Implement area selection.

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 #### Visual Environment
 
+[Area selection][1588]. You can now select multiple nodes at once. Just click
+and drag on the background of your graph and see the beauty of the area
+selection appear.
+
 #### EnsoGL (rendering engine)
 
 <br/>![Bug Fixes](/docs/assets/tags/bug_fixes.svg)
@@ -12,6 +16,8 @@
 
 #### Enso Compiler
 
+[1588]: https://github.com/enso-org/ide/pull/1588
+
 # Enso 2.0.0-alpha.5 (2021-05-14)
 
 <br/>![New Features](/docs/assets/tags/new_features.svg)

src/rust/ide/src/ide/integration/project.rs

@@ -1006,7 +1006,7 @@ impl Model {
                     },
                     Err(other) => return Err(other.into()),
                 };
-                let selected_nodes = this.view.graph().model.selected_nodes().iter().filter_map(|id| {
+                let selected_nodes = this.view.graph().model.nodes.selected_nodes().iter().filter_map(|id| {
                     this.get_controller_node_id(*id).ok()
                 }).collect_vec();
                 let controller = this.graph.clone_ref();

src/rust/ide/view/graph-editor/src/component/node.rs

@@ -37,6 +37,8 @@ use ensogl_theme;
 use std::f32::EPSILON;
 
 use super::edge;
+use super::super::selection::BoundingBox;
+
 
 
 // =================
@@ -273,6 +275,7 @@ ensogl::define_endpoints! {
         error                 (Option<Error>),
         visualization_enabled (bool),
         tooltip               (tooltip::Style),
+        bounding_box          (BoundingBox)
     }
 }
 
@@ -534,6 +537,13 @@ impl Node {
         let style_frp        = &model.style;
         let action_bar       = &model.action_bar.frp;
 
+        // Hook up the display object position updates to the node's FRP. Required to calculate the
+        // bounding box
+        frp::extend! { network
+            position <- source::<Vector2>();
+        }
+        model.display_object.set_on_updated(f!((p) position.emit(p.position().xy())));
+
         frp::extend! { network
 
             // === Hover ===
@@ -581,6 +591,14 @@ impl Node {
             eval new_size ((t) model.output.frp.set_size.emit(t));
 
 
+            // === Bounding Box ===
+            bounding_box_input <- all2(&new_size,&position);
+            out.source.bounding_box <+ bounding_box_input.map(|(size,position)| {
+                let position = position - Vector2::new(0.0,size.y / 2.0);
+                BoundingBox::from_position_size(position,*size)
+            });
+
+
             // === Action Bar ===
 
             let visualization_enabled = action_bar.action_visibility.clone_ref();