code: func NewPatternFromRGBA(red, green, blue, alpha float64) (*Pattern, error) {
  	c := C.cairo_pattern_create_rgba(C.double(red), C.double(green), C.double(blue), C.double(alpha))
  	return newPatternFromNative(c)
  }
docs: // NewPatternFromRGBA is a wrapper around cairo_pattern_create_rgba().