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NM_CUSTOMDRAW (trackbar) notification code

  • Artikkeli

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

NM_CUSTOMDRAW

    lpNMCustomDraw = (LPNMCUSTOMDRAW) lParam;

Parameters

lParam

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:

Value Meaning
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.

Return code Description
CDRF_DODEFAULT
 The control will draw itself. It will not send any additional NM_CUSTOMDRAW notification codes 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 codes 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.

Requirements

Requirement Value
Minimum supported client
 Windows Vista [desktop apps only]
Minimum supported server
 Windows Server 2003 [desktop apps only]
Header
Commctrl.h

See also

Using Custom Draw