cairo:pattern-radial-circles (pattern)

pattern -- a cairo:pattern-t instance

x0 -- a number with the x coordinate for the center of the first circle
y0 -- a number with the y coordinate for the center of the first circle
r0 -- a number with the radius for the first circle
x1 -- a number with the x coordinate for the center of the second circle
y1 -- a numbe with the y coordinate for the center of the second circle
r1 -- a number with the radius for the second circle

Gets the gradient endpoint circles for a radial gradient, each specified as a center coordinate and a radius. Returns nil it the pattern is not a radial gradient pattern. The numbers returned a double floats.