Dynamic Draw is not working on Python3 in Rhino 8

Rhino Developer
,
1

Dear friends.

I want to use a dynamic draw method in Rhino 8 with Python3. I found a tricky problem that the blow python code is okay for Ironpython. However, the dynamic view is not working on Rhino 8. Would you please giev me some suggestions.

from Rhino import *
from Rhino.Geometry import *
from Rhino.Commands import *
from Rhino.Input.Custom import *
from scriptcontext import doc
from System.Drawing import *
 
def RunCommand():
    gp = GetPoint()
    gp.SetCommandPrompt("Center point")
    gp.Get()
    if gp.CommandResult() != Result.Success:
        return gp.CommandResult()
    center_point = gp.Point()
    if center_point == Point3d.Unset:
        return Result.Failure
 
    gcp = GetCircleRadiusPoint(center_point)
    gcp.SetCommandPrompt("Radius")
    gcp.ConstrainToConstructionPlane(False)
    gcp.SetBasePoint(center_point, True)
    gcp.DrawLineFromPoint(center_point, True)
    gcp.Get()
    if gcp.CommandResult() != Result.Success:
        return gcp.CommandResult()
 
    radius = center_point.DistanceTo(gcp.Point())
    cplane = doc.Views.ActiveView.ActiveViewport.ConstructionPlane()
    doc.Objects.AddCircle(Circle(cplane, center_point, radius))
    doc.Views.Redraw()
    return Result.Success
 
class GetCircleRadiusPoint (GetPoint):
    def __init__(self, centerPoint):
        self.m_center_point = centerPoint
 
    def OnDynamicDraw(self, e):
        cplane = e.RhinoDoc.Views.ActiveView.ActiveViewport.ConstructionPlane()
        radius = self.m_center_point.DistanceTo(e.CurrentPoint)
        circle = Circle(cplane, self.m_center_point, radius)
        e.Display.DrawCircle(circle, Color.Black)
 
if __name__ == "__main__":
    RunCommand()