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).

Observe that now if the gradient angle is 45 degrees, the gradient vector is ( w, h ), which goes from top-left to bottom-right of the fill region. If this flag is false, the gradient angle is independent of the fill region and is not scaled using the manipulation described above.

So a 45-degree gradient angle always give a gradient band whose line of constant color is parallel to the vector (1, -1).

This property has effect only when the Type property is GradientType.Linear.