放置在另一个 ScrollViewer 中时 WPF TreeView 不显示滚动条

Question

我有一个问题，当 TreeView 放置在具有 ScrollViewer 的容器中时，TreeView 的滚动条不起作用，而是调整了容器的 ScrollViewer 内容的大小，以便所有 TreeView 项目都可见。

在 WinForms 中我可以设置容器的最小内容宽度和高度，但是如何在 WPF 中实现呢？

以下是 XAML 示例：

<Window x:Class="TestWpfTreeViewInsideScrollViewer.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <ScrollViewer Name="scroll1" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" >
        <Grid MinHeight="230" MinWidth="200" Grid.IsSharedSizeScope="True">
            <Button Content="Button" Width="74" Height="52" Margin="10,24,0,0" HorizontalAlignment="Left" VerticalAlignment="Top"/>
            <Button Content="Button" Height="52" Margin="89,24,10,0" VerticalAlignment="Top"/>
            <Button Content="Button" Width="74" Height="52" Margin="10,81,0,0" HorizontalAlignment="Left" VerticalAlignment="Top"/>

            <TreeView Margin="10,138,10,55">
                <TreeViewItem IsExpanded="True" Header="This is a long text but the treeview is not scrolling">
                    Instead the TreeView is expanding its size to fit all these nodes inside it, i want that the upper scroller take in only when grid minwidth 200 is reached, not before
                    <TreeViewItem IsExpanded="True" Header="This is a long text but the treeview is not scrolling">This is a long text but the treeview is not scrolling
                    </TreeViewItem>
                </TreeViewItem>
                <TreeViewItem IsExpanded="True" Header="This is a long text but the treeview is not scrolling">This is a long text but the treeview is not scrolling</TreeViewItem>
                <TreeViewItem IsExpanded="True" Header="This is a long text but the treeview is not scrolling">This is a long text but the treeview is not scrolling</TreeViewItem>
            </TreeView>

            <Button Content="Button" Margin="10,0,10,10" Height="40" VerticalAlignment="Bottom"/>
        </Grid>
    </ScrollViewer>

</Grid>

Answer 1

Scrollviewer 的内容有一个未定义的空间。

这意味着 TreeView 以不需要显示其 ScrollViewer 的大小显示。

至少应该定义ScrollViewer里面TreeView的Width和Height。

更新：

如果要让 Treeview Width 动态调整大小，则需要使用数据绑定。

<TreeView Margin="10,138,10,55" Width="{Binding ElementName=scroll1, Path=ActualWidth}">

如果 ScrollViewer 不满足 Treeview Width，也可以将 Width 绑定到其他控件。

我希望这会有所帮助。