Custom Scrollbars - Reference

8 minute read • 6 Jan 2002

SCROLLBUT

Specifies the attributes of a button which has been inserted into a window’s scrollbar. This structure is used by the CoolSB_InsertButton, CoolSB_ModifyButton and CoolSB_RemoveButton API calls.

typedef struct 
{
  UINT         fMask;          /* which members are in use */
  UINT         uPlacement;     /* which side of the scrollbar to insert */
  UINT         uCmdId;         /* command identifier (WM\_COMMAND value to send)*/
  UINT         uButType;       /* type of button to insert */
  UINT         uState;         /* what state the button is in (i.e. pressed) */
  int          nSize;          /* size in pixels. -1 for autosize */
  HBITMAP      hBmp;           /* handle to a bitmap to use as the button face */  
  HENHMETAFILE hEmf;           /* handle to an enhanced metafile */
  HCURSOR      hCurs;          /* handle to a mouse cursor to use */

  int          nSizeReserved;  /* private to the coolscroll library */  
  int          nMinSize;       /* minimum size of a resizable button */
  int          nMaxSize;       /* maximum size of a resizable button */

} SCROLLBUT;

Members

fMask is a set of flags OR’d together which specify which of the SCROLLBUT members contain valid information. This member can have one or more of the following values set:

Value	Description
SBBF_TYPE	The nButType member contans valid data
SBBF_ID	The nCmdId member contains a valid command identifier for the button
SBBF_STATE	The nState member contains a valid state identifier
SBBF_PLACEMENT	The nPlacement member contains valid data
SBBF_SIZE	The nSize member contains valid data
SBBF_BITMAP	The hBmp member is a valid handle to a Bitmap resource
SBBF_ENHMETAFILE	The hEmf member is a calid handle to a Enhanced Metafile
SBBF_CURSOR	The hCurs member is a valid handle to a cursor resource
SBBF_BUTMINMAX	The nMinSize and nMaxSize members contain valid thumb sizes

uButType specifies what type of button will be inserted into the scrollbar. This member can be set to just one of the following values:

Value	Description
SBBT_PUSHBUTTON	The button is a standard pushbutton, with the same look and feel as a normal scrollbar button arrow.
SBBT_TOGGLEBUTTON	The button can be toggled between an up and down state
SBBT_FIXED	The button does not respond to mouse clicks
SBBT_FLAT	The button has no 3d-look
SBBT_BLANK	The button is a blank area, and does not respond to clicks
SBBT_DARK	Another type of blank area, but is dark int colour
SBBT_OWNERDRAW	An NM_CUSTOMDRAW message will be sent to the window to paint the button.

In addtion to the above button types, you can also include one of the following button type modifiers by OR’ing it together with the button type:

Value	Description
SBBM_RECESSED	The button has a recessed look when it is being depressed
SBBM_LEFTARROW	The button has the standard left arrow bitmap
SBBM_RIGHTARROW	The button has the standard right arrow bitmap
SBBM_UPARROW	The button has the standard up arrow bitmap
SBBM_DOWNARROW	The button has the standard down arrow bitmap
SBBM_RESIZABLE	The button can be resized using the mouse
SBBM_TYPE2	The button uses a different 3d-look
SBBM_TYPE3	The button uses a different 3d-look

uCmdId specifies a command identifier which is used in the form of a WM_COMMAND message, which is sent whenever the button is clicked with the mouse.

uState specifies an initial state for the button, if it is a push-button or toggle-button. Valid values are defined below.

Value	Description
SBBS_NORMAL	The button is in its default, un-pushed state
SBBS_PUSHED	The button is in a depressed or “clicked” state.

nSize specifies the size of the button. For a button inserted into the horizontal scrollbar, nSize represents the width of the button, in pixels. For a button inserted into the vertical scrollbar, nSize represents the height of the button. A non-negative value is used to specify an exact size, in pixels. A negative number can be used to specify the size in multiples of the standard scrollbar button size. A value of -1 produces a button the same size as a scrollbar arrow. A value of -2 gives a button twice the size of a scrollbar button, and so on.

uPlacement specifies which side of the scrollbar the button should be inserted. This can be one of the following values. The default is SBBP_LEFT or SBBP_ABOVE, if nPlacement is not specified.

Value	Description
SBBP_LEFT	The button is inserted to the left of a horizontal scrollbar
SBBP_RIGHT	The button is inserted to the right of a horizontal scrollbar
SBBP_ABOVE	The button is inserted above of a vertical scrollbar
SBBP_BELOW	The button is inserted below of a vertical scrollbar

hBmp is a handle to a bitmap, which is used as the button’s image. The bitmap is centered in the button. If no bitmap is defined, then the button is left blank. Ownership of the bitmap is the responsibility of the user.

hEmf is a handle to an Enhanced Metafile, which is used as the button’s image when a bitmap hasn’t been supplied. Ownership of the metafile is the responsibility of the user.

hCurs is a handle to mouse cursor. This cursor is used whenever the mouse passes over the button. The standard mouse cursor is used if no cursor is specified.

nMinSize is the minimum size, in pixels, of a resizable button. The uButType member must include the SBBM_RESIZABLE flag.

hCurs is the maximum size, in pixels, of a resizable button. The uButType member must include the SBBM_RESIZABLE flag.

Remarks

This structure could be subject to change in future versions of the cool scrollbar library.

Back to the Cool Scrollbar Reference

NMCOOLBUTMSG

Specifies a mouse event notification on an inserted scrollbar button. Currently, only NM_CLICK notifications are supported

typedef struct
{
   NMHDR   hdr;         /* standard WM\_NOTIFY header */
   RECT	   rect;        /* window-relative coordinates of button */
   POINT   pt;          /* coordinates of the mouse cursor */
   UINT	   uCmdId;      /* command identifier of the button */
   UINT	   uState;      /* item state (clicked / disable etc) */
   UINT	   nBar;        /* which scrollbar (SB\_HORZ / SB\_VERT) */
	
} NMCSBCUSTOMDRAW;

Members

hdr is the standard NMHDR structure used in all WM_NOTIFY messages. The code member of this structure will NMCUSTOMDRAW for this message type.

rect specifies the coordinates of the item to draw. These coordinates are relative to the upper-left corner of the window’s non-client area.

pt specifies the screen coordinates of the cursor, in pixels.

uCmdId specifies which the command identifier of the scrollbar button.

uState this member is not currently used.

nBar specifies which of the window’s two scrollbars the button belongs to. This can be either SB_HORZ or SB_VERT.

Remarks

This structure could be subject to change in future versions of the cool scrollbar library.

Back to the Cool Scrollbar Reference

NMCSBCUSTOMDRAW

Specifies a Custom Draw structure specific to the cool scrollbar libary.

typedef struct
{
   NMHDR   hdr;             /* standard WM\_NOTIFY header */
   DWORD   dwDrawStage;     /* PREPAINT / POSTPAINT etc */
   HDC     hdc;             /* handle to a device context to draw into */
   RECT	   rect;            /* window-relative coordinates of item to draw */
   UINT	   uItem;           /* item id to draw */
   UINT	   uState;          /* item state (clicked / disable etc) */
   UINT	   nBar;            /* which scrollbar (SB\_HORZ / SB\_VERT) */
	
} NMCSBCUSTOMDRAW;

Members

hdr is the standard NMHDR structure used in all WM_NOTIFY messages. The code member of this structure will NMCUSTOMDRAW for this message type.

dwDrawStage specifies what the current stage of the custom draw is. The cool scrollbar library supports three possible values for this member:

Value	Description
CDDS_PREPAINT	The scrollbars are just about to be painted. Only the nBar and hdc members contain valid information. You could use this message to select a palette into the device context, for example. You can return either CDRF_DODEFAULT to let the cool scrollbar paint itself, or CDRF_SKIPDEFAULT to completely take over drawing of the specified scrollbar.
CDDS_POSTPAINT	The scrollbars have finished painting. Only the nBar and hdc members contain valid information. You should restore the device context to its original state if you selected any palettes into it. The return value of this message is not used.
CDDS_ITEMPREPAINT	An item needs to be painted. An item could be a scrollbar arrow, the scroll-thumb or a scrollbar margin. Currently, the cool scrollbar library expects all items to be painted by the user if CDRF_SKIPDEFAULT was returned in the pre-paint message. So, the return value of this message is not currently used.

Currently, no other drawing stage notifications are sent.

hdc specifies a device context which should be drawn into. This device context does not have any clipping regions defined.

rect specifies the coordinates of the item to draw. These coordinates are relative to the upper-left corner of the window’s non-client area.

uItem specifies which scrollbar item needs to be drawn. This can be one of the following values:

Value	Description
HTSCROLL_LEFT / HTSCROLL_UP	The left or up arrow button, depending on the value of nBar
HTSCROLL_RIGHT / HTSCROLL_DOWN	The right or down arrow button
HTSCROLL_PAGELEFT / HTSCROLL_PAGEUP	The left or upper scrollbar margin, before the scroll thumb.
HTSCROLL_PAGERIGHT / HTSCROLL_PAGEDOWN	The right or lower scrollbar margin.
HTSCROLL_THUMB	The scrollbar thumb.

uState defines the current state of the item to be painted. This can be one of the following values:

Value	Description
CDIS_HOT	The item is currently under the mouse pointer (“hot”).
CDIS_DISABLED	The item is disabled.
CDIS_SELECTED	The item is being activated by the mouse (clicked down on).
CDIS_DEFAULT	The item is in its normal state.

nBar specifies which of the window’s two scrollbars the item belongs to. This will be one of four values.
The SB_HORZ and SB_VERT identifiy that the item to draw is part of a horizontal or vertical scrollbar, respectively.
The SB_BOTH value is used when the scrollbar dead area (the size-grip area) needs to be painted. No pre-paint or post-paint notifications are sent when the gripper-area needs to be painted, because this is always a one-off message.
Lastly, the SB_INSBUT value is used when an inserted button needs to be painted. In this case, the uItem member specifies the command identifier of the inserted button. Only a CDDS_ITEMPREPAINT notification is sent, and the inserted button must have the SBBT_OWNERDRAW type set.

Remarks

This structure could be subject to change in future versions of the cool scrollbar library.

Back to the Cool Scrollbar Reference