在 UI 自动化片段提供程序中启用导航
更新：2007 年 11 月
本主题包含示例代码，该示例代码演示如何在 UI 自动化提供程序中为片段内的元素实现导航。
示例
下面的示例代码为列表内的列表项实现 Navigate。父元素是列表框元素，同级元素是列表集合中的其他项。该方法对无效的方向返回 null（在 Visual Basic 中为 Nothing）；在本例中，将返回 FirstChild 和 LastChild，因为该元素没有子元素。
''' <summary>
''' Navigate to adjacent elements in the automation tree.
''' </summary>
''' <param name="direction">Direction to navigate.</param>
''' <returns>The element in that direction, or null.</returns>
''' <remarks>
''' parentControl is the provider for the list box.
''' parentItems is the collection of list item providers.
''' </remarks>
Public Function Navigate(ByVal direction As NavigateDirection) As IRawElementProviderFragment _
Implements IRawElementProviderFragment.Navigate
Dim myIndex As Integer = parentItems.IndexOf(Me)
If direction = NavigateDirection.Parent Then
Return DirectCast(parentControl, IRawElementProviderFragment)
ElseIf direction = NavigateDirection.NextSibling Then
If myIndex < parentItems.Count - 1 Then
Return DirectCast(parentItems((myIndex + 1)), IRawElementProviderFragment)
Else
Return Nothing
End If
ElseIf direction = NavigateDirection.PreviousSibling Then
If myIndex > 0 Then
Return DirectCast(parentItems((myIndex - 1)), IRawElementProviderFragment)
Else
Return Nothing
End If
Else
Return Nothing
End If
End Function 'Navigate
/// <summary>
/// Navigate to adjacent elements in the automation tree.
/// </summary>
/// <param name="direction">Direction to navigate.</param>
/// <returns>The element in that direction, or null.</returns>
/// <remarks>
/// parentControl is the provider for the list box.
/// parentItems is the collection of list item providers.
/// </remarks>
public IRawElementProviderFragment Navigate(NavigateDirection direction)
{
int myIndex = parentItems.IndexOf(this);
if (direction == NavigateDirection.Parent)
{
return (IRawElementProviderFragment)parentControl;
}
else if (direction == NavigateDirection.NextSibling)
{
if (myIndex < parentItems.Count - 1)
{
return (IRawElementProviderFragment)parentItems[myIndex + 1];
}
else
{
return null;
}
}
else if (direction == NavigateDirection.PreviousSibling)
{
if (myIndex > 0)
{
return (IRawElementProviderFragment)parentItems[myIndex - 1];
}
else return null;
}
else return null;
}