Using Only One ForEach Loop

Please see the following Code:-

 Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
           Parallel.ForEach(Segments.OfType(Of Segment),
                             Sub(segment)
                                 Try
                                      segment.DrawLine(e.Graphics)
                                 Catch ex As Exception
                                 End Try
                             End Sub
                             )
        
          Parallel.ForEach(Ellipses.OfType(Of Ellipse),
                             Sub(ellipse)
                                 Try
                                      ellipse.DrawEllipse(e.Graphics)
                                 Catch ex As Exception
                                 End Try
                             End Sub
                             )
      End Sub

Is it Possible to use only One ForEach loop instead of Two as shown above? If No, is there a way to Enhance the Speed of Execution by using async and await?

>Solution :

It would be possible to use only one loop if all types of shapes would be in the same collection. To enable this, you would need to have an abstract base class for shapes.

Public MustInherit Class Shape
    Public Property ForeColor As Color

    ... other common properties

    Public MustOverride Draw(g As Graphics)
End Class

Then you can derive the concrete shapes like this (with Line as an example):

Public Class Line
    Inherits Shape

    Public Property StartPoint As PointF
    Public Property EndPoint As PointF

    Public Overrides Sub Draw(g As Graphics)
        Using pen As New SolidPen(ForeColor)
            g.DrawLine(pen, StartPoint, EndPoint)
        End Using
    End Sub
End Class

The you can add all the kind of shapes to a List(Of Shape) and loop it like this

Parallel.ForEach(Shapes,
    Sub(shape)
        shape.Draw(e.Graphics)
    End Sub
)