procedure SetCanvasZoomFactor(Canvas: TCanvas; AZoomFactor: Integer);
var
i: Integer;
begin
if AZoomFactor = 100 then
SetMapMode(Canvas.Handle, MM_TEXT)
else
begin
SetMapMode(Canvas.Handle, MM_ISOTROPIC);
SetWindowExtEx(Canvas.Handle, AZoomFactor, AZoomFactor, nil);
SetViewportExtEx(Canvas.Handle, 100, 100, nil);
end;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
bitmap: TBitmap;
begin
bitmap := TBitmap.Create;
try
bitmap.Assign(Form1.image1.Picture.Bitmap);
SetCanvasZoomFactor(bitmap.Canvas, 70);
Canvas.Draw(30, 30, bitmap);
finally
bitmap.Free
end;
end;