Mega Code Archive
How to translate a virtual key to ASCII code
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Title: How to translate a virtual-key to ASCII code
{
Typically you would get the scancode needed from the
lparam of a WM_KEYDOWN message.
If you are trying to work from an OnKeyDown handler
here you don't have that either,
so you have to fall back on MapVirtualKey.
The keystate array is obtained from GetKeyboardstate.
}
{: Obtain the character that will result from the virtual key
passed in.
@param vkey is the virtual key code, e.g. Key parameter of an
OnKeyDown handler.
@returns the character or '' if the key does not result in a
character. On rare occasions the function may return two
characters, e.g. if an accent key is pressed followed by another
character that does not have an accented version. }
function GetCharFromVKey(vkey: Word): string;
var
keystate: TKeyboardState;
retcode: Integer;
begin
Win32Check(GetKeyboardState(keystate));
SetLength(Result, 2);
retcode := ToAscii(vkey,
MapVirtualKey(vkey, 0),
keystate, @Result[1],
0);
case retcode of
0: Result := ''; // no character
1: SetLength(Result, 1);
2:;
else
Result := ''; // retcode
end;
end;
procedure TForm1.Memo1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
label1.Caption := GetCharFromVKey(Key);
end;
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