Imports System.Windows       'Verweis auf WindowsBase für Vector hinzufügen!!
Public Class Form1
    Dim WithEvents Pb As New PictureBox With {.Dock = DockStyle.Fill, .Parent = _
      Me}
    Dim plist As New List(Of PointF)({New PointF(20, 25), New PointF(250, 25), _
    New PointF(150, 220)})
 
    Private Sub Pb_MouseMove(sender As Object, e As _
      System.Windows.Forms.MouseEventArgs) Handles Pb.MouseMove
        Dim v1, v2 As Vector, dist As Double = 2000, nr As Int32
        v1 = New Vector(e.X, e.Y) 'Mausposition
        For i = 0 To plist.Count - 1
            v2 = New Vector(plist(i).X, plist(i).Y)
            If (v1 - v2).Length < dist Then
                dist = (v1 - v2).Length
                nr = i
            End If
        Next
        Pb.Invalidate()
        Me.Text = "Pt" & nr & ", " & dist.ToString("0.0") & " Pixel"
    End Sub
 
    Private Sub Pb_Paint(sender As Object, e As _
      System.Windows.Forms.PaintEventArgs) Handles Pb.Paint
        For i = 0 To plist.Count - 1
            e.Graphics.FillEllipse(Brushes.Black, plist(i).X - 5, plist(i).Y - _
              5, 10, 10)
        Next
    End Sub
End Class