多WPF列表框只有一个项目在一个时间选择 [英] Multiple WPF ListBoxes with only one item selected at a time

问题描述

我使用MVVM和我一个窗口上显示两个列表框。我从这两个列表框同时结合于不同领域给他们打电话A和B，A和B是那么这两个修改C.为了使这项工作，我想只有从一次IsSelected两个列表框一个项目，使A不覆盖ç当B IsSelected。我怎么能限制呢？

I am using MVVM and am displaying two listboxes on one window. I am binding from both of those listboxes simultaneously to different fields call them A and B. A and B are then both modifying C. To make this work, I want to only have one item from the two listboxes IsSelected at once, so that A does not override C when B IsSelected. How can I restrict this?

谢谢！

推荐答案

我能想到的几个方法可以做到这一点。

I can think of a couple of ways to do this.

一种方法是你可以绑定 ListBox.SelectedIndex 您2列表框改变，通知视图模型属性。

One way is you could bind the ListBox.SelectedIndex of your 2 ListBoxes to change-notifying ViewModel properties.

例如在您查看：

<ListBox SelectedIndex="{Binding SelectedIndexA}">
     <ListBoxItem Content="Item 1"/>
     <ListBoxItem Content="Item 2"/>
</ListBox>
<ListBox SelectedIndex="{Binding SelectedIndexB}">
     <ListBoxItem Content="Item 1"/>
     <ListBoxItem Content="Item 2"/>
</ListBox>

而在你的视图模型：

And in your ViewModel:

public int SelectedIndexA
{
    get { return _selectedIndexA; }
    set
    {
        _selectedIndexA = value;
        _selectedIndexB = -1;
        OnPropertyChanged("SelectedIndexB");
    }
}

public int SelectedIndexB
{
    get { return _selectedIndexB; }
    set
    {
        _selectedIndexB = value;
        _selectedIndexA = -1;
        OnPropertyChanged("SelectedIndexA");
    }
}

另一种方式是像组名在那里你可以组选择器（的ListBox 从继承选择），以确保只有一个选择组中有在任何一个时间选定的项目。

Another way would be with an attached property like 'GroupName' where you can group Selectors (ListBox inherits from Selector) to ensure only one Selector in the group has a selected item at any one time.

例如：

public static class SingleSelectionGroup
{
    public static readonly DependencyProperty GroupNameProperty =
        DependencyProperty.RegisterAttached("GroupName", typeof(string), typeof(SingleSelectionGroup),
                                            new UIPropertyMetadata(OnGroupNameChanged));

    public static string GetGroupname(Selector selector)
    {
        return (string) selector.GetValue(GroupNameProperty);
    }

    public static void SetGroupName(Selector selector, string value)
    {
        selector.SetValue(GroupNameProperty, value);
    }

    private static void OnGroupNameChanged(DependencyObject dependencyObject, DependencyPropertyChangedEventArgs e)
    {
        var selector = (Selector) dependencyObject;

        if (e.OldValue != null)
            selector.SelectionChanged -= SelectorOnSelectionChanged;
        if (e.NewValue != null)
            selector.SelectionChanged += SelectorOnSelectionChanged;
    }

    private static void SelectorOnSelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        if (e.AddedItems.Count == 0)
            return;

        var selector = (Selector) sender;
        var groupName = (string) selector.GetValue(GroupNameProperty);
        var groupSelectors = GetGroupSelectors(selector, groupName);

        foreach (var groupSelector in groupSelectors.Where(gs => !gs.Equals(sender)))
        {
            groupSelector.SelectedIndex = -1;
        }
    }

    private static IEnumerable<Selector> GetGroupSelectors(DependencyObject selector, string groupName)
    {
        var selectors = new Collection<Selector>();
        var parent = GetParent(selector);
        GetGroupSelectors(parent, selectors, groupName);
        return selectors;
    }

    private static DependencyObject GetParent(DependencyObject depObj)
    {
        var parent = VisualTreeHelper.GetParent(depObj);
        return parent == null ? depObj : GetParent(parent);
    }

    private static void GetGroupSelectors(DependencyObject parent, Collection<Selector> selectors, string groupName)
    {
        var childrenCount = VisualTreeHelper.GetChildrenCount(parent);
        for (int i = 0; i < childrenCount; i++)
        {
            var child = VisualTreeHelper.GetChild(parent, i);
            var selector = child as Selector;
            if (selector != null && (string) selector.GetValue(GroupNameProperty) == groupName)
                selectors.Add(selector);

            GetGroupSelectors(child, selectors, groupName);
        }
    }
}

而在你查看：

<ListBox my:SingleSelectionGroup.GroupName="Group A">
    <ListBoxItem Content="Item 1 (Group A)"/>
    <ListBoxItem Content="Item 2 (Group A)"/>
</ListBox>
<ListBox my:SingleSelectionGroup.GroupName="Group A">
    <ListBoxItem Content="Item 1 (Group A)"/>
    <ListBoxItem Content="Item 2 (Group A)"/>
</ListBox>

<ListBox my:SingleSelectionGroup.GroupName="Group B">
    <ListBoxItem Content="Item 1 (Group B)"/>
    <ListBoxItem Content="Item 2 (Group B)"/>
</ListBox>
<ListBox my:SingleSelectionGroup.GroupName="Group B">
    <ListBoxItem Content="Item 1 (Group B)"/>
    <ListBoxItem Content="Item 2 (Group B)"/>
</ListBox>

如果你必须点击一个项目之前两次被突出显示，你可以用一个快速的解决方法是这样的：

If you have to click an item twice before it is highlighted you can use a quick workaround like this:

<Style TargetType="ListBoxItem">
    <Style.Triggers>
        <EventTrigger RoutedEvent="GotKeyboardFocus">
            <BeginStoryboard>
                <Storyboard>
                    <BooleanAnimationUsingKeyFrames Storyboard.TargetProperty="(ListBoxItem.IsSelected)">
                        <DiscreteBooleanKeyFrame KeyTime="00:00:00" Value="True" />
                    </BooleanAnimationUsingKeyFrames>
                </Storyboard>
            </BeginStoryboard>
        </EventTrigger>
    </Style.Triggers>
</Style>

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