RectF类

Android RectF类的构造函数参数说明：

以下是API中的说明：

public RectF (float left, float top, float right, float bottom)

Added in API level 1

Create a new rectangle with the specified coordinates. Note: no range checking is performed, so the caller must ensure that left <= right and top <= bottom.

Parameters

left	The X coordinate of the left side of the rectangle
top	The Y coordinate of the top of the rectangle
right	The X coordinate of the right side of the rectangle
bottom	The Y coordinate of the bottom of the rectangle

比如new一个RecF类：
RectF rf1 = new RectF(100，100,200,200);

则在屏幕中的位置示意图为：