Merge branch 'master' into ryan-di/freedraw-width

Signed-off-by: Mark Tolmacs <mark@lazycat.hu>

packages/element/src/Scene.ts

@@ -164,9 +164,14 @@ export class Scene {
     return this.frames;
   }
 
-  constructor(elements: ElementsMapOrArray | null = null) {
+  constructor(
+    elements: ElementsMapOrArray | null = null,
+    options?: {
+      skipValidation?: true;
+    },
+  ) {
     if (elements) {
-      this.replaceAllElements(elements);
+      this.replaceAllElements(elements, options);
     }
   }
 
@@ -263,12 +268,19 @@ export class Scene {
     return didChange;
   }
 
-  replaceAllElements(nextElements: ElementsMapOrArray) {
+  replaceAllElements(
+    nextElements: ElementsMapOrArray,
+    options?: {
+      skipValidation?: true;
+    },
+  ) {
     // we do trust the insertion order on the map, though maybe we shouldn't and should prefer order defined by fractional indices
     const _nextElements = toArray(nextElements);
     const nextFrameLikes: ExcalidrawFrameLikeElement[] = [];
 
-    validateIndicesThrottled(_nextElements);
+    if (!options?.skipValidation) {
+      validateIndicesThrottled(_nextElements);
+    }
 
     this.elements = syncInvalidIndices(_nextElements);
     this.elementsMap.clear();

packages/element/src/binding.ts

@@ -999,6 +999,29 @@ export const bindPointToSnapToElementOutline = (
       intersector,
       FIXED_BINDING_DISTANCE,
     ).sort(pointDistanceSq)[0];
+
+    if (!intersection) {
+      const anotherPoint = pointFrom<GlobalPoint>(
+        !isHorizontal ? center[0] : snapPoint[0],
+        isHorizontal ? center[1] : snapPoint[1],
+      );
+      const anotherIntersector = lineSegment(
+        anotherPoint,
+        pointFromVector(
+          vectorScale(
+            vectorNormalize(vectorFromPoint(snapPoint, anotherPoint)),
+            Math.max(bindableElement.width, bindableElement.height) * 2,
+          ),
+          anotherPoint,
+        ),
+      );
+      intersection = intersectElementWithLineSegment(
+        bindableElement,
+        elementsMap,
+        anotherIntersector,
+        FIXED_BINDING_DISTANCE,
+      ).sort(pointDistanceSq)[0];
+    }
   } else {
     intersection = intersectElementWithLineSegment(
       bindableElement,

packages/element/src/bounds.ts

@@ -43,6 +43,7 @@ import {
   isBoundToContainer,
   isFreeDrawElement,
   isLinearElement,
+  isLineElement,
   isTextElement,
 } from "./typeChecks";
 
@@ -322,19 +323,42 @@ export const getElementLineSegments = (
 
   if (shape.type === "polycurve") {
     const curves = shape.data;
-    const points = curves
-      .map((curve) => pointsOnBezierCurves(curve, 10))
-      .flat();
-    let i = 0;
+    const pointsOnCurves = curves.map((curve) =>
+      pointsOnBezierCurves(curve, 10),
+    );
+
     const segments: LineSegment<GlobalPoint>[] = [];
-    while (i < points.length - 1) {
-      segments.push(
-        lineSegment(
-          pointFrom(points[i][0], points[i][1]),
-          pointFrom(points[i + 1][0], points[i + 1][1]),
-        ),
-      );
-      i++;
+
+    if (
+      (isLineElement(element) && !element.polygon) ||
+      isArrowElement(element)
+    ) {
+      for (const points of pointsOnCurves) {
+        let i = 0;
+
+        while (i < points.length - 1) {
+          segments.push(
+            lineSegment(
+              pointFrom(points[i][0], points[i][1]),
+              pointFrom(points[i + 1][0], points[i + 1][1]),
+            ),
+          );
+          i++;
+        }
+      }
+    } else {
+      const points = pointsOnCurves.flat();
+      let i = 0;
+
+      while (i < points.length - 1) {
+        segments.push(
+          lineSegment(
+            pointFrom(points[i][0], points[i][1]),
+            pointFrom(points[i + 1][0], points[i + 1][1]),
+          ),
+        );
+        i++;
+      }
     }
 
     return segments;
@@ -1133,7 +1157,9 @@ export interface BoundingBox {
 }
 
 export const getCommonBoundingBox = (
-  elements: ExcalidrawElement[] | readonly NonDeleted<ExcalidrawElement>[],
+  elements:
+    | readonly ExcalidrawElement[]
+    | readonly NonDeleted<ExcalidrawElement>[],
 ): BoundingBox => {
   const [minX, minY, maxX, maxY] = getCommonBounds(elements);
   return {

packages/element/src/comparisons.ts

@@ -10,7 +10,13 @@ export const hasBackground = (type: ElementOrToolType) =>
   type === "freedraw";
 
 export const hasStrokeColor = (type: ElementOrToolType) =>
-  type !== "image" && type !== "frame" && type !== "magicframe";
+  type === "rectangle" ||
+  type === "ellipse" ||
+  type === "diamond" ||
+  type === "freedraw" ||
+  type === "arrow" ||
+  type === "line" ||
+  type === "text";
 
 export const hasStrokeWidth = (type: ElementOrToolType) =>
   type === "rectangle" ||

packages/element/src/delta.ts

@@ -55,10 +55,10 @@ import { getNonDeletedGroupIds } from "./groups";
 
 import { orderByFractionalIndex, syncMovedIndices } from "./fractionalIndex";
 
-import { Scene } from "./Scene";
-
 import { StoreSnapshot } from "./store";
 
+import { Scene } from "./Scene";
+
 import type { BindableProp, BindingProp } from "./binding";
 
 import type { ElementUpdate } from "./mutateElement";
@@ -150,13 +150,27 @@ export class Delta<T> {
     );
   }
 
+  /**
+   * Merges two deltas into a new one.
+   */
+  public static merge<T>(
+    delta1: Delta<T>,
+    delta2: Delta<T>,
+    delta3: Delta<T> = Delta.empty(),
+  ) {
+    return Delta.create(
+      { ...delta1.deleted, ...delta2.deleted, ...delta3.deleted },
+      { ...delta1.inserted, ...delta2.inserted, ...delta3.inserted },
+    );
+  }
+
   /**
    * Merges deleted and inserted object partials.
    */
   public static mergeObjects<T extends { [key: string]: unknown }>(
     prev: T,
     added: T,
-    removed: T,
+    removed: T = {} as T,
   ) {
     const cloned = { ...prev };
 
@@ -496,6 +510,11 @@ export interface DeltaContainer<T> {
    */
   applyTo(previous: T, ...options: unknown[]): [T, boolean];
 
+  /**
+   * Squashes the current delta with the given one.
+   */
+  squash(delta: DeltaContainer<T>): this;
+
   /**
    * Checks whether all `Delta`s are empty.
    */
@@ -503,7 +522,11 @@ export interface DeltaContainer<T> {
 }
 
 export class AppStateDelta implements DeltaContainer<AppState> {
-  private constructor(public readonly delta: Delta<ObservedAppState>) {}
+  private constructor(public delta: Delta<ObservedAppState>) {}
+
+  public static create(delta: Delta<ObservedAppState>): AppStateDelta {
+    return new AppStateDelta(delta);
+  }
 
   public static calculate<T extends ObservedAppState>(
     prevAppState: T,
@@ -534,53 +557,124 @@ export class AppStateDelta implements DeltaContainer<AppState> {
     return new AppStateDelta(inversedDelta);
   }
 
+  public squash(delta: AppStateDelta): this {
+    if (delta.isEmpty()) {
+      return this;
+    }
+
+    const mergedDeletedSelectedElementIds = Delta.mergeObjects(
+      this.delta.deleted.selectedElementIds ?? {},
+      delta.delta.deleted.selectedElementIds ?? {},
+    );
+
+    const mergedInsertedSelectedElementIds = Delta.mergeObjects(
+      this.delta.inserted.selectedElementIds ?? {},
+      delta.delta.inserted.selectedElementIds ?? {},
+    );
+
+    const mergedDeletedSelectedGroupIds = Delta.mergeObjects(
+      this.delta.deleted.selectedGroupIds ?? {},
+      delta.delta.deleted.selectedGroupIds ?? {},
+    );
+
+    const mergedInsertedSelectedGroupIds = Delta.mergeObjects(
+      this.delta.inserted.selectedGroupIds ?? {},
+      delta.delta.inserted.selectedGroupIds ?? {},
+    );
+
+    const mergedDeletedLockedMultiSelections = Delta.mergeObjects(
+      this.delta.deleted.lockedMultiSelections ?? {},
+      delta.delta.deleted.lockedMultiSelections ?? {},
+    );
+
+    const mergedInsertedLockedMultiSelections = Delta.mergeObjects(
+      this.delta.inserted.lockedMultiSelections ?? {},
+      delta.delta.inserted.lockedMultiSelections ?? {},
+    );
+
+    const mergedInserted: Partial<ObservedAppState> = {};
+    const mergedDeleted: Partial<ObservedAppState> = {};
+
+    if (
+      Object.keys(mergedDeletedSelectedElementIds).length ||
+      Object.keys(mergedInsertedSelectedElementIds).length
+    ) {
+      mergedDeleted.selectedElementIds = mergedDeletedSelectedElementIds;
+      mergedInserted.selectedElementIds = mergedInsertedSelectedElementIds;
+    }
+
+    if (
+      Object.keys(mergedDeletedSelectedGroupIds).length ||
+      Object.keys(mergedInsertedSelectedGroupIds).length
+    ) {
+      mergedDeleted.selectedGroupIds = mergedDeletedSelectedGroupIds;
+      mergedInserted.selectedGroupIds = mergedInsertedSelectedGroupIds;
+    }
+
+    if (
+      Object.keys(mergedDeletedLockedMultiSelections).length ||
+      Object.keys(mergedInsertedLockedMultiSelections).length
+    ) {
+      mergedDeleted.lockedMultiSelections = mergedDeletedLockedMultiSelections;
+      mergedInserted.lockedMultiSelections =
+        mergedInsertedLockedMultiSelections;
+    }
+
+    this.delta = Delta.merge(
+      this.delta,
+      delta.delta,
+      Delta.create(mergedDeleted, mergedInserted),
+    );
+
+    return this;
+  }
+
   public applyTo(
     appState: AppState,
     nextElements: SceneElementsMap,
   ): [AppState, boolean] {
     try {
       const {
-        selectedElementIds: removedSelectedElementIds = {},
-        selectedGroupIds: removedSelectedGroupIds = {},
+        selectedElementIds: deletedSelectedElementIds = {},
+        selectedGroupIds: deletedSelectedGroupIds = {},
+        lockedMultiSelections: deletedLockedMultiSelections = {},
       } = this.delta.deleted;
 
       const {
-        selectedElementIds: addedSelectedElementIds = {},
-        selectedGroupIds: addedSelectedGroupIds = {},
-        selectedLinearElementId,
-        editingLinearElementId,
+        selectedElementIds: insertedSelectedElementIds = {},
+        selectedGroupIds: insertedSelectedGroupIds = {},
+        lockedMultiSelections: insertedLockedMultiSelections = {},
+        selectedLinearElement: insertedSelectedLinearElement,
         ...directlyApplicablePartial
       } = this.delta.inserted;
 
       const mergedSelectedElementIds = Delta.mergeObjects(
         appState.selectedElementIds,
-        addedSelectedElementIds,
-        removedSelectedElementIds,
+        insertedSelectedElementIds,
+        deletedSelectedElementIds,
       );
 
       const mergedSelectedGroupIds = Delta.mergeObjects(
         appState.selectedGroupIds,
-        addedSelectedGroupIds,
-        removedSelectedGroupIds,
+        insertedSelectedGroupIds,
+        deletedSelectedGroupIds,
+      );
+
+      const mergedLockedMultiSelections = Delta.mergeObjects(
+        appState.lockedMultiSelections,
+        insertedLockedMultiSelections,
+        deletedLockedMultiSelections,
       );
 
       const selectedLinearElement =
-        selectedLinearElementId && nextElements.has(selectedLinearElementId)
+        insertedSelectedLinearElement &&
+        nextElements.has(insertedSelectedLinearElement.elementId)
           ? new LinearElementEditor(
               nextElements.get(
-                selectedLinearElementId,
-              ) as NonDeleted<ExcalidrawLinearElement>,
-              nextElements,
-            )
-          : null;
-
-      const editingLinearElement =
-        editingLinearElementId && nextElements.has(editingLinearElementId)
-          ? new LinearElementEditor(
-              nextElements.get(
-                editingLinearElementId,
+                insertedSelectedLinearElement.elementId,
               ) as NonDeleted<ExcalidrawLinearElement>,
               nextElements,
+              insertedSelectedLinearElement.isEditing,
             )
           : null;
 
@@ -589,14 +683,11 @@ export class AppStateDelta implements DeltaContainer<AppState> {
         ...directlyApplicablePartial,
         selectedElementIds: mergedSelectedElementIds,
         selectedGroupIds: mergedSelectedGroupIds,
+        lockedMultiSelections: mergedLockedMultiSelections,
         selectedLinearElement:
-          typeof selectedLinearElementId !== "undefined"
-            ? selectedLinearElement // element was either inserted or deleted
-            : appState.selectedLinearElement, // otherwise assign what we had before
-        editingLinearElement:
-          typeof editingLinearElementId !== "undefined"
-            ? editingLinearElement // element was either inserted or deleted
-            : appState.editingLinearElement, // otherwise assign what we had before
+          typeof insertedSelectedLinearElement !== "undefined"
+            ? selectedLinearElement
+            : appState.selectedLinearElement,
       };
 
       const constainsVisibleChanges = this.filterInvisibleChanges(
@@ -725,52 +816,53 @@ export class AppStateDelta implements DeltaContainer<AppState> {
             }
 
             break;
-          case "selectedLinearElementId":
-          case "editingLinearElementId":
-            const appStateKey = AppStateDelta.convertToAppStateKey(key);
-            const linearElement = nextAppState[appStateKey];
+          case "selectedLinearElement":
+            const nextLinearElement = nextAppState[key];
 
-            if (!linearElement) {
+            if (!nextLinearElement) {
               // previously there was a linear element (assuming visible), now there is none
               visibleDifferenceFlag.value = true;
             } else {
-              const element = nextElements.get(linearElement.elementId);
+              const element = nextElements.get(nextLinearElement.elementId);
 
               if (element && !element.isDeleted) {
                 // previously there wasn't a linear element, now there is one which is visible
                 visibleDifferenceFlag.value = true;
               } else {
                 // there was assigned a linear element now, but it's deleted
-                nextAppState[appStateKey] = null;
+                nextAppState[key] = null;
               }
             }
 
             break;
-          case "lockedMultiSelections": {
+          case "lockedMultiSelections":
             const prevLockedUnits = prevAppState[key] || {};
             const nextLockedUnits = nextAppState[key] || {};
 
+            // TODO: this seems wrong, we are already doing this comparison generically above,
+            // hence instead we should check whether elements are actually visible,
+            // so that once these changes are applied they actually result in a visible change to the user
             if (!isShallowEqual(prevLockedUnits, nextLockedUnits)) {
               visibleDifferenceFlag.value = true;
             }
             break;
-          }
-          case "activeLockedId": {
+          case "activeLockedId":
             const prevHitLockedId = prevAppState[key] || null;
             const nextHitLockedId = nextAppState[key] || null;
 
+            // TODO: this seems wrong, we are already doing this comparison generically above,
+            // hence instead we should check whether elements are actually visible,
+            // so that once these changes are applied they actually result in a visible change to the user
             if (prevHitLockedId !== nextHitLockedId) {
               visibleDifferenceFlag.value = true;
             }
             break;
-          }
-          default: {
+          default:
             assertNever(
               key,
               `Unknown ObservedElementsAppState's key "${key}"`,
               true,
             );
-          }
         }
       }
     }
@@ -778,20 +870,6 @@ export class AppStateDelta implements DeltaContainer<AppState> {
     return visibleDifferenceFlag.value;
   }
 
-  private static convertToAppStateKey(
-    key: keyof Pick<
-      ObservedElementsAppState,
-      "selectedLinearElementId" | "editingLinearElementId"
-    >,
-  ): keyof Pick<AppState, "selectedLinearElement" | "editingLinearElement"> {
-    switch (key) {
-      case "selectedLinearElementId":
-        return "selectedLinearElement";
-      case "editingLinearElementId":
-        return "editingLinearElement";
-    }
-  }
-
   private static filterSelectedElements(
     selectedElementIds: AppState["selectedElementIds"],
     elements: SceneElementsMap,
@@ -856,8 +934,7 @@ export class AppStateDelta implements DeltaContainer<AppState> {
       editingGroupId,
       selectedGroupIds,
       selectedElementIds,
-      editingLinearElementId,
-      selectedLinearElementId,
+      selectedLinearElement,
       croppingElementId,
       lockedMultiSelections,
       activeLockedId,
@@ -911,12 +988,6 @@ export class AppStateDelta implements DeltaContainer<AppState> {
         "lockedMultiSelections",
         (prevValue) => (prevValue ?? {}) as ValueOf<T["lockedMultiSelections"]>,
       );
-      Delta.diffObjects(
-        deleted,
-        inserted,
-        "activeLockedId",
-        (prevValue) => (prevValue ?? null) as ValueOf<T["activeLockedId"]>,
-      );
     } catch (e) {
       // if postprocessing fails it does not make sense to bubble up, but let's make sure we know about it
       console.error(`Couldn't postprocess appstate change deltas.`);
@@ -945,12 +1016,13 @@ type ElementPartial<TElement extends ExcalidrawElement = ExcalidrawElement> =
   Omit<Partial<Ordered<TElement>>, "id" | "updated" | "seed">;
 
 export type ApplyToOptions = {
-  excludedProperties: Set<keyof ElementPartial>;
+  excludedProperties?: Set<keyof ElementPartial>;
 };
 
 type ApplyToFlags = {
   containsVisibleDifference: boolean;
   containsZindexDifference: boolean;
+  applyDirection: "forward" | "backward" | undefined;
 };
 
 /**
@@ -1039,18 +1111,27 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     inserted,
   }: Delta<ElementPartial>) =>
     !!(
-      deleted.version &&
-      inserted.version &&
       // versions are required integers
-      Number.isInteger(deleted.version) &&
-      Number.isInteger(inserted.version) &&
-      // versions should be positive, zero included
-      deleted.version >= 0 &&
-      inserted.version >= 0 &&
-      // versions should never be the same
-      deleted.version !== inserted.version
+      (
+        Number.isInteger(deleted.version) &&
+        Number.isInteger(inserted.version) &&
+        // versions should be positive, zero included
+        deleted.version! >= 0 &&
+        inserted.version! >= 0 &&
+        // versions should never be the same
+        deleted.version !== inserted.version
+      )
     );
 
+  private static satisfiesUniqueInvariants = (
+    elementsDelta: ElementsDelta,
+    id: string,
+  ) => {
+    const { added, removed, updated } = elementsDelta;
+    // it's required that there is only one unique delta type per element
+    return [added[id], removed[id], updated[id]].filter(Boolean).length === 1;
+  };
+
   private static validate(
     elementsDelta: ElementsDelta,
     type: "added" | "removed" | "updated",
@@ -1059,6 +1140,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     for (const [id, delta] of Object.entries(elementsDelta[type])) {
       if (
         !this.satisfiesCommmonInvariants(delta) ||
+        !this.satisfiesUniqueInvariants(elementsDelta, id) ||
         !satifiesSpecialInvariants(delta)
       ) {
         console.error(
@@ -1095,7 +1177,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
       const nextElement = nextElements.get(prevElement.id);
 
       if (!nextElement) {
-        const deleted = { ...prevElement, isDeleted: false } as ElementPartial;
+        const deleted = { ...prevElement } as ElementPartial;
 
         const inserted = {
           isDeleted: true,
@@ -1109,7 +1191,11 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
           ElementsDelta.stripIrrelevantProps,
         );
 
-        removed[prevElement.id] = delta;
+        if (!prevElement.isDeleted) {
+          removed[prevElement.id] = delta;
+        } else {
+          updated[prevElement.id] = delta;
+        }
       }
     }
 
@@ -1125,7 +1211,6 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
 
         const inserted = {
           ...nextElement,
-          isDeleted: false,
         } as ElementPartial;
 
         const delta = Delta.create(
@@ -1134,7 +1219,12 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
           ElementsDelta.stripIrrelevantProps,
         );
 
-        added[nextElement.id] = delta;
+        // ignore updates which would "delete" already deleted element
+        if (!nextElement.isDeleted) {
+          added[nextElement.id] = delta;
+        } else {
+          updated[nextElement.id] = delta;
+        }
 
         continue;
       }
@@ -1163,10 +1253,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
           continue;
         }
 
-        // making sure there are at least some changes
-        if (!Delta.isEmpty(delta)) {
-          updated[nextElement.id] = delta;
-        }
+        updated[nextElement.id] = delta;
       }
     }
 
@@ -1181,8 +1268,8 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     const inverseInternal = (deltas: Record<string, Delta<ElementPartial>>) => {
       const inversedDeltas: Record<string, Delta<ElementPartial>> = {};
 
-      for (const [id, delta] of Object.entries(deltas)) {
-        inversedDeltas[id] = Delta.create(delta.inserted, delta.deleted);
+      for (const [id, { inserted, deleted }] of Object.entries(deltas)) {
+        inversedDeltas[id] = Delta.create({ ...inserted }, { ...deleted });
       }
 
       return inversedDeltas;
@@ -1301,9 +1388,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
   public applyTo(
     elements: SceneElementsMap,
     snapshot: StoreSnapshot["elements"] = StoreSnapshot.empty().elements,
-    options: ApplyToOptions = {
-      excludedProperties: new Set(),
-    },
+    options?: ApplyToOptions,
   ): [SceneElementsMap, boolean] {
     let nextElements = new Map(elements) as SceneElementsMap;
     let changedElements: Map<string, OrderedExcalidrawElement>;
@@ -1311,22 +1396,28 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     const flags: ApplyToFlags = {
       containsVisibleDifference: false,
       containsZindexDifference: false,
+      applyDirection: undefined,
     };
 
     // mimic a transaction by applying deltas into `nextElements` (always new instance, no mutation)
     try {
       const applyDeltas = ElementsDelta.createApplier(
+        elements,
         nextElements,
         snapshot,
-        options,
         flags,
+        options,
       );
 
       const addedElements = applyDeltas(this.added);
       const removedElements = applyDeltas(this.removed);
       const updatedElements = applyDeltas(this.updated);
 
-      const affectedElements = this.resolveConflicts(elements, nextElements);
+      const affectedElements = this.resolveConflicts(
+        elements,
+        nextElements,
+        flags.applyDirection,
+      );
 
       // TODO: #7348 validate elements semantically and syntactically the changed elements, in case they would result data integrity issues
       changedElements = new Map([
@@ -1350,22 +1441,15 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     }
 
     try {
-      // the following reorder performs also mutations, but only on new instances of changed elements
-      // (unless something goes really bad and it fallbacks to fixing all invalid indices)
+      // the following reorder performs mutations, but only on new instances of changed elements,
+      // unless something goes really bad and it fallbacks to fixing all invalid indices
       nextElements = ElementsDelta.reorderElements(
         nextElements,
         changedElements,
         flags,
       );
 
-      // we don't have an up-to-date scene, as we can be just in the middle of applying history entry
-      // we also don't have a scene on the server
-      // so we are creating a temp scene just to query and mutate elements
-      const tempScene = new Scene(nextElements);
-
-      ElementsDelta.redrawTextBoundingBoxes(tempScene, changedElements);
-      // Need ordered nextElements to avoid z-index binding issues
-      ElementsDelta.redrawBoundArrows(tempScene, changedElements);
+      ElementsDelta.redrawElements(nextElements, changedElements);
     } catch (e) {
       console.error(
         `Couldn't mutate elements after applying elements change`,
@@ -1380,12 +1464,113 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     }
   }
 
+  public squash(delta: ElementsDelta): this {
+    if (delta.isEmpty()) {
+      return this;
+    }
+
+    const { added, removed, updated } = delta;
+
+    const mergeBoundElements = (
+      prevDelta: Delta<ElementPartial>,
+      nextDelta: Delta<ElementPartial>,
+    ) => {
+      const mergedDeletedBoundElements =
+        Delta.mergeArrays(
+          prevDelta.deleted.boundElements ?? [],
+          nextDelta.deleted.boundElements ?? [],
+          undefined,
+          (x) => x.id,
+        ) ?? [];
+
+      const mergedInsertedBoundElements =
+        Delta.mergeArrays(
+          prevDelta.inserted.boundElements ?? [],
+          nextDelta.inserted.boundElements ?? [],
+          undefined,
+          (x) => x.id,
+        ) ?? [];
+
+      if (
+        !mergedDeletedBoundElements.length &&
+        !mergedInsertedBoundElements.length
+      ) {
+        return;
+      }
+
+      return Delta.create(
+        {
+          boundElements: mergedDeletedBoundElements,
+        },
+        {
+          boundElements: mergedInsertedBoundElements,
+        },
+      );
+    };
+
+    for (const [id, nextDelta] of Object.entries(added)) {
+      const prevDelta = this.added[id] ?? this.removed[id] ?? this.updated[id];
+
+      if (!prevDelta) {
+        this.added[id] = nextDelta;
+      } else {
+        const mergedDelta = mergeBoundElements(prevDelta, nextDelta);
+        delete this.removed[id];
+        delete this.updated[id];
+
+        this.added[id] = Delta.merge(prevDelta, nextDelta, mergedDelta);
+      }
+    }
+
+    for (const [id, nextDelta] of Object.entries(removed)) {
+      const prevDelta = this.added[id] ?? this.removed[id] ?? this.updated[id];
+
+      if (!prevDelta) {
+        this.removed[id] = nextDelta;
+      } else {
+        const mergedDelta = mergeBoundElements(prevDelta, nextDelta);
+        delete this.added[id];
+        delete this.updated[id];
+
+        this.removed[id] = Delta.merge(prevDelta, nextDelta, mergedDelta);
+      }
+    }
+
+    for (const [id, nextDelta] of Object.entries(updated)) {
+      const prevDelta = this.added[id] ?? this.removed[id] ?? this.updated[id];
+
+      if (!prevDelta) {
+        this.updated[id] = nextDelta;
+      } else {
+        const mergedDelta = mergeBoundElements(prevDelta, nextDelta);
+        const updatedDelta = Delta.merge(prevDelta, nextDelta, mergedDelta);
+
+        if (prevDelta === this.added[id]) {
+          this.added[id] = updatedDelta;
+        } else if (prevDelta === this.removed[id]) {
+          this.removed[id] = updatedDelta;
+        } else {
+          this.updated[id] = updatedDelta;
+        }
+      }
+    }
+
+    if (isTestEnv() || isDevEnv()) {
+      ElementsDelta.validate(this, "added", ElementsDelta.satisfiesAddition);
+      ElementsDelta.validate(this, "removed", ElementsDelta.satisfiesRemoval);
+      ElementsDelta.validate(this, "updated", ElementsDelta.satisfiesUpdate);
+    }
+
+    return this;
+  }
+
   private static createApplier =
     (
+      prevElements: SceneElementsMap,
       nextElements: SceneElementsMap,
       snapshot: StoreSnapshot["elements"],
-      options: ApplyToOptions,
       flags: ApplyToFlags,
+      options?: ApplyToOptions,
     ) =>
     (deltas: Record<string, Delta<ElementPartial>>) => {
       const getElement = ElementsDelta.createGetter(
@@ -1398,15 +1583,26 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
         const element = getElement(id, delta.inserted);
 
         if (element) {
-          const newElement = ElementsDelta.applyDelta(
+          const nextElement = ElementsDelta.applyDelta(
             element,
             delta,
-            options,
             flags,
+            options,
           );
 
-          nextElements.set(newElement.id, newElement);
-          acc.set(newElement.id, newElement);
+          nextElements.set(nextElement.id, nextElement);
+          acc.set(nextElement.id, nextElement);
+
+          if (!flags.applyDirection) {
+            const prevElement = prevElements.get(id);
+
+            if (prevElement) {
+              flags.applyDirection =
+                prevElement.version > nextElement.version
+                  ? "backward"
+                  : "forward";
+            }
+          }
         }
 
         return acc;
@@ -1451,8 +1647,8 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
   private static applyDelta(
     element: OrderedExcalidrawElement,
     delta: Delta<ElementPartial>,
-    options: ApplyToOptions,
     flags: ApplyToFlags,
+    options?: ApplyToOptions,
   ) {
     const directlyApplicablePartial: Mutable<ElementPartial> = {};
 
@@ -1466,7 +1662,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
         continue;
       }
 
-      if (options.excludedProperties.has(key)) {
+      if (options?.excludedProperties?.has(key)) {
         continue;
       }
 
@@ -1506,7 +1702,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
         delta.deleted.index !== delta.inserted.index;
     }
 
-    return newElementWith(element, directlyApplicablePartial);
+    return newElementWith(element, directlyApplicablePartial, true);
   }
 
   /**
@@ -1546,6 +1742,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
   private resolveConflicts(
     prevElements: SceneElementsMap,
     nextElements: SceneElementsMap,
+    applyDirection: "forward" | "backward" = "forward",
   ) {
     const nextAffectedElements = new Map<string, OrderedExcalidrawElement>();
     const updater = (
@@ -1557,21 +1754,36 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
         return;
       }
 
+      const prevElement = prevElements.get(element.id);
+      const nextVersion =
+        applyDirection === "forward"
+          ? nextElement.version + 1
+          : nextElement.version - 1;
+
+      const elementUpdates = updates as ElementUpdate<OrderedExcalidrawElement>;
+
       let affectedElement: OrderedExcalidrawElement;
 
-      if (prevElements.get(element.id) === nextElement) {
+      if (prevElement === nextElement) {
         // create the new element instance in case we didn't modify the element yet
         // so that we won't end up in an incosistent state in case we would fail in the middle of mutations
         affectedElement = newElementWith(
           nextElement,
-          updates as ElementUpdate<OrderedExcalidrawElement>,
+          {
+            ...elementUpdates,
+            version: nextVersion,
+          },
+          true,
         );
       } else {
-        affectedElement = mutateElement(
-          nextElement,
-          nextElements,
-          updates as ElementUpdate<OrderedExcalidrawElement>,
-        );
+        affectedElement = mutateElement(nextElement, nextElements, {
+          ...elementUpdates,
+          // don't modify the version further, if it's already different
+          version:
+            prevElement?.version !== nextElement.version
+              ? nextElement.version
+              : nextVersion,
+        });
       }
 
       nextAffectedElements.set(affectedElement.id, affectedElement);
@@ -1609,25 +1821,12 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
       Array.from(prevElements).filter(([id]) => nextAffectedElements.has(id)),
     );
 
-    // calculate complete deltas for affected elements, and assign them back to all the deltas
-    // technically we could do better here if perf. would become an issue
-    const { added, removed, updated } = ElementsDelta.calculate(
-      prevAffectedElements,
-      nextAffectedElements,
+    // calculate complete deltas for affected elements, and squash them back to the current deltas
+    this.squash(
+      // technically we could do better here if perf. would become an issue
+      ElementsDelta.calculate(prevAffectedElements, nextAffectedElements),
     );
 
-    for (const [id, delta] of Object.entries(added)) {
-      this.added[id] = delta;
-    }
-
-    for (const [id, delta] of Object.entries(removed)) {
-      this.removed[id] = delta;
-    }
-
-    for (const [id, delta] of Object.entries(updated)) {
-      this.updated[id] = delta;
-    }
-
     return nextAffectedElements;
   }
 
@@ -1689,6 +1888,31 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
     BindableElement.rebindAffected(nextElements, nextElement(), updater);
   }
 
+  public static redrawElements(
+    nextElements: SceneElementsMap,
+    changedElements: Map<string, OrderedExcalidrawElement>,
+  ) {
+    try {
+      // we don't have an up-to-date scene, as we can be just in the middle of applying history entry
+      // we also don't have a scene on the server
+      // so we are creating a temp scene just to query and mutate elements
+      const tempScene = new Scene(nextElements, { skipValidation: true });
+
+      ElementsDelta.redrawTextBoundingBoxes(tempScene, changedElements);
+
+      // needs ordered nextElements to avoid z-index binding issues
+      ElementsDelta.redrawBoundArrows(tempScene, changedElements);
+    } catch (e) {
+      console.error(`Couldn't redraw elements`, e);
+
+      if (isTestEnv() || isDevEnv()) {
+        throw e;
+      }
+    } finally {
+      return nextElements;
+    }
+  }
+
   private static redrawTextBoundingBoxes(
     scene: Scene,
     changed: Map<string, OrderedExcalidrawElement>,
@@ -1743,6 +1967,7 @@ export class ElementsDelta implements DeltaContainer<SceneElementsMap> {
   ) {
     for (const element of changed.values()) {
       if (!element.isDeleted && isBindableElement(element)) {
+        // TODO: with precise bindings this is quite expensive, so consider optimisation so it's only triggered when the arrow does not intersect (imprecise) element bounds
         updateBoundElements(element, scene, {
           changedElements: changed,
         });

packages/element/src/elbowArrow.ts

@@ -359,6 +359,12 @@ const handleSegmentRelease = (
     null,
   );
 
+  if (!restoredPoints || restoredPoints.length < 2) {
+    throw new Error(
+      "Property 'points' is required in the update returned by normalizeArrowElementUpdate()",
+    );
+  }
+
   const nextPoints: GlobalPoint[] = [];
 
   // First part of the arrow are the old points
@@ -706,7 +712,7 @@ const handleEndpointDrag = (
   endGlobalPoint: GlobalPoint,
   hoveredStartElement: ExcalidrawBindableElement | null,
   hoveredEndElement: ExcalidrawBindableElement | null,
-) => {
+): ElementUpdate<ExcalidrawElbowArrowElement> => {
   let startIsSpecial = arrow.startIsSpecial ?? null;
   let endIsSpecial = arrow.endIsSpecial ?? null;
   const globalUpdatedPoints = updatedPoints.map((p, i) =>
@@ -741,8 +747,15 @@ const handleEndpointDrag = (
 
   // Calculate the moving second point connection and add the start point
   {
-    const secondPoint = globalUpdatedPoints[startIsSpecial ? 2 : 1];
-    const thirdPoint = globalUpdatedPoints[startIsSpecial ? 3 : 2];
+    const secondPoint = globalUpdatedPoints.at(startIsSpecial ? 2 : 1);
+    const thirdPoint = globalUpdatedPoints.at(startIsSpecial ? 3 : 2);
+
+    if (!secondPoint || !thirdPoint) {
+      throw new Error(
+        `Second and third points must exist when handling endpoint drag (${startIsSpecial})`,
+      );
+    }
+
     const startIsHorizontal = headingIsHorizontal(startHeading);
     const secondIsHorizontal = headingIsHorizontal(
       vectorToHeading(vectorFromPoint(secondPoint, thirdPoint)),
@@ -801,10 +814,19 @@ const handleEndpointDrag = (
 
   // Calculate the moving second to last point connection
   {
-    const secondToLastPoint =
-      globalUpdatedPoints[globalUpdatedPoints.length - (endIsSpecial ? 3 : 2)];
-    const thirdToLastPoint =
-      globalUpdatedPoints[globalUpdatedPoints.length - (endIsSpecial ? 4 : 3)];
+    const secondToLastPoint = globalUpdatedPoints.at(
+      globalUpdatedPoints.length - (endIsSpecial ? 3 : 2),
+    );
+    const thirdToLastPoint = globalUpdatedPoints.at(
+      globalUpdatedPoints.length - (endIsSpecial ? 4 : 3),
+    );
+
+    if (!secondToLastPoint || !thirdToLastPoint) {
+      throw new Error(
+        `Second and third to last points must exist when handling endpoint drag (${endIsSpecial})`,
+      );
+    }
+
     const endIsHorizontal = headingIsHorizontal(endHeading);
     const secondIsHorizontal = headingForPointIsHorizontal(
       thirdToLastPoint,
@@ -2071,16 +2093,7 @@ const normalizeArrowElementUpdate = (
   nextFixedSegments: readonly FixedSegment[] | null,
   startIsSpecial?: ExcalidrawElbowArrowElement["startIsSpecial"],
   endIsSpecial?: ExcalidrawElbowArrowElement["startIsSpecial"],
-): {
-  points: LocalPoint[];
-  x: number;
-  y: number;
-  width: number;
-  height: number;
-  fixedSegments: readonly FixedSegment[] | null;
-  startIsSpecial?: ExcalidrawElbowArrowElement["startIsSpecial"];
-  endIsSpecial?: ExcalidrawElbowArrowElement["startIsSpecial"];
-} => {
+): ElementUpdate<ExcalidrawElbowArrowElement> => {
   const offsetX = global[0][0];
   const offsetY = global[0][1];
   let points = global.map((p) =>

packages/element/src/index.ts

@@ -29,6 +29,9 @@ export const hashElementsVersion = (elements: ElementsMapOrArray): number => {
 
 // string hash function (using djb2). Not cryptographically secure, use only
 // for versioning and such.
+// note: hashes individual code units (not code points),
+// but for hashing purposes this is fine as it iterates through every code unit
+// (as such, no need to encode to byte string first)
 export const hashString = (s: string): number => {
   let hash: number = 5381;
   for (let i = 0; i < s.length; i++) {
@@ -98,6 +101,7 @@ export * from "./image";
 export * from "./linearElementEditor";
 export * from "./mutateElement";
 export * from "./newElement";
+export * from "./positionElementsOnGrid";
 export * from "./renderElement";
 export * from "./resizeElements";
 export * from "./resizeTest";

packages/element/src/linearElementEditor.ts

@@ -149,10 +149,12 @@ export class LinearElementEditor {
   public readonly segmentMidPointHoveredCoords: GlobalPoint | null;
   public readonly elbowed: boolean;
   public readonly customLineAngle: number | null;
+  public readonly isEditing: boolean;
 
   constructor(
     element: NonDeleted<ExcalidrawLinearElement>,
     elementsMap: ElementsMap,
+    isEditing: boolean = false,
   ) {
     this.elementId = element.id as string & {
       _brand: "excalidrawLinearElementId";
@@ -187,6 +189,7 @@ export class LinearElementEditor {
     this.segmentMidPointHoveredCoords = null;
     this.elbowed = isElbowArrow(element) && element.elbowed;
     this.customLineAngle = null;
+    this.isEditing = isEditing;
   }
 
   // ---------------------------------------------------------------------------
@@ -194,6 +197,7 @@ export class LinearElementEditor {
   // ---------------------------------------------------------------------------
 
   static POINT_HANDLE_SIZE = 10;
+
   /**
    * @param id the `elementId` from the instance of this class (so that we can
    *  statically guarantee this method returns an ExcalidrawLinearElement)
@@ -215,11 +219,14 @@ export class LinearElementEditor {
     setState: React.Component<any, AppState>["setState"],
     elementsMap: NonDeletedSceneElementsMap,
   ) {
-    if (!appState.editingLinearElement || !appState.selectionElement) {
+    if (
+      !appState.selectedLinearElement?.isEditing ||
+      !appState.selectionElement
+    ) {
       return false;
     }
-    const { editingLinearElement } = appState;
-    const { selectedPointsIndices, elementId } = editingLinearElement;
+    const { selectedLinearElement } = appState;
+    const { selectedPointsIndices, elementId } = selectedLinearElement;
 
     const element = LinearElementEditor.getElement(elementId, elementsMap);
     if (!element) {
@@ -260,8 +267,8 @@ export class LinearElementEditor {
       });
 
     setState({
-      editingLinearElement: {
-        ...editingLinearElement,
+      selectedLinearElement: {
+        ...selectedLinearElement,
         selectedPointsIndices: nextSelectedPoints.length
           ? nextSelectedPoints
           : null,
@@ -479,9 +486,6 @@ export class LinearElementEditor {
 
       return {
         ...app.state,
-        editingLinearElement: app.state.editingLinearElement
-          ? newLinearElementEditor
-          : null,
         selectedLinearElement: newLinearElementEditor,
         suggestedBindings,
       };
@@ -618,7 +622,7 @@ export class LinearElementEditor {
     // Since its not needed outside editor unless 2 pointer lines or bound text
     if (
       !isElbowArrow(element) &&
-      !appState.editingLinearElement &&
+      !appState.selectedLinearElement?.isEditing &&
       element.points.length > 2 &&
       !boundText
     ) {
@@ -684,7 +688,7 @@ export class LinearElementEditor {
     );
     if (
       points.length >= 3 &&
-      !appState.editingLinearElement &&
+      !appState.selectedLinearElement?.isEditing &&
       !isElbowArrow(element)
     ) {
       return null;
@@ -881,7 +885,7 @@ export class LinearElementEditor {
         segmentMidpoint,
         elementsMap,
       );
-    } else if (event.altKey && appState.editingLinearElement) {
+    } else if (event.altKey && appState.selectedLinearElement?.isEditing) {
       if (linearElementEditor.lastUncommittedPoint == null) {
         scene.mutateElement(element, {
           points: [
@@ -1023,14 +1027,14 @@ export class LinearElementEditor {
     app: AppClassProperties,
   ): LinearElementEditor | null {
     const appState = app.state;
-    if (!appState.editingLinearElement) {
+    if (!appState.selectedLinearElement?.isEditing) {
       return null;
     }
-    const { elementId, lastUncommittedPoint } = appState.editingLinearElement;
+    const { elementId, lastUncommittedPoint } = appState.selectedLinearElement;
     const elementsMap = app.scene.getNonDeletedElementsMap();
     const element = LinearElementEditor.getElement(elementId, elementsMap);
     if (!element) {
-      return appState.editingLinearElement;
+      return appState.selectedLinearElement;
     }
 
     const { points } = element;
@@ -1040,10 +1044,12 @@ export class LinearElementEditor {
       if (lastPoint === lastUncommittedPoint) {
         LinearElementEditor.deletePoints(element, app, [points.length - 1]);
       }
-      return {
-        ...appState.editingLinearElement,
-        lastUncommittedPoint: null,
-      };
+      return appState.selectedLinearElement?.lastUncommittedPoint
+        ? {
+            ...appState.selectedLinearElement,
+            lastUncommittedPoint: null,
+          }
+        : appState.selectedLinearElement;
     }
 
     let newPoint: LocalPoint;
@@ -1067,8 +1073,8 @@ export class LinearElementEditor {
       newPoint = LinearElementEditor.createPointAt(
         element,
         elementsMap,
-        scenePointerX - appState.editingLinearElement.pointerOffset.x,
-        scenePointerY - appState.editingLinearElement.pointerOffset.y,
+        scenePointerX - appState.selectedLinearElement.pointerOffset.x,
+        scenePointerY - appState.selectedLinearElement.pointerOffset.y,
         event[KEYS.CTRL_OR_CMD] || isElbowArrow(element)
           ? null
           : app.getEffectiveGridSize(),
@@ -1092,7 +1098,7 @@ export class LinearElementEditor {
       LinearElementEditor.addPoints(element, app.scene, [newPoint]);
     }
     return {
-      ...appState.editingLinearElement,
+      ...appState.selectedLinearElement,
       lastUncommittedPoint: element.points[element.points.length - 1],
     };
   }
@@ -1251,12 +1257,12 @@ export class LinearElementEditor {
   // ---------------------------------------------------------------------------
   static duplicateSelectedPoints(appState: AppState, scene: Scene): AppState {
     invariant(
-      appState.editingLinearElement,
+      appState.selectedLinearElement?.isEditing,
       "Not currently editing a linear element",
     );
 
     const elementsMap = scene.getNonDeletedElementsMap();
-    const { selectedPointsIndices, elementId } = appState.editingLinearElement;
+    const { selectedPointsIndices, elementId } = appState.selectedLinearElement;
     const element = LinearElementEditor.getElement(elementId, elementsMap);
 
     invariant(
@@ -1318,8 +1324,8 @@ export class LinearElementEditor {
 
     return {
       ...appState,
-      editingLinearElement: {
-        ...appState.editingLinearElement,
+      selectedLinearElement: {
+        ...appState.selectedLinearElement,
         selectedPointsIndices: nextSelectedIndices,
       },
     };
@@ -1331,8 +1337,9 @@ export class LinearElementEditor {
     pointIndices: readonly number[],
   ) {
     const isUncommittedPoint =
-      app.state.editingLinearElement?.lastUncommittedPoint ===
-      element.points[element.points.length - 1];
+      app.state.selectedLinearElement?.isEditing &&
+      app.state.selectedLinearElement?.lastUncommittedPoint ===
+        element.points[element.points.length - 1];
 
     const nextPoints = element.points.filter((_, idx) => {
       return !pointIndices.includes(idx);
@@ -1505,7 +1512,7 @@ export class LinearElementEditor {
       pointFrom(pointerCoords.x, pointerCoords.y),
     );
     if (
-      !appState.editingLinearElement &&
+      !appState.selectedLinearElement?.isEditing &&
       dist < DRAGGING_THRESHOLD / appState.zoom.value
     ) {
       return false;

packages/element/src/positionElementsOnGrid.ts

@@ -0,0 +1,112 @@
+import { getCommonBounds } from "./bounds";
+import { type ElementUpdate, newElementWith } from "./mutateElement";
+
+import type { ExcalidrawElement } from "./types";
+
+// TODO rewrite (mostly vibe-coded)
+export const positionElementsOnGrid = <TElement extends ExcalidrawElement>(
+  elements: TElement[] | TElement[][],
+  centerX: number,
+  centerY: number,
+  padding = 50,
+): TElement[] => {
+  // Ensure there are elements to position
+  if (!elements || elements.length === 0) {
+    return [];
+  }
+
+  const res: TElement[] = [];
+  // Normalize input to work with atomic units (groups of elements)
+  // If elements is a flat array, treat each element as its own atomic unit
+  const atomicUnits: TElement[][] = Array.isArray(elements[0])
+    ? (elements as TElement[][])
+    : (elements as TElement[]).map((element) => [element]);
+
+  // Determine the number of columns for atomic units
+  // A common approach for a "grid-like" layout without specific column constraints
+  // is to aim for a roughly square arrangement.
+  const numUnits = atomicUnits.length;
+  const numColumns = Math.max(1, Math.ceil(Math.sqrt(numUnits)));
+
+  // Group atomic units into rows based on the calculated number of columns
+  const rows: TElement[][][] = [];
+  for (let i = 0; i < numUnits; i += numColumns) {
+    rows.push(atomicUnits.slice(i, i + numColumns));
+  }
+
+  // Calculate properties for each row (total width, max height)
+  // and the total actual height of all row content.
+  let totalGridActualHeight = 0; // Sum of max heights of rows, without inter-row padding
+  const rowProperties = rows.map((rowUnits) => {
+    let rowWidth = 0;
+    let maxUnitHeightInRow = 0;
+
+    const unitBounds = rowUnits.map((unit) => {
+      const [minX, minY, maxX, maxY] = getCommonBounds(unit);
+      return {
+        elements: unit,
+        bounds: [minX, minY, maxX, maxY] as const,
+        width: maxX - minX,
+        height: maxY - minY,
+      };
+    });
+
+    unitBounds.forEach((unitBound, index) => {
+      rowWidth += unitBound.width;
+      // Add padding between units in the same row, but not after the last one
+      if (index < unitBounds.length - 1) {
+        rowWidth += padding;
+      }
+      if (unitBound.height > maxUnitHeightInRow) {
+        maxUnitHeightInRow = unitBound.height;
+      }
+    });
+
+    totalGridActualHeight += maxUnitHeightInRow;
+    return {
+      unitBounds,
+      width: rowWidth,
+      maxHeight: maxUnitHeightInRow,
+    };
+  });
+
+  // Calculate the total height of the grid including padding between rows
+  const totalGridHeightWithPadding =
+    totalGridActualHeight + Math.max(0, rows.length - 1) * padding;
+
+  // Calculate the starting Y position to center the entire grid vertically around centerY
+  let currentY = centerY - totalGridHeightWithPadding / 2;
+
+  // Position atomic units row by row
+  rowProperties.forEach((rowProp) => {
+    const { unitBounds, width: rowWidth, maxHeight: rowMaxHeight } = rowProp;
+
+    // Calculate the starting X for the current row to center it horizontally around centerX
+    let currentX = centerX - rowWidth / 2;
+
+    unitBounds.forEach((unitBound) => {
+      // Calculate the offset needed to position this atomic unit
+      const [originalMinX, originalMinY] = unitBound.bounds;
+      const offsetX = currentX - originalMinX;
+      const offsetY = currentY - originalMinY;
+
+      // Apply the offset to all elements in this atomic unit
+      unitBound.elements.forEach((element) => {
+        res.push(
+          newElementWith(element, {
+            x: element.x + offsetX,
+            y: element.y + offsetY,
+          } as ElementUpdate<TElement>),
+        );
+      });
+
+      // Move X for the next unit in the row
+      currentX += unitBound.width + padding;
+    });
+
+    // Move Y to the starting position for the next row
+    // This accounts for the tallest unit in the current row and the inter-row padding
+    currentY += rowMaxHeight + padding;
+  });
+  return res;
+};

packages/element/src/renderElement.ts

@@ -106,6 +106,11 @@ const getCanvasPadding = (element: ExcalidrawElement) => {
       return element.strokeWidth * 12;
     case "text":
       return element.fontSize / 2;
+    case "arrow":
+      if (element.endArrowhead || element.endArrowhead) {
+        return 40;
+      }
+      return 20;
     default:
       return 20;
   }

packages/element/src/resizeElements.ts

@@ -35,6 +35,7 @@ import {
   getContainerElement,
   handleBindTextResize,
   getBoundTextMaxWidth,
+  computeBoundTextPosition,
 } from "./textElement";
 import {
   getMinTextElementWidth,
@@ -225,7 +226,16 @@ const rotateSingleElement = (
       scene.getElement<ExcalidrawTextElementWithContainer>(boundTextElementId);
 
     if (textElement && !isArrowElement(element)) {
-      scene.mutateElement(textElement, { angle });
+      const { x, y } = computeBoundTextPosition(
+        element,
+        textElement,
+        scene.getNonDeletedElementsMap(),
+      );
+      scene.mutateElement(textElement, {
+        angle,
+        x,
+        y,
+      });
     }
   }
 };
@@ -416,9 +426,15 @@ const rotateMultipleElements = (
 
       const boundText = getBoundTextElement(element, elementsMap);
       if (boundText && !isArrowElement(element)) {
+        const { x, y } = computeBoundTextPosition(
+          element,
+          boundText,
+          elementsMap,
+        );
+
         scene.mutateElement(boundText, {
-          x: boundText.x + (rotatedCX - cx),
-          y: boundText.y + (rotatedCY - cy),
+          x,
+          y,
           angle: normalizeRadians((centerAngle + origAngle) as Radians),
         });
       }

packages/element/src/store.ts

@@ -27,6 +27,8 @@ import {
   isImageElement,
 } from "./index";
 
+import type { ApplyToOptions } from "./delta";
+
 import type {
   ExcalidrawElement,
   OrderedExcalidrawElement,
@@ -74,8 +76,9 @@ type MicroActionsQueue = (() => void)[];
  * Store which captures the observed changes and emits them as `StoreIncrement` events.
  */
 export class Store {
-  // internally used by history
+  // for internal use by history
   public readonly onDurableIncrementEmitter = new Emitter<[DurableIncrement]>();
+  // for public use as part of onIncrement API
   public readonly onStoreIncrementEmitter = new Emitter<
     [DurableIncrement | EphemeralIncrement]
   >();
@@ -237,7 +240,6 @@ export class Store {
     if (!storeDelta.isEmpty()) {
       const increment = new DurableIncrement(storeChange, storeDelta);
 
-      // Notify listeners with the increment
       this.onDurableIncrementEmitter.trigger(increment);
       this.onStoreIncrementEmitter.trigger(increment);
     }
@@ -550,10 +552,26 @@ export class StoreDelta {
   public static load({
     id,
     elements: { added, removed, updated },
+    appState: { delta: appStateDelta },
   }: DTO<StoreDelta>) {
     const elements = ElementsDelta.create(added, removed, updated);
+    const appState = AppStateDelta.create(appStateDelta);
 
-    return new this(id, elements, AppStateDelta.empty());
+    return new this(id, elements, appState);
+  }
+
+  /**
+   * Squash the passed deltas into the aggregated delta instance.
+   */
+  public static squash(...deltas: StoreDelta[]) {
+    const aggregatedDelta = StoreDelta.empty();
+
+    for (const delta of deltas) {
+      aggregatedDelta.elements.squash(delta.elements);
+      aggregatedDelta.appState.squash(delta.appState);
+    }
+
+    return aggregatedDelta;
   }
 
   /**
@@ -570,9 +588,13 @@ export class StoreDelta {
     delta: StoreDelta,
     elements: SceneElementsMap,
     appState: AppState,
+    options?: ApplyToOptions,
   ): [SceneElementsMap, AppState, boolean] {
-    const [nextElements, elementsContainVisibleChange] =
-      delta.elements.applyTo(elements);
+    const [nextElements, elementsContainVisibleChange] = delta.elements.applyTo(
+      elements,
+      StoreSnapshot.empty().elements,
+      options,
+    );
 
     const [nextAppState, appStateContainsVisibleChange] =
       delta.appState.applyTo(appState, nextElements);
@@ -605,6 +627,10 @@ export class StoreDelta {
     );
   }
 
+  public static empty() {
+    return StoreDelta.create(ElementsDelta.empty(), AppStateDelta.empty());
+  }
+
   public isEmpty() {
     return this.elements.isEmpty() && this.appState.isEmpty();
   }
@@ -970,8 +996,7 @@ const getDefaultObservedAppState = (): ObservedAppState => {
     viewBackgroundColor: COLOR_PALETTE.white,
     selectedElementIds: {},
     selectedGroupIds: {},
-    editingLinearElementId: null,
-    selectedLinearElementId: null,
+    selectedLinearElement: null,
     croppingElementId: null,
     activeLockedId: null,
     lockedMultiSelections: {},
@@ -990,14 +1015,12 @@ export const getObservedAppState = (
     croppingElementId: appState.croppingElementId,
     activeLockedId: appState.activeLockedId,
     lockedMultiSelections: appState.lockedMultiSelections,
-    editingLinearElementId:
-      (appState as AppState).editingLinearElement?.elementId ?? // prefer app state, as it's likely newer
-      (appState as ObservedAppState).editingLinearElementId ?? // fallback to observed app state, as it's likely older coming from a previous snapshot
-      null,
-    selectedLinearElementId:
-      (appState as AppState).selectedLinearElement?.elementId ??
-      (appState as ObservedAppState).selectedLinearElementId ??
-      null,
+    selectedLinearElement: appState.selectedLinearElement
+      ? {
+          elementId: appState.selectedLinearElement.elementId,
+          isEditing: !!appState.selectedLinearElement.isEditing,
+        }
+      : null,
   };
 
   Reflect.defineProperty(observedAppState, hiddenObservedAppStateProp, {

packages/element/src/textElement.ts

@@ -10,12 +10,12 @@ import {
   invariant,
 } from "@excalidraw/common";
 
+import { pointFrom, pointRotateRads, type Radians } from "@excalidraw/math";
+
 import type { AppState } from "@excalidraw/excalidraw/types";
 
 import type { ExtractSetType } from "@excalidraw/common/utility-types";
 
-import type { Radians } from "@excalidraw/math";
-
 import {
   resetOriginalContainerCache,
   updateOriginalContainerCache,
@@ -254,6 +254,26 @@ export const computeBoundTextPosition = (
     x =
       containerCoords.x + (maxContainerWidth / 2 - boundTextElement.width / 2);
   }
+  const angle = (container.angle ?? 0) as Radians;
+
+  if (angle !== 0) {
+    const contentCenter = pointFrom(
+      containerCoords.x + maxContainerWidth / 2,
+      containerCoords.y + maxContainerHeight / 2,
+    );
+    const textCenter = pointFrom(
+      x + boundTextElement.width / 2,
+      y + boundTextElement.height / 2,
+    );
+
+    const [rx, ry] = pointRotateRads(textCenter, contentCenter, angle);
+
+    return {
+      x: rx - boundTextElement.width / 2,
+      y: ry - boundTextElement.height / 2,
+    };
+  }
+
   return { x, y };
 };
 

packages/element/src/transformHandles.ts

@@ -2,6 +2,7 @@ import {
   DEFAULT_TRANSFORM_HANDLE_SPACING,
   isAndroid,
   isIOS,
+  isMobileOrTablet,
 } from "@excalidraw/common";
 
 import { pointFrom, pointRotateRads } from "@excalidraw/math";
@@ -326,11 +327,11 @@ export const getTransformHandles = (
   );
 };
 
-export const shouldShowBoundingBox = (
+export const hasBoundingBox = (
   elements: readonly NonDeletedExcalidrawElement[],
   appState: InteractiveCanvasAppState,
 ) => {
-  if (appState.editingLinearElement) {
+  if (appState.selectedLinearElement?.isEditing) {
     return false;
   }
   if (elements.length > 1) {
@@ -345,5 +346,7 @@ export const shouldShowBoundingBox = (
     return true;
   }
 
-  return element.points.length > 2;
+  // on mobile/tablet we currently don't show bbox because of resize issues
+  // (also prob best for simplicity's sake)
+  return element.points.length > 2 && !isMobileOrTablet();
 };

packages/element/tests/binding.test.tsx

@@ -10,6 +10,8 @@ import { API } from "@excalidraw/excalidraw/tests/helpers/api";
 import { UI, Pointer, Keyboard } from "@excalidraw/excalidraw/tests/helpers/ui";
 import { fireEvent, render } from "@excalidraw/excalidraw/tests/test-utils";
 
+import { LinearElementEditor } from "@excalidraw/element";
+
 import { getTransformHandles } from "../src/transformHandles";
 import {
   getTextEditor,
@@ -155,10 +157,10 @@ describe("element binding", () => {
       // NOTE this mouse down/up + await needs to be done in order to repro
       // the issue, due to https://github.com/excalidraw/excalidraw/blob/46bff3daceb602accf60c40a84610797260fca94/src/components/App.tsx#L740
       mouse.reset();
-      expect(h.state.editingLinearElement).not.toBe(null);
+      expect(h.state.selectedLinearElement?.isEditing).toBe(true);
       mouse.down(0, 0);
       await new Promise((r) => setTimeout(r, 100));
-      expect(h.state.editingLinearElement).toBe(null);
+      expect(h.state.selectedLinearElement?.isEditing).toBe(false);
       expect(API.getSelectedElement().type).toBe("rectangle");
       mouse.up();
       expect(API.getSelectedElement().type).toBe("rectangle");
@@ -413,16 +415,12 @@ describe("element binding", () => {
     expect(arrow.endBinding?.elementId).toBe(rectRight.id);
 
     // Drag arrow off of bound rectangle range
-    const handles = getTransformHandles(
+    const [elX, elY] = LinearElementEditor.getPointAtIndexGlobalCoordinates(
       arrow,
-      h.state.zoom,
-      arrayToMap(h.elements),
-      "mouse",
-    ).se!;
-
+      -1,
+      h.scene.getNonDeletedElementsMap(),
+    );
     Keyboard.keyDown(KEYS.CTRL_OR_CMD);
-    const elX = handles[0] + handles[2] / 2;
-    const elY = handles[1] + handles[3] / 2;
     mouse.downAt(elX, elY);
     mouse.moveTo(300, 400);
     mouse.up();

packages/element/tests/delta.test.tsx

@@ -1,13 +1,345 @@
+import { API } from "@excalidraw/excalidraw/tests/helpers/api";
+
 import type { ObservedAppState } from "@excalidraw/excalidraw/types";
 import type { LinearElementEditor } from "@excalidraw/element";
+import type { SceneElementsMap } from "@excalidraw/element/types";
 
-import { AppStateDelta } from "../src/delta";
+import { AppStateDelta, Delta, ElementsDelta } from "../src/delta";
+
+describe("ElementsDelta", () => {
+  describe("elements delta calculation", () => {
+    it("should not throw when element gets removed but was already deleted", () => {
+      const element = API.createElement({
+        type: "rectangle",
+        x: 100,
+        y: 100,
+        isDeleted: true,
+      });
+
+      const prevElements = new Map([[element.id, element]]);
+      const nextElements = new Map();
+
+      expect(() =>
+        ElementsDelta.calculate(prevElements, nextElements),
+      ).not.toThrow();
+    });
+
+    it("should not throw when adding element as already deleted", () => {
+      const element = API.createElement({
+        type: "rectangle",
+        x: 100,
+        y: 100,
+        isDeleted: true,
+      });
+
+      const prevElements = new Map();
+      const nextElements = new Map([[element.id, element]]);
+
+      expect(() =>
+        ElementsDelta.calculate(prevElements, nextElements),
+      ).not.toThrow();
+    });
+
+    it("should create updated delta even when there is only version and versionNonce change", () => {
+      const baseElement = API.createElement({
+        type: "rectangle",
+        x: 100,
+        y: 100,
+        strokeColor: "#000000",
+        backgroundColor: "#ffffff",
+      });
+
+      const modifiedElement = {
+        ...baseElement,
+        version: baseElement.version + 1,
+        versionNonce: baseElement.versionNonce + 1,
+      };
+
+      // Create maps for the delta calculation
+      const prevElements = new Map([[baseElement.id, baseElement]]);
+      const nextElements = new Map([[modifiedElement.id, modifiedElement]]);
+
+      // Calculate the delta
+      const delta = ElementsDelta.calculate(
+        prevElements as SceneElementsMap,
+        nextElements as SceneElementsMap,
+      );
+
+      expect(delta).toEqual(
+        ElementsDelta.create(
+          {},
+          {},
+          {
+            [baseElement.id]: Delta.create(
+              {
+                version: baseElement.version,
+                versionNonce: baseElement.versionNonce,
+              },
+              {
+                version: baseElement.version + 1,
+                versionNonce: baseElement.versionNonce + 1,
+              },
+            ),
+          },
+        ),
+      );
+    });
+  });
+
+  describe("squash", () => {
+    it("should not squash when second delta is empty", () => {
+      const updatedDelta = Delta.create(
+        { x: 100, version: 1, versionNonce: 1 },
+        { x: 200, version: 2, versionNonce: 2 },
+      );
+
+      const elementsDelta1 = ElementsDelta.create(
+        {},
+        {},
+        { id1: updatedDelta },
+      );
+      const elementsDelta2 = ElementsDelta.empty();
+      const elementsDelta = elementsDelta1.squash(elementsDelta2);
+
+      expect(elementsDelta.isEmpty()).toBeFalsy();
+      expect(elementsDelta).toBe(elementsDelta1);
+      expect(elementsDelta.updated.id1).toBe(updatedDelta);
+    });
+
+    it("should squash mutually exclusive delta types", () => {
+      const addedDelta = Delta.create(
+        { x: 100, version: 1, versionNonce: 1, isDeleted: true },
+        { x: 200, version: 2, versionNonce: 2, isDeleted: false },
+      );
+
+      const removedDelta = Delta.create(
+        { x: 100, version: 1, versionNonce: 1, isDeleted: false },
+        { x: 200, version: 2, versionNonce: 2, isDeleted: true },
+      );
+
+      const updatedDelta = Delta.create(
+        { x: 100, version: 1, versionNonce: 1 },
+        { x: 200, version: 2, versionNonce: 2 },
+      );
+
+      const elementsDelta1 = ElementsDelta.create(
+        { id1: addedDelta },
+        { id2: removedDelta },
+        {},
+      );
+
+      const elementsDelta2 = ElementsDelta.create(
+        {},
+        {},
+        { id3: updatedDelta },
+      );
+
+      const elementsDelta = elementsDelta1.squash(elementsDelta2);
+
+      expect(elementsDelta.isEmpty()).toBeFalsy();
+      expect(elementsDelta).toBe(elementsDelta1);
+      expect(elementsDelta.added.id1).toBe(addedDelta);
+      expect(elementsDelta.removed.id2).toBe(removedDelta);
+      expect(elementsDelta.updated.id3).toBe(updatedDelta);
+    });
+
+    it("should squash the same delta types", () => {
+      const elementsDelta1 = ElementsDelta.create(
+        {
+          id1: Delta.create(
+            { x: 100, version: 1, versionNonce: 1, isDeleted: true },
+            { x: 200, version: 2, versionNonce: 2, isDeleted: false },
+          ),
+        },
+        {
+          id2: Delta.create(
+            { x: 100, version: 1, versionNonce: 1, isDeleted: false },
+            { x: 200, version: 2, versionNonce: 2, isDeleted: true },
+          ),
+        },
+        {
+          id3: Delta.create(
+            { x: 100, version: 1, versionNonce: 1 },
+            { x: 200, version: 2, versionNonce: 2 },
+          ),
+        },
+      );
+
+      const elementsDelta2 = ElementsDelta.create(
+        {
+          id1: Delta.create(
+            { y: 100, version: 2, versionNonce: 2, isDeleted: true },
+            { y: 200, version: 3, versionNonce: 3, isDeleted: false },
+          ),
+        },
+        {
+          id2: Delta.create(
+            { y: 100, version: 2, versionNonce: 2, isDeleted: false },
+            { y: 200, version: 3, versionNonce: 3, isDeleted: true },
+          ),
+        },
+        {
+          id3: Delta.create(
+            { y: 100, version: 2, versionNonce: 2 },
+            { y: 200, version: 3, versionNonce: 3 },
+          ),
+        },
+      );
+
+      const elementsDelta = elementsDelta1.squash(elementsDelta2);
+
+      expect(elementsDelta.isEmpty()).toBeFalsy();
+      expect(elementsDelta).toBe(elementsDelta1);
+      expect(elementsDelta.added.id1).toEqual(
+        Delta.create(
+          { x: 100, y: 100, version: 2, versionNonce: 2, isDeleted: true },
+          { x: 200, y: 200, version: 3, versionNonce: 3, isDeleted: false },
+        ),
+      );
+      expect(elementsDelta.removed.id2).toEqual(
+        Delta.create(
+          { x: 100, y: 100, version: 2, versionNonce: 2, isDeleted: false },
+          { x: 200, y: 200, version: 3, versionNonce: 3, isDeleted: true },
+        ),
+      );
+      expect(elementsDelta.updated.id3).toEqual(
+        Delta.create(
+          { x: 100, y: 100, version: 2, versionNonce: 2 },
+          { x: 200, y: 200, version: 3, versionNonce: 3 },
+        ),
+      );
+    });
+
+    it("should squash different delta types ", () => {
+      // id1: added   -> updated => added
+      // id2: removed -> added   => added
+      // id3: updated -> removed => removed
+      const elementsDelta1 = ElementsDelta.create(
+        {
+          id1: Delta.create(
+            { x: 100, version: 1, versionNonce: 1, isDeleted: true },
+            { x: 101, version: 2, versionNonce: 2, isDeleted: false },
+          ),
+        },
+        {
+          id2: Delta.create(
+            { x: 200, version: 1, versionNonce: 1, isDeleted: false },
+            { x: 201, version: 2, versionNonce: 2, isDeleted: true },
+          ),
+        },
+        {
+          id3: Delta.create(
+            { x: 300, version: 1, versionNonce: 1 },
+            { x: 301, version: 2, versionNonce: 2 },
+          ),
+        },
+      );
+
+      const elementsDelta2 = ElementsDelta.create(
+        {
+          id2: Delta.create(
+            { y: 200, version: 2, versionNonce: 2, isDeleted: true },
+            { y: 201, version: 3, versionNonce: 3, isDeleted: false },
+          ),
+        },
+        {
+          id3: Delta.create(
+            { y: 300, version: 2, versionNonce: 2, isDeleted: false },
+            { y: 301, version: 3, versionNonce: 3, isDeleted: true },
+          ),
+        },
+        {
+          id1: Delta.create(
+            { y: 100, version: 2, versionNonce: 2 },
+            { y: 101, version: 3, versionNonce: 3 },
+          ),
+        },
+      );
+
+      const elementsDelta = elementsDelta1.squash(elementsDelta2);
+
+      expect(elementsDelta.isEmpty()).toBeFalsy();
+      expect(elementsDelta).toBe(elementsDelta1);
+      expect(elementsDelta.added).toEqual({
+        id1: Delta.create(
+          { x: 100, y: 100, version: 2, versionNonce: 2, isDeleted: true },
+          { x: 101, y: 101, version: 3, versionNonce: 3, isDeleted: false },
+        ),
+        id2: Delta.create(
+          { x: 200, y: 200, version: 2, versionNonce: 2, isDeleted: true },
+          { x: 201, y: 201, version: 3, versionNonce: 3, isDeleted: false },
+        ),
+      });
+      expect(elementsDelta.removed).toEqual({
+        id3: Delta.create(
+          { x: 300, y: 300, version: 2, versionNonce: 2, isDeleted: false },
+          { x: 301, y: 301, version: 3, versionNonce: 3, isDeleted: true },
+        ),
+      });
+      expect(elementsDelta.updated).toEqual({});
+    });
+
+    it("should squash bound elements", () => {
+      const elementsDelta1 = ElementsDelta.create(
+        {},
+        {},
+        {
+          id1: Delta.create(
+            {
+              version: 1,
+              versionNonce: 1,
+              boundElements: [{ id: "t1", type: "text" }],
+            },
+            {
+              version: 2,
+              versionNonce: 2,
+              boundElements: [{ id: "t2", type: "text" }],
+            },
+          ),
+        },
+      );
+
+      const elementsDelta2 = ElementsDelta.create(
+        {},
+        {},
+        {
+          id1: Delta.create(
+            {
+              version: 2,
+              versionNonce: 2,
+              boundElements: [{ id: "a1", type: "arrow" }],
+            },
+            {
+              version: 3,
+              versionNonce: 3,
+              boundElements: [{ id: "a2", type: "arrow" }],
+            },
+          ),
+        },
+      );
+
+      const elementsDelta = elementsDelta1.squash(elementsDelta2);
+
+      expect(elementsDelta.updated.id1.deleted.boundElements).toEqual([
+        { id: "t1", type: "text" },
+        { id: "a1", type: "arrow" },
+      ]);
+      expect(elementsDelta.updated.id1.inserted.boundElements).toEqual([
+        { id: "t2", type: "text" },
+        { id: "a2", type: "arrow" },
+      ]);
+    });
+  });
+});
 
 describe("AppStateDelta", () => {
   describe("ensure stable delta properties order", () => {
     it("should maintain stable order for root properties", () => {
       const name = "untitled scene";
-      const selectedLinearElementId = "id1" as LinearElementEditor["elementId"];
+      const selectedLinearElement = {
+        elementId: "id1" as LinearElementEditor["elementId"],
+        isEditing: false,
+      };
 
       const commonAppState = {
         viewBackgroundColor: "#ffffff",
@@ -16,6 +348,7 @@ describe("AppStateDelta", () => {
         editingGroupId: null,
         croppingElementId: null,
         editingLinearElementId: null,
+        selectedLinearElementIsEditing: null,
         lockedMultiSelections: {},
         activeLockedId: null,
       };
@@ -23,23 +356,23 @@ describe("AppStateDelta", () => {
       const prevAppState1: ObservedAppState = {
         ...commonAppState,
         name: "",
-        selectedLinearElementId: null,
+        selectedLinearElement: null,
       };
 
       const nextAppState1: ObservedAppState = {
         ...commonAppState,
         name,
-        selectedLinearElementId,
+        selectedLinearElement,
       };
 
       const prevAppState2: ObservedAppState = {
-        selectedLinearElementId: null,
+        selectedLinearElement: null,
         name: "",
         ...commonAppState,
       };
 
       const nextAppState2: ObservedAppState = {
-        selectedLinearElementId,
+        selectedLinearElement,
         name,
         ...commonAppState,
       };
@@ -57,8 +390,7 @@ describe("AppStateDelta", () => {
         selectedGroupIds: {},
         editingGroupId: null,
         croppingElementId: null,
-        selectedLinearElementId: null,
-        editingLinearElementId: null,
+        selectedLinearElement: null,
         activeLockedId: null,
         lockedMultiSelections: {},
       };
@@ -104,8 +436,7 @@ describe("AppStateDelta", () => {
         selectedElementIds: {},
         editingGroupId: null,
         croppingElementId: null,
-        selectedLinearElementId: null,
-        editingLinearElementId: null,
+        selectedLinearElement: null,
         activeLockedId: null,
         lockedMultiSelections: {},
       };
@@ -146,4 +477,97 @@ describe("AppStateDelta", () => {
       expect(JSON.stringify(delta1)).toBe(JSON.stringify(delta2));
     });
   });
+
+  describe("squash", () => {
+    it("should not squash when second delta is empty", () => {
+      const delta = Delta.create(
+        { name: "untitled scene" },
+        { name: "titled scene" },
+      );
+
+      const appStateDelta1 = AppStateDelta.create(delta);
+      const appStateDelta2 = AppStateDelta.empty();
+      const appStateDelta = appStateDelta1.squash(appStateDelta2);
+
+      expect(appStateDelta.isEmpty()).toBeFalsy();
+      expect(appStateDelta).toBe(appStateDelta1);
+      expect(appStateDelta.delta).toBe(delta);
+    });
+
+    it("should squash exclusive properties", () => {
+      const delta1 = Delta.create(
+        { name: "untitled scene" },
+        { name: "titled scene" },
+      );
+      const delta2 = Delta.create(
+        { viewBackgroundColor: "#ffffff" },
+        { viewBackgroundColor: "#000000" },
+      );
+
+      const appStateDelta1 = AppStateDelta.create(delta1);
+      const appStateDelta2 = AppStateDelta.create(delta2);
+      const appStateDelta = appStateDelta1.squash(appStateDelta2);
+
+      expect(appStateDelta.isEmpty()).toBeFalsy();
+      expect(appStateDelta).toBe(appStateDelta1);
+      expect(appStateDelta.delta).toEqual(
+        Delta.create(
+          { name: "untitled scene", viewBackgroundColor: "#ffffff" },
+          { name: "titled scene", viewBackgroundColor: "#000000" },
+        ),
+      );
+    });
+
+    it("should squash selectedElementIds, selectedGroupIds and lockedMultiSelections", () => {
+      const delta1 = Delta.create<Partial<ObservedAppState>>(
+        {
+          name: "untitled scene",
+          selectedElementIds: { id1: true },
+          selectedGroupIds: {},
+          lockedMultiSelections: { g1: true },
+        },
+        {
+          name: "titled scene",
+          selectedElementIds: { id2: true },
+          selectedGroupIds: { g1: true },
+          lockedMultiSelections: {},
+        },
+      );
+      const delta2 = Delta.create<Partial<ObservedAppState>>(
+        {
+          selectedElementIds: { id3: true },
+          selectedGroupIds: { g1: true },
+          lockedMultiSelections: {},
+        },
+        {
+          selectedElementIds: { id2: true },
+          selectedGroupIds: { g2: true, g3: true },
+          lockedMultiSelections: { g3: true },
+        },
+      );
+
+      const appStateDelta1 = AppStateDelta.create(delta1);
+      const appStateDelta2 = AppStateDelta.create(delta2);
+      const appStateDelta = appStateDelta1.squash(appStateDelta2);
+
+      expect(appStateDelta.isEmpty()).toBeFalsy();
+      expect(appStateDelta).toBe(appStateDelta1);
+      expect(appStateDelta.delta).toEqual(
+        Delta.create<Partial<ObservedAppState>>(
+          {
+            name: "untitled scene",
+            selectedElementIds: { id1: true, id3: true },
+            selectedGroupIds: { g1: true },
+            lockedMultiSelections: { g1: true },
+          },
+          {
+            name: "titled scene",
+            selectedElementIds: { id2: true },
+            selectedGroupIds: { g1: true, g2: true, g3: true },
+            lockedMultiSelections: { g3: true },
+          },
+        ),
+      );
+    });
+  });
 });

packages/element/tests/distribute.test.tsx

@@ -0,0 +1,128 @@
+import {
+  distributeHorizontally,
+  distributeVertically,
+} from "@excalidraw/excalidraw/actions";
+import { defaultLang, setLanguage } from "@excalidraw/excalidraw/i18n";
+import { Excalidraw } from "@excalidraw/excalidraw";
+
+import { API } from "@excalidraw/excalidraw/tests/helpers/api";
+import { UI, Pointer, Keyboard } from "@excalidraw/excalidraw/tests/helpers/ui";
+import {
+  act,
+  unmountComponent,
+  render,
+} from "@excalidraw/excalidraw/tests/test-utils";
+
+const mouse = new Pointer("mouse");
+
+// Scenario: three rectangles that will be distributed with gaps
+const createAndSelectThreeRectanglesWithGap = () => {
+  UI.clickTool("rectangle");
+  mouse.down();
+  mouse.up(100, 100);
+  mouse.reset();
+
+  UI.clickTool("rectangle");
+  mouse.down(10, 10);
+  mouse.up(100, 100);
+  mouse.reset();
+
+  UI.clickTool("rectangle");
+  mouse.down(300, 300);
+  mouse.up(100, 100);
+  mouse.reset();
+
+  // Last rectangle is selected by default
+  Keyboard.withModifierKeys({ shift: true }, () => {
+    mouse.click(0, 10);
+    mouse.click(10, 0);
+  });
+};
+
+// Scenario: three rectangles that will be distributed by their centers
+const createAndSelectThreeRectanglesWithoutGap = () => {
+  UI.clickTool("rectangle");
+  mouse.down();
+  mouse.up(100, 100);
+  mouse.reset();
+
+  UI.clickTool("rectangle");
+  mouse.down(10, 10);
+  mouse.up(200, 200);
+  mouse.reset();
+
+  UI.clickTool("rectangle");
+  mouse.down(200, 200);
+  mouse.up(100, 100);
+  mouse.reset();
+
+  // Last rectangle is selected by default
+  Keyboard.withModifierKeys({ shift: true }, () => {
+    mouse.click(0, 10);
+    mouse.click(10, 0);
+  });
+};
+
+describe("distributing", () => {
+  beforeEach(async () => {
+    unmountComponent();
+    mouse.reset();
+
+    await act(() => {
+      return setLanguage(defaultLang);
+    });
+    await render(<Excalidraw handleKeyboardGlobally={true} />);
+  });
+
+  it("should distribute selected elements horizontally", async () => {
+    createAndSelectThreeRectanglesWithGap();
+    expect(API.getSelectedElements()[0].x).toEqual(0);
+    expect(API.getSelectedElements()[1].x).toEqual(10);
+    expect(API.getSelectedElements()[2].x).toEqual(300);
+
+    API.executeAction(distributeHorizontally);
+
+    expect(API.getSelectedElements()[0].x).toEqual(0);
+    expect(API.getSelectedElements()[1].x).toEqual(150);
+    expect(API.getSelectedElements()[2].x).toEqual(300);
+  });
+
+  it("should distribute selected elements vertically", async () => {
+    createAndSelectThreeRectanglesWithGap();
+    expect(API.getSelectedElements()[0].y).toEqual(0);
+    expect(API.getSelectedElements()[1].y).toEqual(10);
+    expect(API.getSelectedElements()[2].y).toEqual(300);
+
+    API.executeAction(distributeVertically);
+
+    expect(API.getSelectedElements()[0].y).toEqual(0);
+    expect(API.getSelectedElements()[1].y).toEqual(150);
+    expect(API.getSelectedElements()[2].y).toEqual(300);
+  });
+
+  it("should distribute selected elements horizontally based on their centers", async () => {
+    createAndSelectThreeRectanglesWithoutGap();
+    expect(API.getSelectedElements()[0].x).toEqual(0);
+    expect(API.getSelectedElements()[1].x).toEqual(10);
+    expect(API.getSelectedElements()[2].x).toEqual(200);
+
+    API.executeAction(distributeHorizontally);
+
+    expect(API.getSelectedElements()[0].x).toEqual(0);
+    expect(API.getSelectedElements()[1].x).toEqual(50);
+    expect(API.getSelectedElements()[2].x).toEqual(200);
+  });
+
+  it("should distribute selected elements vertically with based on their centers", async () => {
+    createAndSelectThreeRectanglesWithoutGap();
+    expect(API.getSelectedElements()[0].y).toEqual(0);
+    expect(API.getSelectedElements()[1].y).toEqual(10);
+    expect(API.getSelectedElements()[2].y).toEqual(200);
+
+    API.executeAction(distributeVertically);
+
+    expect(API.getSelectedElements()[0].y).toEqual(0);
+    expect(API.getSelectedElements()[1].y).toEqual(50);
+    expect(API.getSelectedElements()[2].y).toEqual(200);
+  });
+});

packages/element/tests/linearElementEditor.test.tsx

@@ -136,7 +136,8 @@ describe("Test Linear Elements", () => {
     Keyboard.withModifierKeys({ ctrl: true }, () => {
       Keyboard.keyPress(KEYS.ENTER);
     });
-    expect(h.state.editingLinearElement?.elementId).toEqual(line.id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(line.id);
   };
 
   const drag = (startPoint: GlobalPoint, endPoint: GlobalPoint) => {
@@ -253,75 +254,82 @@ describe("Test Linear Elements", () => {
     });
     fireEvent.click(queryByText(contextMenu as HTMLElement, "Edit line")!);
 
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   it("should enter line editor via enter (line)", () => {
     createTwoPointerLinearElement("line");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     mouse.clickAt(midpoint[0], midpoint[1]);
     Keyboard.keyPress(KEYS.ENTER);
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   // ctrl+enter alias (to align with arrows)
   it("should enter line editor via ctrl+enter (line)", () => {
     createTwoPointerLinearElement("line");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     mouse.clickAt(midpoint[0], midpoint[1]);
     Keyboard.withModifierKeys({ ctrl: true }, () => {
       Keyboard.keyPress(KEYS.ENTER);
     });
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   it("should enter line editor via ctrl+enter (arrow)", () => {
     createTwoPointerLinearElement("arrow");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     mouse.clickAt(midpoint[0], midpoint[1]);
     Keyboard.withModifierKeys({ ctrl: true }, () => {
       Keyboard.keyPress(KEYS.ENTER);
     });
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   it("should enter line editor on ctrl+dblclick (simple arrow)", () => {
     createTwoPointerLinearElement("arrow");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     Keyboard.withModifierKeys({ ctrl: true }, () => {
       mouse.doubleClick();
     });
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   it("should enter line editor on ctrl+dblclick (line)", () => {
     createTwoPointerLinearElement("line");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     Keyboard.withModifierKeys({ ctrl: true }, () => {
       mouse.doubleClick();
     });
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   it("should enter line editor on dblclick (line)", () => {
     createTwoPointerLinearElement("line");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     mouse.doubleClick();
-    expect(h.state.editingLinearElement?.elementId).toEqual(h.elements[0].id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(h.elements[0].id);
   });
 
   it("should not enter line editor on dblclick (arrow)", async () => {
     createTwoPointerLinearElement("arrow");
-    expect(h.state.editingLinearElement?.elementId).toBeUndefined();
+    expect(h.state.selectedLinearElement?.isEditing).toBe(false);
 
     mouse.doubleClick();
-    expect(h.state.editingLinearElement).toEqual(null);
+    expect(h.state.selectedLinearElement).toBe(null);
     await getTextEditor();
   });
 
@@ -330,10 +338,12 @@ describe("Test Linear Elements", () => {
     const arrow = h.elements[0] as ExcalidrawLinearElement;
     enterLineEditingMode(arrow);
 
-    expect(h.state.editingLinearElement?.elementId).toEqual(arrow.id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(arrow.id);
 
     mouse.doubleClick();
-    expect(h.state.editingLinearElement?.elementId).toEqual(arrow.id);
+    expect(h.state.selectedLinearElement?.isEditing).toBe(true);
+    expect(h.state.selectedLinearElement?.elementId).toEqual(arrow.id);
     expect(h.elements.length).toEqual(1);
 
     expect(document.querySelector(TEXT_EDITOR_SELECTOR)).toBe(null);
@@ -367,7 +377,7 @@ describe("Test Linear Elements", () => {
       // drag line from midpoint
       drag(midpoint, pointFrom(midpoint[0] + delta, midpoint[1] + delta));
       expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-        `12`,
+        `11`,
       );
       expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`6`);
 
@@ -469,7 +479,7 @@ describe("Test Linear Elements", () => {
       drag(startPoint, endPoint);
 
       expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-        `12`,
+        `11`,
       );
       expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`7`);
 
@@ -537,7 +547,7 @@ describe("Test Linear Elements", () => {
         );
 
         expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-          `16`,
+          `14`,
         );
         expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`7`);
 
@@ -588,7 +598,7 @@ describe("Test Linear Elements", () => {
         drag(hitCoords, pointFrom(hitCoords[0] - delta, hitCoords[1] - delta));
 
         expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-          `12`,
+          `11`,
         );
         expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`6`);
 
@@ -629,7 +639,7 @@ describe("Test Linear Elements", () => {
         drag(hitCoords, pointFrom(hitCoords[0] + delta, hitCoords[1] + delta));
 
         expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-          `12`,
+          `11`,
         );
         expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`6`);
 
@@ -677,7 +687,7 @@ describe("Test Linear Elements", () => {
         deletePoint(points[2]);
         expect(line.points.length).toEqual(3);
         expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-          `18`,
+          `17`,
         );
         expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`7`);
 
@@ -735,7 +745,7 @@ describe("Test Linear Elements", () => {
           ),
         );
         expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-          `16`,
+          `14`,
         );
         expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`7`);
         expect(line.points.length).toEqual(5);
@@ -833,7 +843,7 @@ describe("Test Linear Elements", () => {
         drag(hitCoords, pointFrom(hitCoords[0] + delta, hitCoords[1] + delta));
 
         expect(renderInteractiveScene.mock.calls.length).toMatchInlineSnapshot(
-          `12`,
+          `11`,
         );
         expect(renderStaticScene.mock.calls.length).toMatchInlineSnapshot(`6`);
 

packages/element/tests/textElement.test.ts

@@ -1,13 +1,14 @@
 import { getLineHeight } from "@excalidraw/common";
 import { API } from "@excalidraw/excalidraw/tests/helpers/api";
 
-import { FONT_FAMILY } from "@excalidraw/common";
+import { FONT_FAMILY, TEXT_ALIGN, VERTICAL_ALIGN } from "@excalidraw/common";
 
 import {
   computeContainerDimensionForBoundText,
   getContainerCoords,
   getBoundTextMaxWidth,
   getBoundTextMaxHeight,
+  computeBoundTextPosition,
 } from "../src/textElement";
 import { detectLineHeight, getLineHeightInPx } from "../src/textMeasurements";
 
@@ -207,3 +208,172 @@ describe("Test getDefaultLineHeight", () => {
     expect(getLineHeight(FONT_FAMILY.Cascadia)).toBe(1.2);
   });
 });
+
+describe("Test computeBoundTextPosition", () => {
+  const createMockElementsMap = () => new Map();
+
+  // Helper function to create rectangle test case with 90-degree rotation
+  const createRotatedRectangleTestCase = (
+    textAlign: string,
+    verticalAlign: string,
+  ) => {
+    const container = API.createElement({
+      type: "rectangle",
+      x: 100,
+      y: 100,
+      width: 200,
+      height: 100,
+      angle: (Math.PI / 2) as any, // 90 degrees
+    });
+
+    const boundTextElement = API.createElement({
+      type: "text",
+      width: 80,
+      height: 40,
+      text: "hello darkness my old friend",
+      textAlign: textAlign as any,
+      verticalAlign: verticalAlign as any,
+      containerId: container.id,
+    }) as ExcalidrawTextElementWithContainer;
+
+    const elementsMap = createMockElementsMap();
+
+    return { container, boundTextElement, elementsMap };
+  };
+
+  describe("90-degree rotation with all alignment combinations", () => {
+    // Test all 9 combinations of horizontal (left, center, right) and vertical (top, middle, bottom) alignment
+
+    it("should position text with LEFT + TOP alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.LEFT, VERTICAL_ALIGN.TOP);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(185, 1);
+      expect(result.y).toBeCloseTo(75, 1);
+    });
+
+    it("should position text with LEFT + MIDDLE alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.LEFT, VERTICAL_ALIGN.MIDDLE);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(160, 1);
+      expect(result.y).toBeCloseTo(75, 1);
+    });
+
+    it("should position text with LEFT + BOTTOM alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.LEFT, VERTICAL_ALIGN.BOTTOM);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(135, 1);
+      expect(result.y).toBeCloseTo(75, 1);
+    });
+
+    it("should position text with CENTER + TOP alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.CENTER, VERTICAL_ALIGN.TOP);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(185, 1);
+      expect(result.y).toBeCloseTo(130, 1);
+    });
+
+    it("should position text with CENTER + MIDDLE alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(
+          TEXT_ALIGN.CENTER,
+          VERTICAL_ALIGN.MIDDLE,
+        );
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(160, 1);
+      expect(result.y).toBeCloseTo(130, 1);
+    });
+
+    it("should position text with CENTER + BOTTOM alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(
+          TEXT_ALIGN.CENTER,
+          VERTICAL_ALIGN.BOTTOM,
+        );
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(135, 1);
+      expect(result.y).toBeCloseTo(130, 1);
+    });
+
+    it("should position text with RIGHT + TOP alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.RIGHT, VERTICAL_ALIGN.TOP);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(185, 1);
+      expect(result.y).toBeCloseTo(185, 1);
+    });
+
+    it("should position text with RIGHT + MIDDLE alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.RIGHT, VERTICAL_ALIGN.MIDDLE);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(160, 1);
+      expect(result.y).toBeCloseTo(185, 1);
+    });
+
+    it("should position text with RIGHT + BOTTOM alignment at 90-degree rotation", () => {
+      const { container, boundTextElement, elementsMap } =
+        createRotatedRectangleTestCase(TEXT_ALIGN.RIGHT, VERTICAL_ALIGN.BOTTOM);
+
+      const result = computeBoundTextPosition(
+        container,
+        boundTextElement,
+        elementsMap,
+      );
+
+      expect(result.x).toBeCloseTo(135, 1);
+      expect(result.y).toBeCloseTo(185, 1);
+    });
+  });
+});