B4J Question use dll to enable joystick support

Imports System.ComponentModel
Imports System.Runtime.InteropServices

Public Class Joystick
    Inherits NativeWindow

    Private parent As Form
    Private Const MM_JOY1MOVE As Integer = &H3A0

    ' Public Event Move(ByVal joystickPosition As Point)
    Public btnValue As String
    Public Event Up()
    Public Event Down()
    Public Event Left()
    Public Event Right()

    <StructLayout(LayoutKind.Explicit)> _
    Private Structure JoyPosition
        <FieldOffset(0)> _
        Public Raw As IntPtr
        <FieldOffset(0)> _
        Public XPos As UShort
        <FieldOffset(2)> _
        Public YPos As UShort
    End Structure

    Private Class NativeMethods

        Private Sub New()
        End Sub

        ' This is a "Stub" function - it has no code in its body.
        ' There is a similarly named function inside a dll that comes with windows called
        ' winmm.dll.
        ' The .Net framework will route calls to this function, through to the dll file.
        <DllImport("winmm", CallingConvention:=CallingConvention.Winapi, EntryPoint:="joySetCapture", SetLastError:=True)> _
        Public Shared Function JoySetCapture(ByVal hwnd As IntPtr, ByVal uJoyID As Integer, ByVal uPeriod As Integer, <MarshalAs(UnmanagedType.Bool)> ByVal changed As Boolean) As Integer
        End Function

    End Class

    Public Sub New(ByVal parent As Form, ByVal joyId As Integer)
        AddHandler parent.HandleCreated, AddressOf Me.OnHandleCreated
        AddHandler parent.HandleDestroyed, AddressOf Me.OnHandleDestroyed
        AssignHandle(parent.Handle)
        Me.parent = parent
        Dim result As Integer = NativeMethods.JoySetCapture(Me.Handle, joyId, 100, True)
    End Sub

    Private Sub OnHandleCreated(ByVal sender As Object, ByVal e As EventArgs)
        AssignHandle(DirectCast(sender, Form).Handle)
    End Sub

    Private Sub OnHandleDestroyed(ByVal sender As Object, ByVal e As EventArgs)
        ReleaseHandle()
    End Sub

    Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)
        If m.Msg = MM_JOY1MOVE Then
            ' Joystick co-ords.
            ' (0,0) (32768,0) (65535, 0)
            '
            '
            '
            ' (0, 32768) (32768, 32768) (65535, 32768)
            '
            '
            '
            '
            ' (0, 65535) (32768, 65535) (65535, 65535)
            '
            Dim p As JoyPosition
            p.Raw = m.LParam
            ' RaiseEvent Move(New Point(p.XPos, p.YPos))
            If p.XPos > 16384 AndAlso p.XPos < 49152 Then
                ' X is near the centre line.
                If p.YPos < 6000 Then
                    ' Y is near the top.
                    RaiseEvent Up()
                ElseIf p.YPos > 59536 Then
                    ' Y is near the bottom.
                    RaiseEvent Down()
                End If
            Else
                If p.YPos > 16384 AndAlso p.YPos < 49152 Then
                    ' Y is near the centre line
                    If p.XPos < 6000 Then
                        ' X is near the left.
                        RaiseEvent Left()
                    ElseIf p.XPos > 59536 Then
                        ' X is near the right
                        RaiseEvent Right()
                    End If
                End If
            End If
        End If
        If btnValue <> m.WParam.ToString Then
            btnValue = m.WParam.ToString
        End If
        MyBase.WndProc(m)
    End Sub

End Class