Node network subgraph editing (#1750)

* Breadcrumb visualization, nested network consistency, create definitions for Merge internal nodes

* Add index to network inputs, remove imports usage from flatten network

* Replace NodeOutput with NodeInput::Node

* Fully remove imports field, remove unnecessary identity nodes, move Output node to encapsulating network

* Replace previous_outputs with root_node, fix adding artboard/layer to empty network

* Import/Export UI nodes

* Display input/output types dynamically from compiled network

* Add LayerNodeIdentifer::ROOT_PARENT

* Prevent .to_node() on ROOT_PARENT

* Separate NodeGraphMessage and GraphOperationMessage

* General bug fixes with nested networks

* Change layer color, various bug fixes and improvements

* Fix disconnect and set node input for proto nodes and UI export node

* Dashed line to export for previewed node

* Fix deleting proto nodes and nodes that feed into export

* Allow modifications to nodes outside of nested network

* Get network from Node Id parameter

* Change root_node to previous_root_node

* Get TaggedValue from proto node implementation type when disconnecting

* Improve preview functionality and state

* Artboard position and delete children fix

* Name inputs/outputs based on DocumentNodeDefinition or type, fix new artboard/layer insertion

* replace "Link" with "Wire", adjust previewing

* Various bug fixes and improvements

* Modify Sample and Poisson-Disk points, fix incorrect input index and deleting currently viewed node

* Open demo artwork

* Fix opening already upgraded documents and refactor FrontendGraphDataType usages

* Fix deleting within network and other bugs

* Get default node input from compiled network when copying, fix previews, tests, demo artwork

* Code cleanup

* Hide EditorApi and add a comment describing unresolved Import node input types

* Code review

* Replace placeholder ROOT_PARENT NodeId with std::u64::MAX

* Breadcrumb padding

---------

Co-authored-by: Keavon Chambers <keavon@keavon.com>

editor/src/messages/tool/common_functionality/graph_modification_utils.rs

@@ -227,6 +227,7 @@ pub struct NodeGraphLayer<'a> {
 impl<'a> NodeGraphLayer<'a> {
 	/// Get the layer node from the document
 	pub fn new(layer: LayerNodeIdentifier, network: &'a NodeNetwork) -> Self {
+		debug_assert!(layer != LayerNodeIdentifier::ROOT_PARENT, "Cannot create new NodeGraphLayer from ROOT_PARENT");
 		Self {
 			node_graph: network,
 			layer_node: layer.to_node(),

editor/src/messages/tool/common_functionality/resize.rs

@@ -33,6 +33,11 @@ impl Resize {
 		let Some(layer) = self.layer else {
 			return None;
 		};
+
+		if layer == LayerNodeIdentifier::ROOT_PARENT {
+			log::error!("Resize layer cannot be ROOT_PARENT");
+		}
+
 		if !document.network().nodes.contains_key(&layer.to_node()) {
 			self.layer.take();
 			return None;

editor/src/messages/tool/common_functionality/snapping.rs

@@ -276,7 +276,13 @@ impl SnapManager {
 				candidates.push(layer);
 			}
 		}
-		add_candidates(LayerNodeIdentifier::ROOT, snap_data, quad, &mut candidates);
+
+		if let Some(root) = snap_data.document.network.get_root_node() {
+			if snap_data.document.network.nodes.get(&root.id).expect("Root should always be a node in find_candidates").is_layer {
+				add_candidates(LayerNodeIdentifier::new(root.id, &snap_data.document.network), snap_data, quad, &mut candidates);
+			}
+		}
+
 		if candidates.len() > 10 {
 			warn!("Snap candidate overflow");
 		}

editor/src/messages/tool/common_functionality/snapping/layer_snapper.rs

@@ -203,7 +203,6 @@ impl LayerSnapper {
 	}
 	pub fn snap_anchors(&mut self, snap_data: &mut SnapData, point: &SnapCandidatePoint, snap_results: &mut SnapResults, c: SnapConstraint, constrained_point: DVec2) {
 		self.collect_anchors(snap_data, point.source_index == 0);
-		//info!("Points to snap {:#?}", self.points_to_snap);
 		let mut best = None;
 		for candidate in &self.points_to_snap {
 			// Candidate is not on constraint