There are two types of gradient filllings: linear and radial. They are represented by ImGearVectorGradientLinear class and ImGearVectorGradientRadial class, correspondingly.

The color of the gradient is defined by an array of stops. A stop is a pair of offset and color. Stop offsets are relative to gradient coordinates. 0.0 corresponds to the start point, 1.0 corresponds to the end points, in the case of a linear gradient, or to a point at the outer circle, in the case of a radial gradient. If first stop offset is greater than 0.0, or the last stop offset is less than 1.0, the gradient is expanded according to its Spread method. Gradient color is linearly interpolated between the stops.

Gradient filling can be transformed with an affine matrix.

System.Object
   ImageGear.Vector.ImGearVectorObject
      ImageGear.Vector.ImGearVectorGradient
         ImageGear.Vector.ImGearVectorGradientLinear
         ImageGear.Vector.ImGearVectorGradientRadial

Reference