feat(svelte): add intersection helpers

Svelte flow get intersecting nodes

examples/svelte/src/components/Header/Header.svelte

@@ -16,6 +16,7 @@
 		'usesvelteflow',
 		'useupdatenodeinternals',
 		'validation',
+		'intersections',
 		'add-node-on-drop'
 	];
 

examples/svelte/src/routes/intersections/+page.svelte

@@ -0,0 +1,8 @@
+<script lang="ts">
+  import { SvelteFlowProvider } from '@xyflow/svelte';
+  import Flow from './Flow.svelte';
+</script>
+
+<SvelteFlowProvider>
+  <Flow />
+</SvelteFlowProvider>

examples/svelte/src/routes/intersections/+server.ts

@@ -0,0 +1,29 @@
+// Template for ALL endpoints serving the code snippets
+// No need to edit these inside /src/routes/**
+// Will be overwritten by "pnpm run create:endpoints"
+
+import { json } from '@sveltejs/kit';
+
+export function POST() {
+  const files = import.meta.glob(['./*.js', './*.ts', './*.svelte', './*css', '!**/+server.ts'], {
+    as: 'raw',
+    eager: true
+  });
+
+  // Loose ./ for each filename
+  // +page.svelte becomes App.svelte for correct display in Sandpack
+  const filesClean: { [key: string]: string } = Object.entries(files).reduce(
+    (filesCleanAcc: { [key: string]: string }, [filename, file]) => {
+      if (filename === './+page.svelte') {
+        filesCleanAcc['App.svelte'] = file;
+      } else {
+        filesCleanAcc[filename.replace('./', '')] = file;
+      }
+
+      return filesCleanAcc;
+    },
+    {}
+  );
+
+  return json(filesClean);
+}

examples/svelte/src/routes/intersections/Flow.svelte

@@ -0,0 +1,60 @@
+<script lang="ts">
+	import { SvelteFlow, Background, Controls, useSvelteFlow } from '@xyflow/svelte';
+	import type { Edge, Node } from '@xyflow/svelte';
+	import { writable } from 'svelte/store';
+
+	import '@xyflow/svelte/dist/style.css';
+
+	import { initialNodes, initialEdges } from './nodes-and-edges';
+
+	const nodes = writable<Node[]>(initialNodes);
+	const edges = writable<Edge[]>(initialEdges);
+
+	const { getIntersectingNodes } = useSvelteFlow();
+
+	function onNodeDrag({ detail: { node } }) {
+		const intersections = getIntersectingNodes(node).map((n) => n.id);
+
+		$nodes.forEach((n) => {
+			n.class = intersections.includes(n.id) ? 'highlight' : '';
+		});
+		$nodes = $nodes;
+	}
+</script>
+
+<div style="height:100vh;">
+	<SvelteFlow {nodes} {edges} fitView class="intersection-flow" on:nodedrag={onNodeDrag}>
+		<Background />
+		<Controls />
+	</SvelteFlow>
+</div>
+
+<style>
+	:global(.svelte-flow__node.highlight) {
+		background-color: #ff0072 !important;
+		color: white;
+	}
+
+	:global(.intersection-flow .svelte-flow__node) {
+		display: flex;
+		justify-content: center;
+		align-items: center;
+		font-weight: 700;
+		border-radius: 1px;
+		border-width: 2px;
+		box-shadow: 6px 6px 0 1px rgba(0, 0, 0, 0.7);
+	}
+
+	:global(
+			.intersection-flow .svelte-flow__node.selected,
+			.intersection-flow .svelte-flow__node:hover,
+			.intersection-flow .svelte-flow__node:focus
+		) {
+		box-shadow: 6px 6px 0 1px rgba(0, 0, 0, 0.7);
+		background-color: #eee;
+	}
+
+	:global(.intersection-flow .svelte-flow__handle) {
+		display: none;
+	}
+</style>

examples/svelte/src/routes/intersections/nodes-and-edges.ts

@@ -0,0 +1,28 @@
+import type { Node, Edge } from '@xyflow/svelte';
+
+export const initialNodes: Node[] = [
+  {
+    id: '1',
+    data: { label: 'Node 1' },
+    position: { x: 0, y: 0 },
+    style: 'width: 200px; height: 100px;'
+  },
+  {
+    id: '2',
+    data: { label: 'Node 2' },
+    position: { x: 0, y: 150 }
+  },
+  {
+    id: '3',
+    data: { label: 'Node 3' },
+    position: { x: 250, y: 0 }
+  },
+  {
+    id: '4',
+    data: { label: 'Node' },
+    position: { x: 350, y: 150 },
+    style: 'width: 50px; height: 50px;'
+  }
+];
+
+export const initialEdges: Edge[] = [];

packages/svelte/src/lib/hooks/useSvelteFlow.ts

@@ -1,5 +1,8 @@
 import { get, type Writable } from 'svelte/store';
 import {
+  getOverlappingArea,
+  isRectObject,
+  nodeToRect,
   pointToRendererPoint,
   type FitBoundsOptions,
   type SetCenterOptions,
@@ -25,6 +28,16 @@ export function useSvelteFlow(): {
   setViewport: (viewport: Viewport, options?: ViewportHelperFunctionOptions) => void;
   getViewport: () => Viewport;
   fitView: (options?: FitViewOptions) => void;
+  getIntersectingNodes: (
+    nodeOrRect: (Partial<Node> & { id: Node['id'] }) | Rect,
+    partially?: boolean,
+    nodesToIntersect?: Node[]
+  ) => Node[];
+  isNodeIntersecting: (
+    nodeOrRect: (Partial<Node> & { id: Node['id'] }) | Rect,
+    area: Rect,
+    partially?: boolean
+  ) => boolean;
   fitBounds: (bounds: Rect, options?: FitBoundsOptions) => void;
   deleteElements: (
     nodesToRemove?: Partial<Node> & { id: string }[],
@@ -50,6 +63,21 @@ export function useSvelteFlow(): {
     domNode
   } = useStore();
 
+  const getNodeRect = (
+    nodeOrRect: (Partial<Node> & { id: Node['id'] }) | Rect
+  ): [Rect | null, Node | null | undefined, boolean] => {
+    const isRect = isRectObject(nodeOrRect);
+    const node = isRect ? null : get(nodes).find((n) => n.id === nodeOrRect.id);
+
+    if (!isRect && !node) {
+      return [null, null, isRect];
+    }
+
+    const nodeRect = isRect ? nodeOrRect : nodeToRect(node!);
+
+    return [nodeRect, node, isRect];
+  };
+
   return {
     zoomIn,
     zoomOut,
@@ -111,6 +139,45 @@ export function useSvelteFlow(): {
         { duration: options?.duration }
       );
     },
+    getIntersectingNodes: (
+      nodeOrRect: (Partial<Node> & { id: Node['id'] }) | Rect,
+      partially = true,
+      nodesToIntersect?: Node[]
+    ) => {
+      const [nodeRect, node, isRect] = getNodeRect(nodeOrRect);
+
+      if (!nodeRect || !node) {
+        return [];
+      }
+
+      return (nodesToIntersect || get(nodes)).filter((n) => {
+        if (!isRect && (n.id === node.id || !n.positionAbsolute)) {
+          return false;
+        }
+
+        const currNodeRect = nodeToRect(n);
+        const overlappingArea = getOverlappingArea(currNodeRect, nodeRect);
+        const partiallyVisible = partially && overlappingArea > 0;
+
+        return partiallyVisible || overlappingArea >= nodeOrRect.width! * nodeOrRect.height!;
+      });
+    },
+    isNodeIntersecting: (
+      nodeOrRect: (Partial<Node> & { id: Node['id'] }) | Rect,
+      area: Rect,
+      partially = true
+    ) => {
+      const [nodeRect] = getNodeRect(nodeOrRect);
+
+      if (!nodeRect) {
+        return false;
+      }
+
+      const overlappingArea = getOverlappingArea(nodeRect, area);
+      const partiallyVisible = partially && overlappingArea > 0;
+
+      return partiallyVisible || overlappingArea >= nodeOrRect.width! * nodeOrRect.height!;
+    },
     deleteElements: (
       nodesToRemove: Partial<Node> & { id: string }[] = [],
       edgesToRemove: Partial<Edge> & { id: string }[] = []