React Native Create Custom Rectangle Shape View. This tutorial explains how to create custom rectangle and square shape view in react native application. In Euclidean plane geometry, a rectangle is a quadrilateral with four right angles. It can also be defined as an equiangular quadrilateral, since equiangular means that all of its angles are equal (360°/4 = 90°). It can also be defined as a parallelogram containing a right angle. A rectangle with four sides of equal length is a square. The formula of finding area of rectangle is ( A = W * L ). The Square shape has the same line structure but the width and height of square is same.