Delphi VirtualKey to WideString

delphi, delphi-7, keyboard, winapi

Solution

You are setting the `cchBuff` parameter of `ToUnicode()` to 0 instead of the actual buffer size, so the function cannot store any characters it translates.

Try this instead:

function VKeytoWideString (Key : Word) : WideString; 
var 
  WBuff         : array [0..255] of WideChar; 
  KeyboardState : TKeyboardState; 
  UResult       : Integer;
begin 
  Result := '';
  GetKeyBoardState (KeyboardState); 
  ZeroMemory(@WBuff[0], SizeOf(WBuff));
  UResult := ToUnicode(key, MapVirtualKey(key, 0), KeyboardState, WBuff, Length(WBuff), 0); 
  if UResult > 0 then
    SetString(Result, WBuff, UResult)
  else if UResult = -1 then
    Result := WBuff;
end;

Problem

I would like to convert a virtual key to a WideString. That's what I have so far... ``` function VKeytoWideString (Key : Word) : WideString; var WBuff : array [0..255] of WideChar; KeyboardState : TKeyboardState; UResult : Integer; begin GetKeyBoardState (KeyboardState); UResult := ToUnicode(key, MapVirtualKey(key, 0), KeyboardState, WBuff, 0,0); Result := WBuff; case UResult of 0 : Result := ''; 1 : SetLength (Result, 1); 2 :; else Result := ''; end; end; ``` it always returns 0 but why? Please help.

Original source