Default label value + demo refactor (#191)

- default label value changed from `id` for nodes and edges to `node
<id>` or `edge <id>`
- extracted drawers and settings into separate modules

examples/demo/src/drawers.rs

@@ -0,0 +1,134 @@
+use egui::Ui;
+
+pub struct ValuesConfigButtonsStartReset {
+    pub simulation_stopped: bool,
+}
+
+pub fn draw_start_reset_buttons(
+    ui: &mut egui::Ui,
+    mut values: ValuesConfigButtonsStartReset,
+    mut on_change: impl FnMut(bool, bool),
+) {
+    ui.vertical(|ui| {
+        ui.label("Stop or start simulation again or reset to default settings.");
+        ui.horizontal(|ui| {
+            let start_simulation_stopped = values.simulation_stopped;
+            if ui
+                .button(match values.simulation_stopped {
+                    true => "start",
+                    false => "stop",
+                })
+                .clicked()
+            {
+                values.simulation_stopped = !values.simulation_stopped;
+            };
+
+            let mut reset_pressed = false;
+            if ui.button("reset").clicked() {
+                reset_pressed = true;
+            }
+
+            if start_simulation_stopped != values.simulation_stopped || reset_pressed {
+                on_change(values.simulation_stopped, reset_pressed);
+            }
+        });
+    });
+}
+
+pub struct ValuesSectionDebug {
+    pub zoom: f32,
+    pub pan: [f32; 2],
+    pub fps: f32,
+}
+
+pub fn draw_section_debug(ui: &mut egui::Ui, values: ValuesSectionDebug) {
+    ui.label(format!("zoom: {:.5}", values.zoom));
+    ui.label(format!("pan: [{:.5}, {:.5}]", values.pan[0], values.pan[1]));
+    ui.label(format!("FPS: {:.1}", values.fps));
+}
+
+pub struct ValuesConfigSlidersGraph {
+    pub node_cnt: usize,
+    pub edge_cnt: usize,
+}
+
+pub fn draw_counts_sliders(
+    ui: &mut egui::Ui,
+    mut values: ValuesConfigSlidersGraph,
+    mut on_change: impl FnMut(i32, i32),
+) {
+    let start_node_cnt = values.node_cnt;
+    let mut delta_node_cnt = 0;
+    ui.horizontal(|ui| {
+        if ui
+            .add(egui::Slider::new(&mut values.node_cnt, 1..=2500).text("nodes"))
+            .changed()
+        {
+            delta_node_cnt = values.node_cnt as i32 - start_node_cnt as i32;
+        };
+    });
+
+    let start = values.edge_cnt;
+    let mut delta_edge_cnt = 0;
+    ui.horizontal(|ui| {
+        if ui
+            .add(egui::Slider::new(&mut values.edge_cnt, 1..=2500).text("edges"))
+            .changed()
+        {
+            delta_edge_cnt = values.edge_cnt as i32 - start as i32;
+        };
+    });
+
+    if delta_node_cnt != 0 || delta_edge_cnt != 0 {
+        on_change(delta_node_cnt, delta_edge_cnt)
+    };
+}
+
+pub struct ValuesConfigSlidersSimulation {
+    pub dt: f32,
+    pub cooloff_factor: f32,
+    pub scale: f32,
+}
+
+pub fn draw_simulation_config_sliders(
+    ui: &mut Ui,
+    mut values: ValuesConfigSlidersSimulation,
+    mut on_change: impl FnMut(f32, f32, f32),
+) {
+    let start_dt = values.dt;
+    let mut delta_dt = 0.;
+    ui.horizontal(|ui| {
+        if ui
+            .add(egui::Slider::new(&mut values.dt, 0.00..=1.).text("dt"))
+            .changed()
+        {
+            delta_dt = values.dt - start_dt;
+        };
+    });
+
+    let start_cooloff_factor = values.cooloff_factor;
+    let mut delta_cooloff_factor = 0.;
+    ui.horizontal(|ui| {
+        if ui
+            .add(egui::Slider::new(&mut values.cooloff_factor, 0.00..=1.).text("cooloff_factor"))
+            .changed()
+        {
+            delta_cooloff_factor = values.cooloff_factor - start_cooloff_factor;
+        };
+    });
+
+    let start_scale = values.scale;
+    let mut delta_scale = 0.;
+    ui.horizontal(|ui| {
+        if ui
+            .add(egui::Slider::new(&mut values.scale, 1.0..=1000.).text("scale"))
+            .changed()
+        {
+            delta_scale = values.scale - start_scale;
+        };
+    });
+
+    if delta_dt != 0. || delta_cooloff_factor != 0. || delta_scale != 0. {
+        on_change(delta_dt, delta_cooloff_factor, delta_scale);
+    }
+}