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操作說明：對 Visual 中的幾何進行點擊測試

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此範例會示範如何在由一或多個 Geometry 物件所組成的視覺物件上執行點擊測試。

範例

下列範例示範如何從使用 GetDrawing 方法的視覺物件擷取 DrawingGroup。 然後，點擊測試會在 DrawingGroup 中所呈現的每個繪製內容上執行，以判斷所點擊的幾何。

注意

在大部分情況下，您會使用 HitTest 方法來判斷點是否與任何呈現的視覺內容相交。

// Determine if a geometry within the visual was hit.
static public void HitTestGeometryInVisual(Visual visual, Point pt)
{
    // Retrieve the group of drawings for the visual.
    DrawingGroup drawingGroup = VisualTreeHelper.GetDrawing(visual);
    EnumDrawingGroup(drawingGroup, pt);
}

// Enumerate the drawings in the DrawingGroup.
static public void EnumDrawingGroup(DrawingGroup drawingGroup, Point pt)
{
    DrawingCollection drawingCollection = drawingGroup.Children;

    // Enumerate the drawings in the DrawingCollection.
    foreach (Drawing drawing in drawingCollection)
    {
        // If the drawing is a DrawingGroup, call the function recursively.
        if (drawing.GetType() == typeof(DrawingGroup))
        {
            EnumDrawingGroup((DrawingGroup)drawing, pt);
        }
        else if (drawing.GetType() == typeof(GeometryDrawing))
        {
            // Determine whether the hit test point falls within the geometry.
            if (((GeometryDrawing)drawing).Geometry.FillContains(pt))
            {
                // Perform action based on hit test on geometry.
            }
        }
    }
}

' Determine if a geometry within the visual was hit.
Public Shared Sub HitTestGeometryInVisual(ByVal visual As Visual, ByVal pt As Point)
    ' Retrieve the group of drawings for the visual.
    Dim drawingGroup As DrawingGroup = VisualTreeHelper.GetDrawing(visual)
    EnumDrawingGroup(drawingGroup, pt)
End Sub

' Enumerate the drawings in the DrawingGroup.
Public Shared Sub EnumDrawingGroup(ByVal drawingGroup As DrawingGroup, ByVal pt As Point)
    Dim drawingCollection As DrawingCollection = drawingGroup.Children

    ' Enumerate the drawings in the DrawingCollection.
    For Each drawing As Drawing In drawingCollection
        ' If the drawing is a DrawingGroup, call the function recursively.
        If drawing.GetType() Is GetType(DrawingGroup) Then
            EnumDrawingGroup(CType(drawing, DrawingGroup), pt)
        ElseIf drawing.GetType() Is GetType(GeometryDrawing) Then
            ' Determine whether the hit test point falls within the geometry.
            If (CType(drawing, GeometryDrawing)).Geometry.FillContains(pt) Then
                ' Perform action based on hit test on geometry.
            End If
        End If

    Next drawing
End Sub

FillContains 方法是多載方法，可讓您使用指定的 Point 或 Geometry 來進行點擊測試。 如果幾何是經過繪製，筆觸可延伸至填滿範圍外。 在該情況下，除了 FillContains 之外，您可能還會想呼叫 StrokeContains。

您也可以提供針對貝茲壓平合併目的所使用的 ToleranceType。

注意

這個範例不會將任何可能套用至幾何的轉換或裁剪列入考慮。 此外，這個範例無法搭配樣式化控制項運作，因為它不具備任何直接與其相關聯的圖案。

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