FrameworkElement.VisualChildrenCount 屬性

protected:
 virtual property int VisualChildrenCount { int get(); };

protected override int VisualChildrenCount { get; }

member this.VisualChildrenCount : int

Protected Overrides ReadOnly Property VisualChildrenCount As Integer

屬性值

該元素的視覺子元素數量。

範例

以下範例展示了自訂裝飾器如何利用其為多個視覺子節點維護的 a VisualCollection 宣告的值，並透過覆寫 和 VisualChildrenCountGetVisualChild來報告這些值。

// To store and manage the adorner's visual children.
VisualCollection visualChildren;

' To store and manage the adorner's visual children.
Private visualChildren As VisualCollection

// Override the VisualChildrenCount and GetVisualChild properties to interface with 
// the adorner's visual collection.
protected override int VisualChildrenCount { get { return visualChildren.Count; } }
protected override Visual GetVisualChild(int index) { return visualChildren[index]; }

' Override the VisualChildrenCount and GetVisualChild properties to interface with 
' the adorner's visual collection.
Protected Overrides ReadOnly Property VisualChildrenCount() As Integer
    Get
        Return visualChildren.Count
    End Get
End Property
Protected Overrides Function GetVisualChild(ByVal index As Integer) As Visual
    Return visualChildren(index)
End Function

備註

FrameworkElement的VisualChildrenCount實作總是回傳零或一。 維持視覺子集合可能超過一個的類別必須同時覆寫此性質與 GetVisualChild。

此特性通常用於確定目前子集合的上限，以便實作版面覆寫（MeasureOverride， ArrangeOverride）。

給繼承者的注意事項

如果你的類別在一個子元素集合中支援多個視覺子節點，請覆寫此屬性以回傳該集合中元素的數量。 即使集合物件本身回傳計數，你也必須這麼做。 WPF框架層級的元素佈局邏輯假設所有元素都會透過其 VisualChildrenCount 屬性回傳有效的計數。