WPF中的绘制线 - DrawingVisual性能问题

Question

我已经实现了两个版本的线条图代码 - 一个使用WPF形状（线条），另一个使用StreamGeometry和DrawingVisual。

DrawingVisual应该更快，但我发现完全相反。初始绘制以及随后调整包含DrawingVisual对象的主机窗口的速度非常慢且不稳定，比WPF行示例更糟糕。

我做错了什么？

WPF行代码：

    Dim Rand As New Random

    For i As Integer = 1 To 1000

        Dim Line As New Line
        Line.X1 = Rand.NextDouble * 500
        Line.X2 = Rand.NextDouble * 500
        Line.Y1 = Rand.NextDouble * 500
        Line.Y2 = Rand.NextDouble * 500
        Line.Stroke = Brushes.Black
        Line.StrokeThickness = 0.25
        BaseGrid.Children.Add(Line)

    Next

DrawingVisual代码：

绘图视觉主机控件：

Public Class VisualHost

    Inherits FrameworkElement

    Dim Visual As New DrawingVisual()
    Dim Context As DrawingContext
    Dim Pen As Pen

    Dim rand As New Random

    Public Sub New()

        Pen = New Pen(Brushes.Black, 0.25)
        Pen.Freeze()

        AddVisualChild(Visual)

    End Sub

    Public Sub Draw()

        Dim Geometry As New StreamGeometry()

        Using GeometryContext As StreamGeometryContext = Geometry.Open()

            GeometryContext.BeginFigure(New Point(rand.NextDouble * 500, rand.NextDouble * 500), False, False)

            For i As Integer = 1 To 1000

                GeometryContext.LineTo(New Point(rand.NextDouble * 500, rand.NextDouble * 500), True, True)

            Next

        End Using

        Geometry.Freeze()

        Using Context = Visual.RenderOpen()
            Context.DrawGeometry(Nothing, Pen, Geometry)
        End Using

    End Sub

    Protected Overrides ReadOnly Property VisualChildrenCount() As Integer
        Get
            Return 1
        End Get
    End Property

    Protected Overrides Function GetVisualChild(index As Integer) As Visual
        Return Visual
    End Function

End Class

将VisualHost分配给网格：

Private Host As New VisualHost
BaseGrid.Children.Add(Host)
Host.Draw()