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

packages/utils/src/bbox.ts

@@ -0,0 +1,73 @@
+import {
+  vectorCross,
+  vectorFromPoint,
+  type GlobalPoint,
+  type LocalPoint,
+} from "@excalidraw/math";
+
+import type { Bounds } from "@excalidraw/element/bounds";
+
+export type LineSegment<P extends LocalPoint | GlobalPoint> = [P, P];
+
+export function getBBox<P extends LocalPoint | GlobalPoint>(
+  line: LineSegment<P>,
+): Bounds {
+  return [
+    Math.min(line[0][0], line[1][0]),
+    Math.min(line[0][1], line[1][1]),
+    Math.max(line[0][0], line[1][0]),
+    Math.max(line[0][1], line[1][1]),
+  ];
+}
+
+export function doBBoxesIntersect(a: Bounds, b: Bounds) {
+  return a[0] <= b[2] && a[2] >= b[0] && a[1] <= b[3] && a[3] >= b[1];
+}
+
+const EPSILON = 0.000001;
+
+export function isPointOnLine<P extends GlobalPoint | LocalPoint>(
+  l: LineSegment<P>,
+  p: P,
+) {
+  const p1 = vectorFromPoint(l[1], l[0]);
+  const p2 = vectorFromPoint(p, l[0]);
+
+  const r = vectorCross(p1, p2);
+
+  return Math.abs(r) < EPSILON;
+}
+
+export function isPointRightOfLine<P extends GlobalPoint | LocalPoint>(
+  l: LineSegment<P>,
+  p: P,
+) {
+  const p1 = vectorFromPoint(l[1], l[0]);
+  const p2 = vectorFromPoint(p, l[0]);
+
+  return vectorCross(p1, p2) < 0;
+}
+
+export function isLineSegmentTouchingOrCrossingLine<
+  P extends GlobalPoint | LocalPoint,
+>(a: LineSegment<P>, b: LineSegment<P>) {
+  return (
+    isPointOnLine(a, b[0]) ||
+    isPointOnLine(a, b[1]) ||
+    (isPointRightOfLine(a, b[0])
+      ? !isPointRightOfLine(a, b[1])
+      : isPointRightOfLine(a, b[1]))
+  );
+}
+
+// https://martin-thoma.com/how-to-check-if-two-line-segments-intersect/
+export function doLineSegmentsIntersect<P extends GlobalPoint | LocalPoint>(
+  a: LineSegment<P>,
+  b: LineSegment<P>,
+) {
+  return (
+    doBBoxesIntersect(getBBox(a), getBBox(b)) &&
+    isLineSegmentTouchingOrCrossingLine(a, b) &&
+    isLineSegmentTouchingOrCrossingLine(b, a)
+  );
+}

packages/utils/src/collision.ts

@@ -0,0 +1,135 @@
+import {
+  lineSegment,
+  pointFrom,
+  polygonIncludesPoint,
+  pointOnLineSegment,
+  pointOnPolygon,
+  polygonFromPoints,
+  type GlobalPoint,
+  type LocalPoint,
+  type Polygon,
+} from "@excalidraw/math";
+
+import type { Curve } from "@excalidraw/math";
+
+import { pointInEllipse, pointOnEllipse } from "./shape";
+
+import type { Polycurve, Polyline, GeometricShape } from "./shape";
+
+// check if the given point is considered on the given shape's border
+export const isPointOnShape = <Point extends GlobalPoint | LocalPoint>(
+  point: Point,
+  shape: GeometricShape<Point>,
+  tolerance = 0,
+) => {
+  // get the distance from the given point to the given element
+  // check if the distance is within the given epsilon range
+  switch (shape.type) {
+    case "polygon":
+      return pointOnPolygon(point, shape.data, tolerance);
+    case "ellipse":
+      return pointOnEllipse(point, shape.data, tolerance);
+    case "line":
+      return pointOnLineSegment(point, shape.data, tolerance);
+    case "polyline":
+      return pointOnPolyline(point, shape.data, tolerance);
+    case "curve":
+      return pointOnCurve(point, shape.data, tolerance);
+    case "polycurve":
+      return pointOnPolycurve(point, shape.data, tolerance);
+    default:
+      throw Error(`shape ${shape} is not implemented`);
+  }
+};
+
+// check if the given point is considered inside the element's border
+export const isPointInShape = <Point extends GlobalPoint | LocalPoint>(
+  point: Point,
+  shape: GeometricShape<Point>,
+) => {
+  switch (shape.type) {
+    case "polygon":
+      return polygonIncludesPoint(point, shape.data);
+    case "line":
+      return false;
+    case "curve":
+      return false;
+    case "ellipse":
+      return pointInEllipse(point, shape.data);
+    case "polyline": {
+      const polygon = polygonFromPoints(shape.data.flat());
+      return polygonIncludesPoint(point, polygon);
+    }
+    case "polycurve": {
+      return false;
+    }
+    default:
+      throw Error(`shape ${shape} is not implemented`);
+  }
+};
+
+// check if the given element is in the given bounds
+export const isPointInBounds = <Point extends GlobalPoint | LocalPoint>(
+  point: Point,
+  bounds: Polygon<Point>,
+) => {
+  return polygonIncludesPoint(point, bounds);
+};
+
+const pointOnPolycurve = <Point extends LocalPoint | GlobalPoint>(
+  point: Point,
+  polycurve: Polycurve<Point>,
+  tolerance: number,
+) => {
+  return polycurve.some((curve) => pointOnCurve(point, curve, tolerance));
+};
+
+const cubicBezierEquation = <Point extends LocalPoint | GlobalPoint>(
+  curve: Curve<Point>,
+) => {
+  const [p0, p1, p2, p3] = curve;
+  // B(t) = p0 * (1-t)^3 + 3p1 * t * (1-t)^2 + 3p2 * t^2 * (1-t) + p3 * t^3
+  return (t: number, idx: number) =>
+    Math.pow(1 - t, 3) * p3[idx] +
+    3 * t * Math.pow(1 - t, 2) * p2[idx] +
+    3 * Math.pow(t, 2) * (1 - t) * p1[idx] +
+    p0[idx] * Math.pow(t, 3);
+};
+
+const polyLineFromCurve = <Point extends LocalPoint | GlobalPoint>(
+  curve: Curve<Point>,
+  segments = 10,
+): Polyline<Point> => {
+  const equation = cubicBezierEquation(curve);
+  let startingPoint = [equation(0, 0), equation(0, 1)] as Point;
+  const lineSegments: Polyline<Point> = [];
+  let t = 0;
+  const increment = 1 / segments;
+
+  for (let i = 0; i < segments; i++) {
+    t += increment;
+    if (t <= 1) {
+      const nextPoint: Point = pointFrom(equation(t, 0), equation(t, 1));
+      lineSegments.push(lineSegment(startingPoint, nextPoint));
+      startingPoint = nextPoint;
+    }
+  }
+
+  return lineSegments;
+};
+
+export const pointOnCurve = <Point extends LocalPoint | GlobalPoint>(
+  point: Point,
+  curve: Curve<Point>,
+  threshold: number,
+) => {
+  return pointOnPolyline(point, polyLineFromCurve(curve), threshold);
+};
+
+export const pointOnPolyline = <Point extends LocalPoint | GlobalPoint>(
+  point: Point,
+  polyline: Polyline<Point>,
+  threshold = 10e-5,
+) => {
+  return polyline.some((line) => pointOnLineSegment(point, line, threshold));
+};

packages/utils/src/export.ts

@@ -0,0 +1,214 @@
+import { MIME_TYPES } from "@excalidraw/common";
+import { getDefaultAppState } from "@excalidraw/excalidraw/appState";
+import {
+  copyBlobToClipboardAsPng,
+  copyTextToSystemClipboard,
+  copyToClipboard,
+} from "@excalidraw/excalidraw/clipboard";
+import { encodePngMetadata } from "@excalidraw/excalidraw/data/image";
+import { serializeAsJSON } from "@excalidraw/excalidraw/data/json";
+import { restore } from "@excalidraw/excalidraw/data/restore";
+import {
+  exportToCanvas as _exportToCanvas,
+  exportToSvg as _exportToSvg,
+} from "@excalidraw/excalidraw/scene/export";
+
+import type {
+  ExcalidrawElement,
+  ExcalidrawFrameLikeElement,
+  NonDeleted,
+} from "@excalidraw/element/types";
+import type { AppState, BinaryFiles } from "@excalidraw/excalidraw/types";
+
+export { MIME_TYPES };
+
+type ExportOpts = {
+  elements: readonly NonDeleted<ExcalidrawElement>[];
+  appState?: Partial<Omit<AppState, "offsetTop" | "offsetLeft">>;
+  files: BinaryFiles | null;
+  maxWidthOrHeight?: number;
+  exportingFrame?: ExcalidrawFrameLikeElement | null;
+  getDimensions?: (
+    width: number,
+    height: number,
+  ) => { width: number; height: number; scale?: number };
+};
+
+export const exportToCanvas = ({
+  elements,
+  appState,
+  files,
+  maxWidthOrHeight,
+  getDimensions,
+  exportPadding,
+  exportingFrame,
+}: ExportOpts & {
+  exportPadding?: number;
+}) => {
+  const { elements: restoredElements, appState: restoredAppState } = restore(
+    { elements, appState },
+    null,
+    null,
+  );
+  const { exportBackground, viewBackgroundColor } = restoredAppState;
+  return _exportToCanvas(
+    restoredElements,
+    { ...restoredAppState, offsetTop: 0, offsetLeft: 0, width: 0, height: 0 },
+    files || {},
+    { exportBackground, exportPadding, viewBackgroundColor, exportingFrame },
+    (width: number, height: number) => {
+      const canvas = document.createElement("canvas");
+
+      if (maxWidthOrHeight) {
+        if (typeof getDimensions === "function") {
+          console.warn(
+            "`getDimensions()` is ignored when `maxWidthOrHeight` is supplied.",
+          );
+        }
+
+        const max = Math.max(width, height);
+
+        // if content is less then maxWidthOrHeight, fallback on supplied scale
+        const scale =
+          maxWidthOrHeight < max
+            ? maxWidthOrHeight / max
+            : appState?.exportScale ?? 1;
+
+        canvas.width = width * scale;
+        canvas.height = height * scale;
+
+        return {
+          canvas,
+          scale,
+        };
+      }
+
+      const ret = getDimensions?.(width, height) || { width, height };
+
+      canvas.width = ret.width;
+      canvas.height = ret.height;
+
+      return {
+        canvas,
+        scale: ret.scale ?? 1,
+      };
+    },
+  );
+};
+
+export const exportToBlob = async (
+  opts: ExportOpts & {
+    mimeType?: string;
+    quality?: number;
+    exportPadding?: number;
+  },
+): Promise<Blob> => {
+  let { mimeType = MIME_TYPES.png, quality } = opts;
+
+  if (mimeType === MIME_TYPES.png && typeof quality === "number") {
+    console.warn(`"quality" will be ignored for "${MIME_TYPES.png}" mimeType`);
+  }
+
+  // typo in MIME type (should be "jpeg")
+  if (mimeType === "image/jpg") {
+    mimeType = MIME_TYPES.jpg;
+  }
+
+  if (mimeType === MIME_TYPES.jpg && !opts.appState?.exportBackground) {
+    console.warn(
+      `Defaulting "exportBackground" to "true" for "${MIME_TYPES.jpg}" mimeType`,
+    );
+    opts = {
+      ...opts,
+      appState: { ...opts.appState, exportBackground: true },
+    };
+  }
+
+  const canvas = await exportToCanvas(opts);
+
+  quality = quality ? quality : /image\/jpe?g/.test(mimeType) ? 0.92 : 0.8;
+
+  return new Promise((resolve, reject) => {
+    canvas.toBlob(
+      async (blob) => {
+        if (!blob) {
+          return reject(new Error("couldn't export to blob"));
+        }
+        if (
+          blob &&
+          mimeType === MIME_TYPES.png &&
+          opts.appState?.exportEmbedScene
+        ) {
+          blob = await encodePngMetadata({
+            blob,
+            metadata: serializeAsJSON(
+              // NOTE as long as we're using the Scene hack, we need to ensure
+              // we pass the original, uncloned elements when serializing
+              // so that we keep ids stable
+              opts.elements,
+              opts.appState,
+              opts.files || {},
+              "local",
+            ),
+          });
+        }
+        resolve(blob);
+      },
+      mimeType,
+      quality,
+    );
+  });
+};
+
+export const exportToSvg = async ({
+  elements,
+  appState = getDefaultAppState(),
+  files = {},
+  exportPadding,
+  renderEmbeddables,
+  exportingFrame,
+  skipInliningFonts,
+  reuseImages,
+}: Omit<ExportOpts, "getDimensions"> & {
+  exportPadding?: number;
+  renderEmbeddables?: boolean;
+  skipInliningFonts?: true;
+  reuseImages?: boolean;
+}): Promise<SVGSVGElement> => {
+  const { elements: restoredElements, appState: restoredAppState } = restore(
+    { elements, appState },
+    null,
+    null,
+  );
+
+  const exportAppState = {
+    ...restoredAppState,
+    exportPadding,
+  };
+
+  return _exportToSvg(restoredElements, exportAppState, files, {
+    exportingFrame,
+    renderEmbeddables,
+    skipInliningFonts,
+    reuseImages,
+  });
+};
+
+export const exportToClipboard = async (
+  opts: ExportOpts & {
+    mimeType?: string;
+    quality?: number;
+    type: "png" | "svg" | "json";
+  },
+) => {
+  if (opts.type === "svg") {
+    const svg = await exportToSvg(opts);
+    await copyTextToSystemClipboard(svg.outerHTML);
+  } else if (opts.type === "png") {
+    await copyBlobToClipboardAsPng(exportToBlob(opts));
+  } else if (opts.type === "json") {
+    await copyToClipboard(opts.elements, opts.files);
+  } else {
+    throw new Error("Invalid export type");
+  }
+};

packages/utils/src/index.ts

@@ -0,0 +1,4 @@
+export * from "./export";
+export * from "./withinBounds";
+export * from "./bbox";
+export { getCommonBounds } from "@excalidraw/element/bounds";

packages/utils/src/shape.ts

@@ -0,0 +1,544 @@
+/**
+ * this file defines pure geometric shapes
+ *
+ * for instance, a cubic bezier curve is specified by its four control points and
+ * an ellipse is defined by its center, angle, semi major axis and semi minor axis
+ * (but in semi-width and semi-height so it's more relevant to Excalidraw)
+ *
+ * the idea with pure shapes is so that we can provide collision and other geoemtric methods not depending on
+ * the specifics of roughjs or elements in Excalidraw; instead, we can focus on the pure shapes themselves
+ *
+ * also included in this file are methods for converting an Excalidraw element or a Drawable from roughjs
+ * to pure shapes
+ */
+import { pointsOnBezierCurves } from "points-on-curve";
+
+import { invariant } from "@excalidraw/common";
+import {
+  curve,
+  lineSegment,
+  pointFrom,
+  pointDistance,
+  pointFromArray,
+  pointFromVector,
+  pointRotateRads,
+  polygon,
+  polygonFromPoints,
+  PRECISION,
+  segmentsIntersectAt,
+  vector,
+  vectorAdd,
+  vectorFromPoint,
+  vectorScale,
+  type GlobalPoint,
+  type LocalPoint,
+} from "@excalidraw/math";
+
+import { getElementAbsoluteCoords } from "@excalidraw/element/bounds";
+
+import type {
+  ElementsMap,
+  ExcalidrawBindableElement,
+  ExcalidrawDiamondElement,
+  ExcalidrawElement,
+  ExcalidrawEllipseElement,
+  ExcalidrawEmbeddableElement,
+  ExcalidrawFrameLikeElement,
+  ExcalidrawFreeDrawElement,
+  ExcalidrawIframeElement,
+  ExcalidrawImageElement,
+  ExcalidrawLinearElement,
+  ExcalidrawRectangleElement,
+  ExcalidrawSelectionElement,
+  ExcalidrawTextElement,
+} from "@excalidraw/element/types";
+import type { Curve, LineSegment, Polygon, Radians } from "@excalidraw/math";
+
+import type { Drawable, Op } from "roughjs/bin/core";
+
+// a polyline (made up term here) is a line consisting of other line segments
+// this corresponds to a straight line element in the editor but it could also
+// be used to model other elements
+export type Polyline<Point extends GlobalPoint | LocalPoint> =
+  LineSegment<Point>[];
+
+// a polycurve is a curve consisting of ther curves, this corresponds to a complex
+// curve on the canvas
+export type Polycurve<Point extends GlobalPoint | LocalPoint> = Curve<Point>[];
+
+// an ellipse is specified by its center, angle, and its major and minor axes
+// but for the sake of simplicity, we've used halfWidth and halfHeight instead
+// in replace of semi major and semi minor axes
+export type Ellipse<Point extends GlobalPoint | LocalPoint> = {
+  center: Point;
+  angle: Radians;
+  halfWidth: number;
+  halfHeight: number;
+};
+
+export type GeometricShape<Point extends GlobalPoint | LocalPoint> =
+  | {
+      type: "line";
+      data: LineSegment<Point>;
+    }
+  | {
+      type: "polygon";
+      data: Polygon<Point>;
+    }
+  | {
+      type: "curve";
+      data: Curve<Point>;
+    }
+  | {
+      type: "ellipse";
+      data: Ellipse<Point>;
+    }
+  | {
+      type: "polyline";
+      data: Polyline<Point>;
+    }
+  | {
+      type: "polycurve";
+      data: Polycurve<Point>;
+    };
+
+type RectangularElement =
+  | ExcalidrawRectangleElement
+  | ExcalidrawDiamondElement
+  | ExcalidrawFrameLikeElement
+  | ExcalidrawEmbeddableElement
+  | ExcalidrawImageElement
+  | ExcalidrawIframeElement
+  | ExcalidrawTextElement
+  | ExcalidrawSelectionElement;
+
+// polygon
+export const getPolygonShape = <Point extends GlobalPoint | LocalPoint>(
+  element: RectangularElement,
+): GeometricShape<Point> => {
+  const { angle, width, height, x, y } = element;
+
+  const cx = x + width / 2;
+  const cy = y + height / 2;
+
+  const center: Point = pointFrom(cx, cy);
+
+  let data: Polygon<Point>;
+
+  if (element.type === "diamond") {
+    data = polygon(
+      pointRotateRads(pointFrom(cx, y), center, angle),
+      pointRotateRads(pointFrom(x + width, cy), center, angle),
+      pointRotateRads(pointFrom(cx, y + height), center, angle),
+      pointRotateRads(pointFrom(x, cy), center, angle),
+    );
+  } else {
+    data = polygon(
+      pointRotateRads(pointFrom(x, y), center, angle),
+      pointRotateRads(pointFrom(x + width, y), center, angle),
+      pointRotateRads(pointFrom(x + width, y + height), center, angle),
+      pointRotateRads(pointFrom(x, y + height), center, angle),
+    );
+  }
+
+  return {
+    type: "polygon",
+    data,
+  };
+};
+
+// return the selection box for an element, possibly rotated as well
+export const getSelectionBoxShape = <Point extends GlobalPoint | LocalPoint>(
+  element: ExcalidrawElement,
+  elementsMap: ElementsMap,
+  padding = 10,
+) => {
+  let [x1, y1, x2, y2, cx, cy] = getElementAbsoluteCoords(
+    element,
+    elementsMap,
+    true,
+  );
+
+  x1 -= padding;
+  x2 += padding;
+  y1 -= padding;
+  y2 += padding;
+
+  //const angleInDegrees = angleToDegrees(element.angle);
+  const center = pointFrom(cx, cy);
+  const topLeft = pointRotateRads(pointFrom(x1, y1), center, element.angle);
+  const topRight = pointRotateRads(pointFrom(x2, y1), center, element.angle);
+  const bottomLeft = pointRotateRads(pointFrom(x1, y2), center, element.angle);
+  const bottomRight = pointRotateRads(pointFrom(x2, y2), center, element.angle);
+
+  return {
+    type: "polygon",
+    data: [topLeft, topRight, bottomRight, bottomLeft],
+  } as GeometricShape<Point>;
+};
+
+// ellipse
+export const getEllipseShape = <Point extends GlobalPoint | LocalPoint>(
+  element: ExcalidrawEllipseElement,
+): GeometricShape<Point> => {
+  const { width, height, angle, x, y } = element;
+
+  return {
+    type: "ellipse",
+    data: {
+      center: pointFrom(x + width / 2, y + height / 2),
+      angle,
+      halfWidth: width / 2,
+      halfHeight: height / 2,
+    },
+  };
+};
+
+export const getCurvePathOps = (shape: Drawable): Op[] => {
+  // NOTE (mtolmacs): Temporary fix for extremely large elements
+  if (!shape) {
+    return [];
+  }
+
+  for (const set of shape.sets) {
+    if (set.type === "path") {
+      return set.ops;
+    }
+  }
+  return shape.sets[0].ops;
+};
+
+// linear
+export const getCurveShape = <Point extends GlobalPoint | LocalPoint>(
+  roughShape: Drawable,
+  startingPoint: Point = pointFrom(0, 0),
+  angleInRadian: Radians,
+  center: Point,
+): GeometricShape<Point> => {
+  const transform = (p: Point): Point =>
+    pointRotateRads(
+      pointFrom(p[0] + startingPoint[0], p[1] + startingPoint[1]),
+      center,
+      angleInRadian,
+    );
+
+  const ops = getCurvePathOps(roughShape);
+  const polycurve: Polycurve<Point> = [];
+  let p0 = pointFrom<Point>(0, 0);
+
+  for (const op of ops) {
+    if (op.op === "move") {
+      const p = pointFromArray<Point>(op.data);
+      invariant(p != null, "Ops data is not a point");
+      p0 = transform(p);
+    }
+    if (op.op === "bcurveTo") {
+      const p1 = transform(pointFrom<Point>(op.data[0], op.data[1]));
+      const p2 = transform(pointFrom<Point>(op.data[2], op.data[3]));
+      const p3 = transform(pointFrom<Point>(op.data[4], op.data[5]));
+      polycurve.push(curve<Point>(p0, p1, p2, p3));
+      p0 = p3;
+    }
+  }
+
+  return {
+    type: "polycurve",
+    data: polycurve,
+  };
+};
+
+const polylineFromPoints = <Point extends GlobalPoint | LocalPoint>(
+  points: Point[],
+): Polyline<Point> => {
+  let previousPoint: Point = points[0];
+  const polyline: LineSegment<Point>[] = [];
+
+  for (let i = 1; i < points.length; i++) {
+    const nextPoint = points[i];
+    polyline.push(lineSegment<Point>(previousPoint, nextPoint));
+    previousPoint = nextPoint;
+  }
+
+  return polyline;
+};
+
+export const getFreedrawShape = <Point extends GlobalPoint | LocalPoint>(
+  element: ExcalidrawFreeDrawElement,
+  center: Point,
+  isClosed: boolean = false,
+): GeometricShape<Point> => {
+  const transform = (p: Point) =>
+    pointRotateRads(
+      pointFromVector(
+        vectorAdd(vectorFromPoint(p), vector(element.x, element.y)),
+      ),
+      center,
+      element.angle,
+    );
+
+  const polyline = polylineFromPoints(
+    element.points.map((p) => transform(p as Point)),
+  );
+
+  return (
+    isClosed
+      ? {
+          type: "polygon",
+          data: polygonFromPoints(polyline.flat()),
+        }
+      : {
+          type: "polyline",
+          data: polyline,
+        }
+  ) as GeometricShape<Point>;
+};
+
+export const getClosedCurveShape = <Point extends GlobalPoint | LocalPoint>(
+  element: ExcalidrawLinearElement,
+  roughShape: Drawable,
+  startingPoint: Point = pointFrom<Point>(0, 0),
+  angleInRadian: Radians,
+  center: Point,
+): GeometricShape<Point> => {
+  const transform = (p: Point) =>
+    pointRotateRads(
+      pointFrom(p[0] + startingPoint[0], p[1] + startingPoint[1]),
+      center,
+      angleInRadian,
+    );
+
+  if (element.roundness === null) {
+    return {
+      type: "polygon",
+      data: polygonFromPoints(
+        element.points.map((p) => transform(p as Point)) as Point[],
+      ),
+    };
+  }
+
+  const ops = getCurvePathOps(roughShape);
+
+  const points: Point[] = [];
+  let odd = false;
+  for (const operation of ops) {
+    if (operation.op === "move") {
+      odd = !odd;
+      if (odd) {
+        points.push(pointFrom(operation.data[0], operation.data[1]));
+      }
+    } else if (operation.op === "bcurveTo") {
+      if (odd) {
+        points.push(pointFrom(operation.data[0], operation.data[1]));
+        points.push(pointFrom(operation.data[2], operation.data[3]));
+        points.push(pointFrom(operation.data[4], operation.data[5]));
+      }
+    } else if (operation.op === "lineTo") {
+      if (odd) {
+        points.push(pointFrom(operation.data[0], operation.data[1]));
+      }
+    }
+  }
+
+  const polygonPoints = pointsOnBezierCurves(points, 10, 5).map((p) =>
+    transform(p as Point),
+  ) as Point[];
+
+  return {
+    type: "polygon",
+    data: polygonFromPoints<Point>(polygonPoints),
+  };
+};
+
+/**
+ * Determine intersection of a rectangular shaped element and a
+ * line segment.
+ *
+ * @param element The rectangular element to test against
+ * @param segment The segment intersecting the element
+ * @param gap Optional value to inflate the shape before testing
+ * @returns An array of intersections
+ */
+// TODO: Replace with final rounded rectangle code
+export const segmentIntersectRectangleElement = <
+  Point extends LocalPoint | GlobalPoint,
+>(
+  element: ExcalidrawBindableElement,
+  segment: LineSegment<Point>,
+  gap: number = 0,
+): Point[] => {
+  const bounds = [
+    element.x - gap,
+    element.y - gap,
+    element.x + element.width + gap,
+    element.y + element.height + gap,
+  ];
+  const center = pointFrom(
+    (bounds[0] + bounds[2]) / 2,
+    (bounds[1] + bounds[3]) / 2,
+  );
+
+  return [
+    lineSegment(
+      pointRotateRads(pointFrom(bounds[0], bounds[1]), center, element.angle),
+      pointRotateRads(pointFrom(bounds[2], bounds[1]), center, element.angle),
+    ),
+    lineSegment(
+      pointRotateRads(pointFrom(bounds[2], bounds[1]), center, element.angle),
+      pointRotateRads(pointFrom(bounds[2], bounds[3]), center, element.angle),
+    ),
+    lineSegment(
+      pointRotateRads(pointFrom(bounds[2], bounds[3]), center, element.angle),
+      pointRotateRads(pointFrom(bounds[0], bounds[3]), center, element.angle),
+    ),
+    lineSegment(
+      pointRotateRads(pointFrom(bounds[0], bounds[3]), center, element.angle),
+      pointRotateRads(pointFrom(bounds[0], bounds[1]), center, element.angle),
+    ),
+  ]
+    .map((s) => segmentsIntersectAt(segment, s))
+    .filter((i): i is Point => !!i);
+};
+
+const distanceToEllipse = <Point extends LocalPoint | GlobalPoint>(
+  p: Point,
+  ellipse: Ellipse<Point>,
+) => {
+  const { angle, halfWidth, halfHeight, center } = ellipse;
+  const a = halfWidth;
+  const b = halfHeight;
+  const translatedPoint = vectorAdd(
+    vectorFromPoint(p),
+    vectorScale(vectorFromPoint(center), -1),
+  );
+  const [rotatedPointX, rotatedPointY] = pointRotateRads(
+    pointFromVector(translatedPoint),
+    pointFrom(0, 0),
+    -angle as Radians,
+  );
+
+  const px = Math.abs(rotatedPointX);
+  const py = Math.abs(rotatedPointY);
+
+  let tx = 0.707;
+  let ty = 0.707;
+
+  for (let i = 0; i < 3; i++) {
+    const x = a * tx;
+    const y = b * ty;
+
+    const ex = ((a * a - b * b) * tx ** 3) / a;
+    const ey = ((b * b - a * a) * ty ** 3) / b;
+
+    const rx = x - ex;
+    const ry = y - ey;
+
+    const qx = px - ex;
+    const qy = py - ey;
+
+    const r = Math.hypot(ry, rx);
+    const q = Math.hypot(qy, qx);
+
+    tx = Math.min(1, Math.max(0, ((qx * r) / q + ex) / a));
+    ty = Math.min(1, Math.max(0, ((qy * r) / q + ey) / b));
+    const t = Math.hypot(ty, tx);
+    tx /= t;
+    ty /= t;
+  }
+
+  const [minX, minY] = [
+    a * tx * Math.sign(rotatedPointX),
+    b * ty * Math.sign(rotatedPointY),
+  ];
+
+  return pointDistance(
+    pointFrom(rotatedPointX, rotatedPointY),
+    pointFrom(minX, minY),
+  );
+};
+
+export const pointOnEllipse = <Point extends LocalPoint | GlobalPoint>(
+  point: Point,
+  ellipse: Ellipse<Point>,
+  threshold = PRECISION,
+) => {
+  return distanceToEllipse(point, ellipse) <= threshold;
+};
+
+export const pointInEllipse = <Point extends LocalPoint | GlobalPoint>(
+  p: Point,
+  ellipse: Ellipse<Point>,
+) => {
+  const { center, angle, halfWidth, halfHeight } = ellipse;
+  const translatedPoint = vectorAdd(
+    vectorFromPoint(p),
+    vectorScale(vectorFromPoint(center), -1),
+  );
+  const [rotatedPointX, rotatedPointY] = pointRotateRads(
+    pointFromVector(translatedPoint),
+    pointFrom(0, 0),
+    -angle as Radians,
+  );
+
+  return (
+    (rotatedPointX / halfWidth) * (rotatedPointX / halfWidth) +
+      (rotatedPointY / halfHeight) * (rotatedPointY / halfHeight) <=
+    1
+  );
+};
+
+export const ellipseAxes = <Point extends LocalPoint | GlobalPoint>(
+  ellipse: Ellipse<Point>,
+) => {
+  const widthGreaterThanHeight = ellipse.halfWidth > ellipse.halfHeight;
+
+  const majorAxis = widthGreaterThanHeight
+    ? ellipse.halfWidth * 2
+    : ellipse.halfHeight * 2;
+  const minorAxis = widthGreaterThanHeight
+    ? ellipse.halfHeight * 2
+    : ellipse.halfWidth * 2;
+
+  return {
+    majorAxis,
+    minorAxis,
+  };
+};
+
+export const ellipseFocusToCenter = <Point extends LocalPoint | GlobalPoint>(
+  ellipse: Ellipse<Point>,
+) => {
+  const { majorAxis, minorAxis } = ellipseAxes(ellipse);
+
+  return Math.sqrt(majorAxis ** 2 - minorAxis ** 2);
+};
+
+export const ellipseExtremes = <Point extends LocalPoint | GlobalPoint>(
+  ellipse: Ellipse<Point>,
+) => {
+  const { center, angle } = ellipse;
+  const { majorAxis, minorAxis } = ellipseAxes(ellipse);
+
+  const cos = Math.cos(angle);
+  const sin = Math.sin(angle);
+
+  const sqSum = majorAxis ** 2 + minorAxis ** 2;
+  const sqDiff = (majorAxis ** 2 - minorAxis ** 2) * Math.cos(2 * angle);
+
+  const yMax = Math.sqrt((sqSum - sqDiff) / 2);
+  const xAtYMax =
+    (yMax * sqSum * sin * cos) /
+    (majorAxis ** 2 * sin ** 2 + minorAxis ** 2 * cos ** 2);
+
+  const xMax = Math.sqrt((sqSum + sqDiff) / 2);
+  const yAtXMax =
+    (xMax * sqSum * sin * cos) /
+    (majorAxis ** 2 * cos ** 2 + minorAxis ** 2 * sin ** 2);
+  const centerVector = vectorFromPoint(center);
+
+  return [
+    vectorAdd(vector(xAtYMax, yMax), centerVector),
+    vectorAdd(vectorScale(vector(xAtYMax, yMax), -1), centerVector),
+    vectorAdd(vector(xMax, yAtXMax), centerVector),
+    vectorAdd(vector(xMax, yAtXMax), centerVector),
+  ];
+};

packages/utils/src/test-utils.ts

@@ -0,0 +1,33 @@
+import { diffStringsUnified } from "jest-diff";
+
+expect.extend({
+  toCloselyEqualPoints(received, expected, precision) {
+    if (!Array.isArray(received) || !Array.isArray(expected)) {
+      throw new Error("expected and received are not point arrays");
+    }
+
+    const COMPARE = 1 / Math.pow(10, precision || 2);
+    const pass = expected.every(
+      (point, idx) =>
+        Math.abs(received[idx]?.[0] - point[0]) < COMPARE &&
+        Math.abs(received[idx]?.[1] - point[1]) < COMPARE,
+    );
+
+    if (!pass) {
+      return {
+        message: () => ` The provided array of points are not close enough.
+
+${diffStringsUnified(
+  JSON.stringify(expected, undefined, 2),
+  JSON.stringify(received, undefined, 2),
+)}`,
+        pass: false,
+      };
+    }
+
+    return {
+      message: () => `expected ${received} to not be close to ${expected}`,
+      pass: true,
+    };
+  },
+});

packages/utils/src/withinBounds.ts

@@ -0,0 +1,229 @@
+import { arrayToMap } from "@excalidraw/common";
+import { getElementBounds } from "@excalidraw/element/bounds";
+import {
+  isArrowElement,
+  isExcalidrawElement,
+  isFreeDrawElement,
+  isLinearElement,
+  isTextElement,
+} from "@excalidraw/element/typeChecks";
+import {
+  rangeIncludesValue,
+  pointFrom,
+  pointRotateRads,
+  rangeInclusive,
+} from "@excalidraw/math";
+
+import type { Bounds } from "@excalidraw/element/bounds";
+import type {
+  ExcalidrawElement,
+  ExcalidrawFreeDrawElement,
+  ExcalidrawLinearElement,
+  NonDeletedExcalidrawElement,
+} from "@excalidraw/element/types";
+import type { LocalPoint } from "@excalidraw/math";
+
+type Element = NonDeletedExcalidrawElement;
+type Elements = readonly NonDeletedExcalidrawElement[];
+
+type Points = readonly LocalPoint[];
+
+/** @returns vertices relative to element's top-left [0,0] position  */
+const getNonLinearElementRelativePoints = (
+  element: Exclude<
+    Element,
+    ExcalidrawLinearElement | ExcalidrawFreeDrawElement
+  >,
+): [
+  TopLeft: LocalPoint,
+  TopRight: LocalPoint,
+  BottomRight: LocalPoint,
+  BottomLeft: LocalPoint,
+] => {
+  if (element.type === "diamond") {
+    return [
+      pointFrom(element.width / 2, 0),
+      pointFrom(element.width, element.height / 2),
+      pointFrom(element.width / 2, element.height),
+      pointFrom(0, element.height / 2),
+    ];
+  }
+  return [
+    pointFrom(0, 0),
+    pointFrom(0 + element.width, 0),
+    pointFrom(0 + element.width, element.height),
+    pointFrom(0, element.height),
+  ];
+};
+
+/** @returns vertices relative to element's top-left [0,0] position  */
+const getElementRelativePoints = (element: ExcalidrawElement): Points => {
+  if (isLinearElement(element) || isFreeDrawElement(element)) {
+    return element.points;
+  }
+  return getNonLinearElementRelativePoints(element);
+};
+
+const getMinMaxPoints = (points: Points) => {
+  const ret = points.reduce(
+    (limits, [x, y]) => {
+      limits.minY = Math.min(limits.minY, y);
+      limits.minX = Math.min(limits.minX, x);
+
+      limits.maxX = Math.max(limits.maxX, x);
+      limits.maxY = Math.max(limits.maxY, y);
+
+      return limits;
+    },
+    {
+      minX: Infinity,
+      minY: Infinity,
+      maxX: -Infinity,
+      maxY: -Infinity,
+      cx: 0,
+      cy: 0,
+    },
+  );
+
+  ret.cx = (ret.maxX + ret.minX) / 2;
+  ret.cy = (ret.maxY + ret.minY) / 2;
+
+  return ret;
+};
+
+const getRotatedBBox = (element: Element): Bounds => {
+  const points = getElementRelativePoints(element);
+
+  const { cx, cy } = getMinMaxPoints(points);
+  const centerPoint = pointFrom<LocalPoint>(cx, cy);
+
+  const rotatedPoints = points.map((p) =>
+    pointRotateRads(p, centerPoint, element.angle),
+  );
+  const { minX, minY, maxX, maxY } = getMinMaxPoints(rotatedPoints);
+
+  return [
+    minX + element.x,
+    minY + element.y,
+    maxX + element.x,
+    maxY + element.y,
+  ];
+};
+
+export const isElementInsideBBox = (
+  element: Element,
+  bbox: Bounds,
+  eitherDirection = false,
+): boolean => {
+  const elementBBox = getRotatedBBox(element);
+
+  const elementInsideBbox =
+    bbox[0] <= elementBBox[0] &&
+    bbox[2] >= elementBBox[2] &&
+    bbox[1] <= elementBBox[1] &&
+    bbox[3] >= elementBBox[3];
+
+  if (!eitherDirection) {
+    return elementInsideBbox;
+  }
+
+  if (elementInsideBbox) {
+    return true;
+  }
+
+  return (
+    elementBBox[0] <= bbox[0] &&
+    elementBBox[2] >= bbox[2] &&
+    elementBBox[1] <= bbox[1] &&
+    elementBBox[3] >= bbox[3]
+  );
+};
+
+export const elementPartiallyOverlapsWithOrContainsBBox = (
+  element: Element,
+  bbox: Bounds,
+): boolean => {
+  const elementBBox = getRotatedBBox(element);
+
+  return (
+    (rangeIncludesValue(elementBBox[0], rangeInclusive(bbox[0], bbox[2])) ||
+      rangeIncludesValue(
+        bbox[0],
+        rangeInclusive(elementBBox[0], elementBBox[2]),
+      )) &&
+    (rangeIncludesValue(elementBBox[1], rangeInclusive(bbox[1], bbox[3])) ||
+      rangeIncludesValue(
+        bbox[1],
+        rangeInclusive(elementBBox[1], elementBBox[3]),
+      ))
+  );
+};
+
+export const elementsOverlappingBBox = ({
+  elements,
+  bounds,
+  type,
+  errorMargin = 0,
+}: {
+  elements: Elements;
+  bounds: Bounds | ExcalidrawElement;
+  /** safety offset. Defaults to 0. */
+  errorMargin?: number;
+  /**
+   * - overlap: elements overlapping or inside bounds
+   * - contain: elements inside bounds or bounds inside elements
+   * - inside: elements inside bounds
+   **/
+  type: "overlap" | "contain" | "inside";
+}) => {
+  if (isExcalidrawElement(bounds)) {
+    bounds = getElementBounds(bounds, arrayToMap(elements));
+  }
+  const adjustedBBox: Bounds = [
+    bounds[0] - errorMargin,
+    bounds[1] - errorMargin,
+    bounds[2] + errorMargin,
+    bounds[3] + errorMargin,
+  ];
+
+  const includedElementSet = new Set<string>();
+
+  for (const element of elements) {
+    if (includedElementSet.has(element.id)) {
+      continue;
+    }
+
+    const isOverlaping =
+      type === "overlap"
+        ? elementPartiallyOverlapsWithOrContainsBBox(element, adjustedBBox)
+        : type === "inside"
+        ? isElementInsideBBox(element, adjustedBBox)
+        : isElementInsideBBox(element, adjustedBBox, true);
+
+    if (isOverlaping) {
+      includedElementSet.add(element.id);
+
+      if (element.boundElements) {
+        for (const boundElement of element.boundElements) {
+          includedElementSet.add(boundElement.id);
+        }
+      }
+
+      if (isTextElement(element) && element.containerId) {
+        includedElementSet.add(element.containerId);
+      }
+
+      if (isArrowElement(element)) {
+        if (element.startBinding) {
+          includedElementSet.add(element.startBinding.elementId);
+        }
+
+        if (element.endBinding) {
+          includedElementSet.add(element.endBinding?.elementId);
+        }
+      }
+    }
+  }
+
+  return elements.filter((element) => includedElementSet.has(element.id));
+};