Find a UI Automation Element for a List Item
This topic shows how to retrieve an AutomationElement for an item within a list when the index of the item is known.
Example
The following example shows two ways of retrieving a specified item from a list, one using TreeWalker and the other using FindAll.
The first technique tends to be faster for Win32 controls, but the second is faster for Windows Presentation Foundation (WPF) controls.
''' <summary>
''' Retrieves an element in a list, using TreeWalker.
''' </summary>
''' <param name="parent">The list element.</param>
''' <param name="index">The index of the element to find.</param>
''' <returns>The list item.</returns>
Function FindChildAt(ByVal parent As AutomationElement, ByVal index As Integer) As AutomationElement
If (index < 0) Then
Throw New ArgumentOutOfRangeException()
End If
Dim walker As TreeWalker = TreeWalker.ControlViewWalker
Dim child As AutomationElement = walker.GetFirstChild(parent)
For x As Integer = 1 To (index - 1)
child = walker.GetNextSibling(child)
If child = Nothing Then
Throw New ArgumentOutOfRangeException()
End If
Next x
Return child
End Function
''' <summary>
''' Retrieves an element in a list, using FindAll.
''' </summary>
''' <param name="parent">The list element.</param>
''' <param name="index">The index of the element to find.</param>
''' <returns>The list item.</returns>
Function FindChildAtB(ByVal parent As AutomationElement, ByVal index As Integer) As AutomationElement
Dim findCondition As Condition = _
New PropertyCondition(AutomationElement.IsControlElementProperty, True)
Dim found As AutomationElementCollection = parent.FindAll(TreeScope.Children, findCondition)
If (index < 0) Or (index >= found.Count) Then
Throw New ArgumentOutOfRangeException()
End If
Return found(index)
End Function
/// <summary>
/// Retrieves an element in a list, using TreeWalker.
/// </summary>
/// <param name="parent">The list element.</param>
/// <param name="index">The index of the element to find.</param>
/// <returns>The list item.</returns>
AutomationElement FindChildAt(AutomationElement parent, int index)
{
if (index < 0)
{
throw new ArgumentOutOfRangeException();
}
TreeWalker walker = TreeWalker.ControlViewWalker;
AutomationElement child = walker.GetFirstChild(parent);
for (int x = 1; x <= index; x+)
{
child = walker.GetNextSibling(child);
if (child == null)
{
throw new ArgumentOutOfRangeException();
}
}
return child;
}
/// <summary>
/// Retrieves an element in a list, using FindAll.
/// </summary>
/// <param name="parent">The list element.</param>
/// <param name="index">The index of the element to find.</param>
/// <returns>The list item.</returns>
AutomationElement FindChildAtB(AutomationElement parent, int index)
{
Condition findCondition = new PropertyCondition(AutomationElement.IsControlElementProperty, true);
AutomationElementCollection found = parent.FindAll(TreeScope.Children, findCondition);
if ((index < 0) || (index >= found.Count))
{
throw new ArgumentOutOfRangeException();
}
return found[index];
}