This message is sent to the owner window of an owner-drawn button or menu item when the control or menu is created.
At a Glance
| Header file: | Winuser.h |
| Windows CE versions: | 1.0 and later |
Syntax
WM_MEASUREITEM idCtl = (UINT) wParam; lpmis = (LPMEASUREITEMSTRUCT) lParam;
Parameters
idCtl
Contains the value of the CtlID member of the MEASUREITEMSTRUCT structure pointed to by the lpmis parameter. This value identifies the control that sent the WM_MEASUREITEM message.
If the value is zero, the message was sent by a menu. If the value is nonzero, the message was sent by a combo box or by a list box. If the value is nonzero, and the value of the itemID member of the MEASUREITEMSTRUCT pointed to by lpmis is (UINT) –1, the message was sent by a combo edit field.
lpmis
Long pointer to a MEASUREITEMSTRUCT structure that contains the dimensions of the owner-drawn control or menu item.
Return Values
An application should return TRUE if it processes this message.
Remarks
When the owner window receives the WM_MEASUREITEM message, the owner fills in the MEASUREITEMSTRUCT structure pointed to by the lParam parameter of the message and returns; this informs the system of the dimensions of the control. If a list box or combo box is created with the LBS_OWNERDRAWVARIABLE or CBS_OWNERDRAWVARIABLE style, this message is sent to the owner for each item in the control; otherwise, this message is sent once.
The system sends the WM_MEASUREITEM message to the owner window of combo boxes and list boxes created with the OWNERDRAWFIXED style before sending the WM_INITDIALOG message. As a result, when the owner receives this message, the system has not yet determined the height and width of the font used in the control; function calls and calculations requiring these values should occur in the main function of the application or library.