wgui: refresh widgets with dirty tree state

wgui/src/components/button.rs

@@ -91,7 +91,9 @@ impl ComponentTrait for ComponentButton {
 		&mut self.base
 	}
 
-	fn refresh(&self, _data: &mut RefreshData) {}
+	fn refresh(&self, _data: &mut RefreshData) {
+		// nothing to do
+	}
 }
 
 impl ComponentButton {

wgui/src/components/checkbox.rs

@@ -76,7 +76,9 @@ impl ComponentTrait for ComponentCheckbox {
 		&mut self.base
 	}
 
-	fn refresh(&self, _data: &mut RefreshData) {}
+	fn refresh(&self, _data: &mut RefreshData) {
+		// nothing to do
+	}
 }
 
 const COLOR_CHECKED: Color = Color::new(0.1, 0.5, 1.0, 1.0);

wgui/src/components/slider.rs

@@ -142,15 +142,24 @@ fn get_width(slider_body_node: taffy::NodeId, tree: &taffy::tree::TaffyTree<Widg
 fn conf_handle_style(
 	values: &ValuesMinMax,
 	slider_body_node: taffy::NodeId,
-	slider_handle_style: &mut taffy::Style,
+	slider_handle_style: &taffy::Style,
 	tree: &taffy::tree::TaffyTree<WidgetID>,
-) {
+) -> Option<taffy::Style> {
 	let norm = values.to_normalized();
 
 	// convert normalized value to taffy percentage margin in percent
 	let width = get_width(slider_body_node, tree);
 	let percent_margin = (HANDLE_WIDTH / width) / 2.0;
-	slider_handle_style.margin.left = percent(percent_margin + norm * (1.0 - percent_margin * 2.0));
+
+	let new_percent = percent(percent_margin + norm * (1.0 - percent_margin * 2.0));
+
+	if slider_handle_style.margin.left == new_percent {
+		None // nothing changed
+	} else {
+		let mut new_style = slider_handle_style.clone();
+		new_style.margin.left = new_percent;
+		Some(new_style)
+	}
 }
 
 const PAD_PERCENT: f32 = 0.75;
@@ -196,11 +205,14 @@ impl State {
 		self.values.set_value(value);
 
 		let changed = self.values.value != before;
-		let mut style = common.state.tree.style(data.slider_handle_node_id).unwrap().clone();
-		conf_handle_style(&self.values, data.slider_body_node, &mut style, &common.state.tree);
+		let style = common.state.tree.style(data.slider_handle_node_id).unwrap();
+		let Some(new_style) = conf_handle_style(&self.values, data.slider_body_node, style, &common.state.tree) else {
+			return; //nothing changed visually
+		};
+
 		common.alterables.mark_dirty(data.slider_handle_node_id);
 		common.alterables.mark_redraw();
-		common.alterables.set_style(data.slider_handle.id, style);
+		common.alterables.set_style(data.slider_handle.id, new_style);
 
 		if let Some(mut label) = common.state.widgets.get_as::<WidgetLabel>(data.slider_text_id) {
 			Self::update_text(common, &mut label, self.values.value);
@@ -482,6 +494,6 @@ pub fn construct(ess: &mut ConstructEssentials, params: Params) -> anyhow::Resul
 
 	let slider = Rc::new(ComponentSlider { base, data, state });
 
-	ess.layout.defer_component_refresh(Component(slider.clone()));
+	ess.layout.register_component_refresh(Component(slider.clone()));
 	Ok((root, slider))
 }

wgui/src/components/tooltip.rs

@@ -73,7 +73,9 @@ impl ComponentTrait for ComponentTooltip {
 		&self.base
 	}
 
-	fn refresh(&self, _data: &mut RefreshData) {}
+	fn refresh(&self, _data: &mut RefreshData) {
+		// nothing to do
+	}
 }
 
 impl ComponentTooltip {}

wgui/src/layout.rs

@@ -1,6 +1,6 @@
 use std::{
 	cell::{RefCell, RefMut},
-	collections::VecDeque,
+	collections::{HashMap, VecDeque},
 	io::Write,
 	rc::{Rc, Weak},
 };
@@ -139,7 +139,8 @@ pub struct Layout {
 
 	pub tasks: LayoutTasks,
 
-	components_to_refresh: Vec<Component>,
+	components_to_refresh_once: Vec<Component>,
+	registered_components_to_refresh: HashMap<taffy::NodeId, Component>,
 
 	pub widgets_to_tick: Vec<WidgetID>,
 
@@ -281,6 +282,7 @@ impl Layout {
 		self.state.widgets.remove_single(widget_id);
 		self.state.nodes.remove(widget_id);
 		if let Some(node_id) = node_id {
+			self.registered_components_to_refresh.remove(&node_id);
 			let _ = self.state.tree.remove(node_id);
 		}
 	}
@@ -312,7 +314,7 @@ impl Layout {
 	}
 
 	fn process_pending_components(&mut self, alterables: &mut EventAlterables) {
-		for comp in &self.components_to_refresh {
+		for comp in &self.components_to_refresh_once {
 			let mut common = CallbackDataCommon {
 				state: &self.state,
 				alterables,
@@ -324,7 +326,7 @@ impl Layout {
 
 			comp.0.refresh(&mut RefreshData { common: &mut common });
 		}
-		self.components_to_refresh.clear();
+		self.components_to_refresh_once.clear();
 	}
 
 	fn process_pending_widget_ticks(&mut self, alterables: &mut EventAlterables) {
@@ -338,8 +340,20 @@ impl Layout {
 		self.widgets_to_tick.clear();
 	}
 
+	// call ComponentTrait::refresh() once
 	pub fn defer_component_refresh(&mut self, component: Component) {
-		self.components_to_refresh.push(component);
+		self.components_to_refresh_once.push(component);
+	}
+
+	// call ComponentTrait::refresh() every time the layout is dirty
+	pub fn register_component_refresh(&mut self, component: Component) {
+		let widget_id = component.0.base().get_id();
+		let Some(node_id) = self.state.nodes.get(widget_id) else {
+			debug_assert!(false);
+			return;
+		};
+
+		self.registered_components_to_refresh.insert(*node_id, component);
 	}
 
 	/// Convenience function to avoid repeated `WidgetID` → `WidgetState` lookups.
@@ -557,22 +571,48 @@ impl Layout {
 			needs_redraw: true,
 			haptics_triggered: false,
 			animations: Animations::default(),
-			components_to_refresh: Vec::new(),
+			components_to_refresh_once: Vec::new(),
+			registered_components_to_refresh: HashMap::new(),
 			widgets_to_tick: Vec::new(),
 			tasks: LayoutTasks::new(),
 		})
 	}
 
+	fn refresh_recursively(&self, node_id: taffy::NodeId, to_refresh: &mut Vec<Component>) {
+		// skip refreshing clean nodes
+		if !self.state.tree.dirty(node_id).unwrap() {
+			return;
+		}
+
+		if let Some(component) = self.registered_components_to_refresh.get(&node_id) {
+			to_refresh.push(component.clone());
+		}
+
+		for child_id in self.state.tree.child_ids(node_id) {
+			self.refresh_recursively(child_id, to_refresh);
+		}
+	}
+
 	fn try_recompute_layout(&mut self, size: Vec2) -> anyhow::Result<()> {
 		if !self.state.tree.dirty(self.tree_root_node)? && self.prev_size == size {
 			// Nothing to do
 			return Ok(());
 		}
 
-		self.mark_redraw();
 		log::debug!("re-computing layout, size {}x{}", size.x, size.y);
+		self.mark_redraw();
 		self.prev_size = size;
 
+		let mut to_refresh = Vec::<Component>::new();
+		self.refresh_recursively(self.tree_root_node, &mut to_refresh);
+
+		if !to_refresh.is_empty() {
+			log::debug!("refreshing {} registered widgets", to_refresh.len());
+			for c in &to_refresh {
+				self.components_to_refresh_once.push(c.clone());
+			}
+		}
+
 		let globals = self.state.globals.get();
 
 		self.state.tree.compute_layout_with_measure(
@@ -686,10 +726,10 @@ impl Layout {
 		}
 
 		for (widget_id, style) in alterables.style_set_requests {
-			if let Some(node_id) = self.state.nodes.get(widget_id) {
-				if let Err(e) = self.state.tree.set_style(*node_id, style) {
-					log::error!("failed to set style for taffy widget ID {node_id:?}: {e:?}");
-				}
+			if let Some(node_id) = self.state.nodes.get(widget_id)
+				&& let Err(e) = self.state.tree.set_style(*node_id, style)
+			{
+				log::error!("failed to set style for taffy widget ID {node_id:?}: {e:?}");
 			}
 		}