int relativeLinearGradient(DoubleArray gradient, double angle = 0, double radius = -1);

Creates a linear gradient color relative to the meter center and radius.

A general linear gradient color can be created by BaseChart.linearGradientColor2, which involves specifying the x and y coordinates of the starting and ending points and the color stops. The relativeLinearGradient simplifies creating a linear gradient by assuming the gradient line passes through the meter center at an configurable angle.

The linear gradient is defined using an array of numbers, in which each pair of numbers represents the relative distance and its associated color. The relative distance is the ratio of the absolute distance to the reference radius, which defaults to the meter scale radius (set by AngularMeter.setMeter).

For example, to define a linear gradient with blue (0000FF) at the bottom-left of reference radius, green (00FF00) at the center, and red (FF0000) at the top-right of the reference radius, the angle should be set to 45 degrees, and the array of numbers should be:


The relative distances in the array should be arranged in increasing order. It is possible to define a relative linear gradient shorter or longer than the reference radius by using a relative distance of magnitude smaller or greater than 1. A negative relative distance means the distance is measured at the opposite side of center.

A 32-bit integer representing the linear gradient color.