draw_foreground.py

import Rhino
import System.Drawing
import scriptcontext
import rhinoscriptsyntax as rs

class CustomConduit(Rhino.Display.DisplayConduit):
    def __init__(self):
        url = 'https://gist.githubusercontent.com/sbaer/bebd530d103a56cdd0076156af66f54b/raw/a92efce9ef85fd09316a42afcd899bd0e2d19b15/greetings.png'
        self.image = Rhino.Display.DisplayBitmap.Load(url)

    def DrawForeground(self, e):
        size = e.Viewport.Size
        center = Rhino.Geometry.Point2d(size.Width*0.5,size.Height*0.5)
        imageSize = self.image.Size
        scaleX = size.Width / imageSize.Width
        scaleY = size.Height / imageSize.Height
        scale = scaleX
        if scaleY > scaleX: scale = scaleY
        width = scale * imageSize.Width
        height = scale * imageSize.Height
        e.Display.DrawSprite(self.image, center, width, height)

if __name__== "__main__":
    conduit = CustomConduit()
    conduit.Enabled = True
    scriptcontext.doc.Views.Redraw()
    rs.GetString("Pausing for user input")
    conduit.Enabled = False
    scriptcontext.doc.Views.Redraw()

greetings.png