说明：  分别实现了以下算法：生成直线的DDA算法、生成直线的中点算法、生成圆的正负法算法、生成椭圆的中点算法、扫描转化为矩形、种子填充算法、平移变换、放缩变换、直线段裁剪 。
(Respectively, implements the following algorithm: generate the linear DDA algorithm, line generating the midpoint algorithm, generating circle of positive and negative method algorithm, generate elliptical midpoint algorithm, scan conversion is rectangular, seed filling algorithm, translation, scaling transformation, cutting a straight line segment)