Question

I have a DrawingVisual object I have created for example using this method:

Private Function CreateDrawingVisualRectangle() As DrawingVisual

   Dim drawingVisual As New DrawingVisual() 
   Dim drawingContext As DrawingContext = drawingVisual.RenderOpen()
   Dim rect As New Rect(New Point(160, 100), New Size(320, 80))
   drawingContext.DrawRectangle(Brushes.LightBlue, New Pen(Brushes.Black, 0.5), rect)

   Return drawingVisual

End Function

There’s a way to get the type of shape drawn by DrawingContext method and its properties?

I.e.:

Dim MyVisual as DrawingVisual = CreateDrawingVisualRectangle()

Dim MyVisualType as MyType = MyVisual.GetDrawingType()
Dim MyBrush as Brush = MyVisual.GetDrawingBrush()
Dim MyPen as Pen = MyVisual.GetDrawingPen()
Dim MyRect as Rect = MyVisual.GetDrawingRect()
...

Obviously the methods I used in the last example is indicative methods that does not exist in reality, but I’d use to get MyVisual properties.

Thanks.

Answer 1

You could recursivly iterate through the Drawing objects in the DrawingGroup provided by the Drawing property of a DrawingVisual and if a child drawing is a GeometryDrawing, check for its Pen, Brush and Geometry properties:

void InspectDrawings(DrawingVisual drawingVisual)
{
    InspectDrawings(drawingVisual.Drawing);
}

void InspectDrawings(DrawingGroup drawingGroup)
{
    foreach (Drawing drawing in drawingGroup.Children)
    {
        if (drawing is GeometryDrawing)
        {
            GeometryDrawing geometryDrawing = (GeometryDrawing)drawing;
            // inspect properties here
        }
        else if (drawing is DrawingGroup)
        {
            // recurse into sub-group
            InspectDrawings((DrawingGroup)drawing);
        }
    }
}

You may now retrieve the type of Geometry and check for more special properties. For example if it is a RectangleGeometry, check its Rect property.