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WM_MEASUREITEM message

Sent to the owner window of a combo box, list box, list-view control, or menu item when the control or menu is created.

A window receives this message through its WindowProc function.


WM_MEASUREITEM

    WPARAM wParam;
    LPARAM lParam; 

Parameters

wParam

Contains the value of the CtlID member of the MEASUREITEMSTRUCT structure pointed to by the lParam 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 lParam is (UINT) –1, the message was sent by a combo edit field.

lParam

Pointer to a MEASUREITEMSTRUCT structure that contains the dimensions of the owner-drawn control or menu item.

Return value

If an application processes this message, it should return TRUE.

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.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Winuser.h (include Windows.h)

See also

Reference
MEASUREITEMSTRUCT
Other Resources
WM_INITDIALOG

 

 

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