1 files changed, 399 insertions, 0 deletions
diff --git a/packages/excalidraw/groups.ts b/packages/excalidraw/groups.ts
new file mode 100644
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--- /dev/null
+++ b/packages/excalidraw/groups.ts
@@ -0,0 +1,399 @@
+import type {
+  GroupId,
+  ExcalidrawElement,
+  NonDeleted,
+  NonDeletedExcalidrawElement,
+  ElementsMapOrArray,
+  ElementsMap,
+} from "./element/types";
+import type {
+  AppClassProperties,
+  AppState,
+  InteractiveCanvasAppState,
+} from "./types";
+import { getSelectedElements } from "./scene";
+import { getBoundTextElement } from "./element/textElement";
+import { makeNextSelectedElementIds } from "./scene/selection";
+import type { Mutable } from "./utility-types";
+
+export const selectGroup = (
+  groupId: GroupId,
+  appState: InteractiveCanvasAppState,
+  elements: readonly NonDeleted<ExcalidrawElement>[],
+): Pick<
+  InteractiveCanvasAppState,
+  "selectedGroupIds" | "selectedElementIds" | "editingGroupId"
+> => {
+  const elementsInGroup = elements.reduce(
+    (acc: Record<string, true>, element) => {
+      if (element.groupIds.includes(groupId)) {
+        acc[element.id] = true;
+      }
+      return acc;
+    },
+    {},
+  );
+
+  if (Object.keys(elementsInGroup).length < 2) {
+    if (
+      appState.selectedGroupIds[groupId] ||
+      appState.editingGroupId === groupId
+    ) {
+      return {
+        selectedElementIds: appState.selectedElementIds,
+        selectedGroupIds: { ...appState.selectedGroupIds, [groupId]: false },
+        editingGroupId: null,
+      };
+    }
+    return appState;
+  }
+
+  return {
+    editingGroupId: appState.editingGroupId,
+    selectedGroupIds: { ...appState.selectedGroupIds, [groupId]: true },
+    selectedElementIds: {
+      ...appState.selectedElementIds,
+      ...elementsInGroup,
+    },
+  };
+};
+
+export const selectGroupsForSelectedElements = (function () {
+  type SelectGroupsReturnType = Pick<
+    InteractiveCanvasAppState,
+    "selectedGroupIds" | "editingGroupId" | "selectedElementIds"
+  >;
+
+  let lastSelectedElements: readonly NonDeleted<ExcalidrawElement>[] | null =
+    null;
+  let lastElements: readonly NonDeleted<ExcalidrawElement>[] | null = null;
+  let lastReturnValue: SelectGroupsReturnType | null = null;
+
+  const _selectGroups = (
+    selectedElements: readonly NonDeleted<ExcalidrawElement>[],
+    elements: readonly NonDeleted<ExcalidrawElement>[],
+    appState: Pick<AppState, "selectedElementIds" | "editingGroupId">,
+    prevAppState: InteractiveCanvasAppState,
+  ): SelectGroupsReturnType => {
+    if (
+      lastReturnValue !== undefined &&
+      elements === lastElements &&
+      selectedElements === lastSelectedElements &&
+      appState.editingGroupId === lastReturnValue?.editingGroupId
+    ) {
+      return lastReturnValue;
+    }
+
+    const selectedGroupIds: Record<GroupId, boolean> = {};
+    // Gather all the groups withing selected elements
+    for (const selectedElement of selectedElements) {
+      let groupIds = selectedElement.groupIds;
+      if (appState.editingGroupId) {
+        // handle the case where a group is nested within a group
+        const indexOfEditingGroup = groupIds.indexOf(appState.editingGroupId);
+        if (indexOfEditingGroup > -1) {
+          groupIds = groupIds.slice(0, indexOfEditingGroup);
+        }
+      }
+      if (groupIds.length > 0) {
+        const lastSelectedGroup = groupIds[groupIds.length - 1];
+        selectedGroupIds[lastSelectedGroup] = true;
+      }
+    }
+
+    // Gather all the elements within selected groups
+    const groupElementsIndex: Record<GroupId, string[]> = {};
+    const selectedElementIdsInGroups = elements.reduce(
+      (acc: Record<string, true>, element) => {
+        if (element.isDeleted) {
+          return acc;
+        }
+
+        const groupId = element.groupIds.find((id) => selectedGroupIds[id]);
+
+        if (groupId) {
+          acc[element.id] = true;
+
+          // Populate the index
+          if (!Array.isArray(groupElementsIndex[groupId])) {
+            groupElementsIndex[groupId] = [element.id];
+          } else {
+            groupElementsIndex[groupId].push(element.id);
+          }
+        }
+        return acc;
+      },
+      {},
+    );
+
+    for (const groupId of Object.keys(groupElementsIndex)) {
+      // If there is one element in the group, and the group is selected or it's being edited, it's not a group
+      if (groupElementsIndex[groupId].length < 2) {
+        if (selectedGroupIds[groupId]) {
+          selectedGroupIds[groupId] = false;
+        }
+      }
+    }
+
+    lastElements = elements;
+    lastSelectedElements = selectedElements;
+
+    lastReturnValue = {
+      editingGroupId: appState.editingGroupId,
+      selectedGroupIds,
+      selectedElementIds: makeNextSelectedElementIds(
+        {
+          ...appState.selectedElementIds,
+          ...selectedElementIdsInGroups,
+        },
+        prevAppState,
+      ),
+    };
+
+    return lastReturnValue;
+  };
+
+  /**
+   * When you select an element, you often want to actually select the whole group it's in, unless
+   * you're currently editing that group.
+   */
+  const selectGroupsForSelectedElements = (
+    appState: Pick<AppState, "selectedElementIds" | "editingGroupId">,
+    elements: readonly NonDeletedExcalidrawElement[],
+    prevAppState: InteractiveCanvasAppState,
+    /**
+     * supply null in cases where you don't have access to App instance and
+     * you don't care about optimizing selectElements retrieval
+     */
+    app: AppClassProperties | null,
+  ): Mutable<
+    Pick<
+      InteractiveCanvasAppState,
+      "selectedGroupIds" | "editingGroupId" | "selectedElementIds"
+    >
+  > => {
+    const selectedElements = app
+      ? app.scene.getSelectedElements({
+          selectedElementIds: appState.selectedElementIds,
+          // supplying elements explicitly in case we're passed non-state elements
+          elements,
+        })
+      : getSelectedElements(elements, appState);
+
+    if (!selectedElements.length) {
+      return {
+        selectedGroupIds: {},
+        editingGroupId: null,
+        selectedElementIds: makeNextSelectedElementIds(
+          appState.selectedElementIds,
+          prevAppState,
+        ),
+      };
+    }
+
+    return _selectGroups(selectedElements, elements, appState, prevAppState);
+  };
+
+  selectGroupsForSelectedElements.clearCache = () => {
+    lastElements = null;
+    lastSelectedElements = null;
+    lastReturnValue = null;
+  };
+
+  return selectGroupsForSelectedElements;
+})();
+
+/**
+ * If the element's group is selected, don't render an individual
+ * selection border around it.
+ */
+export const isSelectedViaGroup = (
+  appState: InteractiveCanvasAppState,
+  element: ExcalidrawElement,
+) => getSelectedGroupForElement(appState, element) != null;
+
+export const getSelectedGroupForElement = (
+  appState: InteractiveCanvasAppState,
+  element: ExcalidrawElement,
+) =>
+  element.groupIds
+    .filter((groupId) => groupId !== appState.editingGroupId)
+    .find((groupId) => appState.selectedGroupIds[groupId]);
+
+export const getSelectedGroupIds = (
+  appState: InteractiveCanvasAppState,
+): GroupId[] =>
+  Object.entries(appState.selectedGroupIds)
+    .filter(([groupId, isSelected]) => isSelected)
+    .map(([groupId, isSelected]) => groupId);
+
+// given a list of elements, return the the actual group ids that should be selected
+// or used to update the elements
+export const selectGroupsFromGivenElements = (
+  elements: readonly NonDeleted<ExcalidrawElement>[],
+  appState: InteractiveCanvasAppState,
+) => {
+  let nextAppState: InteractiveCanvasAppState = {
+    ...appState,
+    selectedGroupIds: {},
+  };
+
+  for (const element of elements) {
+    let groupIds = element.groupIds;
+    if (appState.editingGroupId) {
+      const indexOfEditingGroup = groupIds.indexOf(appState.editingGroupId);
+      if (indexOfEditingGroup > -1) {
+        groupIds = groupIds.slice(0, indexOfEditingGroup);
+      }
+    }
+    if (groupIds.length > 0) {
+      const groupId = groupIds[groupIds.length - 1];
+      nextAppState = {
+        ...nextAppState,
+        ...selectGroup(groupId, nextAppState, elements),
+      };
+    }
+  }
+
+  return nextAppState.selectedGroupIds;
+};
+
+export const editGroupForSelectedElement = (
+  appState: AppState,
+  element: NonDeleted<ExcalidrawElement>,
+): AppState => {
+  return {
+    ...appState,
+    editingGroupId: element.groupIds.length ? element.groupIds[0] : null,
+    selectedGroupIds: {},
+    selectedElementIds: {
+      [element.id]: true,
+    },
+  };
+};
+
+export const isElementInGroup = (element: ExcalidrawElement, groupId: string) =>
+  element.groupIds.includes(groupId);
+
+export const getElementsInGroup = (
+  elements: ElementsMapOrArray,
+  groupId: string,
+) => {
+  const elementsInGroup: ExcalidrawElement[] = [];
+  for (const element of elements.values()) {
+    if (isElementInGroup(element, groupId)) {
+      elementsInGroup.push(element);
+    }
+  }
+  return elementsInGroup;
+};
+
+export const getSelectedGroupIdForElement = (
+  element: ExcalidrawElement,
+  selectedGroupIds: { [groupId: string]: boolean },
+) => element.groupIds.find((groupId) => selectedGroupIds[groupId]);
+
+export const getNewGroupIdsForDuplication = (
+  groupIds: ExcalidrawElement["groupIds"],
+  editingGroupId: AppState["editingGroupId"],
+  mapper: (groupId: GroupId) => GroupId,
+) => {
+  const copy = [...groupIds];
+  const positionOfEditingGroupId = editingGroupId
+    ? groupIds.indexOf(editingGroupId)
+    : -1;
+  const endIndex =
+    positionOfEditingGroupId > -1 ? positionOfEditingGroupId : groupIds.length;
+  for (let index = 0; index < endIndex; index++) {
+    copy[index] = mapper(copy[index]);
+  }
+
+  return copy;
+};
+
+export const addToGroup = (
+  prevGroupIds: ExcalidrawElement["groupIds"],
+  newGroupId: GroupId,
+  editingGroupId: AppState["editingGroupId"],
+) => {
+  // insert before the editingGroupId, or push to the end.
+  const groupIds = [...prevGroupIds];
+  const positionOfEditingGroupId = editingGroupId
+    ? groupIds.indexOf(editingGroupId)
+    : -1;
+  const positionToInsert =
+    positionOfEditingGroupId > -1 ? positionOfEditingGroupId : groupIds.length;
+  groupIds.splice(positionToInsert, 0, newGroupId);
+  return groupIds;
+};
+
+export const removeFromSelectedGroups = (
+  groupIds: ExcalidrawElement["groupIds"],
+  selectedGroupIds: { [groupId: string]: boolean },
+) => groupIds.filter((groupId) => !selectedGroupIds[groupId]);
+
+export const getMaximumGroups = (
+  elements: ExcalidrawElement[],
+  elementsMap: ElementsMap,
+): ExcalidrawElement[][] => {
+  const groups: Map<String, ExcalidrawElement[]> = new Map<
+    String,
+    ExcalidrawElement[]
+  >();
+  elements.forEach((element: ExcalidrawElement) => {
+    const groupId =
+      element.groupIds.length === 0
+        ? element.id
+        : element.groupIds[element.groupIds.length - 1];
+
+    const currentGroupMembers = groups.get(groupId) || [];
+
+    // Include bound text if present when grouping
+    const boundTextElement = getBoundTextElement(element, elementsMap);
+    if (boundTextElement) {
+      currentGroupMembers.push(boundTextElement);
+    }
+    groups.set(groupId, [...currentGroupMembers, element]);
+  });
+
+  return Array.from(groups.values());
+};
+
+export const getNonDeletedGroupIds = (elements: ElementsMap) => {
+  const nonDeletedGroupIds = new Set<string>();
+
+  for (const [, element] of elements) {
+    // defensive check
+    if (element.isDeleted) {
+      continue;
+    }
+
+    // defensive fallback
+    for (const groupId of element.groupIds ?? []) {
+      nonDeletedGroupIds.add(groupId);
+    }
+  }
+
+  return nonDeletedGroupIds;
+};
+
+export const elementsAreInSameGroup = (
+  elements: readonly ExcalidrawElement[],
+) => {
+  const allGroups = elements.flatMap((element) => element.groupIds);
+  const groupCount = new Map<string, number>();
+  let maxGroup = 0;
+
+  for (const group of allGroups) {
+    groupCount.set(group, (groupCount.get(group) ?? 0) + 1);
+    if (groupCount.get(group)! > maxGroup) {
+      maxGroup = groupCount.get(group)!;
+    }
+  }
+
+  return maxGroup === elements.length;
+};
+
+export const isInGroup = (element: NonDeletedExcalidrawElement) => {
+  return element.groupIds.length > 0;
+};