' Multi-touch demo by Richard Russell, http://www.rtrussell.co.uk/
    ' amended for Liberty BASIC by Brandon and Rod using Dennis McKinney's
    ' http://lbpe.wikispaces.com/ArraysAndStructs
    ' Uses WMLiberty.DLL (http://www.b6sw.com/forum/download.php?id=16)

    'nomainwin
    Global WM.TOUCH, hWnd, nPoints, ptrStructArray,sizeofTi
    WM.TOUCH = hexdec("0240")

    'a normal struct for the xy points
    Struct pt, x As long, y As long

    'a normal struct that will be used to define an array of structs
    Struct ti, x            As long, _
               y            As long, _
               hSource      As ulong, _
               dwID         As long, _
               dwFlags      As long, _
               dwMask       As long, _
               dwTime       As long, _
               dwExtraInfo  As long, _
               cxContact    As long, _
               cyContact    As long

    'the size of the structure is
    sizeofTi = Len(ti.struct)

    'the amount of memory needed for the array is
    maxPoints=6
    memBlockSize = maxPoints*sizeofTi

    'allocate memory and get pointer using Richards simplifications
    'structs are accessed by sizeofTi offset
    'so ti.struct=ptrStructArray+sizeofTi*i i=0-5
    ptrStructArray = GlobalAlloc(memBlockSize)

    Open "WMLiberty" For DLL As #wmlib
    WindowWidth = 800
    WindowHeight = 600
    Open "Multi-touch demo" For graphics As #w
    hWnd = hwnd(#w)
    #w "trapclose quit"
    #w "down; fill black ; backcolor red"

    ' set up callback to receive touch messages
    callback lpwmtouch, wmtouch(ulong, ulong, ulong, ulong), long
    calldll #wmlib, "SetWMHandler", hWnd        As ulong, _
                                    WM.TOUCH    As ulong, _
                                    lpwmtouch   As ulong, _
                                    1           As long, _
                                    ret         As long

    ' register the window for touch messaging
    calldll #user32, "RegisterTouchWindow", hWnd        As ulong, _
                                            0           As ulong, _
                                            lpwmtouch   As ulong, _
                                            ret         As long

    ' now scan for messages
    [wait] ' Must use a Scan loop.
    Scan
    Call plot
    CallDLL #kernel32, "Sleep", 5  As Long, ret As Void
    GoTo [wait]



Sub plot
    For i = 0 To nPoints-1
        'fill the ti.struct from the offset
        ti.struct=ptrStructArray+sizeofTi*i
        'get the screen coordinates
        pt.x.struct = ti.x.struct / 100
        pt.y.struct = ti.y.struct / 100
        CallDLL #user32, "ScreenToClient", hWnd As ulong, _
                                           pt   As struct, _
                                           ret  As long
        #w "place ";pt.x.struct;" ";pt.y.struct
        #w "circlefilled 50"
    Next i
    nPoints = 0
End Sub

Sub quit h$
    Close #wmlib
    ret = GlobalFree(ptrStructArray)
    Close #w
    End
End Sub

Function wmtouch(hw, msg, wparam, lparam)
    nPoints = wparam And hexdec("FFFF")
    If nPoints > 6 Then nPoints = 6
    CallDLL #user32, "GetTouchInputInfo", lparam            As ulong, _
                                          nPoints           As ulong, _
                                          ptrStructArray    As ulong, _
                                          sizeofTi          As long, _
                                          ret               As long
    CallDLL #user32, "CloseTouchInputHandle", lparam    As ulong, _
                                              ret       As long
End Function

Function GlobalAlloc( dwBytes )
    'returns pointer to fixed memory block.
    CallDLL #kernel32, "GlobalAlloc",  0              As long, _
                                     dwBytes        As ulong, _
                                     GlobalAlloc    As long
End Function

Function GlobalFree( hMem )
    CallDLL #kernel32, "GlobalFree", hMem         As ulong, _
                                   GlobalFree   As long
End Function