怎么改写Tmemo使它能支持图片的显示和插入图片？(10分)

用Memo显示图片，你可以自己改改这个控件，处理memo的 WM_Paint消息，画个图片。

type
TMyMemo = class(TMemo)
protected
procedure WMPaint(var Message: TWMPaint); message WM_PAINT;
end;


procedure TMyMemo.WMPaint(var Message: TWMPaint);
var
MCanvas: TControlCanvas;
DrawBounds : TRect;
Begin
inherited;
MCanvas:=TControlCanvas.Create;
DrawBounds := ClientRect;
Try
MCanvas.Control:=Self;
With MCanvas do
Begin
Brush.Color := clBtnFace;
FrameRect( DrawBounds );
InflateRect( DrawBounds, -1, -1);
FrameRect( DrawBounds );
FillRect ( DrawBounds );
MoveTo ( 33, 0 );
Brush.Color := clWhite;
LineTo ( 33, ClientHeight );
PaintImages;//定义的画图片过程
end;
finally
MCanvas.Free;
End;
end;



procedure TMyMemo.PaintImages;
var
MCanvas: TControlCanvas;
DrawBounds : TRect;
i, j : Integer;
OriginalRegion : HRGN;
ControlDC : HDC;
begin
MCanvas:=TControlCanvas.Create;
DrawBounds := ClientRect;
try
MCanvas.Control:=Self;
ControlDC := GetDC ( Handle );
MCanvas.Draw(0, 1, Application.Icon);
finally
MCanvas.Free;
end;
end;
里面用的这些函数是怎么用的？这个只是显示一个图片，但是不能显示原来的文本了。