使用 TreeWalker 巡覽 UI 自動化項目
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這份文件適用於想要使用 System.Windows.Automation 命名空間中定義之 Managed UI Automation 類別的 .NET Framework 開發人員。如需 UI Automation 的最新資訊，請參閱 Windows Automation API：使用者介面自動化 (英文)。 |
本主題內含範例程式碼，說明如何使用 TreeWalker 類別以巡覽 Microsoft UI Automation項目。
範例
下列範例使用 GetParent 向上查核 Microsoft UI Automation樹狀目錄直到找到根項目或找到桌面為止。 而在該位置之下的項目，就是所指定項目之的視窗。
''' <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 'Reader
/// <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;
}
下列範例使用 GetFirstChild 及 GetNextSibling 以建立 TreeView，顯示控制項檢視中已啟用之 Microsoft UI Automation項目的整個樹狀子目錄。
''' <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 'WalkEnabledElements
/// <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);
}
}