使用 TreeWalker 巡覽 UI 自動化項目

本主題包含範例程式碼，示範如何使用 TreeWalker 類別在 Microsoft UI 自動化元素之間巡覽。

範例 1

下列範例使用 GetParent 來爬升 Microsoft UI 自動化樹狀結構，直到找到根元素或桌面為止。 位於指定元素之父視窗正下方的元素。

/// <summary>
/// Retrieves the top-level window that contains the specified UI Automation element.
/// </summary>
/// <param name="element">The contained element.</param>
/// <returns>The containing top-level window element.</returns>
private AutomationElement GetTopLevelWindow(AutomationElement element)
{
    TreeWalker walker = TreeWalker.ControlViewWalker;
    AutomationElement elementParent;
    AutomationElement node = element;
    if (node == elementRoot) return node;
    do
    {
        elementParent = walker.GetParent(node);
        if (elementParent == AutomationElement.RootElement) break;
        node = elementParent;
    }
    while (true);
    return node;
}

    ''' <summary>
    ''' Retrieves the top-level window that contains the specified UI Automation element.
    ''' </summary>
    ''' <param name="element">The contained element.</param>
    ''' <returns>The containing top-level window element.</returns>
    Private Function GetTopLevelWindow(ByVal element As AutomationElement) As AutomationElement
        Dim walker As TreeWalker = TreeWalker.ControlViewWalker
        Dim elementParent As AutomationElement
        Dim node As AutomationElement = element
        If node = elementRoot Then
            Return node
        End If
        Do
            elementParent = walker.GetParent(node)
            If elementParent = AutomationElement.RootElement Then
                Exit Do
            End If
            node = elementParent
        Loop While True
        Return node

    End Function 'GetTopLevelWindow
End Class

範例 2

下列範例使用 GetFirstChild 和 GetNextSibling 來建立 TreeView，其中顯示控制項檢視中已啟用之 Microsoft UI 自動化元素的整個子樹狀結構。

/// <summary>
/// Walks the UI Automation tree and adds the control type of each enabled control
/// element it finds to a TreeView.
/// </summary>
/// <param name="rootElement">The root of the search on this iteration.</param>
/// <param name="treeNode">The node in the TreeView for this iteration.</param>
/// <remarks>
/// This is a recursive function that maps out the structure of the subtree beginning at the
/// UI Automation element passed in as rootElement on the first call. This could be, for example,
/// an application window.
/// CAUTION: Do not pass in AutomationElement.RootElement. Attempting to map out the entire subtree of
/// the desktop could take a very long time and even lead to a stack overflow.
/// </remarks>
private void WalkEnabledElements(AutomationElement rootElement, TreeNode treeNode)
{
    Condition condition1 = new PropertyCondition(AutomationElement.IsControlElementProperty, true);
    Condition condition2 = new PropertyCondition(AutomationElement.IsEnabledProperty, true);
    TreeWalker walker = new TreeWalker(new AndCondition(condition1, condition2));
    AutomationElement elementNode = walker.GetFirstChild(rootElement);
    while (elementNode != null)
    {
        TreeNode childTreeNode = treeNode.Nodes.Add(elementNode.Current.ControlType.LocalizedControlType);
        WalkEnabledElements(elementNode, childTreeNode);
        elementNode = walker.GetNextSibling(elementNode);
    }
}

''' <summary>
''' Walks the UI Automation tree and adds the control type of each enabled control 
''' element it finds to a TreeView.
''' </summary>
''' <param name="rootElement">The root of the search on this iteration.</param>
''' <param name="treeNode">The node in the TreeView for this iteration.</param>
''' <remarks>
''' This is a recursive function that maps out the structure of the subtree beginning at the
''' UI Automation element passed in as rootElement on the first call. This could be, for example,
''' an application window.
''' CAUTION: Do not pass in AutomationElement.RootElement. Attempting to map out the entire subtree of
''' the desktop could take a very long time and even lead to a stack overflow.
''' </remarks>
Private Sub WalkEnabledElements(ByVal rootElement As AutomationElement, ByVal treeNode As TreeNode)
    Dim condition1 As New PropertyCondition(AutomationElement.IsControlElementProperty, True)
    Dim condition2 As New PropertyCondition(AutomationElement.IsEnabledProperty, True)
    Dim walker As New TreeWalker(New AndCondition(condition1, condition2))
    Dim elementNode As AutomationElement = walker.GetFirstChild(rootElement)
    While (elementNode IsNot Nothing)
        Dim childTreeNode As TreeNode = treeNode.Nodes.Add(elementNode.Current.ControlType.LocalizedControlType)
        WalkEnabledElements(elementNode, childTreeNode)
        elementNode = walker.GetNextSibling(elementNode)
    End While

End Sub

另請參閱

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