feat(packages/excalidraw): state tracking, api hook, and others (#10870)

excalidraw-app/data/FileManager.ts

@@ -40,10 +40,12 @@ export class FileManager {
 
   private _getFiles;
   private _saveFiles;
+  private _onFileStatusChange;
 
   constructor({
     getFiles,
     saveFiles,
+    onFileStatusChange,
   }: {
     getFiles: (fileIds: FileId[]) => Promise<{
       loadedFiles: BinaryFileData[];
@@ -53,9 +55,13 @@ export class FileManager {
       savedFiles: Map<FileId, BinaryFileData>;
       erroredFiles: Map<FileId, BinaryFileData>;
     }>;
+    onFileStatusChange?: (
+      updates: Array<[FileId, "loading" | "loaded" | "error"]>,
+    ) => void;
   }) {
     this._getFiles = getFiles;
     this._saveFiles = saveFiles;
+    this._onFileStatusChange = onFileStatusChange;
   }
 
   /**
@@ -146,6 +152,8 @@ export class FileManager {
       this.fetchingFiles.set(id, true);
     }
 
+    this._onFileStatusChange?.(ids.map((id) => [id, "loading"]));
+
     try {
       const { loadedFiles, erroredFiles } = await this._getFiles(ids);
 
@@ -156,6 +164,13 @@ export class FileManager {
         this.erroredFiles_fetch.set(fileId, true);
       }
 
+      this._onFileStatusChange?.([
+        ...loadedFiles.map((f) => [f.id, "loaded"] as [FileId, "loaded"]),
+        ...[...erroredFiles.keys()].map(
+          (id) => [id, "error"] as [FileId, "error"],
+        ),
+      ]);
+
       return { loadedFiles, erroredFiles };
     } finally {
       for (const id of ids) {
@@ -195,6 +210,13 @@ export class FileManager {
   };
 
   reset() {
+    if (this._onFileStatusChange && this.fetchingFiles.size) {
+      this._onFileStatusChange(
+        [...this.fetchingFiles.keys()].map(
+          (id) => [id, "error"] as [FileId, "error"],
+        ),
+      );
+    }
     this.fetchingFiles.clear();
     this.savingFiles.clear();
     this.savedFiles.clear();

excalidraw-app/data/LocalData.ts

@@ -42,6 +42,7 @@ import type { MaybePromise } from "@excalidraw/common/utility-types";
 import { SAVE_TO_LOCAL_STORAGE_TIMEOUT, STORAGE_KEYS } from "../app_constants";
 
 import { FileManager } from "./FileManager";
+import { FileStatusStore } from "./fileStatusStore";
 import { Locker } from "./Locker";
 import { updateBrowserStateVersion } from "./tabSync";
 
@@ -166,6 +167,7 @@ export class LocalData {
   // ---------------------------------------------------------------------------
 
   static fileStorage = new LocalFileManager({
+    onFileStatusChange: FileStatusStore.updateStatuses.bind(FileStatusStore),
     getFiles(ids) {
       return getMany(ids, filesStore).then(
         async (filesData: (BinaryFileData | undefined)[]) => {

excalidraw-app/data/fileStatusStore.ts

@@ -0,0 +1,48 @@
+import { VersionedSnapshotStore } from "@excalidraw/common";
+
+import type { FileId } from "@excalidraw/element/types";
+
+export type FileLoadingStatus = "loading" | "loaded" | "error";
+
+export class FileStatusStore {
+  private static store = new VersionedSnapshotStore<
+    Map<FileId, FileLoadingStatus>
+  >(new Map());
+
+  static getSnapshot() {
+    return this.store.getSnapshot();
+  }
+
+  static pull(sinceVersion?: number) {
+    return this.store.pull(sinceVersion);
+  }
+
+  static updateStatuses(updates: Array<[FileId, FileLoadingStatus]>) {
+    if (!updates.length) {
+      return;
+    }
+    this.store.update((prev) => {
+      let changed = false;
+      const next = new Map(prev);
+      for (const [id, status] of updates) {
+        if (next.get(id) !== status) {
+          next.set(id, status);
+          changed = true;
+        }
+      }
+      return changed ? next : prev;
+    });
+  }
+
+  static getPendingCount(statuses: Map<FileId, FileLoadingStatus>) {
+    let pending = 0;
+    let total = 0;
+    for (const status of statuses.values()) {
+      total++;
+      if (status === "loading") {
+        pending++;
+      }
+    }
+    return { pending, total };
+  }
+}