KEYSTATE property (System)

This property returns:

1. The state of a key at the time the last message was read from the Presentation Server’s message queue (the key to check is passed as a virtual-key code in the index parameter), or

2. An array representing the state of all virtual keys if no virtual key code is passed.

If a virtual-key code was specified this property is an integer value that represents a set of bit flags. As a general rule:

• If the key is pressed down the property returns a value < 0 (i.e. The most significant bit is set), otherwise the key is not pressed.

• If the key is toggled (such as the CAPS-LOCK key) then the least significant bit is set (this only applies to keys that can be toggled)

If a virtual-key code was not specified this property returns an @fm-delimited array of flags for all virtual keys (this is a 256-element array) – the meaning of the flags is as described above.

See remarks for more information.

This property is essentially a wrapper around the GetKeyState and GetKeyboardState Windows API functions, so please refer to the documentation on the Microsoft website for further information.

Virtual-key code constants are defined in the MSWin_VirtualKey_Equates insert record.

 
$Insert msWin_VirtualKey_Equates

   

   // Get the state of the Shift key

   ShiftDown = ( Get_Property( "SYSTEM", "KEYSTATE", VK_SHIFT$ ) < 0 )

   

   // Get the state of the CAPS-LOCK key

   CapState   = Get_Property( "SYSTEM", "KEYSTATE", VK_CAPITAL$ )

   CapPressed = ( CapState < 0 )

   CapToggled = BitAnd( CapState, 0x01 )

   

   // Get the state of all keys and extract the CAPS-LOCK state

   KeyboardState = Get_Property( "SYSTEM", "KEYSTATE" )

   CapState = KeyboardState<VK_CAPITAL$>
 
 
 

ASYNCKEYSTATE property