Author: Jonas Bilinkevicius 

How to get the scan code of keyboards

Answer:

1   unit Unit1;
2   
3   interface
4   
5   uses
6     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, 
7   Dialogs;
8   
9   type
10    TKeyInfo = packed record
11      KeyDown: Boolean;
12      VirtualKeyCode: WORD;
13      RepeatCount: Word;
14      VirtualScanCode: Byte;
15      ExtendedKey: Boolean;
16      ContextCode: Boolean;
17      PreviousState: Boolean;
18      AsciiChar: Char;
19      ControlKeyState: DWORD;
20    end;
21  
22    TForm1 = class(TForm)
23    private
24      procedure WMKeyDown(var message: TMessage); message WM_KEYDOWN;
25      function GetKeyInfo(var message: TMessage): TKeyInfo;
26    public
27      { Public declarations }
28    end;
29  
30  var
31    Form1: TForm1;
32  
33  implementation
34  
35  {$R *.dfm}
36  
37  procedure TForm1.WMKeyDown(var message: TMessage);
38  var
39    KeyInfo: TKeyInfo;
40  begin
41    KeyInfo := GetKeyInfo(message);
42    KeyInfo.KeyDown := True;
43    ShowMessage('ScanCode: ' + IntToStr(KeyInfo.VirtualScanCode));
44  end;
45  
46  function TForm1.GetKeyInfo(var message: TMessage): TKeyInfo;
47  
48    function IsWinNT: Boolean;
49    begin
50      Result := (GetVersion < $80000000);
51    end;
52  
53  const
54    AltMask = $20000000;
55  var
56    KeyBoardState: TKeyBoardState;
57    LowerKeyData: WORD;
58    UpperKeyData: WORD;
59  begin
60    ZeroMemory(@Result, SizeOf(TKeyInfo));
61    GetKeyBoardState(KeyBoardState);
62    LowerKeyData := LOWORD(message.LParam);
63    UpperKeyData := HIWORD(message.LParam);
64    Result.VirtualKeyCode := WORD(message.WParam);
65    Result.RepeatCount := LowerKeyData;
66    Result.VirtualScanCode := UpperKeyData and $FF;
67    Result.ExtendedKey := Boolean((UpperKeyData and KF_EXTENDED) shr 8);
68    Result.ContextCode := Boolean((UpperKeyData and KF_ALTDOWN) shr 13);
69    Result.PreviousState := Boolean((UpperKeyData and KF_REPEAT) shr 14);
70    Result.KeyDown := not Boolean((UpperKeyData and KF_UP) shr 15);
71    ToAscii(Result.VirtualKeyCode, Result.VirtualScanCode, KeyBoardState,
72      @Result.AsciiChar, 0);
73    Result.ControlKeyState := (((KeyBoardState[VK_LCONTROL] and 128) shr 7) *
74      LEFT_CTRL_PRESSED) or (((KeyBoardState[VK_RCONTROL] and 128)
75      shr 7) * RIGHT_CTRL_PRESSED) or (((KeyBoardState[VK_LMENU] and
76      128) shr 7) * LEFT_ALT_PRESSED) or (((KeyBoardState[VK_RMENU]
77      and 128) shr 7) * RIGHT_ALT_PRESSED) or ((KeyBoardState
78      [VK_CAPITAL] and 1) * CAPSLOCK_ON) or ((KeyBoardState
79      [VK_NUMLOCK] and 1) * NUMLOCK_ON) or ((KeyBoardState
80      [VK_SCROLL] and 1) * SCROLLLOCK_ON) or ((((KeyBoardState
81      [VK_LSHIFT] or KeyBoardState[VK_RSHIFT]) and 128) shr 7) *
82      SHIFT_PRESSED) or (Integer(Result.ExtendedKey) * ENHANCED_KEY);
83  
84    if (not IsWinNT) then
85    begin
86      if (((Result.ControlKeyState and LEFT_CTRL_PRESSED) or (Result.ControlKeyState 
87  and
88        RIGHT_CTRL_PRESSED)) = 0) and ((KeyBoardState[VK_CONTROL] and 128) <> 0) then
89        Result.ControlKeyState := Result.ControlKeyState or RIGHT_CTRL_PRESSED;
90      if (((Result.ControlKeyState and LEFT_ALT_PRESSED) or (Result.ControlKeyState 
91  and
92        RIGHT_ALT_PRESSED)) = 0) and ((KeyBoardState[VK_MENU] and 128) <> 0) then
93        Result.ControlKeyState := Result.ControlKeyState or RIGHT_ALT_PRESSED;
94    end;
95  end;
96  
97  end.