WM_KEYUP

2.x

WM_KEYUP
wVkey = wParam;         /* virtual-key code */
dwKeyData = lParam;     /* key data         */

The WM_KEYUP message is sent when a nonsystem key is released. A nonsystem key is a key that is pressed when the ALT key is not pressed, or it is a key that is pressed when a window has the input focus.

Parameters

wVkey

Value of wParam. Specifies the virtual-key code of the given key.

dwKeyData

Value of lParam. Specifies the repeat count, scan code, extended key, context code, previous key state, and key-transition state, as shown in the following table:

Bit Description

0–15 Specifies the repeat count. The value is the number of times the keystroke is repeated as a result of the user holding down the key.
16–23 Specifies the scan code. The value depends on the original equipment manufacturer (OEM).
24 Specifies whether the key is an extended key, such as a function key or a key on the numeric keypad. The value is 1 if it is an extended key; otherwise, it is 0.
25–26 Not used.
27–28 Used internally by Windows.
29 Specifies the context code. The value is 1 if the ALT key is held down while the key is pressed; otherwise, the value is 0.
30 Specifies the previous key state. The value is 1 if the key is down before the message is sent, or it is 0 if the key is up.
31 Specifies the key-transition state. The value is 1 if the key is being released, or it is 0 if the key is being pressed.

For a WM_KEYUP message, the value of bit 29 (context code) is 0 and the value of bit 31 (key-transition state) is 1.

Return Value

An application should return zero if it processes this message.

Comments

For IBM Enhanced 101- and 102-key keyboards, enhanced keys are the right ALT key and the right CTRL key 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 division (/) and ENTER keys on the numeric keypad. Some other keyboards may support the extended-key bit in the dwKeyData parameter.

See Also

WM_CHAR, WM_KEYDOWN