Specifies the direction of color change for the gradient. To define this angle, let its value be x measured clockwise. Then ( -sin x, cos x ) is a vector parallel to the line of constant color in the gradient fill.
Whether the gradient angle scales with the fill region. Mathematically, if this flag is true, then the gradient vector ( cos x , sin x ) is scaled by the width (w) and height (h) of the fill region, so that the vector becomes ( w cos x, h sin x ) (before normalization).