设置ListBox的滚动条位置

Question

我可以通过编程方式设置WPF ListBox滚动条的位置吗？默认情况下，我希望它在中心。

Answer 1

要在ListBox中移动垂直滚动条，请执行以下操作：

1. 为列表框命名（x：Name =＆quot; myListBox＆quot;）
2. 为Window添加Loaded事件（Loaded =＆quot; Window_Loaded＆quot;）
3. 使用方法实现Loaded事件：ScrollToVerticalOffset

以下是一份工作样本：

XAML：

<Window x:Class="ListBoxScrollPosition.Views.MainView"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Loaded="Window_Loaded"
  Title="Main Window" Height="100" Width="200">
  <DockPanel>
    <Grid>
      <ListBox x:Name="myListBox">
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
        <ListBoxItem>Zamboni</ListBoxItem>
      </ListBox>
    </Grid>
  </DockPanel>
</Window>

C＃

private void Window_Loaded(object sender, RoutedEventArgs e)
{
  // Get the border of the listview (first child of a listview)
  Decorator border = VisualTreeHelper.GetChild(myListBox, 0) as Decorator;
  if (border != null)
  {
    // Get scrollviewer
    ScrollViewer scrollViewer = border.Child as ScrollViewer;
    if (scrollViewer != null)
    {
      // center the Scroll Viewer...
      double center = scrollViewer.ScrollableHeight / 2.0;
      scrollViewer.ScrollToVerticalOffset(center);
    }
  }
}

Answer 2

Dim cnt as Integer = myListBox.Items.Count
Dim midPoint as Integer = cnt\2
myListBox.ScrollIntoView(myListBox.Items(midPoint))

或

myListBox.SelectedIndex = midPoint

这取决于您是否想要显示或选择中间项目。

Answer 3

我刚刚更改了Zamboni的一些代码并添加了位置计算。

var border = VisualTreeHelper.GetChild(list, 0) as Decorator;
if (border == null) return;
var scrollViewer = border.Child as ScrollViewer;
if (scrollViewer == null) return;
scrollViewer.ScrollToVerticalOffset((scrollViewer.ScrollableHeight/list.Items.Count)*
                                    (list.Items.IndexOf(list.SelectedItem) + 1));

Answer 4

我不认为ListBox有这个，但ListViews有 EnsureVisible 方法，将滚动条移动到所需位置，以确保显示项目。