Companion
Functions
Returns a shader that generates a sweep gradient given a center. The shader accepts negative angles and angles larger than 360, draws between 0 and 360 degrees, similar to the CSS conic-gradient semantics. 0 degrees means horizontal positive x axis. The start angle must be less than the end angle, otherwise a null pointer is returned. If color stops do not contain 0 and 1 but are within this range, the respective outer color stop is repeated for 0 and 1. Color stops less than 0 are clamped to 0, and greater than 1 are clamped to 1.
Returns a shader that generates a conical gradient given two circles, or returns null if the inputs are invalid. The gradient interprets the two circles according to the following HTML spec. http://dev.w3.org/html5/2dcontext/#dom-context-2d-createradialgradient