A Transform widget “transforms” (i.e. changes the shape, size, position and orientation) its child widget before painting it.
Transform.rotate rotates a child by an angle in radians not degrees. So, to rotate by 90 degrees, you need to multiply 90 x π/180 to get the value in radians.
Don't forget to import 'dart:math' to use pi. :) More info on Transform widget here: