Intruder alert

Public Class Form1

    Const WM_CAP As Short = &H400S
    Const WM_CAP_DRIVER_CONNECT As Integer = WM_CAP + 10
    Const WM_CAP_DRIVER_DISCONNECT As Integer = WM_CAP + 11
    Const WM_CAP_EDIT_COPY As Integer = WM_CAP + 30
    Const WM_CAP_SET_PREVIEW As Integer = WM_CAP + 50
    Const WM_CAP_SET_PREVIEWRATE As Integer = WM_CAP + 52
    Const WM_CAP_SET_SCALE As Integer = WM_CAP + 53
    Const WS_CHILD As Integer = &H40000000
    Const WS_VISIBLE As Integer = &H10000000
    Const SWP_NOMOVE As Short = &H2S
    Const SWP_NOSIZE As Short = 1
    Const SWP_NOZORDER As Short = &H4S
    Const HWND_BOTTOM As Short = 1
    Dim iDevice As Integer = 0
    Dim hHwnd As Integer
    Dim last As Bitmap
    Dim starting As Boolean = True
    Dim thread As System.Threading.Thread
    Dim percent As Double

    Declare Function SendMessage Lib "user32" Alias "SendMessageA" (ByVal hwnd As Integer, ByVal wMsg As Integer, ByVal wParam As Integer, ByVal lParam As Object) As Integer
    Declare Function SetWindowPos Lib "user32" Alias "SetWindowPos" (ByVal hwnd As Integer, ByVal hWndInsertAfter As Integer, ByVal x As Integer, ByVal y As Integer, ByVal cx As Integer, ByVal cy As Integer, ByVal wFlags As Integer) As Integer
    Declare Function DestroyWindow Lib "user32" (ByVal hndw As Integer) As Boolean
    Declare Function capCreateCaptureWindowA Lib "avicap32.dll" (ByVal lpszWindowName As String, ByVal dwStyle As Integer, ByVal x As Integer, ByVal y As Integer, ByVal nWidth As Integer, ByVal nHeight As Short, ByVal hWndParent As Integer, ByVal nID As Integer) As Integer
    Declare Function capGetDriverDescriptionA Lib "avicap32.dll" (ByVal wDriver As Short, ByVal lpszName As String, ByVal cbName As Integer, ByVal lpszVer As String, ByVal cbVer As Integer) As Boolean



    Private Sub LoadDeviceList()
        Dim strName As String = Space(100)
        Dim strVer As String = Space(100)
        Dim bReturn As Boolean
        Dim x As Integer = 0
        Do
            bReturn = capGetDriverDescriptionA(x, strName, 100, strVer, 100)
            If bReturn Then lstDevices.Items.Add(strName.Trim)
            x += 1
        Loop Until bReturn = False
    End Sub
    Private Sub OpenPreviewWindow()
        Dim iHeight As Integer = picCapture.Height
        Dim iWidth As Integer = picCapture.Width
        hHwnd = capCreateCaptureWindowA(iDevice, WS_VISIBLE Or WS_CHILD, 0, 0, 640, 480, picCapture.Handle.ToInt32, 0)
        If SendMessage(hHwnd, WM_CAP_DRIVER_CONNECT, iDevice, 0) Then
            SendMessage(hHwnd, WM_CAP_SET_SCALE, True, 0)
            SendMessage(hHwnd, WM_CAP_SET_PREVIEWRATE, 66, 0)
            SendMessage(hHwnd, WM_CAP_SET_PREVIEW, True, 0)
            SetWindowPos(hHwnd, HWND_BOTTOM, 0, 0, picCapture.Width, picCapture.Height, SWP_NOMOVE Or SWP_NOZORDER)
            btnSave.Enabled = True
            btnstop.Enabled = True
            btnstart.Enabled = False
        Else
            DestroyWindow(hHwnd)
            btnSave.Enabled = False
        End If
    End Sub

    Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
        Dim data As IDataObject
        Dim bmap As Image
        SendMessage(hHwnd, WM_CAP_EDIT_COPY, 0, 0)
        data = Clipboard.GetDataObject()
        If data.GetDataPresent(GetType(System.Drawing.Bitmap)) Then
            bmap = CType(data.GetData(GetType(System.Drawing.Bitmap)), Image)
            picCapture.Image = bmap
            ClosePreviewWindow()
            btnSave.Enabled = False
            btnstop.Enabled = False
            btnstart.Enabled = True
        End If
    End Sub

    Private Sub ClosePreviewWindow()
        SendMessage(hHwnd, WM_CAP_DRIVER_DISCONNECT, iDevice, 0)
        DestroyWindow(hHwnd)
    End Sub


    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        LoadDeviceList()
        Me.CheckForIllegalCrossThreadCalls = False
    End Sub



    Private Sub btnStart_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStart.Click

        OpenPreviewWindow()

        btnStart.Enabled = False

        btnStop.Enabled = True

    End Sub



    Private Sub btnStop_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStop.Click

        ClosePreviewWindow()

        btnStart.Enabled = True

        btnStop.Enabled = False

    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        'checking the image
        'define data to collect the image from the webcam
        Dim data As IDataObject
        'define bmap to contain the bitmap that comes from
        'the webcam
        Dim bmap As Bitmap
        'The first time the timer runs we need to set everything up
        'or we will get errors
        If starting Then ' if this is the first time we have run the code
            OpenPreviewWindow() ' start the preveiw window

            'get the first image
            SendMessage(hHwnd, WM_CAP_EDIT_COPY, 0, 0)
            data = Clipboard.GetDataObject()
            'if the image is there then save it to last
            'which is a global variable that stores the last image for comparison
            If data.GetDataPresent(GetType(System.Drawing.Bitmap)) Then
                last = CType(data.GetData(GetType(System.Drawing.Bitmap)), Image)
            End If
            'set the start variable to false so that we start the comparing next run of the timer
            starting = False
        Else
            'This is at least our second run so we can
            'compare
            'We get another image from the webcam
            SendMessage(hHwnd, WM_CAP_EDIT_COPY, 0, 0)
            data = Clipboard.GetDataObject()
            'if we recive an image from the webcam then:
            If data.GetDataPresent(GetType(System.Drawing.Bitmap)) Then

                'get the image data
                bmap = CType(data.GetData(GetType(System.Drawing.Bitmap)), Bitmap)
                'calculate the percentage of pixels the same
                Dim total As Integer
                Dim number As Integer = 0
                Dim absolutle As Integer = 0
                Dim a, b As Integer 'to store the color value for the calulation
                'set total to the size of the image
                total = (bmap.Width) * (bmap.Height)
                For i = 0 To bmap.Height - 1
                    For n = 0 To bmap.Width - 1
                        absolutle += 1
                        'each pixle
                        'each color
                        a = bmap.GetPixel(n, i).R
                        b = last.GetPixel(n, i).R
                        If (a - b) ^ 2 < 100 Then
                            a = bmap.GetPixel(n, i).G
                            b = last.GetPixel(n, i).G
                            If (a - b) ^ 2 < 100 Then
                                a = bmap.GetPixel(n, i).B
                                b = last.GetPixel(n, i).B
                                If (a - b) ^ 2 < 100 Then
                                    number += 1
                                End If
                            End If
                        End If
                    Next
                Next
                Label1.Text = number & "/" & total & " : " & FormatPercent(number / total) & " Absolute : " & absolutle
                percent = number / total
                If percent < 0.7 Then
                    thread = New System.Threading.Thread(AddressOf Speak)
                    thread.Start()
                End If
                last = bmap

            End If
        End If
    End Sub
    Public Sub Speak()
        Dim SAPI
        SAPI = CreateObject("SAPI.spvoice")
        SAPI.Speak("Intruder alert.")
    End Sub
End Class