VisualTreeHelper.GetDrawing(Visual) Method
Definition
Important
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Returns the drawing content of the specified Visual.
public:
static System::Windows::Media::DrawingGroup ^ GetDrawing(System::Windows::Media::Visual ^ reference);
public static System.Windows.Media.DrawingGroup GetDrawing (System.Windows.Media.Visual reference);
static member GetDrawing : System.Windows.Media.Visual -> System.Windows.Media.DrawingGroup
Public Shared Function GetDrawing (reference As Visual) As DrawingGroup
Parameters
Returns
The drawing content of the Visual returned as a DrawingGroup type.
Examples
The following example shows how to retrieve the DrawingGroup from a visual object by using the GetDrawing method. A hit test is then performed on the geometry of each drawing in the DrawingGroup to determine which geometry was hit.
// Determine if a geometry within the visual was hit.
public static 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.
public static 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
Applies to
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