Now the constructor takes four additional parameters, which are the starting and ending points of the viewport.

现在这个构造函数可以利用另外4个参数了，它们分别是viewport的起点和终点。

youdao

Now the constructor takes four additional parameters, which are the starting and ending points of the viewport.

现在这个构造函数可以利用另外4个参数了，它们分别是viewport的起点和终点。

youdao