keybd_event

The keybd_event function synthesizes a keystroke. The system can use such a synthesized keystroke to generate a WM_KEYUP or WM_KEYDOWN message. The keyboard driver's interrupt handler calls the keybd_event function.

VOID keybd_event(

BYTE bVk,	// virtual-key code
BYTE bScan,	// hardware scan code
DWORD dwFlags,	// flags specifying various function options
DWORD dwExtraInfo	// additional data associated with keystroke
);

Parameters

bVk

Specifies a virtual-key code. The code must be a value in the range 1 to 254.

bScan

Specifies a hardware scan code for the key.

dwFlags

A set of flag bits that specify various aspects of function operation. An application can use any combination of the following predefined constant values to set the flags:

Value	Meaning
KEYEVENTF_EXTENDEDKEY	If specified, the scan code was preceded by a prefix byte having the value 0xE0 (224).
KEYEVENTF_KEYUP	If specified, the key is being released. If not specified, the key is being depressed.

dwExtraInfo

Specifies an additional 32-bit value associated with the key stroke.

Return Values

This function has no return value.

Remarks

Although keybd_event passes an OEM-dependent hardware scan code to Windows, applications should not use the scan code. Windows converts scan codes to virtual-key codes internally and clears the up/down bit in the scan code before passing it to applications.

An application can simulate a press of the PRINTSCREEN key in order to obtain a screen snapshot and save it to the Windows clipboard. To do this, call keybd_event with the bVk parameter set to VK_SNAPSHOT, and the bScan parameter set to 0 for a snapshot of the full screen or set bScan to 1 for a snapshot of the active window.

See Also

GetAsyncKeyState, GetKeyState, MapVirtualKey, SetKeyboardState

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