[Original] delphi KeyUp, KeyPress, Keydown differences and usage, how not to call the keyboard event

The KeyPress  (Sender: TObject; var Key: Char); when the user presses character keys (letters, numbers) on the keyboard will trigger the event, it will not function key (F1-F12, Ctrl, Alt , Shift)

KeyUp  (Sender: TObject; var Key: Word; the Shift: TShiftState); when you press a key on the keyboard release triggered OnKeyUp event (any key triggers)

KeyDown (Sender: TObject; var Key: Word; the Shift: TShiftState); press any button will trigger this event

 

KeyPress and two other difference is that, Key values ​​are characters, the other is digital (word 0 · 65535)

Special attention is Shift: TShiftState Its value is: TShiftState = set of (ssShift, ssAlt, ssCtrl, ssLeft, ssRight, ssMiddle, ssDouble); call Examples are:

ssCtrl in Shift

or

[ssCtrl]

 

 

Edit call:

KeyPress

var 
  key: char 
begin 
  key: = '# 13 And'; 
  EditKeyPress (nīl, key); 
end;

 

KeyUp

var
  key:word
begin
  key:=13；
  EditKeyUp(nil,key,[]);
end；

Here not shift value, it is written []

 

Keydown

var
  key:word
begin
  key:=13；
  EditKeydown(nil,key,[]);
end；