在第一个图中，填充了（2，1）至（5，5） 的矩形，整个区域的边界刚好落在像素边缘上，这样就可以得到的矩形有着清晰的边缘。

In the first grid image below, a rectangle from (2,1) to (5,5) is filled. The entire area between them (light red) falls on pixel boundaries, so the resulting filled rectangle will have crisp edges.

youdao

在第一个图中，填充了（2，1）至（5，5） 的矩形，整个区域的边界刚好落在像素边缘上，这样就可以得到的矩形有着清晰的边缘。

In the first grid image below, a rectangle from (2,1) to (5,5) is filled. The entire area between them (light red) falls on pixel boundaries, so the resulting filled rectangle will have crisp edges.

youdao