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;