Refactor layout state and metadata key handling

Replace string-based keys with egui::Id for layout state and metadata
persistence. Simplified set of AnimatedState methods. Rename
`build_tree` to `layout_tree` and simplify hierarchical layout logic.

Author: blitzarx1

crates/egui_graphs/src/layouts/force_directed/implementations/fruchterman_reingold/core.rs

@@ -170,7 +170,7 @@ impl ForceAlgorithm for FruchtermanReingold {
             params.max_step,
         );
         self.state.last_avg_displacement = avg;
-        self.state.inc_step_count();
+        self.state.set_step_count(self.state.step_count + 1);
     }
 
     fn state(&self) -> Self::State {

crates/egui_graphs/src/layouts/force_directed/implementations/fruchterman_reingold/with_extras.rs

@@ -123,7 +123,9 @@ impl<E: ExtrasTuple> ForceAlgorithm for FruchtermanReingoldWithExtras<E> {
             base.max_step,
         );
         self.state.base.last_avg_displacement = avg;
-        self.state.base.inc_step_count();
+        self.state
+            .base
+            .set_step_count(self.state.base.step_count() + 1);
     }
 
     fn state(&self) -> Self::State {

crates/egui_graphs/src/layouts/hierarchical/layout.rs

@@ -81,8 +81,9 @@ impl Layout<State> for Hierarchical {
             if visited.contains(root) {
                 continue;
             }
-            let curr_max_col = build_tree(g, &mut visited, root, &self.state, 0, next_col);
-            next_col = curr_max_col.saturating_add(1);
+
+            let curr_max_col = layout_tree(g, &mut visited, root, &self.state, 0, next_col);
+            next_col = curr_max_col + 1;
         }
 
         // Fallback: if the graph has cycles or no formal roots, lay out any remaining components.
@@ -91,8 +92,9 @@ impl Layout<State> for Hierarchical {
             if visited.contains(n) {
                 continue;
             }
-            let curr_max_col = build_tree(g, &mut visited, n, &self.state, 0, next_col);
-            next_col = curr_max_col.saturating_add(1);
+
+            let curr_max_col = layout_tree(g, &mut visited, n, &self.state, 0, next_col);
+            next_col = curr_max_col + 1;
         }
 
         self.state.triggered = true;
@@ -107,7 +109,7 @@ impl Layout<State> for Hierarchical {
     }
 }
 
-fn build_tree<N, E, Ty, Ix, Dn, De>(
+fn layout_tree<N, E, Ty, Ix, Dn, De>(
     g: &mut Graph<N, E, Ty, Ix, Dn, De>,
     visited: &mut HashSet<NodeIndex<Ix>>,
     root_idx: &NodeIndex<Ix>,
@@ -128,34 +130,26 @@ where
         visited.insert(*root_idx);
     }
 
-    // Traverse children first to compute the horizontal span of this subtree.
-    let mut had_child = false;
-    let mut max_col = start_col;
-    let mut child_col = start_col;
-
     let children: Vec<NodeIndex<Ix>> = g.g().neighbors_directed(*root_idx, Outgoing).collect();
 
+    // Traverse children to compute the horizontal span of this subtree.
+    let mut max_col = start_col;
+    let mut child_col = start_col;
     for neighbour_idx in children.iter() {
         if visited.contains(neighbour_idx) {
             continue;
         }
         visited.insert(*neighbour_idx);
-        had_child = true;
 
-        let child_max_col = build_tree(g, visited, neighbour_idx, state, start_row + 1, child_col);
+        let child_max_col = layout_tree(g, visited, neighbour_idx, state, start_row + 1, child_col);
         if child_max_col > max_col {
             max_col = child_max_col;
         }
         child_col = child_max_col.saturating_add(1);
     }
 
     // Column where the current node will be placed.
-    let place_col = if state.center_parent && had_child {
-        // Center above/beside the span [start_col..=max_col]
-        (start_col + max_col) / 2
-    } else {
-        start_col
-    };
+    let place_col = start_col;
 
     // Compute actual coordinates based on orientation.
     let (x, y) = match state.orientation {

crates/egui_graphs/src/layouts/layout.rs

@@ -5,21 +5,19 @@ use std::fmt::Debug;
 use crate::{DisplayEdge, DisplayNode, Graph};
 
 const KEY_PREFIX: &str = "egui_graphs_layout";
-fn get_key(id: Option<String>) -> String {
-    format!("{KEY_PREFIX}_{}", id.unwrap_or_default())
+
+fn get_id(id: Option<String>) -> egui::Id {
+    egui::Id::new(format!("{KEY_PREFIX}_{}", id.unwrap_or_default()))
 }
 
 pub trait LayoutState: SerializableAny + Default + Debug {
     fn load(ui: &egui::Ui, id: Option<String>) -> Self {
-        ui.data_mut(|data| {
-            data.get_persisted::<Self>(egui::Id::new(get_key(id)))
-                .unwrap_or_default()
-        })
+        ui.data_mut(|data| data.get_persisted::<Self>(get_id(id)).unwrap_or_default())
     }
 
     fn save(self, ui: &mut egui::Ui, id: Option<String>) {
         ui.data_mut(|data| {
-            data.insert_persisted(egui::Id::new(get_key(id)), self);
+            data.insert_persisted(get_id(id), self);
         });
     }
 }
@@ -30,8 +28,8 @@ pub trait LayoutState: SerializableAny + Default + Debug {
 pub trait AnimatedState {
     fn is_running(&self) -> bool;
     fn set_running(&mut self, v: bool);
+
     /// Average per-node displacement from the last simulation step (graph units).
-    /// Default: None (not provided by the layout).
     fn last_avg_displacement(&self) -> Option<f32> {
         None
     }
@@ -42,17 +40,9 @@ pub trait AnimatedState {
     fn step_count(&self) -> u64 {
         0
     }
+
     /// Set total step count.
     fn set_step_count(&mut self, _v: u64) {}
-    /// Convenience: increment step count (saturating add).
-    fn inc_step_count(&mut self) {
-        let n = self.step_count();
-        self.set_step_count(n.saturating_add(1));
-    }
-    /// Convenience: reset step count to zero.
-    fn reset_step_count(&mut self) {
-        self.set_step_count(0);
-    }
 }
 
 // Note: Step counting is part of AnimatedState for animated layouts.

crates/egui_graphs/src/metadata.rs

@@ -91,14 +91,14 @@ impl MetadataFrame {
 
     pub fn load(self, ui: &egui::Ui) -> Self {
         ui.data_mut(|data| {
-            data.get_persisted::<MetadataFrame>(Id::new(self.get_key()))
+            data.get_persisted::<MetadataFrame>(Id::new(self.get_id()))
                 .unwrap_or(self.clone())
         })
     }
 
     pub fn save(self, ui: &mut egui::Ui) {
         ui.data_mut(|data| {
-            data.insert_persisted(Id::new(self.get_key()), self);
+            data.insert_persisted(Id::new(self.get_id()), self);
         });
     }
 
@@ -154,8 +154,8 @@ impl MetadataFrame {
     }
 
     /// Get key which is used to store metadata in egui cache.
-    pub fn get_key(&self) -> String {
-        format!("{KEY_PREFIX}_{}", self.id.clone())
+    pub fn get_id(&self) -> Id {
+        egui::Id::new(format!("{KEY_PREFIX}_{}", self.id.clone()))
     }
 }