WM_KEYUP message

Posted to the window with the keyboard focus when a nonsystem key is released. A nonsystem key is a key that is pressed when the ALT key is not pressed, or a keyboard key that is pressed when a window has the keyboard focus.

#define WM_KEYUP                        0x0101

Parameters

wParam

The virtual-key code of the nonsystem key. See Virtual-Key Codes.

lParam

The repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag, as shown in the following table.

Bits	Meaning
0-15	The repeat count for the current message. The value is the number of times the keystroke is autorepeated as a result of the user holding down the key. The repeat count is always 1 for a WM_KEYUP message.
16-23	The scan code. The value depends on the OEM.
24	Indicates whether the key is an extended key, such as the right-hand ALT and CTRL keys that appear on an enhanced 101- or 102-key keyboard. The value is 1 if it is an extended key; otherwise, it is 0.
25-28	Reserved; do not use.
29	The context code. The value is always 0 for a WM_KEYUP message.
30	The previous key state. The value is always 1 for a WM_KEYUP message.
31	The transition state. The value is always 1 for a WM_KEYUP message.

For more detail, see Keystroke Message Flags.

Return value

An application should return zero if it processes this message.

Remarks

The DefWindowProc function sends a WM_SYSCOMMAND message to the top-level window if the F10 key or the ALT key was released. The wParam parameter of the message is set to SC_KEYMENU.

For enhanced 101- and 102-key keyboards, extended keys are the right ALT and CTRL keys on the main section of the keyboard; the INS, DEL, HOME, END, PAGE UP, PAGE DOWN, and arrow keys in the clusters to the left of the numeric keypad; and the divide (/) and ENTER keys in the numeric keypad. Other keyboards may support the extended-key bit in the lParam parameter.

Applications must pass wParam to TranslateMessage without altering it at all.

Requirements

See also

• DefWindowProc
• TranslateMessage
• WM_KEYDOWN
• WM_SYSCOMMAND
• Keyboard Input
• About Keyboard Input