NM_CUSTOMDRAW (trackbar)

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NM_CUSTOMDRAW lpNMCustomDraw = (LPNMCUSTOMDRAW) lParam;

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.

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.

When dwDrawStage equals CDDS_PREPAINT:

CDRF_DODEFAULT
The control will draw itself. It will not send any additional NM_CUSTOMDRAW messages for this paint cycle.
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.
CDRF_NOTIFYITEMERASE
The control will notify the parent when an item will be erased. It will send NM_CUSTOMDRAW notification messages before and after erasing items.
CDRF_NOTIFYPOSTERASE
The control will notify the parent after erasing an item.
CDRF_NOTIFYPOSTPAINT
The control will notify the parent after painting an item.
CDRF_NOTIFYSUBITEMDRAW
Version 4.71. The control will notify the parent when a list view subitem is being drawn.

When dwDrawStage equals CDDS_ITEMPREPAINT:

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.
CDRF_SKIPDEFAULT
Your application drew the item manually. The control will not draw the item.

lpNMCustomDraw

Address of 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.

Version 4.70


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