Generalize layers as merge nodes to enable adjustment layers (#1712)

* WIP, backward traversal issues

* Fix some tool issues

* Remove debugging

* Change some indices

* WIP: new artboard node

* WIP: add artboard node

* WIP: Artboard node and create_artboard

* WIP: Artboard node implementation complete

* WIP: Artboards input for output node

* Complete Artboard node

* Generalize LayerNodeIdentifier,  monitor_nodes support for Artboard node, adjust ResizeArtboard/ClearArtboards, move alias validation to Rust

* Fix misaligned artboard click targets

* Generalize/clarify create_layer and insert_between

* non-negative dimensions for resize_artboard

* Show artboards in layer panel

* Generalize create_layer for layer output node

* Generalize delete_layer/delete_artboard to NodeGraphMessage::DeleteNodes. Fixed upstream flow Iter

* remove old primary_input function

* Vertical node visuals, remove is_layer function, rename Layer node to Merge node, toggle display as layer

exposed_value_count type fix

Vertical node visuals, remove is_layer function, rename Layer node to Merge node, toggle display as layer

* Fix demo artwork

* Layer display context menu

* Automatically select artboard, fix warnings

* Improvements to context menu and layer invariant enforcement

* Remove display_as_layer and update load_structure

* Improve load_structure to show more layers, improve FlowIter, improve layer naming, layer rearrangement validation.

* Clean up demo artwork using generalized layers

* Improve design of Layers panel and graph nodes

* MoveSelectedLayersTo rewrite to support generalized layer nodes

* Include artboards in deepest_common_ancestor, fix resize_artboard/delete_artboard, sync artboard tool to layer panel

* MoveSelectedLayersTo adjustments

* Sync non layer node visibility with metadata

* Include non layer nodes when moving/creating layer

* Fix group layers and get_post_node_with_index

* Include non layer nodes in UngroupSelectedLayers

* GroupSelected for all selected nodes, UnGroupSelected position adjustments

* Add grouping for layers in different folders

* Fix hidden layers

* Prevent node from connecting to itself, fix undo automatic node insertion,

* Fix undo CreateEmptyFolder, fix grouping nested layer nodes

* Formatting

* Remove test and check if node is layer from network

* Fix undo group layers

* Check off roadmap

* MoveUpstreamSiblingsToChild adjustments

* Replace tabs with spaces, remove mut from argument

* Final code review pass

---------

Co-authored-by: 0hypercube <0hypercube@gmail.com>
Co-authored-by: Keavon Chambers <keavon@keavon.com>

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

@@ -157,11 +157,11 @@ pub fn get_opacity(layer: LayerNodeIdentifier, document_network: &NodeNetwork) -
 }
 
 pub fn get_fill_id(layer: LayerNodeIdentifier, document_network: &NodeNetwork) -> Option<NodeId> {
-	NodeGraphLayer::new(layer, document_network).node_id("Fill")
+	NodeGraphLayer::new(layer, document_network).upstream_node_id_from_name("Fill")
 }
 
 pub fn get_text_id(layer: LayerNodeIdentifier, document_network: &NodeNetwork) -> Option<NodeId> {
-	NodeGraphLayer::new(layer, document_network).node_id("Text")
+	NodeGraphLayer::new(layer, document_network).upstream_node_id_from_name("Text")
 }
 
 /// Gets properties from the Text node
@@ -233,21 +233,21 @@ impl<'a> NodeGraphLayer<'a> {
 		}
 	}
 
-	/// Return an iterator up the primary flow of the layer
-	pub fn primary_layer_flow(&self) -> impl Iterator<Item = (&'a DocumentNode, NodeId)> {
-		self.node_graph.upstream_flow_back_from_nodes(vec![self.layer_node], true)
+	/// Return an iterator up the horizontal flow of the layer
+	pub fn horizontal_layer_flow(&self) -> impl Iterator<Item = (&'a DocumentNode, NodeId)> {
+		self.node_graph.upstream_flow_back_from_nodes(vec![self.layer_node], graph_craft::document::FlowType::HorizontalFlow)
 	}
 
 	/// Node id of a node if it exists in the layer's primary flow
-	pub fn node_id(&self, node_name: &str) -> Option<NodeId> {
-		self.primary_layer_flow().find(|(node, _id)| node.name == node_name).map(|(_node, id)| id)
+	pub fn upstream_node_id_from_name(&self, node_name: &str) -> Option<NodeId> {
+		self.horizontal_layer_flow().find(|(node, _)| node.name == node_name).map(|(_, id)| id)
 	}
 
 	/// Find all of the inputs of a specific node within the layer's primary flow, up until the next layer is reached.
 	pub fn find_node_inputs(&self, node_name: &str) -> Option<&'a Vec<NodeInput>> {
-		self.primary_layer_flow()
-			.skip(1)
-			.take_while(|(node, _)| !node.is_layer())
+		self.horizontal_layer_flow()
+			.skip(1)// Skip self
+			.take_while(|(node, _)| !node.is_layer)
 			.find(|(node, _)| node.name == node_name)
 			.map(|(node, _id)| &node.inputs)
 	}

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

@@ -432,16 +432,16 @@ pub fn are_manipulator_handles_colinear<Id: bezier_rs::Identifier>(group: &bezie
 
 pub fn get_layer_snap_points(layer: LayerNodeIdentifier, snap_data: &SnapData, points: &mut Vec<SnapCandidatePoint>) {
 	let document = snap_data.document;
+
 	if document.metadata().is_artboard(layer) {
-	} else if document.metadata().is_folder(layer) {
+		return;
+	}
+
+	if document.metadata().is_folder(layer) {
 		for child in layer.descendants(document.metadata()) {
 			get_layer_snap_points(child, snap_data, points);
 		}
-	} else {
-		// Skip empty paths
-		if document.metadata.layer_outline(layer).next().is_none() {
-			return;
-		}
+	} else if document.metadata.layer_outline(layer).next().is_some() {
 		let to_document = document.metadata.transform_to_document(layer);
 		for subpath in document.metadata.layer_outline(layer) {
 			subpath_anchor_snap_points(layer, subpath, snap_data, points, to_document);