DisplayPipelineDrawArrow Method (Line, Color, Double, Double)

using Rhino;
using Rhino.Commands;
using Rhino.Geometry;
using Rhino.Input.Custom;

namespace examples_cs
{
  class DrawArrowHeadsConduit : Rhino.Display.DisplayConduit
  {
    private readonly Line m_line;
    private readonly int m_screen_size;
    private readonly double m_world_size;

    public DrawArrowHeadsConduit(Line line, int screenSize, double worldSize)
    {
      m_line = line;
      m_screen_size = screenSize;
      m_world_size = worldSize;
    }

    protected override void DrawForeground(Rhino.Display.DrawEventArgs e)
    {
      e.Display.DrawArrow(m_line, System.Drawing.Color.Black, m_screen_size, m_world_size);
    }
  }


  public class DrawArrowheadsCommand : Command
  {
    public override string EnglishName { get { return "csDrawArrowHeads"; } }

    DrawArrowHeadsConduit m_draw_conduit;

    protected override Result RunCommand(RhinoDoc doc, RunMode mode)
    {
      if (m_draw_conduit != null)
      {
        RhinoApp.WriteLine("Turn off existing arrowhead conduit");
        m_draw_conduit.Enabled = false;
        m_draw_conduit = null;
      }
      else
      {
        // get arrow head size
        var go = new GetOption();
        go.SetCommandPrompt("ArrowHead length in screen size (pixels) or world size (percentage of arrow length)?");
        go.AddOption("screen");
        go.AddOption("world");
        go.Get();
        if (go.CommandResult() != Result.Success)
          return go.CommandResult();

        int screen_size = 0;
        double world_size = 0.0;
        if (go.Option().EnglishName == "screen")
        {
          var gi = new GetInteger();
          gi.SetLowerLimit(0, true);
          gi.SetCommandPrompt("Length of arrow head in pixels");
          gi.Get();
          if (gi.CommandResult() != Result.Success)
            return gi.CommandResult();
          screen_size = gi.Number();
        }
        else
        {
          var gi = new GetInteger();
          gi.SetLowerLimit(0, true);
          gi.SetUpperLimit(100, false);
          gi.SetCommandPrompt("Length of arrow head in percentage of total arrow length");
          gi.Get();
          if (gi.CommandResult() != Result.Success)
            return gi.CommandResult();
          world_size = gi.Number() / 100.0;
        }


        // get arrow start and end points
        var gp = new GetPoint();
        gp.SetCommandPrompt("Start of line");
        gp.Get();
        if (gp.CommandResult() != Result.Success)
          return gp.CommandResult();
        var start_point = gp.Point();

        gp.SetCommandPrompt("End of line");
        gp.SetBasePoint(start_point, false);
        gp.DrawLineFromPoint(start_point, true);
        gp.Get();
        if (gp.CommandResult() != Result.Success)
          return gp.CommandResult();
        var end_point = gp.Point();

        var v = end_point - start_point;
        if (v.IsTiny(Rhino.RhinoMath.ZeroTolerance))
          return Result.Nothing;

        var line = new Line(start_point, end_point);

        m_draw_conduit = new DrawArrowHeadsConduit(line, screen_size, world_size);
        // toggle conduit on/off
        m_draw_conduit.Enabled = true;
        RhinoApp.WriteLine("Draw arrowheads conduit enabled.");
      }
      doc.Views.Redraw();
      return Result.Success;
    }
  }
}

Imports Rhino
Imports Rhino.Commands
Imports Rhino.Geometry
Imports System.Collections.Generic
Imports Rhino.Input.Custom

Namespace examples_vb
  Class DrawArrowHeadsConduit
    Inherits Rhino.Display.DisplayConduit
    Private _line As Line
    Private _screenSize As Integer
    Private _worldSize As Double

    Public Sub New(line As Line, screenSize As Integer, worldSize As Double)
      _line = line
      _screenSize = screenSize
      _worldSize = worldSize
    End Sub

    Protected Overrides Sub DrawForeground(e As Rhino.Display.DrawEventArgs)
      e.Display.DrawArrow(_line, System.Drawing.Color.Black, _screenSize, _worldSize)
    End Sub
  End Class

  Public Class DrawArrowheadsCommand
    Inherits Command
    Public Overrides ReadOnly Property EnglishName() As String
      Get
        Return "vbDrawArrowHeads"
      End Get
    End Property

    Protected Overrides Function RunCommand(doc As RhinoDoc, mode As RunMode) As Result
      ' get arrow head size
      Dim go = New Rhino.Input.Custom.GetOption()
      go.SetCommandPrompt("ArrowHead length in screen size (pixles) or world size (percentage of arrow lenght)?")
      go.AddOption("screen")
      go.AddOption("world")
      go.[Get]()
      If go.CommandResult() <> Result.Success Then
        Return go.CommandResult()
      End If

      Dim screenSize As Integer = 0
      Dim worldSize As Double = 0.0
      If go.[Option]().EnglishName = "screen" Then
        Dim gi = New Rhino.Input.Custom.GetInteger()
        gi.SetLowerLimit(0, True)
        gi.SetCommandPrompt("Length of arrow head in pixels")
        gi.[Get]()
        If gi.CommandResult() <> Result.Success Then
          Return gi.CommandResult()
        End If
        screenSize = gi.Number()
      Else
        Dim gi = New Rhino.Input.Custom.GetInteger()
        gi.SetLowerLimit(0, True)
        gi.SetUpperLimit(100, False)
        gi.SetCommandPrompt("Lenght of arrow head in percentage of total arrow lenght")
        gi.[Get]()
        If gi.CommandResult() <> Result.Success Then
          Return gi.CommandResult()
        End If
        worldSize = gi.Number() / 100.0
      End If


      ' get arrow start and end points
      Dim gp = New Rhino.Input.Custom.GetPoint()
      gp.SetCommandPrompt("Start of line")
      gp.[Get]()
      If gp.CommandResult() <> Result.Success Then
        Return gp.CommandResult()
      End If
      Dim startPoint = gp.Point()

      gp.SetCommandPrompt("End of line")
      gp.SetBasePoint(startPoint, False)
      gp.DrawLineFromPoint(startPoint, True)
      gp.[Get]()
      If gp.CommandResult() <> Result.Success Then
        Return gp.CommandResult()
      End If
      Dim endPoint = gp.Point()

      Dim v = endPoint - startPoint
      If v.IsTiny(Rhino.RhinoMath.ZeroTolerance) Then
        Return Result.[Nothing]
      End If

      Dim line = New Line(startPoint, endPoint)

      Dim conduit = New DrawArrowHeadsConduit(line, screenSize, worldSize)
      ' toggle conduit on/off
      conduit.Enabled = Not conduit.Enabled
      RhinoApp.WriteLine("draw arrowheads conduit enabled = {0}", conduit.Enabled)

      doc.Views.Redraw()
      Return Result.Success
    End Function
  End Class
End Namespace

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

class DrawArrowHeadsConduit(Rhino.Display.DisplayConduit):
  def __init__(self, line, screenSize, worldSize):
    self.line = line
    self.screenSize = screenSize
    self.worldSize = worldSize

  def DrawForeground(self, e):
    e.Display.DrawArrow(self.line, System.Drawing.Color.Black, self.screenSize, self.worldSize)

def RunCommand():
  # get arrow head size
  go = Rhino.Input.Custom.GetOption()
  go.SetCommandPrompt("ArrowHead length in screen size (pixles) or world size (percentage of arrow lenght)?")
  go.AddOption("screen")
  go.AddOption("world")
  go.Get()
  if (go.CommandResult() != Rhino.Commands.Result.Success):
    return go.CommandResult()

  screenSize = 0
  worldSize = 0.0
  if (go.Option().EnglishName == "screen"):
    gi = Rhino.Input.Custom.GetInteger()
    gi.SetLowerLimit(0,True)
    gi.SetCommandPrompt("Length of arrow head in pixels")
    gi.Get()
    if (gi.CommandResult() != Rhino.Commands.Result.Success):
      return gi.CommandResult()
    screenSize = gi.Number()
  else:
    gi = Rhino.Input.Custom.GetInteger()
    gi.SetLowerLimit(0, True)
    gi.SetUpperLimit(100, False)
    gi.SetCommandPrompt("Lenght of arrow head in percentage of total arrow lenght")
    gi.Get()
    if (gi.CommandResult() != Rhino.Commands.Result.Success):
      return gi.CommandResult()
    worldSize = gi.Number()/100.0


  # get arrow start and end points
  gp = Rhino.Input.Custom.GetPoint()
  gp.SetCommandPrompt("Start of line")
  gp.Get()
  if (gp.CommandResult() != Rhino.Commands.Result.Success):
    return gp.CommandResult()
  ptStart = gp.Point()

  gp.SetCommandPrompt("End of line")
  gp.SetBasePoint(ptStart, False)
  gp.DrawLineFromPoint(ptStart, True)
  gp.Get()
  if (gp.CommandResult() != Rhino.Commands.Result.Success):
    return gp.CommandResult()
  ptEnd = gp.Point()


  v = ptEnd - ptStart
  if (v.IsTiny(Rhino.RhinoMath.ZeroTolerance)):
    return Rhino.Commands.Result.Nothing

  line = Rhino.Geometry.Line(ptStart, ptEnd)

  conduit = DrawArrowHeadsConduit(line, screenSize, worldSize)
  conduit.Enabled = True
  scriptcontext.doc.Views.Redraw()
  rs.GetString("Pausing for user input")
  conduit.Enabled = False
  scriptcontext.doc.Views.Redraw()

  return Rhino.Commands.Result.Success

if __name__=="__main__":
  RunCommand()