WPF 限制 Expander 的大小

Question

WPF 限制 Expander 的大小

wpfresizeheightexpander

3

我有多个树形视图在可展开的控件内，随着内容的增加可以增长高度。但当高度大于窗口大小时，会超出窗口。

显而易见的解决方法是设置Treeview的MaxHeight，但我无法轻松确定它，因为可用高度取决于：

- 窗口高度 - 其他展开器（打开/关闭）

我需要改变什么才能使树形视图的高度仍然自动增长，但永远不会大于窗口的高度？

<StackPanel CanVerticallyScroll="True" ClipToBounds="False" Height="Auto" Name="StackPanel2" Width="250" DockPanel.Dock="Left" Orientation="Vertical" VerticalAlignment="Top" CanHorizontallyScroll="False" Margin="5">
    <Border BorderThickness="0" CornerRadius="5" Padding="1" BorderBrush="Red" Margin="0,5" >
        <Expander Header="Expander3" Height="Auto" IsExpanded="False" Width="Auto" Margin="2" BorderThickness="1">
           <Grid  Height="Auto" Width="Auto" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" >

            <TreeView Height="Auto" BorderThickness="1" Margin="0,0,0,0" Padding="7" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" >
           </TreeView>

        </Grid>
    </Expander>
    </Border>
</StackPanel>

- Maestro

1个回答

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- Fredrik Hedblad · Accepted Answer

我能想到的一个方法是将StackPanel放在一个ScrollViewer中。这样可以确保它不会超出窗口的高度。如果您的expanders都在同一个StackPanel中，您将不会为每个expander获得单独的滚动条，但我不确定您想要什么。

<ScrollViewer Name="stackPanelScrollViewer"
              Loaded="stackPanelScrollViewer_Loaded"
              VerticalScrollBarVisibility="Auto">
    <StackPanel CanVerticallyScroll="True" ClipToBounds="False" Height="Auto" Name="StackPanel2" Width="250" DockPanel.Dock="Left" Orientation="Vertical" VerticalAlignment="Top" CanHorizontallyScroll="False" Margin="5">
        <Border BorderThickness="0" CornerRadius="5" Padding="1" BorderBrush="Red" Margin="0,5" >
            <Expander Header="Expander3" Height="Auto" IsExpanded="False" Width="Auto" Margin="2" BorderThickness="1">
                <Grid  Height="Auto" Width="Auto" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" >
                    <TreeView Name="treeView1" Height="Auto" BorderThickness="1" Margin="0,0,0,0" Padding="7" VerticalAlignment="Stretch" HorizontalAlignment="Stretch" >
                    </TreeView>
                </Grid>
            </Expander>
        </Border>
    </StackPanel>
</ScrollViewer>

这种方法的缺点是，TreeView 在其 ControlTemplate 中定义了自己的 ScrollViewer，因此如果鼠标位于 TreeView 上方，则无法使用鼠标滚轮进行滚动。解决方法是为每个 TreeView 附加一个 MouseWheel 事件处理程序，并从那里实现滚动。

private void stackPanelScrollViewer_Loaded(object sender, RoutedEventArgs e)
{
    treeView1.AddHandler(MouseWheelEvent, new RoutedEventHandler(StackPanelMouseWheel), true);
    //treeView2.AddHandler(MouseWheelEvent, new RoutedEventHandler(StackPanelMouseWheel), true);
}
private void StackPanelMouseWheel(object sender, RoutedEventArgs e)
{
    MouseWheelEventArgs eargs = (MouseWheelEventArgs)e;
    double x = (double)eargs.Delta;
    double y = stackPanelScrollViewer.VerticalOffset;
    stackPanelScrollViewer.ScrollToVerticalOffset(y - x);
}