refactor: separate elements logic into a standalone package (#9285)

packages/element/src/duplicate.ts

@@ -0,0 +1,485 @@
+import {
+  ORIG_ID,
+  randomId,
+  randomInteger,
+  arrayToMap,
+  castArray,
+  findLastIndex,
+  getUpdatedTimestamp,
+  isTestEnv,
+} from "@excalidraw/common";
+
+import type { Mutable } from "@excalidraw/common/utility-types";
+
+import type { AppState } from "@excalidraw/excalidraw/types";
+
+import {
+  getElementsInGroup,
+  getNewGroupIdsForDuplication,
+  getSelectedGroupForElement,
+} from "./groups";
+
+import {
+  bindElementsToFramesAfterDuplication,
+  getFrameChildren,
+} from "./frame";
+
+import { normalizeElementOrder } from "./sortElements";
+
+import { bumpVersion } from "./mutateElement";
+
+import {
+  hasBoundTextElement,
+  isBoundToContainer,
+  isFrameLikeElement,
+} from "./typeChecks";
+
+import { getBoundTextElement, getContainerElement } from "./textElement";
+
+import { fixBindingsAfterDuplication } from "./binding";
+
+import type {
+  ElementsMap,
+  ExcalidrawElement,
+  GroupId,
+  NonDeletedSceneElementsMap,
+} from "./types";
+
+/**
+ * Duplicate an element, often used in the alt-drag operation.
+ * Note that this method has gotten a bit complicated since the
+ * introduction of gruoping/ungrouping elements.
+ * @param editingGroupId The current group being edited. The new
+ *                       element will inherit this group and its
+ *                       parents.
+ * @param groupIdMapForOperation A Map that maps old group IDs to
+ *                               duplicated ones. If you are duplicating
+ *                               multiple elements at once, share this map
+ *                               amongst all of them
+ * @param element Element to duplicate
+ * @param overrides Any element properties to override
+ */
+export const duplicateElement = <TElement extends ExcalidrawElement>(
+  editingGroupId: AppState["editingGroupId"],
+  groupIdMapForOperation: Map<GroupId, GroupId>,
+  element: TElement,
+  overrides?: Partial<TElement>,
+  randomizeSeed?: boolean,
+): Readonly<TElement> => {
+  let copy = deepCopyElement(element);
+
+  if (isTestEnv()) {
+    __test__defineOrigId(copy, element.id);
+  }
+
+  copy.id = randomId();
+  copy.updated = getUpdatedTimestamp();
+  if (randomizeSeed) {
+    copy.seed = randomInteger();
+    bumpVersion(copy);
+  }
+
+  copy.groupIds = getNewGroupIdsForDuplication(
+    copy.groupIds,
+    editingGroupId,
+    (groupId) => {
+      if (!groupIdMapForOperation.has(groupId)) {
+        groupIdMapForOperation.set(groupId, randomId());
+      }
+      return groupIdMapForOperation.get(groupId)!;
+    },
+  );
+  if (overrides) {
+    copy = Object.assign(copy, overrides);
+  }
+  return copy;
+};
+
+export const duplicateElements = (
+  opts: {
+    elements: readonly ExcalidrawElement[];
+    randomizeSeed?: boolean;
+    overrides?: (
+      originalElement: ExcalidrawElement,
+    ) => Partial<ExcalidrawElement>;
+  } & (
+    | {
+        /**
+         * Duplicates all elements in array.
+         *
+         * Use this when programmaticaly duplicating elements, without direct
+         * user interaction.
+         */
+        type: "everything";
+      }
+    | {
+        /**
+         * Duplicates specified elements and inserts them back into the array
+         * in specified order.
+         *
+         * Use this when duplicating Scene elements, during user interaction
+         * such as alt-drag or on duplicate action.
+         */
+        type: "in-place";
+        idsOfElementsToDuplicate: Map<
+          ExcalidrawElement["id"],
+          ExcalidrawElement
+        >;
+        appState: {
+          editingGroupId: AppState["editingGroupId"];
+          selectedGroupIds: AppState["selectedGroupIds"];
+        };
+        /**
+         * If true, duplicated elements are inserted _before_ specified
+         * elements. Case: alt-dragging elements to duplicate them.
+         *
+         * TODO: remove this once (if) we stop replacing the original element
+         * with the duplicated one in the scene array.
+         */
+        reverseOrder: boolean;
+      }
+  ),
+) => {
+  let { elements } = opts;
+
+  const appState =
+    "appState" in opts
+      ? opts.appState
+      : ({
+          editingGroupId: null,
+          selectedGroupIds: {},
+        } as const);
+
+  const reverseOrder = opts.type === "in-place" ? opts.reverseOrder : false;
+
+  // Ids of elements that have already been processed so we don't push them
+  // into the array twice if we end up backtracking when retrieving
+  // discontiguous group of elements (can happen due to a bug, or in edge
+  // cases such as a group containing deleted elements which were not selected).
+  //
+  // This is not enough to prevent duplicates, so we do a second loop afterwards
+  // to remove them.
+  //
+  // For convenience we mark even the newly created ones even though we don't
+  // loop over them.
+  const processedIds = new Map<ExcalidrawElement["id"], true>();
+  const groupIdMap = new Map();
+  const newElements: ExcalidrawElement[] = [];
+  const oldElements: ExcalidrawElement[] = [];
+  const oldIdToDuplicatedId = new Map();
+  const duplicatedElementsMap = new Map<string, ExcalidrawElement>();
+  const elementsMap = arrayToMap(elements) as ElementsMap;
+  const _idsOfElementsToDuplicate =
+    opts.type === "in-place"
+      ? opts.idsOfElementsToDuplicate
+      : new Map(elements.map((el) => [el.id, el]));
+
+  // For sanity
+  if (opts.type === "in-place") {
+    for (const groupId of Object.keys(opts.appState.selectedGroupIds)) {
+      elements
+        .filter((el) => el.groupIds?.includes(groupId))
+        .forEach((el) => _idsOfElementsToDuplicate.set(el.id, el));
+    }
+  }
+
+  elements = normalizeElementOrder(elements);
+
+  const elementsWithClones: ExcalidrawElement[] = elements.slice();
+
+  // helper functions
+  // -------------------------------------------------------------------------
+
+  // Used for the heavy lifing of copying a single element, a group of elements
+  // an element with bound text etc.
+  const copyElements = <T extends ExcalidrawElement | ExcalidrawElement[]>(
+    element: T,
+  ): T extends ExcalidrawElement[]
+    ? ExcalidrawElement[]
+    : ExcalidrawElement | null => {
+    const elements = castArray(element);
+
+    const _newElements = elements.reduce(
+      (acc: ExcalidrawElement[], element) => {
+        if (processedIds.has(element.id)) {
+          return acc;
+        }
+
+        processedIds.set(element.id, true);
+
+        const newElement = duplicateElement(
+          appState.editingGroupId,
+          groupIdMap,
+          element,
+          opts.overrides?.(element),
+          opts.randomizeSeed,
+        );
+
+        processedIds.set(newElement.id, true);
+
+        duplicatedElementsMap.set(newElement.id, newElement);
+        oldIdToDuplicatedId.set(element.id, newElement.id);
+
+        oldElements.push(element);
+        newElements.push(newElement);
+
+        acc.push(newElement);
+        return acc;
+      },
+      [],
+    );
+
+    return (
+      Array.isArray(element) ? _newElements : _newElements[0] || null
+    ) as T extends ExcalidrawElement[]
+      ? ExcalidrawElement[]
+      : ExcalidrawElement | null;
+  };
+
+  // Helper to position cloned elements in the Z-order the product needs it
+  const insertBeforeOrAfterIndex = (
+    index: number,
+    elements: ExcalidrawElement | null | ExcalidrawElement[],
+  ) => {
+    if (!elements) {
+      return;
+    }
+
+    if (reverseOrder && index < 1) {
+      elementsWithClones.unshift(...castArray(elements));
+      return;
+    }
+
+    if (!reverseOrder && index > elementsWithClones.length - 1) {
+      elementsWithClones.push(...castArray(elements));
+      return;
+    }
+
+    elementsWithClones.splice(
+      index + (reverseOrder ? 0 : 1),
+      0,
+      ...castArray(elements),
+    );
+  };
+
+  const frameIdsToDuplicate = new Set(
+    elements
+      .filter(
+        (el) => _idsOfElementsToDuplicate.has(el.id) && isFrameLikeElement(el),
+      )
+      .map((el) => el.id),
+  );
+
+  for (const element of elements) {
+    if (processedIds.has(element.id)) {
+      continue;
+    }
+
+    if (!_idsOfElementsToDuplicate.has(element.id)) {
+      continue;
+    }
+
+    // groups
+    // -------------------------------------------------------------------------
+
+    const groupId = getSelectedGroupForElement(appState, element);
+    if (groupId) {
+      const groupElements = getElementsInGroup(elements, groupId).flatMap(
+        (element) =>
+          isFrameLikeElement(element)
+            ? [...getFrameChildren(elements, element.id), element]
+            : [element],
+      );
+
+      const targetIndex = reverseOrder
+        ? elementsWithClones.findIndex((el) => {
+            return el.groupIds?.includes(groupId);
+          })
+        : findLastIndex(elementsWithClones, (el) => {
+            return el.groupIds?.includes(groupId);
+          });
+
+      insertBeforeOrAfterIndex(targetIndex, copyElements(groupElements));
+      continue;
+    }
+
+    // frame duplication
+    // -------------------------------------------------------------------------
+
+    if (element.frameId && frameIdsToDuplicate.has(element.frameId)) {
+      continue;
+    }
+
+    if (isFrameLikeElement(element)) {
+      const frameId = element.id;
+
+      const frameChildren = getFrameChildren(elements, frameId);
+
+      const targetIndex = findLastIndex(elementsWithClones, (el) => {
+        return el.frameId === frameId || el.id === frameId;
+      });
+
+      insertBeforeOrAfterIndex(
+        targetIndex,
+        copyElements([...frameChildren, element]),
+      );
+      continue;
+    }
+
+    // text container
+    // -------------------------------------------------------------------------
+
+    if (hasBoundTextElement(element)) {
+      const boundTextElement = getBoundTextElement(element, elementsMap);
+
+      const targetIndex = findLastIndex(elementsWithClones, (el) => {
+        return (
+          el.id === element.id ||
+          ("containerId" in el && el.containerId === element.id)
+        );
+      });
+
+      if (boundTextElement) {
+        insertBeforeOrAfterIndex(
+          targetIndex + (reverseOrder ? -1 : 0),
+          copyElements([element, boundTextElement]),
+        );
+      } else {
+        insertBeforeOrAfterIndex(targetIndex, copyElements(element));
+      }
+
+      continue;
+    }
+
+    if (isBoundToContainer(element)) {
+      const container = getContainerElement(element, elementsMap);
+
+      const targetIndex = findLastIndex(elementsWithClones, (el) => {
+        return el.id === element.id || el.id === container?.id;
+      });
+
+      if (container) {
+        insertBeforeOrAfterIndex(
+          targetIndex,
+          copyElements([container, element]),
+        );
+      } else {
+        insertBeforeOrAfterIndex(targetIndex, copyElements(element));
+      }
+
+      continue;
+    }
+
+    // default duplication (regular elements)
+    // -------------------------------------------------------------------------
+
+    insertBeforeOrAfterIndex(
+      findLastIndex(elementsWithClones, (el) => el.id === element.id),
+      copyElements(element),
+    );
+  }
+
+  // ---------------------------------------------------------------------------
+
+  fixBindingsAfterDuplication(
+    newElements,
+    oldIdToDuplicatedId,
+    duplicatedElementsMap as NonDeletedSceneElementsMap,
+  );
+
+  bindElementsToFramesAfterDuplication(
+    elementsWithClones,
+    oldElements,
+    oldIdToDuplicatedId,
+  );
+
+  return {
+    newElements,
+    elementsWithClones,
+  };
+};
+
+// Simplified deep clone for the purpose of cloning ExcalidrawElement.
+//
+// Only clones plain objects and arrays. Doesn't clone Date, RegExp, Map, Set,
+// Typed arrays and other non-null objects.
+//
+// Adapted from https://github.com/lukeed/klona
+//
+// The reason for `deepCopyElement()` wrapper is type safety (only allow
+// passing ExcalidrawElement as the top-level argument).
+const _deepCopyElement = (val: any, depth: number = 0) => {
+  // only clone non-primitives
+  if (val == null || typeof val !== "object") {
+    return val;
+  }
+
+  const objectType = Object.prototype.toString.call(val);
+
+  if (objectType === "[object Object]") {
+    const tmp =
+      typeof val.constructor === "function"
+        ? Object.create(Object.getPrototypeOf(val))
+        : {};
+    for (const key in val) {
+      if (val.hasOwnProperty(key)) {
+        // don't copy non-serializable objects like these caches. They'll be
+        // populated when the element is rendered.
+        if (depth === 0 && (key === "shape" || key === "canvas")) {
+          continue;
+        }
+        tmp[key] = _deepCopyElement(val[key], depth + 1);
+      }
+    }
+    return tmp;
+  }
+
+  if (Array.isArray(val)) {
+    let k = val.length;
+    const arr = new Array(k);
+    while (k--) {
+      arr[k] = _deepCopyElement(val[k], depth + 1);
+    }
+    return arr;
+  }
+
+  // we're not cloning non-array & non-plain-object objects because we
+  // don't support them on excalidraw elements yet. If we do, we need to make
+  // sure we start cloning them, so let's warn about it.
+  if (import.meta.env.DEV) {
+    if (
+      objectType !== "[object Object]" &&
+      objectType !== "[object Array]" &&
+      objectType.startsWith("[object ")
+    ) {
+      console.warn(
+        `_deepCloneElement: unexpected object type ${objectType}. This value will not be cloned!`,
+      );
+    }
+  }
+
+  return val;
+};
+
+/**
+ * Clones ExcalidrawElement data structure. Does not regenerate id, nonce, or
+ * any value. The purpose is to to break object references for immutability
+ * reasons, whenever we want to keep the original element, but ensure it's not
+ * mutated.
+ *
+ * Only clones plain objects and arrays. Doesn't clone Date, RegExp, Map, Set,
+ * Typed arrays and other non-null objects.
+ */
+export const deepCopyElement = <T extends ExcalidrawElement>(
+  val: T,
+): Mutable<T> => {
+  return _deepCopyElement(val);
+};
+
+const __test__defineOrigId = (clonedObj: object, origId: string) => {
+  Object.defineProperty(clonedObj, ORIG_ID, {
+    value: origId,
+    writable: false,
+    enumerable: false,
+  });
+};