convert.ChangeType(this, typeof(T)));
}
}
这个是干什么的。
很明显，Isslected属性触发，我们想通知viewmodel，treeview的selecteditem属性变了，或者叫做selectindex也变了的意思。所以简单的实现了一个事件聚合器，这个部分代码比较简单，整体如下
public interface IChanged<T>
{
void OnModelChanged(T Model);
bool Accepted { get; set; }
}
public sealed class ModelChangedManger
{
private ModelChangedManger()
{
}
static ModelChangedManger() { }
private class Inner
{
private Inner() { }
internal readonly static ModelChangedManger manger = new ModelChangedManger();
}
private ConcurrentDictionary<Type, object> Keys { get; set; } = new ConcurrentDictionary<Type, object>();
public IChanged<T> Get<T>()
{
if (Keys.TryGetValue(typeof(T), out object val))
{
return val as IChanged<T>;
}
return null;
}
public void Set<T>(IChanged<T> model)
{
if (!Keys.ContainsKey(typeof(T)))
{
Keys.TryAdd(typeof(T), model);
}
}
public void Remove<T>()
{
Keys.TryRemove(typeof(T), out _);
}
public static ModelChangedManger Sub
{
get => Inner.manger;
}
}
主要是Ichanged接口和manger的一起搭配使用。使用字典将要引发和被引发的类型，类存储起来，这样就可以全局或者大范围的使用了。
同理 我们需要viewmodel上继承一个引发事件的ichanged类
public abstract class TreeViewModel<T> : Notify, IChanged<T>
{
public virtual void OnModelChanged(T Model)
{
SelectedItem = Model;
}
private bool _Accepted;
public bool Accepted
{
get { return _Accepted; }
set
{
_Accepted = value;
OnChanged();
}
}
private T _SelectedItem;
public T SelectedItem
{
get { return _SelectedItem; }
set
{
_SelectedItem = value;
OnChanged();
}
}
}
public class ViewModel : TreeViewModel<GroupModel>
{
private System.Collections.ObjectModel.ObservableCollection<GroupModel> _list = new System.Collections.ObjectModel.ObservableCollection<GroupModel>();
public System.Collections.ObjectModel.ObservableCollection<GroupModel> Items
{
get { return _list; }
set
{
_list = value;
OnChanged();
}
}
public ViewModel()
{
GroupModel groupModel1 = new GroupModel();
groupModel1.Name = "Ken";
GroupModel groupModel_1 = new GroupModel();
groupModel_1.Name = "A";
GroupModel groupModel_2 = new GroupModel();
groupModel_2.Name = "B";
GroupModel groupModel_3 = new GroupModel();
groupModel_3.Name = "C";
GroupModel groupModel_4 = new GroupModel();
groupModel_4.Name = "D";
groupModel1.Items.Add(groupModel_1);
groupModel1.Items.Add(groupModel_2);
groupModel1.Items.Add(groupModel_3);
groupModel1.Items.Add(groupModel_4);
GroupModel groupModel2 = new GroupModel();
groupModel2.Name = "TOM";
GroupModel groupModel_5 = new GroupModel();
groupModel_5.Name = "a";
GroupModel groupModel_6 = new GroupModel();
groupModel_6.Name = "b";
GroupModel groupModel_7 = new GroupModel();
groupModel_7.Name = "c";
GroupModel groupModel_8 = new GroupModel();
groupModel_8.Name = "d";
groupModel2.Items.Add(groupModel_5);
groupModel2.Items.Add(groupModel_6);
groupModel2.Items.Add(groupModel_7);
groupModel2.Items.Add(groupModel_8);
Items.Add(groupModel1);
Items.Add(groupModel2);
ModelChangedManger.Sub.Set(this);
this.Accepted = true;
}
}
这样，就可以简单的实现了对selectedItem的变化的监控了
标签：Items,GroupModel,private,groupModel,SelectedItem,new,WPF,TreeView,public From： https://www.cnblogs.com/T-ARF/p/17553107.html