Question

我有一个用作搜索结果框的silverlight列表框。我正在使用动态搜索（搜索框中的键盘会导致触发事件以过滤此列表框的内容）。我遇到的问题是如果用户在未经过滤的情况下向下滚动，然后进行搜索，则重新绑定列表框不会导致滚动返回到顶部，使得结果看起来只有一个它的价值。

我目前为列表框的代码是这个（这是一个简化版本）：

XAML：

<Grid x:Name="MainGrid" Rows="2">
    <StackPanel Orientation="Horizontal" Grid.Row="0">
         <TextBlock text="Search" Grid.Row="0" />
         <Textbox x:name="textboxSearch" Keyup="textBoxSearch_KeyUp" width="200" 
                  Height="25"/>
    </StackPanel>
    <ListBox x:Name="SearchResultBox" Visibility="Visible" Grid.Row="1"
             ScrollViewer.HorizontalScrollBarVisibility="Auto"
             ScrollViewer.VerticalscrollbarVisibility="Auto">
         <ListBox.ItemTemplate>
              <DataTemplate>
                   <StackPanel Orientation="Vertical">
                        <TextBlock Text="{Binding ReportName}" />
                        <TextBlock Text="{Binding ReportDescription}" />
                   </StackPanel>
              </DataTemplate>
         </Listbox.ItemTemplate>
    </ListBox>
</Grid>

VB：

Imports System.Threading
Imports System.Collections.ObjectModel
Imports System.ComponentModel
Partial Public Class ucSearch
     Inherits UserControl
     Private WithEvents BGwork As New BackgroundWorker()
     Private mReportList as New List(Of cFilter)

     Public Sub New()
          InitializeComponent()
          FillReportList()
          NewFilterList()
     End Sub

     Private Sub FillReportList()
          mReportList.Add(new cFilter("Report A", "Report A desc")
          mReportList.Add(new cFilter("Report B", "Report B desc")
          mReportList.Add(new cFilter("Report C", "Report C desc")
          mReportList.Add(new cFilter("Report D", "Report D desc")
          mReportList.Add(new cFilter("Report E", "Report E desc")
          mReportList.Add(new cFilter("Report F", "Report F desc")
          mReportList.Add(new cFilter("Report G", "Report G desc")
          mReportList.Add(new cFilter("Report H", "Report H desc")
          mReportList.Add(new cFilter("Report I", "Report I desc")
          mReportList.Add(new cFilter("Report J", "Report J desc")
          mReportList.Add(new cFilter("Report K", "Report K desc")
          mReportList.Add(new cFilter("Report L", "Report L desc")
          mReportList.Add(new cFilter("Report M", "Report M desc")
     End Sub

     Private Sub textboxSearch_KeyUp(ByVal sender as System.Object, _
                                     ByVal e as System.Windows.Input.KeyeventArgs)
         NewFilterList()
     End Sub

     Private Sub NewFilterList()
          If BGwork.IsBusy Then
               If Not BGWork.cancellationPending Then BGwork.CancelAsync()
               Exit Sub
          End If

          With BGwork
               .WorkerSupportsCancellation = True
               .RunWorkerAsync(textboxSearch.Text)
          End With
     End Sub

     Private Sub BGwork_DoWork(ByVal sender as Object, _
                               ByVal e as System.ComponentModel.DoWorkEventArgs) _
                               Handles BGwork.DoWork
          Dim Filtered as New List(of cFilter)
          If textboxSearch.Text.Length > 0
               dim q = FROM ri In mReportList Where ri.Reportname.ToLower.contains(textboxSearch.Text.ToLower) Select ri
               Filtered = q
          Else
               Filtered = mReportList
          End If
          Dim RTN as List(Of cFilter) = Filtered
          e.Cancel = False
          e.Result = RTN
     End Sub

     Private Sub BGwork_RunWorkerCompleted(ByVal sender As Object_
                                           ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) _
                                           Handles BGwork.RunWorkerCompleted
          If e.Cancelled Then
               NewFilterList()
               Exit Sub
          End If

          Dim RTN as cFilter = TryCast(e.Result, cFilter)
          If IsNothing(RTN) Then Exit Sub

          SearchResultBox.ItemsSource = RTN
          SearchResultBox.InvalidateArrange()
     End Sub
 End Class

 Public Class cFilter
      Inherits BaseDataClass
      Private mReportName as String = ""
      Private mReportDescription as String = ""

      Public Sub New()
           mReportName = ""
           mReportDescription = ""
      End Sub

      Public Sub New(ByVal reportName as String, ByVal reportDescription as String)
           mReportName = reportName
           mReportDescription = reportDescription
      End Sub

      Public Property ReportName() as String
           Get
                Return mReportName
           End Get
           Set(ByVal value as String)
                mReportName = value
           End Set
      End Property

      Public Property ReportDescription() as String
           Get
                Return mReportDescription
           End Get
           Set(ByVal value as String)
                mReportDescription = value
           End Set
      End Property
 End Class

这再次简化了发生的事情（我去数据库获取报告名称等）。当我重新绑定列表框时，如何让它一直滚动以使第一个项目位于列表顶部？由于我无法访问ListBox对象中的scrollviewer控件，我是否必须创建一个围绕列表框的scrollviewer控件，然后设置它的视图来自哪里？

Answer 1

看完这篇文章后

Automatic Scrolling in a Silverlight List Box

我尝试了以下内容，它对我来说很好。

 theListBox.ItemsSource = data;
 theListBox.UpdateLayout();
 theListBox.ScrollIntoView(theListBox.Items[0]);

Answer 2

你试过

吗？

mReportList.SelectedIndex = 0

重新绑定Silverlight Listbox控件之后如何让它列表框滚动到顶部？

2 个答案: