Author: Attila Torda-Pilisi

Replace chracters while typing

This code allows you to replaces umlauts (i.e. 'ä', 'ö', etc.)  with 'ae', 'oe', 
etc. while typing.

Answer:
1   
2   procedure TForm1.AppOnMessage(var Msg: TMsg; var Handled: Boolean);
3   type
4     TReplacement = record
5       chIn: Char;
6       chOut: string[2]
7     end;
8     TReplacements = array[0..6] of TReplacement;
9   const
10    Replacements: TReplacements = ((chIn: 'ä'; chOut: 'ae'),
11      (chIn: 'ö'; chOut: 'oe'),
12      (chIn: 'ü'; chOut: 'ue'),
13      (chIn: 'Ä'; chOut: 'Ae'),
14      (chIn: 'Ö'; chOut: 'Oe'),
15      (chIn: 'Ü'; chOut: 'Ue'),
16      (chIn: 'ß'; chOut: 'ss'));
17  var
18    i: Integer;
19    c: Char;
20  begin
21    Handled := False;
22    if Msg.message = WM_CHAR then
23    begin
24      if Chr(Msg.wParam) in ['ä', 'ö', 'ü', 'Ä', 'Ö', 'Ü', 'ß'] then
25      begin
26        for i := Low(Replacements) to High(Replacements) do
27          if Chr(Msg.wParam) = Replacements[i].chIn then
28          begin
29            Msg.wParam := Ord(Replacements[i].chOut[1]);
30            with Longrec(Msg.lParam) do
31              Hi := (Hi and $FF00) or VKKeyScan(Replacements[i].chOut[2]);
32            PostMessage(Msg.hwnd, WM_CHAR, Ord(Replacements[i].chOut[2]),
33              Msg.wParam);
34            with Longrec(Msg.lParam) do
35              Hi := (Hi and $FF00) or VKKeyScan(Char(Msg.wParam));
36            Break;
37          end;
38      end;
39    end;
40  end;
41  
42  procedure TForm1.FormCreate(Sender: TObject);
43  begin
44    Application.OnMessage := AppOnMessage;
45  end;