Problema na criação de um componente

unit BitColor;

interface 
uses 
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, 
Dialogs, StdCtrls, Buttons; 

type
  TBitColor = class(TBitBtn)
private 
IsFocused: boolean; 
FCanvas: TCanvas; 
F3DFrame: boolean; 
FButtonColor: TColor; 
procedure Set3DFrame(Value: boolean); 
procedure SetButtonColor(Value: TColor); 
procedure CNDrawItem(var Message: TWMDrawItem); 
message CN_DRAWITEM; 
procedure WMLButtonDblClk(var Message: TWMLButtonDblClk); 
message WM_LBUTTONDBLCLK; 
procedure DrawButtonText(const Caption: string; TRC: TRect; 
State: TButtonState; BiDiFlags: Longint); 
procedure CalcuateTextPosition(const Caption: string; 
var TRC: TRect; BiDiFlags: Longint); 
protected 
procedure CreateParams(var Params: TCreateParams); override; 
procedure SetButtonStyle(ADefault: boolean); override; 
public 
constructor Create(AOwner: TComponent); override; 
destructor Destroy; override; 
published 
property ButtonColor: TColor read FButtonColor 
write SetButtonColor default clBtnFace; 
property Frame3D: boolean read F3DFrame write Set3DFrame 
default False; 
end; 

procedure Register; 

implementation 

{ TBitColor } 

constructor TBitColor.Create(AOwner: TComponent);
begin 
Inherited Create(AOwner); 
FCanvas:= TCanvas.Create; 
FButtonColor:= clBtnFace; 
F3DFrame:= False; 
end; 

destructor TBitColor.Destroy;
begin 
FCanvas.Free; 
Inherited Destroy; 
end; 

procedure TBitColor.CreateParams(var Params: TCreateParams); 
begin 
Inherited CreateParams(Params); 
with Params do Style:= Style or BS_OWNERDRAW; 
end; 

procedure TBitColor.Set3DFrame(Value: boolean); 
begin 
if F3DFrame <> Value then F3DFrame:= Value; 
end; 

procedure TBitColor.SetButtonColor(Value: TColor); 
begin 
if FButtonColor <> Value then begin 
FButtonColor:= Value; 
Invalidate; 
end; 
end; 

procedure TBitColor.WMLButtonDblClk(var Message: TWMLButtonDblClk); 
begin 
Perform(WM_LBUTTONDOWN, Message.Keys, Longint(Message.Pos)); 
end; 

procedure TBitColor.SetButtonStyle(ADefault: Boolean); 
begin 
if IsFocused <> ADefault then IsFocused:= ADefault; 
end; 

procedure TBitColor.CNDrawItem(var Message: TWMDrawItem); 
var 
RC: TRect; 
Flags: Longint; 
State: TButtonState; 
IsDown, IsDefault: Boolean; 
DrawItemStruct: TDrawItemStruct; 
begin 
DrawItemStruct:= Message.DrawItemStruct^; 
FCanvas.Handle:= DrawItemStruct.HDC; 
RC:= ClientRect; 
with DrawItemStruct do begin 
IsDown:= ItemState and ODS_SELECTED <> 0; 
IsDefault:= ItemState and ODS_FOCUS <> 0; 
if not Enabled then State:= bsDisabled 
else if IsDown then State:= bsDown 
else State:= bsUp; 
end; 
Flags:= DFCS_BUTTONPUSH or DFCS_ADJUSTRECT; 
if IsDown then Flags:= Flags or DFCS_PUSHED; 
if DrawItemStruct.ItemState and ODS_DISABLED <> 0 then 
Flags:= Flags or DFCS_INACTIVE; 
if IsFocused or IsDefault then begin 
FCanvas.Pen.Color:= clWindowFrame; 
FCanvas.Pen.Width:= 1; 
FCanvas.Brush.Style:= bsClear; 
FCanvas.Rectangle(RC.Left, RC.Top, RC.Right, RC.Bottom); 
InflateRect(RC, -1, -1); 
end; 
if IsDown then begin 
FCanvas.Pen.Color:= clBtnShadow; 
FCanvas.Pen.Width:= 1; 
FCanvas.Rectangle(RC.Left, RC.Top, RC.Right, RC.Bottom); 
InflateRect(RC, -1, -1); 
if F3DFrame then begin 
FCanvas.Pen.Color:= FButtonColor; 
FCanvas.Pen.Width:= 1; 
DrawFrameControl(DrawItemStruct.HDC, RC, DFC_BUTTON, Flags); 
end; 
end else 
DrawFrameControl(DrawItemStruct.HDC, RC, DFC_BUTTON, Flags); 
FCanvas.Brush.Color:= FButtonColor; 
FCanvas.FillRect(RC); 
InflateRect(RC, 1, 1); 
if IsFocused then begin 
RC:= ClientRect; 
InflateRect(RC, -1, -1); 
end; 
if IsDown then OffsetRect(RC, 1, 1); 
FCanvas.Font:= Self.Font; 
DrawButtonText(Caption, RC, State, 0); 
if IsFocused and IsDefault then begin 
RC:= ClientRect; 
InflateRect(RC, -4, -4); 
FCanvas.Pen.Color:= clWindowFrame; 
Windows.DrawFocusRect(FCanvas.Handle, RC); 
end; 
FCanvas.Handle:= 0; 
end; 

procedure TBitColor.CalcuateTextPosition(const Caption: string; 
var TRC: TRect; BiDiFlags: Integer); 
var 
TB: TRect; 
TS, TP: TPoint; 
begin 
with FCanvas do begin 
TB:= Rect(0, 0, TRC.Right + TRC.Left, TRC.Top + TRC.Bottom); 
DrawText(Handle, PChar(Caption), Length(Caption), TB, 
DT_CALCRECT or BiDiFlags); 
TS := Point(TB.Right - TB.Left, TB.Bottom - TB.Top); 
TP.X := ((TRC.Right - TRC.Left) - TS.X + 1) div 2; 
TP.Y := ((TRC.Bottom - TRC.Top) - TS.Y + 1) div 2; 
OffsetRect(TB, TP.X + TRC.Left, TP.Y + TRC.Top); 
TRC:= TB; 
end; 
end; 

procedure TBitColor.DrawButtonText(const Caption: string; TRC: TRect; 
State: TButtonState; BiDiFlags: Integer); 
begin 
with FCanvas do begin 
CalcuateTextPosition(Caption, TRC, BiDiFlags); 
Brush.Style:= bsClear; 
if State = bsDisabled then begin 
OffsetRect(TRC, 1, 1); 
Font.Color:= clBtnHighlight; 
DrawText(Handle, PChar(Caption), Length(Caption), TRC, 
DT_CENTER or DT_VCENTER or BiDiFlags); 
OffsetRect(TRC, -1, -1); 
Font.Color:= clBtnShadow; 
DrawText(Handle, PChar(Caption), Length(Caption), TRC, 
DT_CENTER or DT_VCENTER or BiDiFlags); 
end else 
DrawText(Handle, PChar(Caption), Length(Caption), TRC, 
DT_CENTER or DT_VCENTER or BiDiFlags); 
end; 
end; 

procedure Register;
begin
  RegisterComponents(´Standard´, [TBitColor]);
end;

end.