code: func NewPatternLinear(x0, y0, x1, y1 float64) (*Pattern, error) {
  	c := C.cairo_pattern_create_linear(C.double(x0), C.double(y0), C.double(x1), C.double(y1))
  	return newPatternFromNative(c)
  }
docs: // NewPatternLinear is a wrapper around cairo_pattern_create_linear().