create event system

src/tree/container.rs

@@ -29,6 +29,7 @@ use {
             clonecell::CloneCell,
             double_click_state::DoubleClickState,
             errorfmt::ErrorFmt,
+            event_listener::LazyEventSource,
             hash_map_ext::HashMapExt,
             linkedlist::{LinkedList, LinkedNode, NodeRef},
             numcell::NumCell,
@@ -140,6 +141,10 @@ pub struct ContainerNode {
     attention_requests: ThresholdCounter,
     pending_layout_damage: Cell<bool>,
     layout_damage_timeout: Cell<Option<SpawnedFuture<()>>>,
+    pub layout_complete: Rc<LazyEventSource>,
+    pub child_added: Rc<LazyEventSource>,
+    pub child_removed: Rc<LazyEventSource>,
+    pub all_children_resized: Rc<LazyEventSource>,
 }
 
 impl Debug for ContainerNode {
@@ -258,6 +263,10 @@ impl ContainerNode {
             attention_requests: Default::default(),
             pending_layout_damage: Cell::new(false),
             layout_damage_timeout: Cell::new(None),
+            layout_complete: state.post_layout_event_sources.create_source(),
+            child_added: state.lazy_event_sources.create_source(),
+            child_removed: state.lazy_event_sources.create_source(),
+            all_children_resized: state.post_layout_event_sources.create_source(),
         });
         child.tl_set_parent(slf.clone());
         slf.pull_child_properties(&child_node_ref);
@@ -368,6 +377,7 @@ impl ContainerNode {
         // log::info!("add_child");
         self.schedule_layout();
         self.cancel_seat_ops();
+        self.child_added.trigger();
     }
 
     fn cancel_seat_ops(&self) {
@@ -461,6 +471,22 @@ impl ContainerNode {
         }
     }
 
+    fn all_children_match_body(&self) -> bool {
+        if let Some(mono) = self.mono_child.get() {
+            let body = self.mono_body.get();
+            let content = mono.content.get();
+            return content.width() == body.width() && content.height() == body.height();
+        }
+        for child in self.children.iter() {
+            let body = child.body.get();
+            let content = child.content.get();
+            if content.width() != body.width() || content.height() != body.height() {
+                return false;
+            }
+        }
+        true
+    }
+
     fn perform_layout(self: &Rc<Self>) {
         if self.num_children.get() == 0 {
             return;
@@ -475,6 +501,7 @@ impl ContainerNode {
         // log::info!("perform_layout");
         self.schedule_render_titles();
         self.schedule_compute_render_positions();
+        self.layout_complete.trigger();
         if self.pending_layout_damage.get() {
             let slf = self.clone();
             let timeout = self.state.eng.spawn("layout damage timeout", async move {
@@ -1832,6 +1859,9 @@ impl Node for ContainerNode {
         if let Some(node) = cn.get(&child.node_id()) {
             self.update_child_size(node, width, height);
         }
+        if self.pending_layout_damage.get() && self.all_children_match_body() {
+            self.all_children_resized.trigger();
+        }
         self.flush_layout_damage();
     }
 
@@ -2115,6 +2145,7 @@ impl ContainingNode for ContainerNode {
         // log::info!("cnode_remove_child2");
         self.schedule_layout();
         self.cancel_seat_ops();
+        self.child_removed.trigger();
     }
 
     fn cnode_accepts_child(&self, _node: &dyn Node) -> bool {