Сделать немерцающей анимацию при помощи CopyRect

Оформил: DeeCo
var
   Form1: TForm1;
   x, y, xvel, yvel, xold, yold: Integer;

 implementation

 {$R *.dfm}

 {You will need an image, called ImageSprite, containing a sprite bitmap with 
 black as the background (the transparent part). You will also need an image, 
 called ImageMask, containing a black silouette of the sprite with white as the 
 background and an Image called ImageBackground containing the background 
 image. All these images are set to visible := false. Image1 is the image you 
 will see and is the same size as the background image.}

 procedure TForm1.Button1Click(Sender: TObject);
 var
   ARect: TRect; // Destination/Source rectangles 
begin
   //Initialize sprites position/velocity 
  x    := 0;
    y    := 100;
   xvel := 3;
    yvel := 2;
   xold := 0;
    yold := 0;

   // copy background to the image 
  ARect := Rect(0, 0, ImageBackground.Width, ImageBackground.Height);
   with Image1.Canvas do
   begin
     CopyMode := cmSrcCopy;
     CopyRect(ARect, ImageBackground.Canvas, ARect);
   end;

   // start animation 
  Timer1.Enabled := True;
 end;

 procedure TForm1.Timer1Timer(Sender: TObject);
 var
   Dest, Sour: TRect; // Destination/Source rectangles 
begin
   // Erase sprite from old position 
  Sour := Rect(xold, yold, xold + ImageMask.Width, yold + ImageMask.Height);
   with Image1.Canvas do
   begin
     CopyMode := cmSrcCopy;
     CopyRect(Sour, ImageBackground.Canvas, Sour);
   end;

   // Draw new sprite 
  Sour := Rect(0, 0, ImageMask.Width, ImageMask.Height);
   Dest := Rect(x, y, x + ImageMask.Width, y + ImageMask.Height);
   with Image1.Canvas do
   begin
     // Place mask onto image 
    CopyMode := cmSrcAnd;
     CopyRect(Dest, ImageMask.Canvas, Sour);
     // Place sprite into mask 
    CopyMode := cmSrcPaint;
     CopyRect(Dest, ImageSprite.Canvas, Sour);
   end;

  {if multiple sprites are being used, then erase them all before drawing them 
  all. Do not erase and draw each sprite in turn}

   // store sprites old position before updating 
  xold := x;
   yold := y;

   { Update sprites position (equations to describe movement of sprite }
   Inc(x, xvel);
   Inc(y, yvel);
   if (x > ImageBackground.Width - ImageMask.Width) or (x < 0) then xvel := -xvel;
   if (y > ImageBackground.Height - ImageMask.Height) or (y < 0) then yvel := -yvel;
 end;