excalidraw/src/components/App.tsx

import React from "react";

import rough from "roughjs/bin/rough";
import { RoughCanvas } from "roughjs/bin/canvas";
import { simplify, Point } from "points-on-curve";
import { SocketUpdateData } from "../types";

import {
  newElement,
  newTextElement,
  duplicateElement,
  isInvisiblySmallElement,
  isTextElement,
  textWysiwyg,
  getCommonBounds,
  getCursorForResizingElement,
  getPerfectElementSize,
  getNormalizedDimensions,
  getElementMap,
  getDrawingVersion,
  getSyncableElements,
  newLinearElement,
  resizeElements,
  getElementWithTransformHandleType,
  getResizeOffsetXY,
  getResizeArrowDirection,
  getTransformHandleTypeFromCoords,
  isNonDeletedElement,
  updateTextElement,
  dragSelectedElements,
  getDragOffsetXY,
  dragNewElement,
  hitTest,
  isHittingElementBoundingBoxWithoutHittingElement,
} from "../element";
import {
  getElementsWithinSelection,
  isOverScrollBars,
  getElementsAtPosition,
  getElementContainingPosition,
  getNormalizedZoom,
  getSelectedElements,
  isSomeElementSelected,
  calculateScrollCenter,
} from "../scene";
import {
  decryptAESGEM,
  loadScene,
  loadFromBlob,
  SOCKET_SERVER,
  SocketUpdateDataSource,
  exportCanvas,
} from "../data";
import Portal from "./Portal";

import { renderScene } from "../renderer";
import { AppState, GestureEvent, Gesture, ExcalidrawProps } from "../types";
import {
  ExcalidrawElement,
  ExcalidrawTextElement,
  NonDeleted,
  ExcalidrawGenericElement,
  ExcalidrawLinearElement,
  ExcalidrawBindableElement,
} from "../element/types";

import { distance2d, isPathALoop, getGridPoint } from "../math";

import {
  isWritableElement,
  isInputLike,
  isToolIcon,
  debounce,
  distance,
  resetCursor,
  viewportCoordsToSceneCoords,
  sceneCoordsToViewportCoords,
  setCursorForShape,
  tupleToCoors,
} from "../utils";
import {
  KEYS,
  isArrowKey,
  getResizeCenterPointKey,
  getResizeWithSidesSameLengthKey,
  getRotateWithDiscreteAngleKey,
} from "../keys";

import { findShapeByKey } from "../shapes";
import { createHistory, SceneHistory } from "../history";

import ContextMenu from "./ContextMenu";

import { ActionManager } from "../actions/manager";
import "../actions";
import { actions } from "../actions/register";

import { ActionResult } from "../actions/types";
import { getDefaultAppState } from "../appState";
import { t, getLanguage } from "../i18n";

import {
  copyToAppClipboard,
  getClipboardContent,
  probablySupportsClipboardBlob,
  probablySupportsClipboardWriteText,
} from "../clipboard";
import { normalizeScroll } from "../scene";
import { getCenter, getDistance } from "../gesture";
import { createUndoAction, createRedoAction } from "../actions/actionHistory";

import {
  CURSOR_TYPE,
  ELEMENT_SHIFT_TRANSLATE_AMOUNT,
  ELEMENT_TRANSLATE_AMOUNT,
  POINTER_BUTTON,
  DRAGGING_THRESHOLD,
  TEXT_TO_CENTER_SNAP_THRESHOLD,
  LINE_CONFIRM_THRESHOLD,
  SCENE,
  EVENT,
  ENV,
  CANVAS_ONLY_ACTIONS,
  DEFAULT_VERTICAL_ALIGN,
  GRID_SIZE,
  LOCAL_STORAGE_KEY_COLLAB_FORCE_FLAG,
} from "../constants";
import {
  INITIAL_SCENE_UPDATE_TIMEOUT,
  TAP_TWICE_TIMEOUT,
  SYNC_FULL_SCENE_INTERVAL_MS,
  TOUCH_CTX_MENU_TIMEOUT,
} from "../time_constants";

import LayerUI from "./LayerUI";
import { ScrollBars, SceneState } from "../scene/types";
import { generateCollaborationLink, getCollaborationLinkData } from "../data";
import { mutateElement, newElementWith } from "../element/mutateElement";
import { invalidateShapeForElement } from "../renderer/renderElement";
import { unstable_batchedUpdates } from "react-dom";
import {
  isLinearElement,
  isLinearElementType,
  isBindingElement,
  isBindingElementType,
  isBindableElement,
} from "../element/typeChecks";
import { actionFinalize, actionDeleteSelected } from "../actions";
import { loadLibrary } from "../data/localStorage";

import throttle from "lodash.throttle";
import { LinearElementEditor } from "../element/linearElementEditor";
import {
  getSelectedGroupIds,
  isSelectedViaGroup,
  selectGroupsForSelectedElements,
  isElementInGroup,
  getSelectedGroupIdForElement,
  getElementsInGroup,
} from "../groups";
import { Library } from "../data/library";
import Scene from "../scene/Scene";
import {
  getHoveredElementForBinding,
  maybeBindLinearElement,
  getEligibleElementsForBinding,
  bindOrUnbindSelectedElements,
  unbindLinearElements,
  fixBindingsAfterDuplication,
  maybeBindBindableElement,
  getElligibleElementForBindingElementAtCoors,
  fixBindingsAfterDeletion,
  isLinearElementSimpleAndAlreadyBound,
  isBindingEnabled,
} from "../element/binding";
import { MaybeTransformHandleType } from "../element/transformHandles";

/**
 * @param func handler taking at most single parameter (event).
 */
const withBatchedUpdates = <
  TFunction extends ((event: any) => void) | (() => void)
>(
  func: Parameters<TFunction>["length"] extends 0 | 1 ? TFunction : never,
) =>
  ((event) => {
    unstable_batchedUpdates(func as TFunction, event);
  }) as TFunction;

const { history } = createHistory();

let didTapTwice: boolean = false;
let tappedTwiceTimer = 0;
let cursorX = 0;
let cursorY = 0;
let isHoldingSpace: boolean = false;
let isPanning: boolean = false;
let isDraggingScrollBar: boolean = false;
let currentScrollBars: ScrollBars = { horizontal: null, vertical: null };
let touchTimeout = 0;
let touchMoving = false;

let lastPointerUp: ((event: any) => void) | null = null;
const gesture: Gesture = {
  pointers: new Map(),
  lastCenter: null,
  initialDistance: null,
  initialScale: null,
};

type PointerDownState = Readonly<{
  // The first position at which pointerDown happened
  origin: Readonly<{ x: number; y: number }>;
  // Same as "origin" but snapped to the grid, if grid is on
  originInGrid: Readonly<{ x: number; y: number }>;
  // Scrollbar checks
  scrollbars: ReturnType<typeof isOverScrollBars>;
  // The previous pointer position
  lastCoords: { x: number; y: number };
  resize: {
    // Handle when resizing, might change during the pointer interaction
    handleType: MaybeTransformHandleType;
    // This is determined on the initial pointer down event
    isResizing: boolean;
    // This is determined on the initial pointer down event
    offset: { x: number; y: number };
    // This is determined on the initial pointer down event
    arrowDirection: "origin" | "end";
    // This is a center point of selected elements determined on the initial pointer down event (for rotation only)
    center: { x: number; y: number };
    // This is a list of selected elements determined on the initial pointer down event (for rotation only)
    originalElements: readonly NonDeleted<ExcalidrawElement>[];
  };
  hit: {
    // The element the pointer is "hitting", is determined on the initial
    // pointer down event
    element: NonDeleted<ExcalidrawElement> | null;
    // The elements the pointer is "hitting", is determined on the initial
    // pointer down event
    allHitElements: NonDeleted<ExcalidrawElement>[];
    // This is determined on the initial pointer down event
    wasAddedToSelection: boolean;
    // Whether selected element(s) were duplicated, might change during the
    // pointer interaction
    hasBeenDuplicated: boolean;
    hasHitCommonBoundingBoxOfSelectedElements: boolean;
  };
  drag: {
    // Might change during the pointer interation
    hasOccurred: boolean;
    // Might change during the pointer interation
    offset: { x: number; y: number } | null;
  };
  // We need to have these in the state so that we can unsubscribe them
  eventListeners: {
    // It's defined on the initial pointer down event
    onMove: null | ((event: PointerEvent) => void);
    // It's defined on the initial pointer down event
    onUp: null | ((event: PointerEvent) => void);
  };
}>;

class App extends React.Component<ExcalidrawProps, AppState> {
  canvas: HTMLCanvasElement | null = null;
  rc: RoughCanvas | null = null;
  portal: Portal = new Portal(this);
  lastBroadcastedOrReceivedSceneVersion: number = -1;
  broadcastedElementVersions: Map<string, number> = new Map();
  unmounted: boolean = false;
  actionManager: ActionManager;
  private excalidrawRef: any;

  public static defaultProps: Partial<ExcalidrawProps> = {
    width: window.innerWidth,
    height: window.innerHeight,
  };
  private scene: Scene;

  constructor(props: ExcalidrawProps) {
    super(props);
    const defaultAppState = getDefaultAppState();

    const { width, height, user } = props;
    this.state = {
      ...defaultAppState,
      isLoading: true,
      width,
      height,
      username: user?.name || "",
      ...this.getCanvasOffsets(),
    };

    this.scene = new Scene();
    this.excalidrawRef = React.createRef();
    this.actionManager = new ActionManager(
      this.syncActionResult,
      () => this.state,
      () => this.scene.getElementsIncludingDeleted(),
    );
    this.actionManager.registerAll(actions);

    this.actionManager.registerAction(createUndoAction(history));
    this.actionManager.registerAction(createRedoAction(history));
  }

  public render() {
    const {
      zenModeEnabled,
      width: canvasDOMWidth,
      height: canvasDOMHeight,
      offsetTop,
      offsetLeft,
    } = this.state;

    const { onUsernameChange } = this.props;
    const canvasScale = window.devicePixelRatio;

    const canvasWidth = canvasDOMWidth * canvasScale;
    const canvasHeight = canvasDOMHeight * canvasScale;

    return (
      <div
        className="excalidraw"
        ref={this.excalidrawRef}
        style={{
          width: canvasDOMWidth,
          height: canvasDOMHeight,
          top: offsetTop,
          left: offsetLeft,
        }}
      >
        <LayerUI
          canvas={this.canvas}
          appState={this.state}
          setAppState={this.setAppState}
          actionManager={this.actionManager}
          elements={this.scene.getElements()}
          onRoomCreate={this.openPortal}
          onRoomDestroy={this.closePortal}
          onUsernameChange={(username) => {
            onUsernameChange && onUsernameChange(username);
            this.setState({ username });
          }}
          onLockToggle={this.toggleLock}
          onInsertShape={(elements) =>
            this.addElementsFromPasteOrLibrary(elements)
          }
          zenModeEnabled={zenModeEnabled}
          toggleZenMode={this.toggleZenMode}
          lng={getLanguage().lng}
        />
        <main>
          <canvas
            id="canvas"
            style={{
              width: canvasDOMWidth,
              height: canvasDOMHeight,
            }}
            width={canvasWidth}
            height={canvasHeight}
            ref={this.handleCanvasRef}
            onContextMenu={this.handleCanvasContextMenu}
            onPointerDown={this.handleCanvasPointerDown}
            onDoubleClick={this.handleCanvasDoubleClick}
            onPointerMove={this.handleCanvasPointerMove}
            onPointerUp={this.removePointer}
            onPointerCancel={this.removePointer}
            onTouchMove={this.handleTouchMove}
            onDrop={this.handleCanvasOnDrop}
          >
            {t("labels.drawingCanvas")}
          </canvas>
        </main>
      </div>
    );
  }

  private syncActionResult = withBatchedUpdates(
    (actionResult: ActionResult) => {
      if (this.unmounted || actionResult === false) {
        return;
      }

      let editingElement: AppState["editingElement"] | null = null;
      if (actionResult.elements) {
        actionResult.elements.forEach((element) => {
          if (
            this.state.editingElement?.id === element.id &&
            this.state.editingElement !== element &&
            isNonDeletedElement(element)
          ) {
            editingElement = element;
          }
        });
        this.scene.replaceAllElements(actionResult.elements);
        if (actionResult.commitToHistory) {
          history.resumeRecording();
        }
      }

      if (actionResult.appState || editingElement) {
        if (actionResult.commitToHistory) {
          history.resumeRecording();
        }
        this.setState(
          (state) => ({
            ...actionResult.appState,
            editingElement:
              editingElement || actionResult.appState?.editingElement || null,
            isCollaborating: state.isCollaborating,
            collaborators: state.collaborators,
            width: state.width,
            height: state.height,
            offsetTop: state.offsetTop,
            offsetLeft: state.offsetLeft,
          }),
          () => {
            if (actionResult.syncHistory) {
              history.setCurrentState(
                this.state,
                this.scene.getElementsIncludingDeleted(),
              );
            }
          },
        );
      }
    },
  );

  // Lifecycle

  private onBlur = withBatchedUpdates(() => {
    isHoldingSpace = false;
    this.setState({ isBindingEnabled: true });
  });

  private onUnload = () => {
    this.destroySocketClient();
    this.onBlur();
  };

  private disableEvent: EventHandlerNonNull = (event) => {
    event.preventDefault();
  };

  private onFontLoaded = () => {
    this.scene.getElementsIncludingDeleted().forEach((element) => {
      if (isTextElement(element)) {
        invalidateShapeForElement(element);
      }
    });
    this.onSceneUpdated();
  };

  private shouldForceLoadScene(
    scene: ResolutionType<typeof loadScene>,
  ): boolean {
    if (!scene.elements.length) {
      return true;
    }

    const roomMatch = getCollaborationLinkData(window.location.href);

    if (!roomMatch) {
      return false;
    }

    let collabForceLoadFlag;
    try {
      collabForceLoadFlag = localStorage?.getItem(
        LOCAL_STORAGE_KEY_COLLAB_FORCE_FLAG,
      );
    } catch {}

    if (collabForceLoadFlag) {
      try {
        const {
          room: previousRoom,
          timestamp,
        }: { room: string; timestamp: number } = JSON.parse(
          collabForceLoadFlag,
        );
        // if loading same room as the one previously unloaded within 15sec
        //  force reload without prompting
        if (previousRoom === roomMatch[1] && Date.now() - timestamp < 15000) {
          return true;
        }
      } catch {}
    }
    return false;
  }

  private initializeScene = async () => {
    const searchParams = new URLSearchParams(window.location.search);
    const id = searchParams.get("id");
    const jsonMatch = window.location.hash.match(
      /^#json=([0-9]+),([a-zA-Z0-9_-]+)$/,
    );

    if (!this.state.isLoading) {
      this.setState({ isLoading: true });
    }

    let scene = await loadScene(null, null, this.props.initialData);

    let isCollaborationScene = !!getCollaborationLinkData(window.location.href);
    const isExternalScene = !!(id || jsonMatch || isCollaborationScene);

    if (isExternalScene) {
      if (
        this.shouldForceLoadScene(scene) ||
        window.confirm(t("alerts.loadSceneOverridePrompt"))
      ) {
        // Backwards compatibility with legacy url format
        if (id) {
          scene = await loadScene(id);
        } else if (jsonMatch) {
          scene = await loadScene(jsonMatch[1], jsonMatch[2]);
        }
        if (!isCollaborationScene) {
          window.history.replaceState({}, "Excalidraw", window.location.origin);
        }
      } else {
        // https://github.com/excalidraw/excalidraw/issues/1919
        if (document.hidden) {
          window.addEventListener("focus", () => this.initializeScene(), {
            once: true,
          });
          return;
        }

        isCollaborationScene = false;
        window.history.replaceState({}, "Excalidraw", window.location.origin);
      }
    }

    if (this.state.isLoading) {
      this.setState({ isLoading: false });
    }

    if (isCollaborationScene) {
      this.initializeSocketClient({ showLoadingState: true });
    } else if (scene) {
      if (scene.appState) {
        scene.appState = {
          ...scene.appState,
          ...calculateScrollCenter(
            scene.elements,
            {
              ...scene.appState,
              offsetTop: this.state.offsetTop,
              offsetLeft: this.state.offsetLeft,
            },
            null,
          ),
        };
      }
      this.syncActionResult(scene);
    }
  };

  public async componentDidMount() {
    if (
      process.env.NODE_ENV === ENV.TEST ||
      process.env.NODE_ENV === ENV.DEVELOPMENT
    ) {
      const setState = this.setState.bind(this);
      Object.defineProperties(window.h, {
        state: {
          configurable: true,
          get: () => {
            return this.state;
          },
        },
        setState: {
          configurable: true,
          value: (...args: Parameters<typeof setState>) => {
            return this.setState(...args);
          },
        },
        app: {
          configurable: true,
          value: this,
        },
      });
    }

    this.scene.addCallback(this.onSceneUpdated);

    this.addEventListeners();
    this.setState(this.getCanvasOffsets(), () => {
      this.initializeScene();
    });
  }

  public componentWillUnmount() {
    this.unmounted = true;
    this.removeEventListeners();
    this.scene.destroy();
    clearTimeout(touchTimeout);
  }

  private onResize = withBatchedUpdates(() => {
    this.scene
      .getElementsIncludingDeleted()
      .forEach((element) => invalidateShapeForElement(element));
    this.setState({});
  });

  private onHashChange = (event: HashChangeEvent) => {
    if (window.location.hash.length > 1) {
      this.initializeScene();
    }
  };

  private removeEventListeners() {
    document.removeEventListener(EVENT.COPY, this.onCopy);
    document.removeEventListener(EVENT.PASTE, this.pasteFromClipboard);
    document.removeEventListener(EVENT.CUT, this.onCut);

    document.removeEventListener(EVENT.KEYDOWN, this.onKeyDown, false);
    document.removeEventListener(
      EVENT.MOUSE_MOVE,
      this.updateCurrentCursorPosition,
      false,
    );
    document.removeEventListener(EVENT.KEYUP, this.onKeyUp);
    window.removeEventListener(EVENT.RESIZE, this.onResize, false);
    window.removeEventListener(EVENT.UNLOAD, this.onUnload, false);
    window.removeEventListener(EVENT.BLUR, this.onBlur, false);
    window.removeEventListener(EVENT.DRAG_OVER, this.disableEvent, false);
    window.removeEventListener(EVENT.DROP, this.disableEvent, false);
    window.removeEventListener(EVENT.HASHCHANGE, this.onHashChange, false);

    document.removeEventListener(
      EVENT.GESTURE_START,
      this.onGestureStart as any,
      false,
    );
    document.removeEventListener(
      EVENT.GESTURE_CHANGE,
      this.onGestureChange as any,
      false,
    );
    document.removeEventListener(
      EVENT.GESTURE_END,
      this.onGestureEnd as any,
      false,
    );
    window.removeEventListener(EVENT.BEFORE_UNLOAD, this.beforeUnload);
  }

  private addEventListeners() {
    document.addEventListener(EVENT.COPY, this.onCopy);
    document.addEventListener(EVENT.PASTE, this.pasteFromClipboard);
    document.addEventListener(EVENT.CUT, this.onCut);

    document.addEventListener(EVENT.KEYDOWN, this.onKeyDown, false);
    document.addEventListener(EVENT.KEYUP, this.onKeyUp, { passive: true });
    document.addEventListener(
      EVENT.MOUSE_MOVE,
      this.updateCurrentCursorPosition,
    );
    window.addEventListener(EVENT.RESIZE, this.onResize, false);
    window.addEventListener(EVENT.UNLOAD, this.onUnload, false);
    window.addEventListener(EVENT.BLUR, this.onBlur, false);
    window.addEventListener(EVENT.DRAG_OVER, this.disableEvent, false);
    window.addEventListener(EVENT.DROP, this.disableEvent, false);
    window.addEventListener(EVENT.HASHCHANGE, this.onHashChange, false);

    // rerender text elements on font load to fix #637 && #1553
    document.fonts?.addEventListener?.("loadingdone", this.onFontLoaded);

    // Safari-only desktop pinch zoom
    document.addEventListener(
      EVENT.GESTURE_START,
      this.onGestureStart as any,
      false,
    );
    document.addEventListener(
      EVENT.GESTURE_CHANGE,
      this.onGestureChange as any,
      false,
    );
    document.addEventListener(
      EVENT.GESTURE_END,
      this.onGestureEnd as any,
      false,
    );
    window.addEventListener(EVENT.BEFORE_UNLOAD, this.beforeUnload);
  }

  private beforeUnload = withBatchedUpdates((event: BeforeUnloadEvent) => {
    if (this.state.isCollaborating && this.portal.roomID) {
      try {
        localStorage?.setItem(
          LOCAL_STORAGE_KEY_COLLAB_FORCE_FLAG,
          JSON.stringify({
            timestamp: Date.now(),
            room: this.portal.roomID,
          }),
        );
      } catch {}
    }
    if (this.state.isCollaborating && this.scene.getElements().length > 0) {
      event.preventDefault();
      // NOTE: modern browsers no longer allow showing a custom message here
      event.returnValue = "";
    }
  });

  queueBroadcastAllElements = throttle(() => {
    this.broadcastScene(SCENE.UPDATE, /* syncAll */ true);
  }, SYNC_FULL_SCENE_INTERVAL_MS);

  componentDidUpdate(prevProps: ExcalidrawProps, prevState: AppState) {
    const { width: prevWidth, height: prevHeight } = prevProps;
    const { width: currentWidth, height: currentHeight, onChange } = this.props;
    if (prevWidth !== currentWidth || prevHeight !== currentHeight) {
      this.setState({
        width: currentWidth,
        height: currentHeight,
        ...this.getCanvasOffsets(),
      });
    }

    document.documentElement.classList.toggle(
      "Appearance_dark",
      this.state.appearance === "dark",
    );

    if (this.state.isCollaborating && !this.portal.socket) {
      this.initializeSocketClient({ showLoadingState: true });
    }

    if (
      this.state.editingLinearElement &&
      !this.state.selectedElementIds[this.state.editingLinearElement.elementId]
    ) {
      // defer so that the commitToHistory flag isn't reset via current update
      setTimeout(() => {
        this.actionManager.executeAction(actionFinalize);
      });
    }
    const { multiElement } = prevState;
    if (
      prevState.elementType !== this.state.elementType &&
      multiElement != null &&
      isBindingEnabled(this.state) &&
      isBindingElement(multiElement)
    ) {
      maybeBindLinearElement(
        multiElement,
        this.state,
        this.scene,
        tupleToCoors(
          LinearElementEditor.getPointAtIndexGlobalCoordinates(
            multiElement,
            -1,
          ),
        ),
      );
    }

    const cursorButton: {
      [id: string]: string | undefined;
    } = {};
    const pointerViewportCoords: SceneState["remotePointerViewportCoords"] = {};
    const remoteSelectedElementIds: SceneState["remoteSelectedElementIds"] = {};
    const pointerUsernames: { [id: string]: string } = {};
    this.state.collaborators.forEach((user, socketId) => {
      if (user.selectedElementIds) {
        for (const id of Object.keys(user.selectedElementIds)) {
          if (!(id in remoteSelectedElementIds)) {
            remoteSelectedElementIds[id] = [];
          }
          remoteSelectedElementIds[id].push(socketId);
        }
      }
      if (!user.pointer) {
        return;
      }
      if (user.username) {
        pointerUsernames[socketId] = user.username;
      }
      pointerViewportCoords[socketId] = sceneCoordsToViewportCoords(
        {
          sceneX: user.pointer.x,
          sceneY: user.pointer.y,
        },
        this.state,
        this.canvas,
        window.devicePixelRatio,
      );
      cursorButton[socketId] = user.button;
    });
    const elements = this.scene.getElements();
    const { atLeastOneVisibleElement, scrollBars } = renderScene(
      elements.filter((element) => {
        // don't render text element that's being currently edited (it's
        //  rendered on remote only)
        return (
          !this.state.editingElement ||
          this.state.editingElement.type !== "text" ||
          element.id !== this.state.editingElement.id
        );
      }),
      this.state,
      this.state.selectionElement,
      window.devicePixelRatio,
      this.rc!,
      this.canvas!,
      {
        scrollX: this.state.scrollX,
        scrollY: this.state.scrollY,
        viewBackgroundColor: this.state.viewBackgroundColor,
        zoom: this.state.zoom,
        remotePointerViewportCoords: pointerViewportCoords,
        remotePointerButton: cursorButton,
        remoteSelectedElementIds: remoteSelectedElementIds,
        remotePointerUsernames: pointerUsernames,
        shouldCacheIgnoreZoom: this.state.shouldCacheIgnoreZoom,
      },
      {
        renderOptimizations: true,
      },
    );
    if (scrollBars) {
      currentScrollBars = scrollBars;
    }
    const scrolledOutside =
      // hide when editing text
      this.state.editingElement?.type === "text"
        ? false
        : !atLeastOneVisibleElement && elements.length > 0;
    if (this.state.scrolledOutside !== scrolledOutside) {
      this.setState({ scrolledOutside: scrolledOutside });
    }

    if (
      getDrawingVersion(this.scene.getElementsIncludingDeleted()) >
      this.lastBroadcastedOrReceivedSceneVersion
    ) {
      this.broadcastScene(SCENE.UPDATE, /* syncAll */ false);
      this.queueBroadcastAllElements();
    }

    history.record(this.state, this.scene.getElementsIncludingDeleted());

    if (onChange) {
      onChange(this.scene.getElementsIncludingDeleted(), this.state);
    }
  }

  // Copy/paste

  private onCut = withBatchedUpdates((event: ClipboardEvent) => {
    if (isWritableElement(event.target)) {
      return;
    }
    this.copyAll();
    this.actionManager.executeAction(actionDeleteSelected);
    event.preventDefault();
  });

  private onCopy = withBatchedUpdates((event: ClipboardEvent) => {
    if (isWritableElement(event.target)) {
      return;
    }
    this.copyAll();
    event.preventDefault();
  });

  private copyAll = () => {
    copyToAppClipboard(this.scene.getElements(), this.state);
  };

  private copyToClipboardAsPng = () => {
    const elements = this.scene.getElements();

    const selectedElements = getSelectedElements(elements, this.state);
    exportCanvas(
      "clipboard",
      selectedElements.length ? selectedElements : elements,
      this.state,
      this.canvas!,
      this.state,
    );
  };

  private copyToClipboardAsSvg = () => {
    const selectedElements = getSelectedElements(
      this.scene.getElements(),
      this.state,
    );
    exportCanvas(
      "clipboard-svg",
      selectedElements.length ? selectedElements : this.scene.getElements(),
      this.state,
      this.canvas!,
      this.state,
    );
  };

  private static resetTapTwice() {
    didTapTwice = false;
  }

  private onTapStart = (event: TouchEvent) => {
    if (!didTapTwice) {
      didTapTwice = true;
      clearTimeout(tappedTwiceTimer);
      tappedTwiceTimer = window.setTimeout(
        App.resetTapTwice,
        TAP_TWICE_TIMEOUT,
      );
      return;
    }
    // insert text only if we tapped twice with a single finger
    // event.touches.length === 1 will also prevent inserting text when user's zooming
    if (didTapTwice && event.touches.length === 1) {
      const [touch] = event.touches;
      // @ts-ignore
      this.handleCanvasDoubleClick({
        clientX: touch.clientX,
        clientY: touch.clientY,
      });
      didTapTwice = false;
      clearTimeout(tappedTwiceTimer);
    }
    event.preventDefault();
    if (event.touches.length === 2) {
      this.setState({
        selectedElementIds: {},
      });
    }
  };

  private onTapEnd = (event: TouchEvent) => {
    event.preventDefault();
    if (event.touches.length > 0) {
      const { previousSelectedElementIds } = this.state;
      this.setState({
        previousSelectedElementIds: {},
        selectedElementIds: previousSelectedElementIds,
      });
    }
  };

  private pasteFromClipboard = withBatchedUpdates(
    async (event: ClipboardEvent | null) => {
      // #686
      const target = document.activeElement;
      const elementUnderCursor = document.elementFromPoint(cursorX, cursorY);
      if (
        // if no ClipboardEvent supplied, assume we're pasting via contextMenu
        //  thus these checks don't make sense
        event &&
        (!(elementUnderCursor instanceof HTMLCanvasElement) ||
          isWritableElement(target))
      ) {
        return;
      }
      const data = await getClipboardContent(
        this.state,
        cursorX,
        cursorY,
        event,
      );
      if (data.error) {
        alert(data.error);
      } else if (data.elements) {
        this.addElementsFromPasteOrLibrary(data.elements);
      } else if (data.text) {
        this.addTextFromPaste(data.text);
      }
      this.selectShapeTool("selection");
      event?.preventDefault();
    },
  );

  private addElementsFromPasteOrLibrary = (
    clipboardElements: readonly ExcalidrawElement[],
    clientX = cursorX,
    clientY = cursorY,
  ) => {
    const [minX, minY, maxX, maxY] = getCommonBounds(clipboardElements);

    const elementsCenterX = distance(minX, maxX) / 2;
    const elementsCenterY = distance(minY, maxY) / 2;

    const { x, y } = viewportCoordsToSceneCoords(
      { clientX, clientY },
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );

    const dx = x - elementsCenterX;
    const dy = y - elementsCenterY;
    const groupIdMap = new Map();

    const oldIdToDuplicatedId = new Map();
    const newElements = clipboardElements.map((element) => {
      const newElement = duplicateElement(
        this.state.editingGroupId,
        groupIdMap,
        element,
        {
          x: element.x + dx - minX,
          y: element.y + dy - minY,
        },
      );
      oldIdToDuplicatedId.set(element.id, newElement.id);
      return newElement;
    });
    const nextElements = [
      ...this.scene.getElementsIncludingDeleted(),
      ...newElements,
    ];
    fixBindingsAfterDuplication(
      nextElements,
      clipboardElements,
      oldIdToDuplicatedId,
    );

    this.scene.replaceAllElements(nextElements);
    history.resumeRecording();
    this.setState(
      selectGroupsForSelectedElements(
        {
          ...this.state,
          isLibraryOpen: false,
          selectedElementIds: newElements.reduce((map, element) => {
            map[element.id] = true;
            return map;
          }, {} as any),
          selectedGroupIds: {},
        },
        this.scene.getElements(),
      ),
    );
  };

  private addTextFromPaste(text: any) {
    const { x, y } = viewportCoordsToSceneCoords(
      { clientX: cursorX, clientY: cursorY },
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );

    const element = newTextElement({
      x: x,
      y: y,
      strokeColor: this.state.currentItemStrokeColor,
      backgroundColor: this.state.currentItemBackgroundColor,
      fillStyle: this.state.currentItemFillStyle,
      strokeWidth: this.state.currentItemStrokeWidth,
      strokeStyle: this.state.currentItemStrokeStyle,
      roughness: this.state.currentItemRoughness,
      opacity: this.state.currentItemOpacity,
      strokeSharpness: this.state.currentItemStrokeSharpness,
      text: text,
      fontSize: this.state.currentItemFontSize,
      fontFamily: this.state.currentItemFontFamily,
      textAlign: this.state.currentItemTextAlign,
      verticalAlign: DEFAULT_VERTICAL_ALIGN,
    });

    this.scene.replaceAllElements([
      ...this.scene.getElementsIncludingDeleted(),
      element,
    ]);
    this.setState({ selectedElementIds: { [element.id]: true } });
    history.resumeRecording();
  }

  // Collaboration

  setAppState = (obj: any) => {
    this.setState(obj);
  };

  removePointer = (event: React.PointerEvent<HTMLElement>) => {
    // remove touch handler for context menu on touch devices
    if (event.pointerType === "touch" && touchTimeout) {
      clearTimeout(touchTimeout);
      touchMoving = false;
    }

    gesture.pointers.delete(event.pointerId);
  };

  openPortal = async () => {
    window.history.pushState(
      {},
      "Excalidraw",
      await generateCollaborationLink(),
    );
    this.initializeSocketClient({ showLoadingState: false });
  };

  closePortal = () => {
    window.history.pushState({}, "Excalidraw", window.location.origin);
    this.destroySocketClient();
  };

  toggleLock = () => {
    this.setState((prevState) => ({
      elementLocked: !prevState.elementLocked,
      elementType: prevState.elementLocked
        ? "selection"
        : prevState.elementType,
    }));
  };

  toggleZenMode = () => {
    this.setState({
      zenModeEnabled: !this.state.zenModeEnabled,
    });
  };

  toggleGridMode = () => {
    this.setState({
      gridSize: this.state.gridSize ? null : GRID_SIZE,
    });
  };

  private destroySocketClient = () => {
    this.setState({
      isCollaborating: false,
      collaborators: new Map(),
    });
    this.portal.close();
  };

  private initializeSocketClient = async (opts: {
    showLoadingState: boolean;
  }) => {
    if (this.portal.socket) {
      return;
    }
    const roomMatch = getCollaborationLinkData(window.location.href);
    if (roomMatch) {
      const initialize = () => {
        this.portal.socketInitialized = true;
        clearTimeout(initializationTimer);
        if (this.state.isLoading && !this.unmounted) {
          this.setState({ isLoading: false });
        }
      };
      // fallback in case you're not alone in the room but still don't receive
      //  initial SCENE_UPDATE message
      const initializationTimer = setTimeout(
        initialize,
        INITIAL_SCENE_UPDATE_TIMEOUT,
      );

      const updateScene = (
        decryptedData: SocketUpdateDataSource[SCENE.INIT | SCENE.UPDATE],
        { scrollToContent = false }: { scrollToContent?: boolean } = {},
      ) => {
        const { elements: remoteElements } = decryptedData.payload;

        if (scrollToContent) {
          this.setState({
            ...this.state,
            ...calculateScrollCenter(
              remoteElements.filter((element: { isDeleted: boolean }) => {
                return !element.isDeleted;
              }),
              this.state,
              this.canvas,
            ),
          });
        }

        // Perform reconciliation - in collaboration, if we encounter
        // elements with more staler versions than ours, ignore them
        // and keep ours.
        if (
          this.scene.getElementsIncludingDeleted() == null ||
          this.scene.getElementsIncludingDeleted().length === 0
        ) {
          this.scene.replaceAllElements(remoteElements);
        } else {
          // create a map of ids so we don't have to iterate
          // over the array more than once.
          const localElementMap = getElementMap(
            this.scene.getElementsIncludingDeleted(),
          );

          // Reconcile
          const newElements = remoteElements
            .reduce((elements, element) => {
              // if the remote element references one that's currently
              //  edited on local, skip it (it'll be added in the next
              //  step)
              if (
                element.id === this.state.editingElement?.id ||
                element.id === this.state.resizingElement?.id ||
                element.id === this.state.draggingElement?.id
              ) {
                return elements;
              }

              if (
                localElementMap.hasOwnProperty(element.id) &&
                localElementMap[element.id].version > element.version
              ) {
                elements.push(localElementMap[element.id]);
                delete localElementMap[element.id];
              } else if (
                localElementMap.hasOwnProperty(element.id) &&
                localElementMap[element.id].version === element.version &&
                localElementMap[element.id].versionNonce !==
                  element.versionNonce
              ) {
                // resolve conflicting edits deterministically by taking the one with the lowest versionNonce
                if (
                  localElementMap[element.id].versionNonce <
                  element.versionNonce
                ) {
                  elements.push(localElementMap[element.id]);
                } else {
                  // it should be highly unlikely that the two versionNonces are the same. if we are
                  // really worried about this, we can replace the versionNonce with the socket id.
                  elements.push(element);
                }
                delete localElementMap[element.id];
              } else {
                elements.push(element);
                delete localElementMap[element.id];
              }

              return elements;
            }, [] as Mutable<typeof remoteElements>)
            // add local elements that weren't deleted or on remote
            .concat(...Object.values(localElementMap));

          // Avoid broadcasting to the rest of the collaborators the scene
          // we just received!
          // Note: this needs to be set before replaceAllElements as it
          // syncronously calls render.
          this.lastBroadcastedOrReceivedSceneVersion = getDrawingVersion(
            newElements,
          );

          this.scene.replaceAllElements(newElements);
        }

        // We haven't yet implemented multiplayer undo functionality, so we clear the undo stack
        // when we receive any messages from another peer. This UX can be pretty rough -- if you
        // undo, a user makes a change, and then try to redo, your element(s) will be lost. However,
        // right now we think this is the right tradeoff.
        history.clear();
        if (!this.portal.socketInitialized) {
          initialize();
        }
      };

      const { default: socketIOClient }: any = await import(
        /* webpackChunkName: "socketIoClient" */ "socket.io-client"
      );

      this.portal.open(
        socketIOClient(SOCKET_SERVER),
        roomMatch[1],
        roomMatch[2],
      );

      // All socket listeners are moving to Portal
      this.portal.socket!.on(
        "client-broadcast",
        async (encryptedData: ArrayBuffer, iv: Uint8Array) => {
          if (!this.portal.roomKey) {
            return;
          }
          const decryptedData = await decryptAESGEM(
            encryptedData,
            this.portal.roomKey,
            iv,
          );

          switch (decryptedData.type) {
            case "INVALID_RESPONSE":
              return;
            case SCENE.INIT: {
              if (!this.portal.socketInitialized) {
                updateScene(decryptedData, { scrollToContent: true });
              }
              break;
            }
            case SCENE.UPDATE:
              updateScene(decryptedData);
              break;
            case "MOUSE_LOCATION": {
              const {
                socketId,
                pointer,
                button,
                username,
                selectedElementIds,
              } = decryptedData.payload;
              // NOTE purposefully mutating collaborators map in case of
              //  pointer updates so as not to trigger LayerUI rerender
              this.setState((state) => {
                if (!state.collaborators.has(socketId)) {
                  state.collaborators.set(socketId, {});
                }
                const user = state.collaborators.get(socketId)!;
                user.pointer = pointer;
                user.button = button;
                user.selectedElementIds = selectedElementIds;
                user.username = username;
                state.collaborators.set(socketId, user);
                return state;
              });
              break;
            }
          }
        },
      );
      this.portal.socket!.on("first-in-room", () => {
        if (this.portal.socket) {
          this.portal.socket.off("first-in-room");
        }
        initialize();
      });

      this.setState({
        isCollaborating: true,
        isLoading: opts.showLoadingState ? true : this.state.isLoading,
      });
    }
  };

  // Portal-only
  setCollaborators(sockets: string[]) {
    this.setState((state) => {
      const collaborators: typeof state.collaborators = new Map();
      for (const socketId of sockets) {
        if (state.collaborators.has(socketId)) {
          collaborators.set(socketId, state.collaborators.get(socketId)!);
        } else {
          collaborators.set(socketId, {});
        }
      }
      return {
        ...state,
        collaborators,
      };
    });
  }

  private broadcastMouseLocation = (payload: {
    pointer: SocketUpdateDataSource["MOUSE_LOCATION"]["payload"]["pointer"];
    button: SocketUpdateDataSource["MOUSE_LOCATION"]["payload"]["button"];
  }) => {
    if (this.portal.socket?.id) {
      const data: SocketUpdateDataSource["MOUSE_LOCATION"] = {
        type: "MOUSE_LOCATION",
        payload: {
          socketId: this.portal.socket.id,
          pointer: payload.pointer,
          button: payload.button || "up",
          selectedElementIds: this.state.selectedElementIds,
          username: this.state.username,
        },
      };
      return this.portal._broadcastSocketData(
        data as SocketUpdateData,
        true, // volatile
      );
    }
  };

  // maybe should move to Portal
  broadcastScene = (sceneType: SCENE.INIT | SCENE.UPDATE, syncAll: boolean) => {
    if (sceneType === SCENE.INIT && !syncAll) {
      throw new Error("syncAll must be true when sending SCENE.INIT");
    }

    let syncableElements = getSyncableElements(
      this.scene.getElementsIncludingDeleted(),
    );

    if (!syncAll) {
      // sync out only the elements we think we need to to save bandwidth.
      // periodically we'll resync the whole thing to make sure no one diverges
      // due to a dropped message (server goes down etc).
      syncableElements = syncableElements.filter(
        (syncableElement) =>
          !this.broadcastedElementVersions.has(syncableElement.id) ||
          syncableElement.version >
            this.broadcastedElementVersions.get(syncableElement.id)!,
      );
    }

    const data: SocketUpdateDataSource[typeof sceneType] = {
      type: sceneType,
      payload: {
        elements: syncableElements,
      },
    };
    this.lastBroadcastedOrReceivedSceneVersion = Math.max(
      this.lastBroadcastedOrReceivedSceneVersion,
      getDrawingVersion(this.scene.getElementsIncludingDeleted()),
    );
    for (const syncableElement of syncableElements) {
      this.broadcastedElementVersions.set(
        syncableElement.id,
        syncableElement.version,
      );
    }
    return this.portal._broadcastSocketData(data as SocketUpdateData);
  };

  private onSceneUpdated = () => {
    this.setState({});
  };

  private updateCurrentCursorPosition = withBatchedUpdates(
    (event: MouseEvent) => {
      cursorX = event.x;
      cursorY = event.y;
    },
  );

  // Input handling

  private onKeyDown = withBatchedUpdates((event: KeyboardEvent) => {
    // ensures we don't prevent devTools select-element feature
    if (event[KEYS.CTRL_OR_CMD] && event.shiftKey && event.key === "C") {
      return;
    }

    if (
      (isWritableElement(event.target) && event.key !== KEYS.ESCAPE) ||
      // case: using arrows to move between buttons
      (isArrowKey(event.key) && isInputLike(event.target))
    ) {
      return;
    }

    if (event.key === KEYS.QUESTION_MARK) {
      this.setState({
        showShortcutsDialog: true,
      });
    }

    if (
      !event[KEYS.CTRL_OR_CMD] &&
      event.altKey &&
      event.keyCode === KEYS.Z_KEY_CODE
    ) {
      this.toggleZenMode();
    }

    if (event[KEYS.CTRL_OR_CMD] && event.keyCode === KEYS.GRID_KEY_CODE) {
      this.toggleGridMode();
    }
    if (event[KEYS.CTRL_OR_CMD]) {
      this.setState({ isBindingEnabled: false });
    }

    if (event.code === "KeyC" && event.altKey && event.shiftKey) {
      this.copyToClipboardAsPng();
      event.preventDefault();
      return;
    }

    if (this.actionManager.handleKeyDown(event)) {
      return;
    }

    if (event.code === "Digit9") {
      this.setState({ isLibraryOpen: !this.state.isLibraryOpen });
    }

    if (isArrowKey(event.key)) {
      const step =
        (this.state.gridSize &&
          (event.shiftKey ? ELEMENT_TRANSLATE_AMOUNT : this.state.gridSize)) ||
        (event.shiftKey
          ? ELEMENT_SHIFT_TRANSLATE_AMOUNT
          : ELEMENT_TRANSLATE_AMOUNT);
      this.scene.replaceAllElements(
        this.scene.getElementsIncludingDeleted().map((el) => {
          if (this.state.selectedElementIds[el.id]) {
            const update: { x?: number; y?: number } = {};
            if (event.key === KEYS.ARROW_LEFT) {
              update.x = el.x - step;
            } else if (event.key === KEYS.ARROW_RIGHT) {
              update.x = el.x + step;
            } else if (event.key === KEYS.ARROW_UP) {
              update.y = el.y - step;
            } else if (event.key === KEYS.ARROW_DOWN) {
              update.y = el.y + step;
            }
            return newElementWith(el, update);
          }
          return el;
        }),
      );
      event.preventDefault();
    } else if (event.key === KEYS.ENTER) {
      const selectedElements = getSelectedElements(
        this.scene.getElements(),
        this.state,
      );

      if (
        selectedElements.length === 1 &&
        isLinearElement(selectedElements[0])
      ) {
        if (
          !this.state.editingLinearElement ||
          this.state.editingLinearElement.elementId !== selectedElements[0].id
        ) {
          history.resumeRecording();
          this.setState({
            editingLinearElement: new LinearElementEditor(
              selectedElements[0],
              this.scene,
            ),
          });
        }
      } else if (
        selectedElements.length === 1 &&
        !isLinearElement(selectedElements[0])
      ) {
        const selectedElement = selectedElements[0];
        this.startTextEditing({
          sceneX: selectedElement.x + selectedElement.width / 2,
          sceneY: selectedElement.y + selectedElement.height / 2,
        });
        event.preventDefault();
        return;
      }
    } else if (
      !event.ctrlKey &&
      !event.altKey &&
      !event.metaKey &&
      this.state.draggingElement === null
    ) {
      const shape = findShapeByKey(event.key);
      if (shape) {
        this.selectShapeTool(shape);
      } else if (event.key === "q") {
        this.toggleLock();
      }
    }
    if (event.key === KEYS.SPACE && gesture.pointers.size === 0) {
      isHoldingSpace = true;
      document.documentElement.style.cursor = CURSOR_TYPE.GRABBING;
    }
  });

  private onKeyUp = withBatchedUpdates((event: KeyboardEvent) => {
    if (event.key === KEYS.SPACE) {
      if (this.state.elementType === "selection") {
        resetCursor();
      } else {
        setCursorForShape(this.state.elementType);
        this.setState({
          selectedElementIds: {},
          selectedGroupIds: {},
          editingGroupId: null,
        });
      }
      isHoldingSpace = false;
    }
    if (!event[KEYS.CTRL_OR_CMD] && !this.state.isBindingEnabled) {
      this.setState({ isBindingEnabled: true });
    }
  });

  private selectShapeTool(elementType: AppState["elementType"]) {
    if (!isHoldingSpace) {
      setCursorForShape(elementType);
    }
    if (isToolIcon(document.activeElement)) {
      document.activeElement.blur();
    }
    if (!isLinearElementType(elementType)) {
      this.setState({ suggestedBindings: [] });
    }
    if (elementType !== "selection") {
      this.setState({
        elementType,
        selectedElementIds: {},
        selectedGroupIds: {},
        editingGroupId: null,
      });
    } else {
      this.setState({ elementType });
    }
  }

  private onGestureStart = withBatchedUpdates((event: GestureEvent) => {
    event.preventDefault();
    this.setState({
      selectedElementIds: {},
    });
    gesture.initialScale = this.state.zoom;
  });

  private onGestureChange = withBatchedUpdates((event: GestureEvent) => {
    event.preventDefault();

    this.setState({
      zoom: getNormalizedZoom(gesture.initialScale! * event.scale),
    });
  });

  private onGestureEnd = withBatchedUpdates((event: GestureEvent) => {
    event.preventDefault();
    const { previousSelectedElementIds } = this.state;
    this.setState({
      previousSelectedElementIds: {},
      selectedElementIds: previousSelectedElementIds,
    });
    gesture.initialScale = null;
  });

  private handleTextWysiwyg(
    element: ExcalidrawTextElement,
    {
      isExistingElement = false,
    }: {
      isExistingElement?: boolean;
    },
  ) {
    const updateElement = (text: string, isDeleted = false) => {
      this.scene.replaceAllElements([
        ...this.scene.getElementsIncludingDeleted().map((_element) => {
          if (_element.id === element.id && isTextElement(_element)) {
            return updateTextElement(_element, {
              text,
              isDeleted,
            });
          }
          return _element;
        }),
      ]);
    };

    textWysiwyg({
      id: element.id,
      appState: this.state,
      getViewportCoords: (x, y) => {
        const { x: viewportX, y: viewportY } = sceneCoordsToViewportCoords(
          {
            sceneX: x,
            sceneY: y,
          },
          this.state,
          this.canvas,
          window.devicePixelRatio,
        );
        return [viewportX, viewportY];
      },
      onChange: withBatchedUpdates((text) => {
        updateElement(text);
      }),
      onSubmit: withBatchedUpdates((text) => {
        const isDeleted = !text.trim();
        updateElement(text, isDeleted);
        if (!isDeleted) {
          this.setState((prevState) => ({
            selectedElementIds: {
              ...prevState.selectedElementIds,
              [element.id]: true,
            },
          }));
        } else {
          fixBindingsAfterDeletion(this.scene.getElements(), [element]);
        }
        if (!isDeleted || isExistingElement) {
          history.resumeRecording();
        }

        this.setState({
          draggingElement: null,
          editingElement: null,
        });
        if (this.state.elementLocked) {
          setCursorForShape(this.state.elementType);
        }
      }),
      element,
    });
    // deselect all other elements when inserting text
    this.setState({
      selectedElementIds: {},
      selectedGroupIds: {},
      editingGroupId: null,
    });

    // do an initial update to re-initialize element position since we were
    //  modifying element's x/y for sake of editor (case: syncing to remote)
    updateElement(element.text);
  }

  private getTextElementAtPosition(
    x: number,
    y: number,
  ): NonDeleted<ExcalidrawTextElement> | null {
    const element = this.getElementAtPosition(x, y);

    if (element && isTextElement(element) && !element.isDeleted) {
      return element;
    }
    return null;
  }

  private getElementAtPosition(
    x: number,
    y: number,
  ): NonDeleted<ExcalidrawElement> | null {
    const allHitElements = this.getElementsAtPosition(x, y);
    if (allHitElements.length > 1) {
      const elementWithHighestZIndex =
        allHitElements[allHitElements.length - 1];
      // If we're hitting element with highest z-index only on its bounding box
      // while also hitting other element figure, the latter should be considered.
      return isHittingElementBoundingBoxWithoutHittingElement(
        elementWithHighestZIndex,
        this.state,
        x,
        y,
      )
        ? allHitElements[allHitElements.length - 2]
        : elementWithHighestZIndex;
    }
    if (allHitElements.length === 1) {
      return allHitElements[0];
    }
    return null;
  }

  private getElementsAtPosition(
    x: number,
    y: number,
  ): NonDeleted<ExcalidrawElement>[] {
    return getElementsAtPosition(this.scene.getElements(), (element) =>
      hitTest(element, this.state, x, y),
    );
  }

  private startTextEditing = ({
    sceneX,
    sceneY,
    insertAtParentCenter = true,
  }: {
    /** X position to insert text at */
    sceneX: number;
    /** Y position to insert text at */
    sceneY: number;
    /** whether to attempt to insert at element center if applicable */
    insertAtParentCenter?: boolean;
  }) => {
    const existingTextElement = this.getTextElementAtPosition(sceneX, sceneY);

    const parentCenterPosition =
      insertAtParentCenter &&
      this.getTextWysiwygSnappedToCenterPosition(
        sceneX,
        sceneY,
        this.state,
        this.canvas,
        window.devicePixelRatio,
      );

    const element = existingTextElement
      ? existingTextElement
      : newTextElement({
          x: parentCenterPosition
            ? parentCenterPosition.elementCenterX
            : sceneX,
          y: parentCenterPosition
            ? parentCenterPosition.elementCenterY
            : sceneY,
          strokeColor: this.state.currentItemStrokeColor,
          backgroundColor: this.state.currentItemBackgroundColor,
          fillStyle: this.state.currentItemFillStyle,
          strokeWidth: this.state.currentItemStrokeWidth,
          strokeStyle: this.state.currentItemStrokeStyle,
          roughness: this.state.currentItemRoughness,
          opacity: this.state.currentItemOpacity,
          strokeSharpness: this.state.currentItemStrokeSharpness,
          text: "",
          fontSize: this.state.currentItemFontSize,
          fontFamily: this.state.currentItemFontFamily,
          textAlign: parentCenterPosition
            ? "center"
            : this.state.currentItemTextAlign,
          verticalAlign: parentCenterPosition
            ? "middle"
            : DEFAULT_VERTICAL_ALIGN,
        });

    this.setState({ editingElement: element });

    if (existingTextElement) {
      // if text element is no longer centered to a container, reset
      //  verticalAlign to default because it's currently internal-only
      if (!parentCenterPosition || element.textAlign !== "center") {
        mutateElement(element, { verticalAlign: DEFAULT_VERTICAL_ALIGN });
      }
    } else {
      this.scene.replaceAllElements([
        ...this.scene.getElementsIncludingDeleted(),
        element,
      ]);

      // case: creating new text not centered to parent elemenent → offset Y
      //  so that the text is centered to cursor position
      if (!parentCenterPosition) {
        mutateElement(element, {
          y: element.y - element.baseline / 2,
        });
      }
    }

    this.setState({
      editingElement: element,
    });

    this.handleTextWysiwyg(element, {
      isExistingElement: !!existingTextElement,
    });
  };

  private handleCanvasDoubleClick = (
    event: React.MouseEvent<HTMLCanvasElement>,
  ) => {
    // case: double-clicking with arrow/line tool selected would both create
    //  text and enter multiElement mode
    if (this.state.multiElement) {
      return;
    }
    // we should only be able to double click when mode is selection
    if (this.state.elementType !== "selection") {
      return;
    }

    const selectedElements = getSelectedElements(
      this.scene.getElements(),
      this.state,
    );

    if (selectedElements.length === 1 && isLinearElement(selectedElements[0])) {
      if (
        !this.state.editingLinearElement ||
        this.state.editingLinearElement.elementId !== selectedElements[0].id
      ) {
        history.resumeRecording();
        this.setState({
          editingLinearElement: new LinearElementEditor(
            selectedElements[0],
            this.scene,
          ),
        });
      }
      return;
    }

    resetCursor();

    const { x: sceneX, y: sceneY } = viewportCoordsToSceneCoords(
      event,
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );

    const selectedGroupIds = getSelectedGroupIds(this.state);

    if (selectedGroupIds.length > 0) {
      const hitElement = this.getElementAtPosition(sceneX, sceneY);

      const selectedGroupId =
        hitElement &&
        getSelectedGroupIdForElement(hitElement, this.state.selectedGroupIds);

      if (selectedGroupId) {
        this.setState((prevState) =>
          selectGroupsForSelectedElements(
            {
              ...prevState,
              editingGroupId: selectedGroupId,
              selectedElementIds: { [hitElement!.id]: true },
              selectedGroupIds: {},
            },
            this.scene.getElements(),
          ),
        );
        return;
      }
    }

    resetCursor();

    this.startTextEditing({
      sceneX,
      sceneY,
      insertAtParentCenter: !event.altKey,
    });
  };

  private handleCanvasPointerMove = (
    event: React.PointerEvent<HTMLCanvasElement>,
  ) => {
    this.savePointer(event.clientX, event.clientY, this.state.cursorButton);

    if (gesture.pointers.has(event.pointerId)) {
      gesture.pointers.set(event.pointerId, {
        x: event.clientX,
        y: event.clientY,
      });
    }

    if (gesture.pointers.size === 2) {
      const center = getCenter(gesture.pointers);
      const deltaX = center.x - gesture.lastCenter!.x;
      const deltaY = center.y - gesture.lastCenter!.y;
      gesture.lastCenter = center;

      const distance = getDistance(Array.from(gesture.pointers.values()));
      const scaleFactor = distance / gesture.initialDistance!;

      this.setState({
        scrollX: normalizeScroll(this.state.scrollX + deltaX / this.state.zoom),
        scrollY: normalizeScroll(this.state.scrollY + deltaY / this.state.zoom),
        zoom: getNormalizedZoom(gesture.initialScale! * scaleFactor),
        shouldCacheIgnoreZoom: true,
      });
      this.resetShouldCacheIgnoreZoomDebounced();
    } else {
      gesture.lastCenter = gesture.initialDistance = gesture.initialScale = null;
    }

    if (isHoldingSpace || isPanning || isDraggingScrollBar) {
      return;
    }
    const isPointerOverScrollBars = isOverScrollBars(
      currentScrollBars,
      event.clientX,
      event.clientY,
    );
    const isOverScrollBar = isPointerOverScrollBars.isOverEither;
    if (!this.state.draggingElement && !this.state.multiElement) {
      if (isOverScrollBar) {
        resetCursor();
      } else {
        setCursorForShape(this.state.elementType);
      }
    }

    const scenePointer = viewportCoordsToSceneCoords(
      event,
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );
    const { x: scenePointerX, y: scenePointerY } = scenePointer;

    if (
      this.state.editingLinearElement &&
      !this.state.editingLinearElement.isDragging
    ) {
      const editingLinearElement = LinearElementEditor.handlePointerMove(
        event,
        scenePointerX,
        scenePointerY,
        this.state.editingLinearElement,
        this.state.gridSize,
      );
      if (editingLinearElement !== this.state.editingLinearElement) {
        this.setState({ editingLinearElement });
      }
      if (editingLinearElement.lastUncommittedPoint != null) {
        this.maybeSuggestBindingAtCursor(scenePointer);
      } else {
        this.setState({ suggestedBindings: [] });
      }
    }

    if (isBindingElementType(this.state.elementType)) {
      // Hovering with a selected tool or creating new linear element via click
      // and point
      const { draggingElement } = this.state;
      if (isBindingElement(draggingElement)) {
        this.maybeSuggestBindingForLinearElementAtCursor(
          draggingElement,
          "end",
          scenePointer,
          this.state.startBoundElement,
        );
      } else {
        this.maybeSuggestBindingAtCursor(scenePointer);
      }
    }

    if (this.state.multiElement) {
      const { multiElement } = this.state;
      const { x: rx, y: ry } = multiElement;

      const { points, lastCommittedPoint } = multiElement;
      const lastPoint = points[points.length - 1];

      setCursorForShape(this.state.elementType);

      if (lastPoint === lastCommittedPoint) {
        // if we haven't yet created a temp point and we're beyond commit-zone
        //  threshold, add a point
        if (
          distance2d(
            scenePointerX - rx,
            scenePointerY - ry,
            lastPoint[0],
            lastPoint[1],
          ) >= LINE_CONFIRM_THRESHOLD
        ) {
          mutateElement(multiElement, {
            points: [...points, [scenePointerX - rx, scenePointerY - ry]],
          });
        } else {
          document.documentElement.style.cursor = CURSOR_TYPE.POINTER;
          // in this branch, we're inside the commit zone, and no uncommitted
          //  point exists. Thus do nothing (don't add/remove points).
        }
      } else {
        // cursor moved inside commit zone, and there's uncommitted point,
        //  thus remove it
        if (
          points.length > 2 &&
          lastCommittedPoint &&
          distance2d(
            scenePointerX - rx,
            scenePointerY - ry,
            lastCommittedPoint[0],
            lastCommittedPoint[1],
          ) < LINE_CONFIRM_THRESHOLD
        ) {
          document.documentElement.style.cursor = CURSOR_TYPE.POINTER;
          mutateElement(multiElement, {
            points: points.slice(0, -1),
          });
        } else {
          if (isPathALoop(points)) {
            document.documentElement.style.cursor = CURSOR_TYPE.POINTER;
          }
          // update last uncommitted point
          mutateElement(multiElement, {
            points: [
              ...points.slice(0, -1),
              [scenePointerX - rx, scenePointerY - ry],
            ],
          });
        }
      }

      return;
    }

    const hasDeselectedButton = Boolean(event.buttons);
    if (
      hasDeselectedButton ||
      (this.state.elementType !== "selection" &&
        this.state.elementType !== "text")
    ) {
      return;
    }

    const elements = this.scene.getElements();

    const selectedElements = getSelectedElements(elements, this.state);
    if (
      selectedElements.length === 1 &&
      !isOverScrollBar &&
      !this.state.editingLinearElement
    ) {
      const elementWithTransformHandleType = getElementWithTransformHandleType(
        elements,
        this.state,
        scenePointerX,
        scenePointerY,
        this.state.zoom,
        event.pointerType,
      );
      if (
        elementWithTransformHandleType &&
        elementWithTransformHandleType.transformHandleType
      ) {
        document.documentElement.style.cursor = getCursorForResizingElement(
          elementWithTransformHandleType,
        );
        return;
      }
    } else if (selectedElements.length > 1 && !isOverScrollBar) {
      const transformHandleType = getTransformHandleTypeFromCoords(
        getCommonBounds(selectedElements),
        scenePointerX,
        scenePointerY,
        this.state.zoom,
        event.pointerType,
      );
      if (transformHandleType) {
        document.documentElement.style.cursor = getCursorForResizingElement({
          transformHandleType,
        });
        return;
      }
    }

    const hitElement = this.getElementAtPosition(
      scenePointer.x,
      scenePointer.y,
    );
    if (this.state.elementType === "text") {
      document.documentElement.style.cursor = isTextElement(hitElement)
        ? CURSOR_TYPE.TEXT
        : CURSOR_TYPE.CROSSHAIR;
    } else if (isOverScrollBar) {
      document.documentElement.style.cursor = CURSOR_TYPE.AUTO;
    } else if (
      hitElement ||
      this.isHittingCommonBoundingBoxOfSelectedElements(
        scenePointer,
        selectedElements,
      )
    ) {
      document.documentElement.style.cursor = CURSOR_TYPE.MOVE;
    } else {
      document.documentElement.style.cursor = CURSOR_TYPE.AUTO;
    }
  };

  // set touch moving for mobile context menu
  private handleTouchMove = (event: React.TouchEvent<HTMLCanvasElement>) => {
    touchMoving = true;
  };

  private handleCanvasPointerDown = (
    event: React.PointerEvent<HTMLCanvasElement>,
  ) => {
    event.persist();

    this.maybeOpenContextMenuAfterPointerDownOnTouchDevices(event);
    this.maybeCleanupAfterMissingPointerUp(event);

    if (isPanning) {
      return;
    }

    this.setState({
      lastPointerDownWith: event.pointerType,
      cursorButton: "down",
    });
    this.savePointer(event.clientX, event.clientY, "down");

    if (this.handleCanvasPanUsingWheelOrSpaceDrag(event)) {
      return;
    }

    // only handle left mouse button or touch
    if (
      event.button !== POINTER_BUTTON.MAIN &&
      event.button !== POINTER_BUTTON.TOUCH
    ) {
      return;
    }

    this.updateGestureOnPointerDown(event);

    // fixes pointermove causing selection of UI texts #32
    event.preventDefault();
    // Preventing the event above disables default behavior
    //  of defocusing potentially focused element, which is what we
    //  want when clicking inside the canvas.
    if (document.activeElement instanceof HTMLElement) {
      document.activeElement.blur();
    }

    // don't select while panning
    if (gesture.pointers.size > 1) {
      return;
    }

    // State for the duration of a pointer interaction, which starts with a
    // pointerDown event, ends with a pointerUp event (or another pointerDown)
    const pointerDownState = this.initialPointerDownState(event);

    if (this.handleDraggingScrollBar(event, pointerDownState)) {
      return;
    }

    this.clearSelectionIfNotUsingSelection();

    if (this.handleSelectionOnPointerDown(event, pointerDownState)) {
      return;
    }

    if (this.state.elementType === "text") {
      this.handleTextOnPointerDown(event, pointerDownState);
      return;
    } else if (
      this.state.elementType === "arrow" ||
      this.state.elementType === "draw" ||
      this.state.elementType === "line"
    ) {
      this.handleLinearElementOnPointerDown(
        event,
        this.state.elementType,
        pointerDownState,
      );
    } else {
      this.createGenericElementOnPointerDown(
        this.state.elementType,
        pointerDownState,
      );
    }

    const onPointerMove = this.onPointerMoveFromPointerDownHandler(
      pointerDownState,
    );

    const onPointerUp = this.onPointerUpFromPointerDownHandler(
      pointerDownState,
    );

    lastPointerUp = onPointerUp;

    window.addEventListener(EVENT.POINTER_MOVE, onPointerMove);
    window.addEventListener(EVENT.POINTER_UP, onPointerUp);
    pointerDownState.eventListeners.onMove = onPointerMove;
    pointerDownState.eventListeners.onUp = onPointerUp;
  };

  private maybeOpenContextMenuAfterPointerDownOnTouchDevices = (
    event: React.PointerEvent<HTMLCanvasElement>,
  ): void => {
    // deal with opening context menu on touch devices
    if (event.pointerType === "touch") {
      touchMoving = false;

      // open the context menu with the first touch's clientX and clientY
      // if the touch is not moving
      touchTimeout = window.setTimeout(() => {
        if (!touchMoving) {
          this.openContextMenu({
            clientX: event.clientX,
            clientY: event.clientY,
          });
        }
      }, TOUCH_CTX_MENU_TIMEOUT);
    }
  };

  private maybeCleanupAfterMissingPointerUp(
    event: React.PointerEvent<HTMLCanvasElement>,
  ): void {
    if (lastPointerUp !== null) {
      // Unfortunately, sometimes we don't get a pointerup after a pointerdown,
      // this can happen when a contextual menu or alert is triggered. In order to avoid
      // being in a weird state, we clean up on the next pointerdown
      lastPointerUp(event);
    }
  }

  // Returns whether the event is a panning
  private handleCanvasPanUsingWheelOrSpaceDrag = (
    event: React.PointerEvent<HTMLCanvasElement>,
  ): boolean => {
    if (
      !(
        gesture.pointers.size === 0 &&
        (event.button === POINTER_BUTTON.WHEEL ||
          (event.button === POINTER_BUTTON.MAIN && isHoldingSpace))
      )
    ) {
      return false;
    }
    isPanning = true;

    let nextPastePrevented = false;
    const isLinux = /Linux/.test(window.navigator.platform);

    document.documentElement.style.cursor = CURSOR_TYPE.GRABBING;
    let { clientX: lastX, clientY: lastY } = event;
    const onPointerMove = withBatchedUpdates((event: PointerEvent) => {
      const deltaX = lastX - event.clientX;
      const deltaY = lastY - event.clientY;
      lastX = event.clientX;
      lastY = event.clientY;

      /*
       * Prevent paste event if we move while middle clicking on Linux.
       * See issue #1383.
       */
      if (
        isLinux &&
        !nextPastePrevented &&
        (Math.abs(deltaX) > 1 || Math.abs(deltaY) > 1)
      ) {
        nextPastePrevented = true;

        /* Prevent the next paste event */
        const preventNextPaste = (event: ClipboardEvent) => {
          document.body.removeEventListener(EVENT.PASTE, preventNextPaste);
          event.stopPropagation();
        };

        /*
         * Reenable next paste in case of disabled middle click paste for
         * any reason:
         * - rigth click paste
         * - empty clipboard
         */
        const enableNextPaste = () => {
          setTimeout(() => {
            document.body.removeEventListener(EVENT.PASTE, preventNextPaste);
            window.removeEventListener(EVENT.POINTER_UP, enableNextPaste);
          }, 100);
        };

        document.body.addEventListener(EVENT.PASTE, preventNextPaste);
        window.addEventListener(EVENT.POINTER_UP, enableNextPaste);
      }

      this.setState({
        scrollX: normalizeScroll(this.state.scrollX - deltaX / this.state.zoom),
        scrollY: normalizeScroll(this.state.scrollY - deltaY / this.state.zoom),
      });
    });
    const teardown = withBatchedUpdates(
      (lastPointerUp = () => {
        lastPointerUp = null;
        isPanning = false;
        if (!isHoldingSpace) {
          setCursorForShape(this.state.elementType);
        }
        this.setState({
          cursorButton: "up",
        });
        this.savePointer(event.clientX, event.clientY, "up");
        window.removeEventListener(EVENT.POINTER_MOVE, onPointerMove);
        window.removeEventListener(EVENT.POINTER_UP, teardown);
        window.removeEventListener(EVENT.BLUR, teardown);
      }),
    );
    window.addEventListener(EVENT.BLUR, teardown);
    window.addEventListener(EVENT.POINTER_MOVE, onPointerMove, {
      passive: true,
    });
    window.addEventListener(EVENT.POINTER_UP, teardown);
    return true;
  };

  private updateGestureOnPointerDown(
    event: React.PointerEvent<HTMLCanvasElement>,
  ): void {
    gesture.pointers.set(event.pointerId, {
      x: event.clientX,
      y: event.clientY,
    });

    if (gesture.pointers.size === 2) {
      gesture.lastCenter = getCenter(gesture.pointers);
      gesture.initialScale = this.state.zoom;
      gesture.initialDistance = getDistance(
        Array.from(gesture.pointers.values()),
      );
    }
  }

  private initialPointerDownState(
    event: React.PointerEvent<HTMLCanvasElement>,
  ): PointerDownState {
    const origin = viewportCoordsToSceneCoords(
      event,
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );
    const selectedElements = getSelectedElements(
      this.scene.getElements(),
      this.state,
    );
    const [minX, minY, maxX, maxY] = getCommonBounds(selectedElements);

    return {
      origin,
      originInGrid: tupleToCoors(
        getGridPoint(origin.x, origin.y, this.state.gridSize),
      ),
      scrollbars: isOverScrollBars(
        currentScrollBars,
        event.clientX,
        event.clientY,
      ),
      // we need to duplicate because we'll be updating this state
      lastCoords: { ...origin },
      resize: {
        handleType: false,
        isResizing: false,
        offset: { x: 0, y: 0 },
        arrowDirection: "origin",
        center: { x: (maxX + minX) / 2, y: (maxY + minY) / 2 },
        originalElements: selectedElements.map((element) => ({ ...element })),
      },
      hit: {
        element: null,
        allHitElements: [],
        wasAddedToSelection: false,
        hasBeenDuplicated: false,
        hasHitCommonBoundingBoxOfSelectedElements: this.isHittingCommonBoundingBoxOfSelectedElements(
          origin,
          selectedElements,
        ),
      },
      drag: {
        hasOccurred: false,
        offset: null,
      },
      eventListeners: {
        onMove: null,
        onUp: null,
      },
    };
  }

  // Returns whether the event is a dragging a scrollbar
  private handleDraggingScrollBar(
    event: React.PointerEvent<HTMLCanvasElement>,
    pointerDownState: PointerDownState,
  ): boolean {
    if (
      !(pointerDownState.scrollbars.isOverEither && !this.state.multiElement)
    ) {
      return false;
    }
    isDraggingScrollBar = true;
    pointerDownState.lastCoords.x = event.clientX;
    pointerDownState.lastCoords.y = event.clientY;
    const onPointerMove = withBatchedUpdates((event: PointerEvent) => {
      const target = event.target;
      if (!(target instanceof HTMLElement)) {
        return;
      }

      this.handlePointerMoveOverScrollbars(event, pointerDownState);
    });

    const onPointerUp = withBatchedUpdates(() => {
      isDraggingScrollBar = false;
      setCursorForShape(this.state.elementType);
      lastPointerUp = null;
      this.setState({
        cursorButton: "up",
      });
      this.savePointer(event.clientX, event.clientY, "up");
      window.removeEventListener(EVENT.POINTER_MOVE, onPointerMove);
      window.removeEventListener(EVENT.POINTER_UP, onPointerUp);
    });

    lastPointerUp = onPointerUp;

    window.addEventListener(EVENT.POINTER_MOVE, onPointerMove);
    window.addEventListener(EVENT.POINTER_UP, onPointerUp);
    return true;
  }

  private clearSelectionIfNotUsingSelection = (): void => {
    if (this.state.elementType !== "selection") {
      this.setState({
        selectedElementIds: {},
        selectedGroupIds: {},
        editingGroupId: null,
      });
    }
  };

  // Returns whether the pointer event has been completely handled
  private handleSelectionOnPointerDown = (
    event: React.PointerEvent<HTMLCanvasElement>,
    pointerDownState: PointerDownState,
  ): boolean => {
    if (this.state.elementType === "selection") {
      const elements = this.scene.getElements();
      const selectedElements = getSelectedElements(elements, this.state);
      if (selectedElements.length === 1 && !this.state.editingLinearElement) {
        const elementWithTransformHandleType = getElementWithTransformHandleType(
          elements,
          this.state,
          pointerDownState.origin.x,
          pointerDownState.origin.y,
          this.state.zoom,
          event.pointerType,
        );
        if (elementWithTransformHandleType != null) {
          this.setState({
            resizingElement: elementWithTransformHandleType.element,
          });
          pointerDownState.resize.handleType =
            elementWithTransformHandleType.transformHandleType;
        }
      } else if (selectedElements.length > 1) {
        pointerDownState.resize.handleType = getTransformHandleTypeFromCoords(
          getCommonBounds(selectedElements),
          pointerDownState.origin.x,
          pointerDownState.origin.y,
          this.state.zoom,
          event.pointerType,
        );
      }
      if (pointerDownState.resize.handleType) {
        document.documentElement.style.cursor = getCursorForResizingElement({
          transformHandleType: pointerDownState.resize.handleType,
        });
        pointerDownState.resize.isResizing = true;
        pointerDownState.resize.offset = tupleToCoors(
          getResizeOffsetXY(
            pointerDownState.resize.handleType,
            selectedElements,
            pointerDownState.origin.x,
            pointerDownState.origin.y,
          ),
        );
        if (
          selectedElements.length === 1 &&
          isLinearElement(selectedElements[0]) &&
          selectedElements[0].points.length === 2
        ) {
          pointerDownState.resize.arrowDirection = getResizeArrowDirection(
            pointerDownState.resize.handleType,
            selectedElements[0],
          );
        }
      } else {
        if (this.state.editingLinearElement) {
          const ret = LinearElementEditor.handlePointerDown(
            event,
            this.state,
            (appState) => this.setState(appState),
            history,
            pointerDownState.origin,
          );
          if (ret.hitElement) {
            pointerDownState.hit.element = ret.hitElement;
          }
          if (ret.didAddPoint) {
            return true;
          }
        }

        // hitElement may already be set above, so check first
        pointerDownState.hit.element =
          pointerDownState.hit.element ??
          this.getElementAtPosition(
            pointerDownState.origin.x,
            pointerDownState.origin.y,
          );

        // For overlapped elements one position may hit
        // multiple elements
        pointerDownState.hit.allHitElements = this.getElementsAtPosition(
          pointerDownState.origin.x,
          pointerDownState.origin.y,
        );

        const hitElement = pointerDownState.hit.element;
        const someHitElementIsSelected = pointerDownState.hit.allHitElements.some(
          (element) => this.isASelectedElement(element),
        );
        if (
          (hitElement === null || !someHitElementIsSelected) &&
          !event.shiftKey &&
          !pointerDownState.hit.hasHitCommonBoundingBoxOfSelectedElements
        ) {
          this.clearSelection(hitElement);
        }

        // If we click on something
        if (hitElement != null) {
          // deselect if item is selected
          // if shift is not clicked, this will always return true
          // otherwise, it will trigger selection based on current
          // state of the box
          if (!this.state.selectedElementIds[hitElement.id]) {
            // if we are currently editing a group, treat all selections outside of the group
            // as exiting editing mode.
            if (
              this.state.editingGroupId &&
              !isElementInGroup(hitElement, this.state.editingGroupId)
            ) {
              this.setState({
                selectedElementIds: {},
                selectedGroupIds: {},
                editingGroupId: null,
              });
              return true;
            }

            // Add hit element to selection. At this point if we're not holding
            //  SHIFT the previously selected element(s) were deselected above
            //  (make sure you use setState updater to use latest state)
            if (
              !someHitElementIsSelected &&
              !pointerDownState.hit.hasHitCommonBoundingBoxOfSelectedElements
            ) {
              this.setState((prevState) => {
                return selectGroupsForSelectedElements(
                  {
                    ...prevState,
                    selectedElementIds: {
                      ...prevState.selectedElementIds,
                      [hitElement!.id]: true,
                    },
                  },
                  this.scene.getElements(),
                );
              });
              pointerDownState.hit.wasAddedToSelection = true;
            }
          }
        }

        const { selectedElementIds } = this.state;
        this.setState({
          previousSelectedElementIds: selectedElementIds,
        });
      }
    }
    return false;
  };

  private isASelectedElement(hitElement: ExcalidrawElement | null): boolean {
    return hitElement != null && this.state.selectedElementIds[hitElement.id];
  }

  private isHittingCommonBoundingBoxOfSelectedElements(
    point: Readonly<{ x: number; y: number }>,
    selectedElements: readonly ExcalidrawElement[],
  ): boolean {
    if (selectedElements.length < 2) {
      return false;
    }

    // How many pixels off the shape boundary we still consider a hit
    const threshold = 10 / this.state.zoom;
    const [x1, y1, x2, y2] = getCommonBounds(selectedElements);
    return (
      point.x > x1 - threshold &&
      point.x < x2 + threshold &&
      point.y > y1 - threshold &&
      point.y < y2 + threshold
    );
  }

  private handleTextOnPointerDown = (
    event: React.PointerEvent<HTMLCanvasElement>,
    pointerDownState: PointerDownState,
  ): void => {
    // if we're currently still editing text, clicking outside
    //  should only finalize it, not create another (irrespective
    //  of state.elementLocked)
    if (this.state.editingElement?.type === "text") {
      return;
    }

    this.startTextEditing({
      sceneX: pointerDownState.origin.x,
      sceneY: pointerDownState.origin.y,
      insertAtParentCenter: !event.altKey,
    });

    resetCursor();
    if (!this.state.elementLocked) {
      this.setState({
        elementType: "selection",
      });
    }
  };

  private handleLinearElementOnPointerDown = (
    event: React.PointerEvent<HTMLCanvasElement>,
    elementType: ExcalidrawLinearElement["type"],
    pointerDownState: PointerDownState,
  ): void => {
    if (this.state.multiElement) {
      const { multiElement } = this.state;

      // finalize if completing a loop
      if (multiElement.type === "line" && isPathALoop(multiElement.points)) {
        mutateElement(multiElement, {
          lastCommittedPoint:
            multiElement.points[multiElement.points.length - 1],
        });
        this.actionManager.executeAction(actionFinalize);
        return;
      }

      const { x: rx, y: ry, lastCommittedPoint } = multiElement;

      // clicking inside commit zone → finalize arrow
      if (
        multiElement.points.length > 1 &&
        lastCommittedPoint &&
        distance2d(
          pointerDownState.origin.x - rx,
          pointerDownState.origin.y - ry,
          lastCommittedPoint[0],
          lastCommittedPoint[1],
        ) < LINE_CONFIRM_THRESHOLD
      ) {
        this.actionManager.executeAction(actionFinalize);
        return;
      }

      this.setState((prevState) => ({
        selectedElementIds: {
          ...prevState.selectedElementIds,
          [multiElement.id]: true,
        },
      }));
      // clicking outside commit zone → update reference for last committed
      //  point
      mutateElement(multiElement, {
        lastCommittedPoint: multiElement.points[multiElement.points.length - 1],
      });
      document.documentElement.style.cursor = CURSOR_TYPE.POINTER;
    } else {
      const [gridX, gridY] = getGridPoint(
        pointerDownState.origin.x,
        pointerDownState.origin.y,
        elementType === "draw" ? null : this.state.gridSize,
      );
      const element = newLinearElement({
        type: elementType,
        x: gridX,
        y: gridY,
        strokeColor: this.state.currentItemStrokeColor,
        backgroundColor: this.state.currentItemBackgroundColor,
        fillStyle: this.state.currentItemFillStyle,
        strokeWidth: this.state.currentItemStrokeWidth,
        strokeStyle: this.state.currentItemStrokeStyle,
        roughness: this.state.currentItemRoughness,
        opacity: this.state.currentItemOpacity,
        strokeSharpness: this.state.currentItemLinearStrokeSharpness,
      });
      this.setState((prevState) => ({
        selectedElementIds: {
          ...prevState.selectedElementIds,
          [element.id]: false,
        },
      }));
      mutateElement(element, {
        points: [...element.points, [0, 0]],
      });
      const boundElement = getHoveredElementForBinding(
        pointerDownState.origin,
        this.scene,
      );
      this.scene.replaceAllElements([
        ...this.scene.getElementsIncludingDeleted(),
        element,
      ]);
      this.setState({
        draggingElement: element,
        editingElement: element,
        startBoundElement: boundElement,
        suggestedBindings: [],
      });
    }
  };

  private createGenericElementOnPointerDown = (
    elementType: ExcalidrawGenericElement["type"],
    pointerDownState: PointerDownState,
  ): void => {
    const [gridX, gridY] = getGridPoint(
      pointerDownState.origin.x,
      pointerDownState.origin.y,
      this.state.gridSize,
    );
    const element = newElement({
      type: elementType,
      x: gridX,
      y: gridY,
      strokeColor: this.state.currentItemStrokeColor,
      backgroundColor: this.state.currentItemBackgroundColor,
      fillStyle: this.state.currentItemFillStyle,
      strokeWidth: this.state.currentItemStrokeWidth,
      strokeStyle: this.state.currentItemStrokeStyle,
      roughness: this.state.currentItemRoughness,
      opacity: this.state.currentItemOpacity,
      strokeSharpness: this.state.currentItemStrokeSharpness,
    });

    if (element.type === "selection") {
      this.setState({
        selectionElement: element,
        draggingElement: element,
      });
    } else {
      this.scene.replaceAllElements([
        ...this.scene.getElementsIncludingDeleted(),
        element,
      ]);
      this.setState({
        multiElement: null,
        draggingElement: element,
        editingElement: element,
      });
    }
  };

  private onPointerMoveFromPointerDownHandler(
    pointerDownState: PointerDownState,
  ): (event: PointerEvent) => void {
    return withBatchedUpdates((event: PointerEvent) => {
      // We need to initialize dragOffsetXY only after we've updated
      // `state.selectedElementIds` on pointerDown. Doing it here in pointerMove
      // event handler should hopefully ensure we're already working with
      // the updated state.
      if (pointerDownState.drag.offset === null) {
        pointerDownState.drag.offset = tupleToCoors(
          getDragOffsetXY(
            getSelectedElements(this.scene.getElements(), this.state),
            pointerDownState.origin.x,
            pointerDownState.origin.y,
          ),
        );
      }

      const target = event.target;
      if (!(target instanceof HTMLElement)) {
        return;
      }

      if (this.handlePointerMoveOverScrollbars(event, pointerDownState)) {
        return;
      }

      const pointerCoords = viewportCoordsToSceneCoords(
        event,
        this.state,
        this.canvas,
        window.devicePixelRatio,
      );
      const [gridX, gridY] = getGridPoint(
        pointerCoords.x,
        pointerCoords.y,
        this.state.gridSize,
      );

      // for arrows/lines, don't start dragging until a given threshold
      //  to ensure we don't create a 2-point arrow by mistake when
      //  user clicks mouse in a way that it moves a tiny bit (thus
      //  triggering pointermove)
      if (
        !pointerDownState.drag.hasOccurred &&
        (this.state.elementType === "arrow" ||
          this.state.elementType === "line")
      ) {
        if (
          distance2d(
            pointerCoords.x,
            pointerCoords.y,
            pointerDownState.origin.x,
            pointerDownState.origin.y,
          ) < DRAGGING_THRESHOLD
        ) {
          return;
        }
      }

      if (pointerDownState.resize.isResizing) {
        const selectedElements = getSelectedElements(
          this.scene.getElements(),
          this.state,
        );
        const transformHandleType = pointerDownState.resize.handleType;
        this.setState({
          // TODO: rename this state field to "isScaling" to distinguish
          // it from the generic "isResizing" which includes scaling and
          // rotating
          isResizing: transformHandleType && transformHandleType !== "rotation",
          isRotating: transformHandleType === "rotation",
        });
        const [resizeX, resizeY] = getGridPoint(
          pointerCoords.x - pointerDownState.resize.offset.x,
          pointerCoords.y - pointerDownState.resize.offset.y,
          this.state.gridSize,
        );
        if (
          resizeElements(
            transformHandleType,
            (newTransformHandle) => {
              pointerDownState.resize.handleType = newTransformHandle;
            },
            selectedElements,
            pointerDownState.resize.arrowDirection,
            getRotateWithDiscreteAngleKey(event),
            getResizeWithSidesSameLengthKey(event),
            getResizeCenterPointKey(event),
            resizeX,
            resizeY,
            pointerDownState.resize.center.x,
            pointerDownState.resize.center.y,
            pointerDownState.resize.originalElements,
          )
        ) {
          this.maybeSuggestBindingForAll(selectedElements);
          return;
        }
      }

      if (this.state.editingLinearElement) {
        const didDrag = LinearElementEditor.handlePointDragging(
          this.state,
          (appState) => this.setState(appState),
          pointerCoords.x,
          pointerCoords.y,
          (element, startOrEnd) => {
            this.maybeSuggestBindingForLinearElementAtCursor(
              element,
              startOrEnd,
              pointerCoords,
            );
          },
        );

        if (didDrag) {
          pointerDownState.lastCoords.x = pointerCoords.x;
          pointerDownState.lastCoords.y = pointerCoords.y;
          return;
        }
      }

      const hasHitASelectedElement = pointerDownState.hit.allHitElements.some(
        (element) => this.isASelectedElement(element),
      );
      if (
        hasHitASelectedElement ||
        pointerDownState.hit.hasHitCommonBoundingBoxOfSelectedElements
      ) {
        // Marking that click was used for dragging to check
        // if elements should be deselected on pointerup
        pointerDownState.drag.hasOccurred = true;
        const selectedElements = getSelectedElements(
          this.scene.getElements(),
          this.state,
        );
        if (selectedElements.length > 0) {
          const [dragX, dragY] = getGridPoint(
            pointerCoords.x - pointerDownState.drag.offset.x,
            pointerCoords.y - pointerDownState.drag.offset.y,
            this.state.gridSize,
          );
          dragSelectedElements(selectedElements, dragX, dragY, this.scene);
          this.maybeSuggestBindingForAll(selectedElements);

          // We duplicate the selected element if alt is pressed on pointer move
          if (event.altKey && !pointerDownState.hit.hasBeenDuplicated) {
            // Move the currently selected elements to the top of the z index stack, and
            // put the duplicates where the selected elements used to be.
            // (the origin point where the dragging started)

            pointerDownState.hit.hasBeenDuplicated = true;

            const nextElements = [];
            const elementsToAppend = [];
            const groupIdMap = new Map();
            const oldIdToDuplicatedId = new Map();
            const hitElement = pointerDownState.hit.element;
            for (const element of this.scene.getElementsIncludingDeleted()) {
              if (
                this.state.selectedElementIds[element.id] ||
                // case: the state.selectedElementIds might not have been
                //  updated yet by the time this mousemove event is fired
                (element.id === hitElement?.id &&
                  pointerDownState.hit.wasAddedToSelection)
              ) {
                const duplicatedElement = duplicateElement(
                  this.state.editingGroupId,
                  groupIdMap,
                  element,
                );
                const [originDragX, originDragY] = getGridPoint(
                  pointerDownState.origin.x - pointerDownState.drag.offset.x,
                  pointerDownState.origin.y - pointerDownState.drag.offset.y,
                  this.state.gridSize,
                );
                mutateElement(duplicatedElement, {
                  x: duplicatedElement.x + (originDragX - dragX),
                  y: duplicatedElement.y + (originDragY - dragY),
                });
                nextElements.push(duplicatedElement);
                elementsToAppend.push(element);
                oldIdToDuplicatedId.set(element.id, duplicatedElement.id);
              } else {
                nextElements.push(element);
              }
            }
            const nextSceneElements = [...nextElements, ...elementsToAppend];
            fixBindingsAfterDuplication(
              nextSceneElements,
              elementsToAppend,
              oldIdToDuplicatedId,
              "duplicatesServeAsOld",
            );
            this.scene.replaceAllElements(nextSceneElements);
          }
          return;
        }
      }

      // It is very important to read this.state within each move event,
      // otherwise we would read a stale one!
      const draggingElement = this.state.draggingElement;
      if (!draggingElement) {
        return;
      }

      if (isLinearElement(draggingElement)) {
        pointerDownState.drag.hasOccurred = true;
        const points = draggingElement.points;
        let dx: number;
        let dy: number;
        if (draggingElement.type === "draw") {
          dx = pointerCoords.x - draggingElement.x;
          dy = pointerCoords.y - draggingElement.y;
        } else {
          dx = gridX - draggingElement.x;
          dy = gridY - draggingElement.y;
        }

        if (getRotateWithDiscreteAngleKey(event) && points.length === 2) {
          ({ width: dx, height: dy } = getPerfectElementSize(
            this.state.elementType,
            dx,
            dy,
          ));
        }

        if (points.length === 1) {
          mutateElement(draggingElement, { points: [...points, [dx, dy]] });
        } else if (points.length > 1) {
          if (draggingElement.type === "draw") {
            mutateElement(draggingElement, {
              points: simplify(
                [...(points as Point[]), [dx, dy]],
                0.7 / this.state.zoom,
              ),
            });
          } else {
            mutateElement(draggingElement, {
              points: [...points.slice(0, -1), [dx, dy]],
            });
          }
        }
        if (isBindingElement(draggingElement)) {
          // When creating a linear element by dragging
          this.maybeSuggestBindingForLinearElementAtCursor(
            draggingElement,
            "end",
            pointerCoords,
            this.state.startBoundElement,
          );
        }
      } else if (draggingElement.type === "selection") {
        dragNewElement(
          draggingElement,
          this.state.elementType,
          pointerDownState.origin.x,
          pointerDownState.origin.y,
          pointerCoords.x,
          pointerCoords.y,
          distance(pointerDownState.origin.x, pointerCoords.x),
          distance(pointerDownState.origin.y, pointerCoords.y),
          getResizeWithSidesSameLengthKey(event),
          getResizeCenterPointKey(event),
        );
      } else {
        dragNewElement(
          draggingElement,
          this.state.elementType,
          pointerDownState.originInGrid.x,
          pointerDownState.originInGrid.y,
          gridX,
          gridY,
          distance(pointerDownState.originInGrid.x, gridX),
          distance(pointerDownState.originInGrid.y, gridY),
          getResizeWithSidesSameLengthKey(event),
          getResizeCenterPointKey(event),
        );
        this.maybeSuggestBindingForAll([draggingElement]);
      }

      if (this.state.elementType === "selection") {
        const elements = this.scene.getElements();
        if (!event.shiftKey && isSomeElementSelected(elements, this.state)) {
          this.setState({
            selectedElementIds: {},
            selectedGroupIds: {},
            editingGroupId: null,
          });
        }
        const elementsWithinSelection = getElementsWithinSelection(
          elements,
          draggingElement,
        );
        this.setState((prevState) =>
          selectGroupsForSelectedElements(
            {
              ...prevState,
              selectedElementIds: {
                ...prevState.selectedElementIds,
                ...elementsWithinSelection.reduce((map, element) => {
                  map[element.id] = true;
                  return map;
                }, {} as any),
              },
            },
            this.scene.getElements(),
          ),
        );
      }
    });
  }

  // Returns whether the pointer move happened over either scrollbar
  private handlePointerMoveOverScrollbars(
    event: PointerEvent,
    pointerDownState: PointerDownState,
  ): boolean {
    if (pointerDownState.scrollbars.isOverHorizontal) {
      const x = event.clientX;
      const dx = x - pointerDownState.lastCoords.x;
      this.setState({
        scrollX: normalizeScroll(this.state.scrollX - dx / this.state.zoom),
      });
      pointerDownState.lastCoords.x = x;
      return true;
    }

    if (pointerDownState.scrollbars.isOverVertical) {
      const y = event.clientY;
      const dy = y - pointerDownState.lastCoords.y;
      this.setState({
        scrollY: normalizeScroll(this.state.scrollY - dy / this.state.zoom),
      });
      pointerDownState.lastCoords.y = y;
      return true;
    }
    return false;
  }

  private onPointerUpFromPointerDownHandler(
    pointerDownState: PointerDownState,
  ): (event: PointerEvent) => void {
    return withBatchedUpdates((childEvent: PointerEvent) => {
      const {
        draggingElement,
        resizingElement,
        multiElement,
        elementType,
        elementLocked,
        isResizing,
      } = this.state;

      this.setState({
        isResizing: false,
        isRotating: false,
        resizingElement: null,
        selectionElement: null,
        cursorButton: "up",
        // text elements are reset on finalize, and resetting on pointerup
        //  may cause issues with double taps
        editingElement:
          multiElement || isTextElement(this.state.editingElement)
            ? this.state.editingElement
            : null,
      });

      this.savePointer(childEvent.clientX, childEvent.clientY, "up");

      // Handle end of dragging a point of a linear element, might close a loop
      // and sets binding element
      if (this.state.editingLinearElement) {
        const editingLinearElement = LinearElementEditor.handlePointerUp(
          childEvent,
          this.state.editingLinearElement,
          this.state,
        );
        if (editingLinearElement !== this.state.editingLinearElement) {
          this.setState({
            editingLinearElement,
            suggestedBindings: [],
          });
        }
      }

      lastPointerUp = null;

      window.removeEventListener(
        EVENT.POINTER_MOVE,
        pointerDownState.eventListeners.onMove!,
      );
      window.removeEventListener(
        EVENT.POINTER_UP,
        pointerDownState.eventListeners.onUp!,
      );

      if (draggingElement?.type === "draw") {
        this.actionManager.executeAction(actionFinalize);
        return;
      }

      if (isLinearElement(draggingElement)) {
        if (draggingElement!.points.length > 1) {
          history.resumeRecording();
        }
        const pointerCoords = viewportCoordsToSceneCoords(
          childEvent,
          this.state,
          this.canvas,
          window.devicePixelRatio,
        );

        if (
          !pointerDownState.drag.hasOccurred &&
          draggingElement &&
          !multiElement
        ) {
          mutateElement(draggingElement, {
            points: [
              ...draggingElement.points,
              [
                pointerCoords.x - draggingElement.x,
                pointerCoords.y - draggingElement.y,
              ],
            ],
          });
          this.setState({
            multiElement: draggingElement,
            editingElement: this.state.draggingElement,
          });
        } else if (pointerDownState.drag.hasOccurred && !multiElement) {
          if (
            isBindingEnabled(this.state) &&
            isBindingElement(draggingElement)
          ) {
            maybeBindLinearElement(
              draggingElement,
              this.state,
              this.scene,
              pointerCoords,
            );
          }
          this.setState({ suggestedBindings: [], startBoundElement: null });
          if (!elementLocked) {
            resetCursor();
            this.setState((prevState) => ({
              draggingElement: null,
              elementType: "selection",
              selectedElementIds: {
                ...prevState.selectedElementIds,
                [this.state.draggingElement!.id]: true,
              },
            }));
          } else {
            this.setState((prevState) => ({
              draggingElement: null,
              selectedElementIds: {
                ...prevState.selectedElementIds,
                [this.state.draggingElement!.id]: true,
              },
            }));
          }
        }

        return;
      }

      if (
        elementType !== "selection" &&
        draggingElement &&
        isInvisiblySmallElement(draggingElement)
      ) {
        // remove invisible element which was added in onPointerDown
        this.scene.replaceAllElements(
          this.scene.getElementsIncludingDeleted().slice(0, -1),
        );
        this.setState({
          draggingElement: null,
        });
        return;
      }

      if (draggingElement) {
        mutateElement(
          draggingElement,
          getNormalizedDimensions(draggingElement),
        );

        if (
          isBindingEnabled(this.state) &&
          isBindableElement(draggingElement)
        ) {
          maybeBindBindableElement(draggingElement);
        }
      }

      if (resizingElement) {
        history.resumeRecording();
      }

      if (resizingElement && isInvisiblySmallElement(resizingElement)) {
        this.scene.replaceAllElements(
          this.scene
            .getElementsIncludingDeleted()
            .filter((el) => el.id !== resizingElement.id),
        );
      }

      // Code below handles selection when element(s) weren't
      // drag or added to selection on pointer down phase.
      const hitElement = pointerDownState.hit.element;
      if (
        hitElement &&
        !pointerDownState.drag.hasOccurred &&
        !pointerDownState.hit.wasAddedToSelection
      ) {
        if (childEvent.shiftKey) {
          if (this.state.selectedElementIds[hitElement.id]) {
            if (isSelectedViaGroup(this.state, hitElement)) {
              // We want to unselect all groups hitElement is part of
              //  as well as all elements that are part of the groups
              //  hitElement is part of
              const idsOfSelectedElementsThatAreInGroups = hitElement.groupIds
                .flatMap((groupId) =>
                  getElementsInGroup(this.scene.getElements(), groupId),
                )
                .map((element) => ({ [element.id]: false }))
                .reduce((prevId, acc) => ({ ...prevId, ...acc }), {});

              this.setState((_prevState) => ({
                selectedGroupIds: {
                  ..._prevState.selectedElementIds,
                  ...hitElement.groupIds
                    .map((gId) => ({ [gId]: false }))
                    .reduce((prev, acc) => ({ ...prev, ...acc }), {}),
                },
                selectedElementIds: {
                  ..._prevState.selectedElementIds,
                  ...idsOfSelectedElementsThatAreInGroups,
                },
              }));
            } else {
              // remove element from selection while
              // keeping prev elements selected
              this.setState((prevState) => ({
                selectedElementIds: {
                  ...prevState.selectedElementIds,
                  [hitElement!.id]: false,
                },
              }));
            }
          } else {
            // add element to selection while
            // keeping prev elements selected
            this.setState((_prevState) => ({
              selectedElementIds: {
                ..._prevState.selectedElementIds,
                [hitElement!.id]: true,
              },
            }));
          }
        } else {
          if (isSelectedViaGroup(this.state, hitElement)) {
            /*
            We want to select the group(s) the hit element is in not the particular element.
            That means we have to deselect elements that are not part of the groups of the
             hit element, while keeping the elements that are.
            */
            const idsOfSelectedElementsThatAreInGroups = hitElement.groupIds
              .flatMap((groupId) =>
                getElementsInGroup(this.scene.getElements(), groupId),
              )
              .map((element) => ({ [element.id]: true }))
              .reduce((prevId, acc) => ({ ...prevId, ...acc }), {});

            this.setState((_prevState) => ({
              selectedGroupIds: {
                ...hitElement.groupIds
                  .map((gId) => ({ [gId]: true }))
                  .reduce((prevId, acc) => ({ ...prevId, ...acc }), {}),
              },
              selectedElementIds: { ...idsOfSelectedElementsThatAreInGroups },
            }));
          } else {
            this.setState((_prevState) => ({
              selectedGroupIds: {},
              selectedElementIds: { [hitElement!.id]: true },
            }));
          }
        }
      }

      if (
        !this.state.editingLinearElement &&
        !pointerDownState.drag.hasOccurred &&
        !this.state.isResizing &&
        ((hitElement &&
          isHittingElementBoundingBoxWithoutHittingElement(
            hitElement,
            this.state,
            pointerDownState.origin.x,
            pointerDownState.origin.y,
          )) ||
          (!hitElement &&
            pointerDownState.hit.hasHitCommonBoundingBoxOfSelectedElements))
      ) {
        // Deselect selected elements
        this.setState({
          selectedElementIds: {},
          selectedGroupIds: {},
        });
      }

      if (draggingElement === null) {
        // if no element is clicked, clear the selection and redraw
        this.setState({
          selectedElementIds: {},
          selectedGroupIds: {},
          editingGroupId: null,
        });
        return;
      }

      if (!elementLocked) {
        this.setState((prevState) => ({
          selectedElementIds: {
            ...prevState.selectedElementIds,
            [draggingElement.id]: true,
          },
        }));
      }

      if (
        elementType !== "selection" ||
        isSomeElementSelected(this.scene.getElements(), this.state)
      ) {
        history.resumeRecording();
      }

      if (pointerDownState.drag.hasOccurred || isResizing) {
        (isBindingEnabled(this.state)
          ? bindOrUnbindSelectedElements
          : unbindLinearElements)(
          getSelectedElements(this.scene.getElements(), this.state),
        );
      }

      if (!elementLocked) {
        resetCursor();
        this.setState({
          draggingElement: null,
          suggestedBindings: [],
          elementType: "selection",
        });
      } else {
        this.setState({
          draggingElement: null,
          suggestedBindings: [],
        });
      }
    });
  }

  private maybeSuggestBindingAtCursor = (pointerCoords: {
    x: number;
    y: number;
  }): void => {
    const hoveredBindableElement = getHoveredElementForBinding(
      pointerCoords,
      this.scene,
    );
    this.setState({
      suggestedBindings:
        hoveredBindableElement != null ? [hoveredBindableElement] : [],
    });
  };

  private maybeSuggestBindingForLinearElementAtCursor = (
    linearElement: NonDeleted<ExcalidrawLinearElement>,
    startOrEnd: "start" | "end",
    pointerCoords: {
      x: number;
      y: number;
    },
    // During line creation the start binding hasn't been written yet
    // into `linearElement`
    oppositeBindingBoundElement?: ExcalidrawBindableElement | null,
  ): void => {
    const hoveredBindableElement = getElligibleElementForBindingElementAtCoors(
      linearElement,
      startOrEnd,
      pointerCoords,
    );
    this.setState({
      suggestedBindings:
        hoveredBindableElement != null &&
        !isLinearElementSimpleAndAlreadyBound(
          linearElement,
          oppositeBindingBoundElement?.id,
          hoveredBindableElement,
        )
          ? [hoveredBindableElement]
          : [],
    });
  };

  private maybeSuggestBindingForAll(
    selectedElements: NonDeleted<ExcalidrawElement>[],
  ): void {
    const suggestedBindings = getEligibleElementsForBinding(selectedElements);
    this.setState({ suggestedBindings });
  }

  private clearSelection(hitElement: ExcalidrawElement | null): void {
    this.setState((prevState) => ({
      selectedElementIds: {},
      selectedGroupIds: {},
      // Continue editing the same group if the user selected a different
      // element from it
      editingGroupId:
        prevState.editingGroupId &&
        hitElement != null &&
        isElementInGroup(hitElement, prevState.editingGroupId)
          ? prevState.editingGroupId
          : null,
    }));
    const { selectedElementIds } = this.state;
    this.setState({
      selectedElementIds: {},
      previousSelectedElementIds: selectedElementIds,
    });
  }

  private handleCanvasRef = (canvas: HTMLCanvasElement) => {
    // canvas is null when unmounting
    if (canvas !== null) {
      this.canvas = canvas;
      this.rc = rough.canvas(this.canvas);

      this.canvas.addEventListener(EVENT.WHEEL, this.handleWheel, {
        passive: false,
      });
      this.canvas.addEventListener(EVENT.TOUCH_START, this.onTapStart);
      this.canvas.addEventListener(EVENT.TOUCH_END, this.onTapEnd);
    } else {
      this.canvas?.removeEventListener(EVENT.WHEEL, this.handleWheel);
      this.canvas?.removeEventListener(EVENT.TOUCH_START, this.onTapStart);
      this.canvas?.removeEventListener(EVENT.TOUCH_END, this.onTapEnd);
    }
  };

  private handleCanvasOnDrop = (event: React.DragEvent<HTMLCanvasElement>) => {
    const libraryShapes = event.dataTransfer.getData(
      "application/vnd.excalidrawlib+json",
    );
    if (libraryShapes !== "") {
      this.addElementsFromPasteOrLibrary(
        JSON.parse(libraryShapes),
        event.clientX,
        event.clientY,
      );
      return;
    }

    const file = event.dataTransfer?.files[0];
    if (
      file?.type === "application/json" ||
      file?.name.endsWith(".excalidraw")
    ) {
      this.setState({ isLoading: true });
      loadFromBlob(file, this.state)
        .then(({ elements, appState }) =>
          this.syncActionResult({
            elements,
            appState: {
              ...(appState || this.state),
              isLoading: false,
            },
            commitToHistory: false,
          }),
        )
        .catch((error) => {
          this.setState({ isLoading: false, errorMessage: error.message });
        });
    } else if (
      file?.type === "application/vnd.excalidrawlib+json" ||
      file?.name.endsWith(".excalidrawlib")
    ) {
      Library.importLibrary(file)
        .then(() => {
          this.setState({ isLibraryOpen: false });
        })
        .catch((error) =>
          this.setState({ isLoading: false, errorMessage: error.message }),
        );
    } else {
      this.setState({
        isLoading: false,
        errorMessage: t("alerts.couldNotLoadInvalidFile"),
      });
    }
  };

  private handleCanvasContextMenu = (
    event: React.PointerEvent<HTMLCanvasElement>,
  ) => {
    event.preventDefault();
    this.openContextMenu(event);
  };

  private openContextMenu = ({
    clientX,
    clientY,
  }: {
    clientX: number;
    clientY: number;
  }) => {
    const { x, y } = viewportCoordsToSceneCoords(
      { clientX, clientY },
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );

    const elements = this.scene.getElements();
    const element = this.getElementAtPosition(x, y);
    if (!element) {
      ContextMenu.push({
        options: [
          navigator.clipboard && {
            label: t("labels.paste"),
            action: () => this.pasteFromClipboard(null),
          },
          probablySupportsClipboardBlob &&
            elements.length > 0 && {
              label: t("labels.copyAsPng"),
              action: this.copyToClipboardAsPng,
            },
          probablySupportsClipboardWriteText &&
            elements.length > 0 && {
              label: t("labels.copyAsSvg"),
              action: this.copyToClipboardAsSvg,
            },
          ...this.actionManager.getContextMenuItems((action) =>
            CANVAS_ONLY_ACTIONS.includes(action.name),
          ),
          {
            label: t("labels.toggleGridMode"),
            action: this.toggleGridMode,
          },
        ],
        top: clientY,
        left: clientX,
      });
      return;
    }

    if (!this.state.selectedElementIds[element.id]) {
      this.setState({ selectedElementIds: { [element.id]: true } });
    }

    ContextMenu.push({
      options: [
        navigator.clipboard && {
          label: t("labels.copy"),
          action: this.copyAll,
        },
        navigator.clipboard && {
          label: t("labels.paste"),
          action: () => this.pasteFromClipboard(null),
        },
        probablySupportsClipboardBlob && {
          label: t("labels.copyAsPng"),
          action: this.copyToClipboardAsPng,
        },
        probablySupportsClipboardWriteText && {
          label: t("labels.copyAsSvg"),
          action: this.copyToClipboardAsSvg,
        },
        ...this.actionManager.getContextMenuItems(
          (action) => !CANVAS_ONLY_ACTIONS.includes(action.name),
        ),
      ],
      top: clientY,
      left: clientX,
    });
  };

  private handleWheel = withBatchedUpdates((event: WheelEvent) => {
    event.preventDefault();
    const { deltaX, deltaY } = event;
    const { selectedElementIds, previousSelectedElementIds } = this.state;

    // note that event.ctrlKey is necessary to handle pinch zooming
    if (event.metaKey || event.ctrlKey) {
      const sign = Math.sign(deltaY);
      const MAX_STEP = 10;
      let delta = Math.abs(deltaY);
      if (delta > MAX_STEP) {
        delta = MAX_STEP;
      }
      delta *= sign;
      if (Object.keys(previousSelectedElementIds).length !== 0) {
        setTimeout(() => {
          this.setState({
            selectedElementIds: previousSelectedElementIds,
            previousSelectedElementIds: {},
          });
        }, 1000);
      }
      this.setState(({ zoom }) => ({
        zoom: getNormalizedZoom(zoom - delta / 100),
        selectedElementIds: {},
        previousSelectedElementIds:
          Object.keys(selectedElementIds).length !== 0
            ? selectedElementIds
            : previousSelectedElementIds,
      }));
      return;
    }

    // scroll horizontally when shift pressed
    if (event.shiftKey) {
      this.setState(({ zoom, scrollX }) => ({
        // on Mac, shift+wheel tends to result in deltaX
        scrollX: normalizeScroll(scrollX - (deltaY || deltaX) / zoom),
      }));
      return;
    }

    this.setState(({ zoom, scrollX, scrollY }) => ({
      scrollX: normalizeScroll(scrollX - deltaX / zoom),
      scrollY: normalizeScroll(scrollY - deltaY / zoom),
    }));
  });

  private getTextWysiwygSnappedToCenterPosition(
    x: number,
    y: number,
    appState: AppState,
    canvas: HTMLCanvasElement | null,
    scale: number,
  ) {
    const elementClickedInside = getElementContainingPosition(
      this.scene
        .getElementsIncludingDeleted()
        .filter((element) => !isTextElement(element)),
      x,
      y,
    );
    if (elementClickedInside) {
      const elementCenterX =
        elementClickedInside.x + elementClickedInside.width / 2;
      const elementCenterY =
        elementClickedInside.y + elementClickedInside.height / 2;
      const distanceToCenter = Math.hypot(
        x - elementCenterX,
        y - elementCenterY,
      );
      const isSnappedToCenter =
        distanceToCenter < TEXT_TO_CENTER_SNAP_THRESHOLD;
      if (isSnappedToCenter) {
        const { x: viewportX, y: viewportY } = sceneCoordsToViewportCoords(
          { sceneX: elementCenterX, sceneY: elementCenterY },
          appState,
          canvas,
          scale,
        );
        return { viewportX, viewportY, elementCenterX, elementCenterY };
      }
    }
  }

  private savePointer = (x: number, y: number, button: "up" | "down") => {
    if (!x || !y) {
      return;
    }
    const pointer = viewportCoordsToSceneCoords(
      { clientX: x, clientY: y },
      this.state,
      this.canvas,
      window.devicePixelRatio,
    );

    if (isNaN(pointer.x) || isNaN(pointer.y)) {
      // sometimes the pointer goes off screen
      return;
    }
    this.portal.socket &&
      // do not broadcast when more than 1 pointer since that shows flickering on the other side
      gesture.pointers.size < 2 &&
      this.broadcastMouseLocation({
        pointer,
        button,
      });
  };

  private resetShouldCacheIgnoreZoomDebounced = debounce(() => {
    this.setState({ shouldCacheIgnoreZoom: false });
  }, 300);

  private getCanvasOffsets() {
    if (this.excalidrawRef?.current) {
      const parentElement = this.excalidrawRef.current.parentElement;
      const { left, top } = parentElement.getBoundingClientRect();
      return {
        offsetLeft: left,
        offsetTop: top,
      };
    }
    return {
      offsetLeft: 0,
      offsetTop: 0,
    };
  }
}

// -----------------------------------------------------------------------------
// TEST HOOKS
// -----------------------------------------------------------------------------

declare global {
  interface Window {
    h: {
      elements: readonly ExcalidrawElement[];
      state: AppState;
      setState: React.Component<any, AppState>["setState"];
      history: SceneHistory;
      app: InstanceType<typeof App>;
      library: ReturnType<typeof loadLibrary>;
    };
  }
}

if (
  process.env.NODE_ENV === ENV.TEST ||
  process.env.NODE_ENV === ENV.DEVELOPMENT
) {
  window.h = {} as Window["h"];

  Object.defineProperties(window.h, {
    elements: {
      get() {
        return this.app.scene.getElementsIncludingDeleted();
      },
      set(elements: ExcalidrawElement[]) {
        return this.app.scene.replaceAllElements(elements);
      },
    },
    history: {
      get: () => history,
    },
    library: {
      get: () => loadLibrary(),
    },
  });
}
export default App;