A Small GDI+ Sprite Animation Library

Imports System.Runtime.InteropServices
Imports System.Reflection
Imports System.Drawing
Imports System.Threading

Public NotInheritable Class winKeyboardHandler

#Region " Events "
    Public Event KeyPressed(ByVal theKey As winKeyboardAPI.eKeys, ByVal isDown As Boolean)
#End Region

#Region " Variables "
    Private m_KeyboardHandle As Integer
    <MarshalAs(UnmanagedType.FunctionPtr)> Private m_Callback As winKeyboardAPI.KeyboardHookDelegate
#End Region

#Region " Functions "
    Private Function IsHooked(ByRef Hookstruct As winKeyboardAPI.KBDLLHOOKSTRUCT) As Boolean
        If (Hookstruct.vkCode = winKeyboardAPI.eKeys.kControl Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kDownArrow Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kEscape Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF1 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF10 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF11 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF12 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF2 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF3 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF4 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF5 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF6 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF7 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF8 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kF9 Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kLeftArrow Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kLeftMouse Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kMiddleMouse Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kReturn Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kRightArrow Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kRightMouse Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kShift Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kSpace Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kTab Or _
            Hookstruct.vkCode = winKeyboardAPI.eKeys.kUpArrow) Then
            Return True
        End If

        Return False
    End Function

    Private Function KeyboardCallback(ByVal Code As Integer, ByVal wParam As Integer, _
                                     ByRef lParam As winKeyboardAPI.KBDLLHOOKSTRUCT) As Integer

        If (Code = winKeyboardAPI.HC_ACTION) Then
            If (IsHooked(lParam)) Then
                RaiseEvent KeyPressed(CType(lParam.vkCode, winKeyboardAPI.eKeys), CBool(wParam = winKeyboardAPI.WM_KEYDOWN))
                Return 1
            End If
        End If

        Return winKeyboardAPI.CallNextHookEx(m_KeyboardHandle, Code, wParam, lParam)
    End Function

    Private Function Hooked()
        Return m_KeyboardHandle <> 0
    End Function
#End Region

#Region " Subs "
    Public Sub AquireKeyboard()
        m_Callback = New winKeyboardAPI.KeyboardHookDelegate(AddressOf KeyboardCallback)

        m_KeyboardHandle = winKeyboardAPI.SetWindowsHookEx(winKeyboardAPI.WH_KEYBOARD_LL, m_Callback, _
                                                      Marshal.GetHINSTANCE([Assembly].GetExecutingAssembly.GetModules()(0)).ToInt32, 0)
    End Sub

    Public Sub ReleaseKeyboard()
        If (Hooked()) Then
            winKeyboardAPI.UnhookWindowsHookEx(m_KeyboardHandle)
            m_KeyboardHandle = 0
        End If
    End Sub
#End Region

#Region " Overrides "
    Protected Overrides Sub Finalize()
        ReleaseKeyboard()
        MyBase.Finalize()
    End Sub
#End Region

End Class