Question

我在SL4中有一个已经填充的TreeView，并且选择了某个TreeViewItem。

刚做

treeview.Visibility=Visibility.Collapsed;

然后

treeview.Visibility=Visibility.Visible;

修改选择的TreeViewItem。为什么？有没有办法避免这种情况？

编辑2012.02.04 03:29

我已将问题追溯到根本。这是我发现的（对我而言，令人惊讶的）结论：如果满足以下所有条件：

1）TreeView有两个（或更多）深度级别，

2）我首先扩展其所有节点，

3）我开始在第二级选择一个节点，

4）（这是最奇怪的一个）我用来折叠的按钮再次显示TreeView不是制表位，

然后TreeView在折叠后不再保留其选择并再次显示!!!

请下载从中重现问题的小型解决方案+示例 http://src041.bluemosfet.net/treeviewselectsanotheritem.zip 并尝试一下。

或者看看这两段代码：

<UserControl x:Class="PRJ.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    d:DesignHeight="300" d:DesignWidth="400" xmlns:sdk="http://schemas.microsoft.com/winfx/2006/xaml/presentation/sdk" Loaded="UserControl_Loaded">

    <Grid x:Name="LayoutRoot" Background="White">
        <StackPanel Name="sp1">
            <!-- ################################################################### -->
            <!-- First, in the TreeView, expand TreeViewItems "a0", "a1" and "a2". -->
            <!-- Then, select "a0b0". -->
            <!-- Then, click the button twice. -->
            <!-- If you don't remove   IsTabStop="False"   from the following line of code, the TreeView reappears with "a1" selected !!! -->
            <!-- If you continue clicking the button, the selection shifts to "a1b0", "a2", and finally "a2b0". -->
            <!-- If you remove   IsTabStop="False"  , or change it to True, the TreeView works OK and keeps its selection. -->
            <!-- Isn't it odd, that the capability of the TreeView to keep its selection depends on whether the button used to hide and show the TreeView is a tab stop or not??? -->
            <Button Content="Hide/Show TreeView" Name="b1" Click="b1_Click" IsTabStop="False" />
            <!-- ################################################################### -->
            <sdk:TreeView Name="tv1" />
        </StackPanel>
    </Grid>
</UserControl>

和

namespace PRJ
{
    public partial class MainPage : UserControl
    {
        public MainPage()
        {
            InitializeComponent();
        }

        private void b1_Click(object sender, RoutedEventArgs e)
        {
            if (tv1.Visibility==Visibility.Collapsed)
                tv1.Visibility=Visibility.Visible;
            else
                tv1.Visibility=Visibility.Collapsed;
        }

        private void UserControl_Loaded(object sender, RoutedEventArgs e)
        {
            for (int a=0;a<3;a++)
            {
                TreeViewItem    tvia    =new TreeViewItem();
                tvia.Header                =String.Format("a{0}",a);
                for (int b=0;b<2;b++)
                {
                    TreeViewItem    tvib    =new TreeViewItem();
                    tvib.Header                =String.Format("a{0}b{1}",a,b);
                    tvia.Items.Add(tvib);
                } // for b
                tv1.Items.Add(tvia);
            } // for a
        }
    }
}

TreeView保持其选择的能力是否很奇怪取决于用于隐藏和显示TreeView的按钮是否是制表位？

Answer 1

用一个全新的项目和一个用字符串列表提供的树视图进行测试。折叠后再也不会丢失所选项目。

再次隐藏和显示TreeView会修改选择的TreeViewItem。为什么？

1 个答案: