Sent by a trackbar control to notify its parent windows about drawing operations. This notification is sent in the form of a WM_NOTIFY message.

Syntax

NM_CUSTOMDRAW

    lpNMCustomDraw = (LPNMCUSTOMDRAW) lParam;

Parameters

lpNMCustomDraw

Pointer to an NMCUSTOMDRAW structure that contains information about the drawing operation. The dwItemSpec member of this structure will contain one of the Custom Draw Values that indicates which part of the control is being drawn. Trackbar controls insert the following values into the dwItemSpec member of this structure to identify the portion of the control being drawn:

TBCD_CHANNEL

Identifies the channel that the trackbar control's thumb marker slides along.

TBCD_THUMB

Identifies the trackbar control's thumb marker. This is the portion of the control that the user moves.

TBCD_TICS

Identifies the increment tick marks that appear along the edge of the trackbar control.

Return Value

The value your application can return depends on the current drawing stage. The dwDrawStage member of the associated NMCUSTOMDRAW structure holds a value that specifies the drawing stage. You must return one of the following values.

CDRF_DODEFAULT	The control will draw itself. It will not send any additional NM_CUSTOMDRAW notification messages for this paint cycle. This occurs when dwDrawStage equals CDDS_PREPAINT.
CDRF_NOTIFYITEMDRAW	The control will notify the parent of any item-related drawing operations. It will send NM_CUSTOMDRAW notification messages before and after drawing items. This occurs when dwDrawStage equals CDDS_PREPAINT.
CDRF_NOTIFYPOSTERASE	The control will notify the parent after erasing an item. This occurs when dwDrawStage equals CDDS_PREPAINT.
CDRF_NOTIFYPOSTPAINT	The control will notify the parent after painting an item. This occurs when dwDrawStage equals CDDS_PREPAINT.
CDRF_NOTIFYSUBITEMDRAW	Version 4.71. The control will notify the parent when a list-view subitem is being drawn. This occurs when dwDrawStage equals CDDS_PREPAINT.
CDRF_NEWFONT	Your application specified a new font for the item; the control will use the new font. For more information on changing fonts, see Changing fonts and colors. This occurs when dwDrawStage equals CDDS_ITEMPREPAINT.
CDRF_SKIPDEFAULT	Your application drew the item manually. The control will not draw the item. This occurs when dwDrawStage equals CDDS_ITEMPREPAINT.

Notification Requirements

Minimum DLL Version	comctl32.dll version 4.70 or later
Header	commctrl.h
Minimum operating systems	Windows 2000, Windows NT 4.0 with Internet Explorer 3.0, Windows 98, Windows 95 with Internet Explorer 3.0

See Also

Using Custom Draw