Get Shift Ctrl Alt Key state - Delphi Tips

Delphi Tips

Get Shift Ctrl Alt Key State

This code determines the state of 
shift, alt and ctrl keys. You can 
do this while your application is 
initializing, in order to do 
something or not to do something.

Keywords: keystate, keyboard state

Note: Thanks to Mary Atkins-Shington for reporting this

GetKeyState and GetAsyncKeyState only work with Win95, 
Win98, NT4, Terminal Server and Windows 2000. But on 
WinME it always returns zero. These two functions are 
simply skipped by Millenium Edition!

Official explanation from Microsoft:

Intentionally disabled.
It didn't work all that well on some newer hardware,
 and worked less well with the passage of time, so 
it was fully disabled in ME.


//Tests whether the high order bit of the given 
//word is set.
function HighOrderBitSet (theWord: Word): Boolean;
const
  HighOrderBit = 15;
type
  BitSet = set of 0..15;
begin
  HighOrderBitSet := (HighOrderBit in BitSet(theWord));
end;

 ..
begin
 ..
 AltKeyDown := HighOrderBitSet(Word(GetKeyState(
                                          VK_MENU)));
 CtrlKeyDown := HighOrderBitSet(Word(GetKeyState(
                                          VK_CONTROL)));
 ShiftKeyDown := HighOrderBitSet(Word(GetKeyState(
                                          VK_SHIFT)));
 LeftShiftKeyDown := HighOrderBitSet(Word(GetKeyState(
                                          VK_LSHIFT)));
   // other VK's:
  // VK_LSHIFT	    VK_RSHIFT
  // VK_LCONTROL    VK_RCONTROL
  // VK_LMENU       VK_RMENU
end.

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