Imports System.Drawing.Drawing2D

Imports System.IO

Imports System.Drawing

Public Class Form1

    Private startPoint As Point

    Private endPoint As Point

    Private lineColor As Color = Color.Black ' Set the default color to black

    Private arrowColor As Color = Color.Black ' Set the default color to black

    Private arrowPoints As Point() ' The points of the last drawn arrow

    Private Sub PictureBox1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseDown

        If e.Button = MouseButtons.Left Then

            startPoint = e.Location

        End If

    End Sub





    Private Sub PictureBox1_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles PictureBox1.MouseUp

        If e.Button = MouseButtons.Left Then

            endPoint = e.Location

            Using g As Graphics = Graphics.FromHwnd(PictureBox1.Handle)

                'Show the color dialog to select the line and arrow color

                Using colorDialog As New ColorDialog()

                    colorDialog.Color = lineColor

                    If colorDialog.ShowDialog() = DialogResult.OK Then

                        lineColor = colorDialog.Color

                        arrowColor = colorDialog.Color

                    End If

                End Using





                g.DrawLine(New Pen(lineColor, 4), startPoint, endPoint)





                'Calculate the angle of the line

                Dim angle As Single = CSng(Math.Atan2(endPoint.Y - startPoint.Y, endPoint.X - startPoint.X) * 180 / Math.PI)





                'Draw the arrowhead with the selected color

                Dim arrowSize As Integer = 6

                Dim arrowBrush As New SolidBrush(arrowColor)

                Dim arrowPen As New Pen(arrowBrush, 4)

                arrowPoints = {New Point(endPoint.X, endPoint.Y), New Point(endPoint.X - arrowSize, endPoint.Y - arrowSize), New Point(endPoint.X - arrowSize, endPoint.Y + arrowSize)}

                Dim transform As New Matrix()

                transform.RotateAt(angle, endPoint)

                g.Transform = transform

                g.FillPolygon(arrowBrush, arrowPoints)

                g.DrawPolygon(arrowPen, arrowPoints)

                g.ResetTransform()

            End Using

        End If

    End Sub

      

End Class