Restored from previous forum. Originally posted by ebs.
Balrog,
From
http://msdn.microsoft.com/library/defau ... wheel.asp:
WM_MOUSEWHEEL Notification
The WM_MOUSEWHEEL message is sent to the focus window when the mouse wheel is rotated. The DefWindowProc function propagates the message to the window's parent. There should be no internal forwarding of the message, since DefWindowProc propagates it up the parent chain until it finds a window that processes it.
A window receives this message through its WindowProc function.
Syntax
WM_MOUSEWHEEL
WPARAM wParam
LPARAM lParam;
Parameters
wParam
The high-order word indicates the distance the wheel is rotated, expressed in multiples or divisions of WHEEL_DELTA, which is 120. A positive value indicates that the wheel was rotated forward, away from the user; a negative value indicates that the wheel was rotated backward, toward the user.
The low-order word indicates whether various virtual keys are down. This parameter can be one or more of the following values.
MK_CONTROL
The CTRL key is down.
MK_LBUTTON
The left mouse button is down.
MK_MBUTTON
The middle mouse button is down.
MK_RBUTTON
The right mouse button is down.
MK_SHIFT
The SHIFT key is down.
MK_XBUTTON1
Windows 2000/XP: The first X button is down.
MK_XBUTTON2
Windows 2000/XP: The second X button is down.
lParam
The low-order word specifies the x-coordinate of the pointer, relative to the upper-left corner of the screen.
The high-order word specifies the y-coordinate of the pointer, relative to the upper-left corner of the screen.
Return Value
If an application processes this message, it should return zero.
Eric
Originally posted by BalrogSoft
Thanks, and how to know the direction of the wheel movement?
Originally posted by ebs
Balrog,
#WM_MOUSEWHEEL = $20A
HTH,
Eric