fixed-max.vala

public class Example : Gtk.Window {
        
    public Example() {
        this.title = "Live Chart Demo";
        this.destroy.connect(Gtk.main_quit);
        this.set_default_size(800, 350);

        var cpu = new LiveChart.Serie("CPU 1 usage", new LiveChart.SmoothLineArea());
        cpu.line.color = { 0.8, 0.8, 0.1, 1.0};
        
        var config = new LiveChart.Config();
        config.y_axis.unit = "%";
        config.y_axis.tick_interval = 25;
        config.y_axis.fixed_max = LiveChart.cap(96);

        var chart = new LiveChart.Chart(config);

        var export_button = new Gtk.Button.with_label("Export to PNG");
		export_button.clicked.connect (() => {
            try {
                chart.to_png("export-fixed-max.png");
            } catch (Error e) {
                GLib.error(e.message);
            }
            
        });
        
        Gtk.Box box = new Gtk.Box(Gtk.Orientation.VERTICAL, 0);
        box.pack_start(export_button, false, false, 5);
        box.pack_start(chart, true, true, 0);

        this.add(box);

        chart.add_serie(cpu);
         
        var cpu_value = 50.0;
        cpu.add(cpu_value);

        Timeout.add(1000, () => {
            if (Random.double_range(0.0, 1.0) > 0.2) {
                var new_value = Random.double_range(-25, 25.0);
                if (cpu_value + new_value > 100.0) {
                    cpu_value = 100.0;
                } else if (cpu_value + new_value < 0.0) {
                    cpu_value = 0.0;
                } else {
                    cpu_value += new_value;
                }
            }
           
            cpu.add(cpu_value);
            return true;
        });
     }
}

static int main (string[] args) {
    Gtk.init(ref args);

    var view = new Example();
    view.show_all();

    Gtk.main();

    return 0;
}