Method add_hline

src/plot_widget.rs:262–265

Add a horizontal reference line to the plot. If there exists a line with the same `hline.id` ([ShapeId]), the old one will be replaced.

(&mut self, hline: HLine)

            return Err(SeriesError::FillEndpointNotFound(fill.begin));
        }
        if !self.is_fill_endpoint_available(fill.end) {
            return Err(SeriesError::FillEndpointNotFound(fill.end));
        }
        self.fills.insert(fill.id, fill);
        self.data_version = self.data_version.wrapping_add(1);
        Ok(())
    }