Report edits to user with Behavior::on_edit (#29)

src/behavior.rs

@@ -287,6 +287,12 @@ pub trait Behavior<Pane> {
     fn ideal_tile_aspect_ratio(&self) -> f32 {
         4.0 / 3.0
     }
+
+    // Callbacks:
+
+    /// Called if the user edits the tree somehow, e.g. changes the size of some container,
+    /// clicks a tab, or drags a tile.
+    fn on_edit(&mut self) {}
 }
 
 /// How many columns should we use to fit `n` children in a grid?

src/container/grid.rs

@@ -397,12 +397,16 @@ fn resize_interaction<Pane>(
     let right = i + 1;
 
     if splitter_response.double_clicked() {
+        behavior.on_edit();
+
         // double-click to center the split between left and right:
         let mean = 0.5 * (shares[left] + shares[right]);
         shares[left] = mean;
         shares[right] = mean;
         ResizeState::Hovering
     } else if splitter_response.dragged() {
+        behavior.on_edit();
+
         if dx < 0.0 {
             // Expand right, shrink stuff to the left:
             shares[right] += shrink_shares(

src/container/linear.rs

@@ -374,12 +374,16 @@ fn resize_interaction<Pane>(
     tile_width: impl Fn(TileId) -> f32,
 ) -> ResizeState {
     if splitter_response.double_clicked() {
+        behavior.on_edit();
+
         // double-click to center the split between left and right:
         let mean = 0.5 * (shares[left] + shares[right]);
         shares[left] = mean;
         shares[right] = mean;
         ResizeState::Hovering
     } else if splitter_response.dragged() {
+        behavior.on_edit();
+
         if dx < 0.0 {
             // Expand right, shrink stuff to the left:
             shares[right] += shrink_shares(

src/container/tabs.rs

@@ -126,6 +126,7 @@ impl Tabs {
                         .on_hover_cursor(egui::CursorIcon::Grab)
                         .drag_started()
                     {
+                        behavior.on_edit();
                         ui.memory_mut(|mem| mem.set_dragged_id(tile_id.egui_id()));
                     }
                 }
@@ -144,6 +145,7 @@ impl Tabs {
                         behavior.tab_ui(&tree.tiles, ui, id, child_id, selected, is_being_dragged);
                     let response = response.on_hover_cursor(egui::CursorIcon::Grab);
                     if response.clicked() {
+                        behavior.on_edit();
                         next_active = Some(child_id);
                     }
 
@@ -152,6 +154,7 @@ impl Tabs {
                             && response.rect.contains(mouse_pos)
                         {
                             // Expand this tab - maybe the user wants to drop something into it!
+                            behavior.on_edit();
                             next_active = Some(child_id);
                         }
                     }

src/tree.rs

@@ -304,6 +304,7 @@ impl<Pane> Tree<Pane> {
         if ui.input(|i| i.pointer.any_released()) {
             ui.memory_mut(|mem| mem.stop_dragging());
             if let Some(insertion_point) = drop_context.best_insertion {
+                behavior.on_edit();
                 self.move_tile(dragged_tile_id, insertion_point);
             }
             clear_smooth_preview_rect(ui.ctx(), dragged_tile_id);