wpf TreeView - 如何在 IsExpanded 属性更改时调用函数 [英] wpf TreeView - How to call function on IsExpanded property change

问题描述

当 TreeViewItem 属性 IsExpanded 更改时，XAML 中是否可以调用函数?

Is there a way in XAML to call a function when the TreeViewItem property IsExpanded changes?

我相信不太好的替代方法是循环遍历所有 TreeViewItems 并执行 item.IsExpanded += 处理程序调用，如果我理解正确的话.

I believe the not so good alternative would be to loop through all TreeViewItems and do an item.IsExpanded += handler call if I understand things correctly.

或者我想我可以检查扩展器元素上的点击次数.

Or I could check for clicks on the expander element I guess.

我正在做的是保持树的展开/折叠状态.请在建议替代方法来坚持这一点之前回答第一个问题，只是为了让我了解属性和 xaml.

What I'm doing is persisting the expand/collapse state of the tree. Please answer the first question before suggesting alternative ways to persist this just to edify me on properties and xaml.

推荐答案

我会使用以下方法将 TreeViewItem 的 IsExpanded 属性绑定到我的模型:

I would bind the IsExpanded property of the TreeViewItem to my model using something like:

                    <TreeView.ItemContainerStyle>
                        <Style TargetType="TreeViewItem">
                            <Setter Property="IsSelected" Value="{Binding IsSelected}" />
                            <Setter Property="IsExpanded" Value="{Binding IsExpanded}" />
                        </Style>
                    </TreeView.ItemContainerStyle>

然后我可以运行模型并获取 IsExpanded 的值并保存它.此外，在恢复时，只需设置 IsExpanded 属性即可.

Then I can run thru the model and get the value for IsExpanded and save it. Additionally, when restoring, simply set the IsExpanded property.

由于更改时需要调用其他代码，请像这样实现 IsExpanded:

Since you need to call other code when changed, implement IsExpanded like so:

private bool _IsExpanded;
public bool IsExpanded
{
    get { return _IsExpanded; }
    set
    {
        if (_IsExpanded == value) return;
        _IsExpanded = value;
        NotifyPropertyChanged( "IsExpanded" );//or however you need to do it
        CallSomeOtherFunc();//this is the code that you need to be called when changed.
    }
}

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