The WM_UNICHAR message is posted to the window with the keyboard focus when a WM_KEYDOWN message is translated by the TranslateMessage function. The WM_UNICHAR message contains the character code of the key that was pressed.
The WM_UNICHAR message is equivalent to WM_CHAR, but it uses Unicode Transformation Format (UTF)-32, whereas WM_CHAR uses UTF-16. It is designed to send or post Unicode characters to ANSI windows and it can can handle Unicode Supplementary Plane characters.
Syntax
WM_UNICHAR
WPARAM wParam
LPARAM lParam;
Parameters
- wParam
-
Specifies the character code of the key.
If
wParam is UNICODE_NOCHAR and the application processes this message, then return TRUE. The
DefWindowProc function will return FALSE (the default).
If
wParam is not UNICODE_NOCHAR, return FALSE. The Unicode DefWindowProc posts a WM_CHAR message with the same parameters and the ANSI DefWindowProc function posts either one or two WM_CHAR messages with the corresponding ANSI character(s).
- lParam
-
Specifies the repeat count, scan code, extended-key flag, context code, previous key-state flag, and transition-state flag, as shown in the following table.
0-15- Specifies 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. If the keystroke is held long enough, multiple messages are sent. However, the repeat count is not cumulative.
16-23- Specifies the scan code. The value depends on the OEM.
24- Specifies 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- 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 transition state. The value is 1 if the key is being released, or it is 0 if the key is being pressed.
Return Value
An application should return zero if it processes this message.
Remarks
Because there is not necessarily a one-to-one correspondence between keys pressed and character messages generated, the information in the high-order word of the
lParam parameter is generally not useful to applications. The information in the high-order word applies only to the most recent WM_KEYDOWN message that precedes the posting of the WM_UNICHAR message.
For enhanced 101- and 102-key keyboards, extended keys are the right ALT and the right 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. Some other keyboards may support the extended-key bit in the
lParam parameter.
Notification Requirements
| Minimum DLL Version |
None |
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| Header | Declared in Winuser.h, include Windows.h |
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| Minimum operating systems |
Windows XP |
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See Also