Как сделать аналогию распыляющего баллончика в рисовалке

Public Class Form1
    WithEvents Timer1 As New Timer With {.Interval = 100, .Enabled = False}
 
    Private bmp1 As Bitmap
 
    Private MouseCoords As Point
    Private MouseLeftDown As Boolean = False
 
    Private SprayIntensity = 10
    Private SprayRadius = 10
    Private SprayColor As Color = Color.Black
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.SetStyle(ControlStyles.OptimizedDoubleBuffer, True)
        Me.SetStyle(ControlStyles.UserPaint, True)
        Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)
 
        Me.BackColor = Color.LightCyan
 
        bmp1 = New Bitmap(Me.ClientRectangle.Width, Me.ClientRectangle.Height, Imaging.PixelFormat.Format32bppArgb)
    End Sub
 
    Private Sub Form1_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseDown
        If e.Button = Windows.Forms.MouseButtons.Left Then
            MouseLeftDown = True
            MouseCoords = New Point(e.Location)
            Timer1.Start()
        End If
    End Sub
    Protected Overrides Sub OnMouseMove(ByVal e As System.Windows.Forms.MouseEventArgs)
        MyBase.OnMouseMove(e)
 
        If MouseLeftDown Then MouseCoords = New Point(e.Location)
    End Sub
    Private Sub Form1_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseUp
        Timer1.Stop()
        MouseLeftDown = False
    End Sub
 
    Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
        e.Graphics.DrawImage(bmp1, 0, 0)
    End Sub
 
    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        Dim x, y As Integer
        Dim dx, dy As Integer
        Dim r As New Random
 
        For n As Integer = 1 To SprayIntensity
            Do
                dx = r.Next(-SprayRadius, SprayRadius)
                dy = r.Next(-SprayRadius, SprayRadius)
                x = MouseCoords.X + dx
                y = MouseCoords.Y + dy
            Loop While x < 0 Or x > bmp1.Width - 1 Or _
                       y < 0 Or y > bmp1.Height - 1 Or _
                       Math.Pow(SprayRadius, 2) < Math.Pow(Math.Abs(dx), 2) + Math.Pow(Math.Abs(dy), 2)
 
            bmp1.SetPixel(x, y, SprayColor)
        Next
 
        Me.Invalidate()
    End Sub
End Class

Public Class Form1
    Private _Bitmap As Bitmap
 
    Private MouseCoords As Point
    Private SprayIntensity = 50
    Private SprayRadius = 5
    Private SprayColor As Color = Color.Black
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Me.SetStyle(ControlStyles.OptimizedDoubleBuffer, True)
        Me.SetStyle(ControlStyles.UserPaint, True)
        Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)
        Me.BackColor = Color.LightCyan
        _Bitmap = New Bitmap(Me.ClientSize.Width, Me.ClientSize.Height, Imaging.PixelFormat.Format32bppArgb)
    End Sub
    Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint
        e.Graphics.DrawImage(_Bitmap, 0, 0)
    End Sub
    Private Sub Form1_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseMove
        If e.Button = Windows.Forms.MouseButtons.Left Then
            MouseCoords = New Point(e.Location)
 
            Dim x, y As Integer
            Dim dx, dy As Integer
            Dim r As New Random
 
            For n As Integer = 1 To SprayIntensity
                dx = r.Next(-SprayRadius, SprayRadius)
                dy = r.Next(-SprayRadius, SprayRadius)
                x = MouseCoords.X + dx
                y = MouseCoords.Y + dy
                If (x > 0 And x < _Bitmap.Width And y > 0 And y < _Bitmap.Height) _
                    Then _Bitmap.SetPixel(x, y, SprayColor)
            Next
            Me.Refresh()
        End If
    End Sub
End Class