Image 的奇怪问题，求助

Question

代码如下： 
unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls, ComCtrls;type
  TForm1 = class(TForm)
    Panel_PRTFanWei: TPanel;
    Panel_BP: TPanel;
    Image_BP: TImage;
    Button1: TButton;
    Button6: TButton;
    Button7: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormActivate(Sender: TObject);
    procedure Button6Click(Sender: TObject);
    procedure Button7Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  i : integer;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
var
  RT : TRect;
begin
//  Panel_PRTFanWei.Width := Panel_PRTFanWei.Width * 2 ;
//  Panel_PRTFanWei.Height := Panel_PRTFanWei.Height * 2 ;
  Image_BP.Width := Image_BP.Width +50 ;
  Image_BP.Height := Image_BP.Height +50 ;
  i := i + 1 ;  RT := Rect(0,0,Image_BP.Width ,Image_BP.Height);
  Image_BP.Canvas.Pen.Color := clBlack;
  Image_BP.Canvas.Brush.Color := clBlack;
  Image_BP.Canvas.Brush.Style := bsSolid;
  Image_BP.Canvas.Pen.Mode := pmCopy;
  Image_BP.Canvas.Rectangle(RT);
  Image_BP.Refresh;end;procedure TForm1.FormActivate(Sender: TObject);
var
  RT : TRect;
begin
  Image_BP.Width := 400 ;
  Image_BP.Height := 200 ;
  i := 1;{  RT := Rect(0,0,Image_BP.Width ,Image_BP.Height);
  Image_BP.Canvas.Pen.Color := clRed;
  Image_BP.Canvas.Brush.Color := clBlack;
  Image_BP.Canvas.Brush.Style := bsSolid;
  Image_BP.Canvas.Pen.Mode := pmCopy;
  Image_BP.Canvas.Rectangle(RT);
  Image_BP.Refresh;  }end;procedure TForm1.Button6Click(Sender: TObject);
var
  RT : TRect;
begin
  RT := Rect(0,0,Image_BP.Width ,Image_BP.Height);
  Image_BP.Canvas.Pen.Color := clRed;
  Image_BP.Canvas.Brush.Color := clRed;
  Image_BP.Canvas.Brush.Style := bsSolid;
  Image_BP.Canvas.Pen.Mode := pmCopy;
  Image_BP.Canvas.Rectangle(RT);
  Image_BP.Refresh;
end;procedure TForm1.Button7Click(Sender: TObject);
var
  RT : TRect;
begin
//  Panel_PRTFanWei.Width := Panel_PRTFanWei.Width * 2 ;
//  Panel_PRTFanWei.Height := Panel_PRTFanWei.Height * 2 ;
  Image_BP.Width := Image_BP.Width -50 ;
  Image_BP.Height := Image_BP.Height -50 ;
  i := i + 1 ;  RT := Rect(0,0,Image_BP.Width ,Image_BP.Height);
  Image_BP.Canvas.Pen.Color := clBlack;
  Image_BP.Canvas.Brush.Color := clBlack;
  Image_BP.Canvas.Brush.Style := bsSolid;
  Image_BP.Canvas.Pen.Mode := pmCopy;
  Image_BP.Canvas.Rectangle(RT);
  Image_BP.Refresh;end;end.我按Button1时  有时显示不正确，请问如何解决

Answer 1

按Button1  image 不放大显示啊，但实际上已经放大了

Answer 2

Image_BP.Canvas.Rectangle(RT);
这句有问题我试了也是这问题，

Answer 3

Image_BP.Width := Image_BP.Width +50 ;
  Image_BP.Height := Image_BP.Height +50 ;
这两句改成:
  Image_BP.Picture.Graphic.Width := Image_BP.Width +50 ;
  Image_BP.Picture.Graphic.Height := Image_BP.Height +50 ;

Answer 4

高手如何解决。
to SuanAddMiao(算苗) 不行啊