#790 – How a Rotation Transform Works

A 2D rotation transform in WPF is accomplished by using a transformation matrix.  The transformation matrix is multiplied by another matrix representing a single 2D point to be transformed.  The resulting matrix describes the transformed point.  When rotating a user interface element, this transformation is done individually on each point to generate the set of points representing the transformed element.

The transformation operation for rotation looks like:

Where ϴ represents the Angle property of the ScaleTransform, indicating the number of degrees to rotate the point in a clockwise direction.

This leads to the equations: