BUTTON Control

Button controls are used as triggers or toggles. Toggles may be 2-way or 3-way.

[See Introduction to Controls]

Button types and styles

Button types:

BS_PUSHBUTTON
BS_DEFPUSHBUTTON

BS_CHECKBOX
BS_AUTOCHECKBOX
BS_3STATE
BS_AUTO3STATE
    [ See check box example (caption options). ]

BS_RADIOBUTTON
BS_AUTORADIOBUTTON

BS_GROUPBOX

BS_USERBUTTON
BS_OWNERDRAW

Button styles:

BS_TEXT
BS_LEFTTEXT BS_RIGHTBUTTON

BS_ICON
BS_BITMAP

BS_LEFT
BS_CENTER
BS_RIGHT
BS_TOP
BS_VCENTER
BS_BOTTOM

BS_PUSHLIKE
BS_MULTILINE
BS_FLAT

BS_NOTIFY

Button messages

There are some APIs for buttons and there are some general APIs like SetFocus EnableWindow and SetWindowText.

Button messages:

BM_GETCHECK
BM_SETCHECK ; wParam = new check state
BM_GETSTATE
BM_SETSTATE ; wParam = new push state
BM_SETSTYLE  ; wParam = new style lParam = redraw
BM_CLICK ; simulate click
BM_GETIMAGE
BM_SETIMAGE ; lParam = new image handle

Button states:

BST_UNCHECKED
BST_CHECKED
BST_INDETERMINATE

; Button state masks for BM_GETSTATE

; get check state = 3h
BST_PUSHED ; get push/highlight state
BST_FOCUS ; get focus state

Button notifications

Buttons notify their parents by sending a WM_COMMAND message to them with a notification code.

Button notification codes:

BN_CLICKED
BN_PAINT
BN_HILITE BN_PUSHED
BN_UNHILITE BN_UNPUSHED
BN_DISABLE
BN_DOUBLECLICKED BN_DBLCLK
BN_SETFOCUS
BN_KILLFOCUS

Some specialized API button functions

These functions were created for use in dialogs. However they will work for any window that has button controls. When working with dialog boxes the Wnd argument is the dialog box.

DWORD IsDlgButtonChecked(HWND Wnd int ButtonID)
    Same as sending BM_GETSTATE. Effectively used when a button needs to be queried by a handler for another control.

void CheckDlgButton(HWND Wnd int ButtonID DWORD NewState)
    Same as sending BM_SETSTATE. Effectively used when a button needs to be changed by another control handler.

void CheckRadioButton(HWND Wnd int FirstBtnID int LastBtnID int SelectBtnID)
    This is a very useful function. Makes several buttons work together as a "select one" control. The buttons affected have control IDs in the range from FirstBtnID to LastBtnID. The button with the SelectBtnID is the one that gets "checked" and the others become "unchecked".