Mouse Control

[Jim_Hubbard]

I need to take control of the mouse (on a system wide level) for an application to help people with special disabilities. I have tried Desaware's Spyworks control, but the system wide ocx that allows you to trap mouse events, doesn't allow you to actually change these windows system messages that are sent to the graphical mouse pointer. Is there a way to take control of the mouse from Windows?

[Aaron Young]

You can use the Mouse_Event API to Simulate Mouse Operations, here's a quick example which allows you to control to Mouse Pointer using the Cursor Keys, and the Zero Key on the NumericPad as the Left Mouse Button.

In a Module, (No Forms Needed For this Project)..

Private Declare Sub mouse_event Lib "user32" (ByVal dwFlags As Long, ByVal dx As Long, ByVal dy As Long, ByVal cButtons As Long, ByVal dwExtraInfo As Long)
Private Declare Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer
Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

Private Const MOUSEEVENTF_LEFTDOWN = &H2
Private Const MOUSEEVENTF_LEFTUP = &H4
Private Const MOUSEEVENTF_MOVE = &H1

Private Const MOUSESPEED = 2

Sub Main()
Dim bClick As Boolean
Dim x As Integer
Dim y As Integer

'Wait for a Clear Keyboard Buffer
While GetAsyncKeyState(1)
DoEvents
Wend
Do
x = 0
y = 0
If GetAsyncKeyState(vbKeyLeft) Then
x = -MOUSESPEED
ElseIf GetAsyncKeyState(vbKeyRight) Then
x = MOUSESPEED
End If
If GetAsyncKeyState(vbKeyUp) Then
y = -MOUSESPEED
ElseIf GetAsyncKeyState(vbKeyDown) Then
y = MOUSESPEED
End If
If GetAsyncKeyState(vbKeyNumpad0) <> 0 Then
If Not bClick Then
'Simulate Left Mouse Button Down
mouse_event MOUSEEVENTF_MOVE Or MOUSEEVENTF_LEFTDOWN, x, y, 0, 0
Else
'Simulate Mouse Movement with Left Mouse Button Down, (Drag).
mouse_event MOUSEEVENTF_MOVE, x, y, 0, 0
End If
bClick = True
Else
If bClick Then
'Simulate Left Mouse Button Up
mouse_event MOUSEEVENTF_MOVE Or MOUSEEVENTF_LEFTUP, x, y, 0, 0
ElseIf x <> 0 Or y <> 0 Then
'Simulate Mouse Movement
mouse_event MOUSEEVENTF_MOVE, x, y, 0, 0
End If
bClick = False
End If
DoEvents
Sleep 1 'Pause to allow the cursor action to be seen.
Loop Until GetAsyncKeyState(vbKeyEscape) 'Press ESC to Quit
End Sub


------------------
Aaron Young
Analyst Programmer
aarony@redwingsoftware.com
adyoung@win.bright.net