feat: apply deltas API (#9869)

packages/excalidraw/components/App.tsx

@@ -233,6 +233,8 @@ import {
   hitElementBoundingBox,
   isLineElement,
   isSimpleArrow,
+  StoreDelta,
+  type ApplyToOptions,
 } from "@excalidraw/element";
 
 import type { LocalPoint, Radians } from "@excalidraw/math";
@@ -259,6 +261,7 @@ import type {
   MagicGenerationData,
   ExcalidrawArrowElement,
   ExcalidrawElbowArrowElement,
+  SceneElementsMap,
 } from "@excalidraw/element/types";
 
 import type { Mutable, ValueOf } from "@excalidraw/common/utility-types";
@@ -697,6 +700,7 @@ class App extends React.Component<AppProps, AppState> {
     if (excalidrawAPI) {
       const api: ExcalidrawImperativeAPI = {
         updateScene: this.updateScene,
+        applyDeltas: this.applyDeltas,
         mutateElement: this.mutateElement,
         updateLibrary: this.library.updateLibrary,
         addFiles: this.addFiles,
@@ -3938,6 +3942,27 @@ class App extends React.Component<AppProps, AppState> {
     },
   );
 
+  public applyDeltas = (
+    deltas: StoreDelta[],
+    options?: ApplyToOptions,
+  ): [SceneElementsMap, AppState, boolean] => {
+    // squash all deltas together, starting with a fresh new delta instance
+    const aggregatedDelta = StoreDelta.squash(...deltas);
+
+    // create new instance of elements map & appState, so we don't accidentaly mutate existing ones
+    const nextAppState = { ...this.state };
+    const nextElements = new Map(
+      this.scene.getElementsMapIncludingDeleted(),
+    ) as SceneElementsMap;
+
+    return StoreDelta.applyTo(
+      aggregatedDelta,
+      nextElements,
+      nextAppState,
+      options,
+    );
+  };
+
   public mutateElement = <TElement extends Mutable<ExcalidrawElement>>(
     element: TElement,
     updates: ElementUpdate<TElement>,