This notification message is sent by the OS to the parent window of an up-down control when the position of the control is about to change. This happens when the user requests a change in the value by pressing the control's up or down arrow. It is sent in the form of a WM_NOTIFY message.
At a Glance
| Header file: | Commctrl.h |
| Windows CE versions: | 1.0 and later |
Syntax
UDN_DELTAPOS pnmud = (NM_UPDOWN FAR *) lParam
Parameters
lpnmud
Long pointer to an NMUPDOWN structure that contains information about the position change.
The iPos member of this structure contains the current position of the control. The iDelta member of the structure is a signed integer that contains the proposed change in position. If the user has clicked the up button, this is a positive value. If the user has clicked the down button, this is a negative value.
Return Values
Nonzero prevents the change in the control's position. Zero accepts the change.
Remarks
The UDN_DELTAPOS notification is sent before the WM_HSCROLL message, which actually changes the control's position. This enables you to examine, accept, modify, or reject the change.
See Also