pub trait GradientBackend {
// Required methods
fn new_linear(x1: Float, y1: Float, x2: Float, y2: Float) -> Self
where Self: Sized;
fn new_radial(x1: Float, y1: Float, x2: Float, y2: Float, r: Float) -> Self
where Self: Sized;
fn add_color_stop(&mut self, offset: Float, color: Color) -> bool;
}