Coordinate update event when litho scrolls or is shifted

Summary: See doc comment for explanation

Reviewed By: lblasa

Differential Revision: D40587610

fbshipit-source-id: f0909440c4e6e3cc9f5c7b557198a93ba8809bd9

desktop/plugins/public/ui-debugger/index.tsx

@@ -24,6 +24,18 @@ export function plugin(client: PluginClient<Events>) {
 
   const nodesAtom = createState<Map<Id, UINode>>(new Map());
   const snapshotsAtom = createState<Map<Id, Snapshot>>(new Map());
+
+  client.onMessage('coordinateUpdate', (event) => {
+    nodesAtom.update((draft) => {
+      const node = draft.get(event.nodeId);
+      if (!node) {
+        console.warn(`Coordinate update for non existing node `, event);
+      } else {
+        node.bounds.x = event.coordinate.x;
+        node.bounds.y = event.coordinate.y;
+      }
+    });
+  });
   client.onMessage('subtreeUpdate', (event) => {
     snapshotsAtom.update((draft) => {
       draft.set(event.rootId, event.snapshot);

desktop/plugins/public/ui-debugger/types.tsx

@@ -10,9 +10,16 @@
 export type Events = {
   init: InitEvent;
   subtreeUpdate: SubtreeUpdateEvent;
+  coordinateUpdate: CoordinateUpdateEvent;
   perfStats: PerfStatsEvent;
 };
 
+export type CoordinateUpdateEvent = {
+  observerType: String;
+  nodeId: Id;
+  coordinate: Coordinate;
+};
+
 export type SubtreeUpdateEvent = {
   txId: number;
   rootId: Id;
@@ -39,7 +46,7 @@ export type UINode = {
   name: string;
   attributes: Record<string, Inspectable>;
   children: Id[];
-  bounds?: Bounds;
+  bounds: Bounds;
   tags: Tag[];
   activeChild?: Id;
 };