最近要用WPF写一个树，同事给了我一个Demo（不知道是从哪里找来的），我基本上就是参照了这个Demo。
先放一下效果图（3棵树）：
这个树索要满足的条件是：
- 父节点.Checked=true时，子节点全部选中(反之成立)；
- 父节点.Checked=false时，子节点全部不选中(反之成立)；
- 子节点存在部分节点选中，部分节点未选中时，父节点为非全选状态（null）(反之成立)；
那么这个树究竟要怎么造出来呢？
由于用WPF，且用MVVM模式，故TreeView的ItemSource及复选框的选中状态IsChecked需要从ViewModel层进行绑定。先看一下树的xaml：
<Window x:Class="MyWpfCheckTreeDemo.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:VM="clr-namespace:MyWpfCheckTreeDemo.AppViewModel"
xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
Title="MainWindow" Height="350" Width="525" Loaded="LoadedEvent">
<Window.Resources>
<HierarchicalDataTemplate x:Key="MyTreeItemTemplate"
DataType="{x:Type VM:CommonTreeView}"
ItemsSource="{Binding Path=Children,Mode=OneWay}">
<StackPanel x:Name="My_SP" Orientation="Horizontal" Margin="2">
<CheckBox IsChecked="{Binding Path=IsChecked}" >
</CheckBox>
<ContentPresenter Content="{Binding Path=NodeName,Mode=OneTime}" Margin="2,0"/>
</StackPanel>
</HierarchicalDataTemplate>
<Style x:Key="TreeViewItemStyle" TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded" Value="True" />
</Style>
</Window.Resources>
<Grid>
<TreeView Grid.Row="1" x:Name="tv" ItemsSource="{Binding MyTrees}"
ItemContainerStyle="{StaticResource TreeViewItemStyle}"
ItemTemplate="{StaticResource MyTreeItemTemplate}">
</TreeView>
</Grid>
</Window>
TreeView.xaml
在xaml中的数据绑定好之后，就是在后台如何实现数据的传递了。
先来看一下每个节点所需要包含的数据：
- 节点名称：NodeName,
- 父节点：Parent ,
- 该父节点的所有孩子:Children，为每一个节点增加创建孩子的方法
- 每个节点的选中状态：IsChecked,每次子节点的IsChecked变化时，需要去更新Parent节点的IsChecked.
现在将上述数据封装成一个树节点类：
public class CommonTreeView : NotifyPropertyBase
{
/// <summary>
/// 父
/// </summary>
public CommonTreeView Parent
{
get;
set;
} /// <summary>
/// 子
/// </summary>
public List<CommonTreeView> Children
{
get;
set;
} /// <summary>
/// 节点的名字
/// </summary>
public string NodeName
{
get;
set;
} public bool? _isChecked;
/// <summary>
/// CheckBox是否选中
/// </summary>
public bool? IsChecked
{
get
{
return _isChecked;
}
set
{
SetIsChecked(value, true, true);
}
} public CommonTreeView(string name)
{
this.NodeName=name;
this.Children=new List<CommonTreeView>();
}
public CommonTreeView() { } private void SetIsChecked(bool? value, bool checkedChildren, bool checkedParent)
{
if (_isChecked == value) return;
_isChecked = value;
//选中和取消子类
if (checkedChildren && value.HasValue && Children != null)
Children.ForEach(ch => ch.SetIsChecked(value, true, false)); //选中和取消父类
if (checkedParent && this.Parent != null)
this.Parent.CheckParentCheckState(); //通知更改
this.SetProperty(x => x.IsChecked);
} /// <summary>
/// 检查父类是否选 中
/// 如果父类的子类中有一个和第一个子类的状态不一样父类ischecked为null
/// </summary>
private void CheckParentCheckState()
{
List<CommonTreeView> checkedItems = new List<CommonTreeView>();
string checkedNames = string.Empty;
bool? _currentState = this.IsChecked;
bool? _firstState = null;
for (int i = 0; i < this.Children.Count(); i++)
{
bool? childrenState = this.Children[i].IsChecked;
if (i == 0)
{
_firstState = childrenState;
}
else if (_firstState != childrenState)
{
_firstState = null;
}
}
if (_firstState != null) _currentState = _firstState;
SetIsChecked(_firstState, false, true);
} /// <summary>
/// 创建树
/// </summary>
/// <param name="children"></param>
/// <param name="isChecked"></param> public void CreateTreeWithChildre( CommonTreeView children,bool? isChecked)
{
this.Children.Add(children);
//必须先把孩子加入再为Parent赋值，
//否则当只有一个子节点时Parent的IsChecked状态会出错 children.Parent = this;
children.IsChecked = isChecked;
}
}
CommonTreeView.cs
节点值变化时对UI进行通知的方法PropertyNotify：
public class NotifyPropertyBase : INotifyPropertyChanged
{
public void OnPropertyChanged(string propertyName)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
}
public event PropertyChangedEventHandler PropertyChanged;
} /// <summary>
/// 扩展方法
/// 避免硬编码问题
/// </summary>
public static class NotifyPropertyBaseEx
{
public static void SetProperty<T, U>(this T tvm, Expression<Func<T, U>> expre) where T : NotifyPropertyBase, new()
{
string _pro = CommonFun.GetPropertyName(expre);
tvm.OnPropertyChanged(_pro);
}//为什么扩展方法必须是静态的
} public class CommonFun
{
/// <summary>
/// 返回属性名
/// </summary>
/// <typeparam name="T"></typeparam>
/// <typeparam name="U"></typeparam>
/// <param name="expr"></param>
/// <returns></returns>
public static string GetPropertyName<T, U>(Expression<Func<T, U>> expr)
{
string _propertyName = "";
if (expr.Body is MemberExpression)
{
_propertyName = (expr.Body as MemberExpression).Member.Name;
}
else if (expr.Body is UnaryExpression)
{
_propertyName = ((expr.Body as UnaryExpression).Operand as MemberExpression).Member.Name;
}
return _propertyName;
}
}
INotifyPropertyChanged
到这里基本上这个树就可以投入使用了，现在在ViewModel中给树赋值，并取出选中状态的叶子的节点名称：
这个里面的方法只给出重点部分：
/// <summary>
/// 创建树
/// </summary>
/// <returns></returns>
public List<CommonTreeView> MyCreateTree()
{
List<CommonTreeView> views = new List<CommonTreeView>();
//CommonTreeView _myT = new CommonTreeView("合约");
CommonTreeView _myy = new CommonTreeView("CCP");
views.Add(_myy);
CommonTreeView _myy1 = new CommonTreeView("CCP_1");
_myy.CreateTreeWithChildre(_myy1, true);
CommonTreeView _myy1_1 = new CommonTreeView("CCP_1.1");
_myy1.CreateTreeWithChildre(_myy1_1, true);
} /// <summary>
/// 选中的节点名称保存在_names中
/// </summary>
public void SaveC()
{
_names = new List<string>();
//SelectedTree=MyTrees.FindAll(r => r.IsChecked == true);
foreach (CommonTreeView tree in MyTrees)
{
GetCheckedItems(tree);
}
} /// <summary>
/// 获取选中项
/// </summary>
/// <param name="tree"></param>
private void GetCheckedItems(CommonTreeView tree)
{
if (tree.Parent != null && (tree.Children == null || tree.Children.Count == 0))
{
if (tree.IsChecked.HasValue && tree.IsChecked == true)
_names.Add(tree.NodeName);
}
else if (tree.Children != null && tree.Children.Count > 0)
{
foreach (CommonTreeView tv in tree.Children)
GetCheckedItems(tv);
}
}
TreeViewModel.cs
到这里就结束啦。。。