ToAscii
The ToAscii
function translates the specified virtual-key code and keyboard state to the
corresponding Windows character or characters. The function translates the code
using the input language and physical keyboard layout identified by the given
keyboard layout handle.
int ToAscii(
|
UINT uVirtKey, |
// virtual-key code |
|
UINT uScanCode, |
// scan code |
|
PBYTE lpKeyState, |
// address of
key-state array |
|
LPWORD lpChar, |
// buffer for
translated key |
|
UINT uFlags |
// active-menu flag |
|
); |
|
Parameters
uVirtKey
Specifies the
virtual-key code to be translated.
uScanCode
Specifies the
hardware scan code of the key to be translated. The high-order bit of this
value is set if the key is up (not pressed).
lpKeyState
Points to a
256-byte array that contains the current keyboard state. Each element (byte) in
the array contains the state of one key. If the high-order bit of a byte is
set, the key is down (pressed).
The low bit,
if set, indicates that the key is toggled on. In this function, only the toggle
bit of the CAPS LOCK key is relevant. The toggle state of the NUM LOCK and SCROLL LOCK keys
is ignored.
lpChar
Points to the
buffer that will receive the translated Windows character or characters.
uFlags
Specifies whether
a menu is active. This parameter must be 1 if a menu is active, or 0 otherwise.
Return Values
If the
specified key is a dead key, the return value is negative. Otherwise, it is one
of the following values:
|
Value |
Meaning |
|
0 |
The specified
virtual key has no translation for the current state of the keyboard. |
|
1 |
One Windows
character was copied to the buffer. |
|
2 |
Two
characters were copied to the buffer. This usually happens when a dead-key
character (accent or diacritic) stored in the keyboard layout cannot be
composed with the specified virtual key to form a single character. |
Remarks
The
parameters supplied to the ToAscii function might not be sufficient to
translate the virtual-key code, because a previous dead key is stored in the
keyboard layout.
Typically, ToAscii
performs the translation based on the virtual-key code. In some cases, however,
bit 15 of the uScanCode parameter may be used to distinguish between a
key press and a key release. The scan code is used for translating ALT+number
key combinations.
Although NUM LOCK is a
toggle key that affects keyboard behavior, ToAscii ignores the toggle
setting (the low bit) of lpKeyState (VK_NUMLOCK, because the uVirtKey
parameter alone is sufficient to distinguish the cursor movement keys (VK_HOME,
VK_INSERT, and so on) from the numeric keys (VK_DECIMAL, VK_NUMPAD0 -
VK_NUMPAD9).
See Also