unit caret1;
interface
{$IFDEF WIN32}
uses
 Windows, Messages, SysUtils, Classes, Graphics, Controls,
 Forms, Dialogs, StdCtrls;
{$ELSE}
uses
 WinTypes, WinProcs, Messages, SysUtils, Classes, Graphics,
 Controls, Forms, Dialogs, StdCtrls;
{$ENDIF}
type
 TForm1 = class(TForm)
  Edit1: TEdit;
  procedure FormCreate(Sender: TObject);
  procedure FormDestroy(Sender: TObject);
  private
  {Private declarations}
  public
  {Public declarations}
  CaretBm: TBitmap;
  CaretBmBk: TBitmap;
  OldEditsWindowProc: Pointer;
end;
var
 Form1: TForm1;
implementation
{$R *.DFM}
type
 {$IFDEF WIN32}
 WParameter = LongInt;
 {$ELSE}
 WParameter = Word;
 {$ENDIF}
 LParameter = LongInt;
{New windows procedure for the edit control}
function NewWindowProc(WindowHandle : hWnd;
TheMessage : WParameter; ParamW : WParameter;
ParamL : LParameter) : LongInt
{$IFDEF WIN32} stdcall; {$ELSE} ; export; {$ENDIF}
begin
 {Call the old edit controls windows procedure}
 NewWindowProc := CallWindowProc(Form1.OldEditsWindowProc,
 WindowHandle, TheMessage, ParamW, ParamL);
 if TheMessage = WM_SETFOCUS then
 begin
  CreateCaret(WindowHandle, Form1.CaretBm.Handle, 0, 0);
  ShowCaret(WindowHandle);
 end;
 if TheMessage = WM_KILLFOCUS then
 begin
  HideCaret(WindowHandle);
  DestroyCaret;
 end;
 if TheMessage = WM_KEYDOWN then
 begin
  if ParamW = VK_BACK then
  CreateCaret(WindowHandle, Form1.CaretBmBk.Handle, 0, 0)
  else
  CreateCaret(WindowHandle, Form1.CaretBm.Handle, 0, 0);
  ShowCaret(WindowHandle);
 end;
end;
procedure TForm1.FormCreate(Sender: TObject);
begin
 {Create a smiling bitmap using the wingdings font}
 CaretBm := TBitmap.Create;
 CaretBm.Canvas.Font.name := 'WingDings';
 CaretBm.Canvas.Font.Height := Edit1.Font.Height;
 CaretBm.Canvas.Font.Color := clWhite;
 CaretBm.Width := CaretBm.Canvas.TextWidth('J') + 2;
 CaretBm.Height := CaretBm.Canvas.TextHeight('J') + 2;
 CaretBm.Canvas.Brush.Color := clBlue;
 CaretBm.Canvas.FillRect(Rect(0, 0, CaretBm.Width,
 CaretBm.Height));
 CaretBm.Canvas.TextOut(1, 1, 'J');
 {Create a frowming bitmap using the wingdings font}
 CaretBmBk := TBitmap.Create;
 CaretBmBk.Canvas.Font.name := 'WingDings';
 CaretBmBk.Canvas.Font.Height := Edit1.Font.Height;
 CaretBmBk.Canvas.Font.Color := clWhite;
 CaretBmBk.Width := CaretBmBk.Canvas.TextWidth('L') + 2;
 CaretBmBk.Height := CaretBmBk.Canvas.TextHeight('L') + 2;
 CaretBmBk.Canvas.Brush.Color := clBlue;
 CaretBmBk.Canvas.FillRect(Rect(0,0, CaretBmBk.Width,
 CaretBmBk.Height));
 CaretBmBk.Canvas.TextOut(1, 1, 'L');
 {Hook the edit controls window procedure}
 OldEditsWindowProc := Pointer(SetWindowLong(Edit1.Handle,
 GWL_WNDPROC, LongInt(@NewWindowProc)));
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
 {Unhook the edit controls window procedure and clean up}
 SetWindowLong(Edit1.Handle,GWL_WNDPROC,
 LongInt(OldEditsWindowProc));
 CaretBm.Free;
 CaretBmBk.Free;
end;
end.