success/packages/excalidraw/element/bounds.ts

import {
  ExcalidrawElement,
  ExcalidrawLinearElement,
  Arrowhead,
  ExcalidrawFreeDrawElement,
  NonDeleted,
  ExcalidrawTextElementWithContainer,
} from "./types";
import { distance2d, rotate, rotatePoint } from "../math";
import rough from "roughjs/bin/rough";
import { Drawable, Op } from "roughjs/bin/core";
import { AppState, Point } from "../types";
import { generateRoughOptions } from "../scene/Shape";
import {
  isArrowElement,
  isBoundToContainer,
  isFreeDrawElement,
  isLinearElement,
  isTextElement,
} from "./typeChecks";
import { rescalePoints } from "../points";
import { getBoundTextElement, getContainerElement } from "./textElement";
import { LinearElementEditor } from "./linearElementEditor";
import { Mutable } from "../utility-types";
import { ShapeCache } from "../scene/ShapeCache";
import Scene from "../scene/Scene";

export type RectangleBox = {
  x: number;
  y: number;
  width: number;
  height: number;
  angle: number;
};

type MaybeQuadraticSolution = [number | null, number | null] | false;

/**
 * x and y position of top left corner, x and y position of bottom right corner
 */
export type Bounds = readonly [
  minX: number,
  minY: number,
  maxX: number,
  maxY: number,
];

export type SceneBounds = readonly [
  sceneX: number,
  sceneY: number,
  sceneX2: number,
  sceneY2: number,
];

export class ElementBounds {
  private static boundsCache = new WeakMap<
    ExcalidrawElement,
    {
      bounds: Bounds;
      version: ExcalidrawElement["version"];
    }
  >();

  static getBounds(element: ExcalidrawElement) {
    const cachedBounds = ElementBounds.boundsCache.get(element);

    if (
      cachedBounds?.version &&
      cachedBounds.version === element.version &&
      // we don't invalidate cache when we update containers and not labels,
      // which is causing problems down the line. Fix TBA.
      !isBoundToContainer(element)
    ) {
      return cachedBounds.bounds;
    }

    const bounds = ElementBounds.calculateBounds(element);

    // hack to ensure that downstream checks could retrieve element Scene
    // so as to have correctly calculated bounds
    // FIXME remove when we get rid of all the id:Scene / element:Scene mapping
    const shouldCache = Scene.getScene(element);

    if (shouldCache) {
      ElementBounds.boundsCache.set(element, {
        version: element.version,
        bounds,
      });
    }

    return bounds;
  }

  private static calculateBounds(element: ExcalidrawElement): Bounds {
    let bounds: Bounds;

    const [x1, y1, x2, y2, cx, cy] = getElementAbsoluteCoords(element);

    if (isFreeDrawElement(element)) {
      const [minX, minY, maxX, maxY] = getBoundsFromPoints(
        element.points.map(([x, y]) =>
          rotate(x, y, cx - element.x, cy - element.y, element.angle),
        ),
      );

      return [
        minX + element.x,
        minY + element.y,
        maxX + element.x,
        maxY + element.y,
      ];
    } else if (isLinearElement(element)) {
      bounds = getLinearElementRotatedBounds(element, cx, cy);
    } else if (element.type === "diamond") {
      const [x11, y11] = rotate(cx, y1, cx, cy, element.angle);
      const [x12, y12] = rotate(cx, y2, cx, cy, element.angle);
      const [x22, y22] = rotate(x1, cy, cx, cy, element.angle);
      const [x21, y21] = rotate(x2, cy, cx, cy, element.angle);
      const minX = Math.min(x11, x12, x22, x21);
      const minY = Math.min(y11, y12, y22, y21);
      const maxX = Math.max(x11, x12, x22, x21);
      const maxY = Math.max(y11, y12, y22, y21);
      bounds = [minX, minY, maxX, maxY];
    } else if (element.type === "ellipse") {
      const w = (x2 - x1) / 2;
      const h = (y2 - y1) / 2;
      const cos = Math.cos(element.angle);
      const sin = Math.sin(element.angle);
      const ww = Math.hypot(w * cos, h * sin);
      const hh = Math.hypot(h * cos, w * sin);
      bounds = [cx - ww, cy - hh, cx + ww, cy + hh];
    } else {
      const [x11, y11] = rotate(x1, y1, cx, cy, element.angle);
      const [x12, y12] = rotate(x1, y2, cx, cy, element.angle);
      const [x22, y22] = rotate(x2, y2, cx, cy, element.angle);
      const [x21, y21] = rotate(x2, y1, cx, cy, element.angle);
      const minX = Math.min(x11, x12, x22, x21);
      const minY = Math.min(y11, y12, y22, y21);
      const maxX = Math.max(x11, x12, x22, x21);
      const maxY = Math.max(y11, y12, y22, y21);
      bounds = [minX, minY, maxX, maxY];
    }

    return bounds;
  }
}

// Scene -> Scene coords, but in x1,x2,y1,y2 format.
//
// If the element is created from right to left, the width is going to be negative
// This set of functions retrieves the absolute position of the 4 points.
export const getElementAbsoluteCoords = (
  element: ExcalidrawElement,
  includeBoundText: boolean = false,
): [number, number, number, number, number, number] => {
  if (isFreeDrawElement(element)) {
    return getFreeDrawElementAbsoluteCoords(element);
  } else if (isLinearElement(element)) {
    return LinearElementEditor.getElementAbsoluteCoords(
      element,
      includeBoundText,
    );
  } else if (isTextElement(element)) {
    const container = getContainerElement(element);
    if (isArrowElement(container)) {
      const coords = LinearElementEditor.getBoundTextElementPosition(
        container,
        element as ExcalidrawTextElementWithContainer,
      );
      return [
        coords.x,
        coords.y,
        coords.x + element.width,
        coords.y + element.height,
        coords.x + element.width / 2,
        coords.y + element.height / 2,
      ];
    }
  }
  return [
    element.x,
    element.y,
    element.x + element.width,
    element.y + element.height,
    element.x + element.width / 2,
    element.y + element.height / 2,
  ];
};

/*
 * for a given element, `getElementLineSegments` returns line segments
 * that can be used for visual collision detection (useful for frames)
 * as opposed to bounding box collision detection
 */
export const getElementLineSegments = (
  element: ExcalidrawElement,
): [Point, Point][] => {
  const [x1, y1, x2, y2, cx, cy] = getElementAbsoluteCoords(element);

  const center: Point = [cx, cy];

  if (isLinearElement(element) || isFreeDrawElement(element)) {
    const segments: [Point, Point][] = [];

    let i = 0;

    while (i < element.points.length - 1) {
      segments.push([
        rotatePoint(
          [
            element.points[i][0] + element.x,
            element.points[i][1] + element.y,
          ] as Point,
          center,
          element.angle,
        ),
        rotatePoint(
          [
            element.points[i + 1][0] + element.x,
            element.points[i + 1][1] + element.y,
          ] as Point,
          center,
          element.angle,
        ),
      ]);
      i++;
    }

    return segments;
  }

  const [nw, ne, sw, se, n, s, w, e] = (
    [
      [x1, y1],
      [x2, y1],
      [x1, y2],
      [x2, y2],
      [cx, y1],
      [cx, y2],
      [x1, cy],
      [x2, cy],
    ] as Point[]
  ).map((point) => rotatePoint(point, center, element.angle));

  if (element.type === "diamond") {
    return [
      [n, w],
      [n, e],
      [s, w],
      [s, e],
    ];
  }

  if (element.type === "ellipse") {
    return [
      [n, w],
      [n, e],
      [s, w],
      [s, e],
      [n, w],
      [n, e],
      [s, w],
      [s, e],
    ];
  }

  return [
    [nw, ne],
    [sw, se],
    [nw, sw],
    [ne, se],
    [nw, e],
    [sw, e],
    [ne, w],
    [se, w],
  ];
};

/**
 * Scene -> Scene coords, but in x1,x2,y1,y2 format.
 *
 * Rectangle here means any rectangular frame, not an excalidraw element.
 */
export const getRectangleBoxAbsoluteCoords = (boxSceneCoords: RectangleBox) => {
  return [
    boxSceneCoords.x,
    boxSceneCoords.y,
    boxSceneCoords.x + boxSceneCoords.width,
    boxSceneCoords.y + boxSceneCoords.height,
    boxSceneCoords.x + boxSceneCoords.width / 2,
    boxSceneCoords.y + boxSceneCoords.height / 2,
  ];
};

export const pointRelativeTo = (
  element: ExcalidrawElement,
  absoluteCoords: Point,
): Point => {
  return [absoluteCoords[0] - element.x, absoluteCoords[1] - element.y];
};

export const getDiamondPoints = (element: ExcalidrawElement) => {
  // Here we add +1 to avoid these numbers to be 0
  // otherwise rough.js will throw an error complaining about it
  const topX = Math.floor(element.width / 2) + 1;
  const topY = 0;
  const rightX = element.width;
  const rightY = Math.floor(element.height / 2) + 1;
  const bottomX = topX;
  const bottomY = element.height;
  const leftX = 0;
  const leftY = rightY;

  return [topX, topY, rightX, rightY, bottomX, bottomY, leftX, leftY];
};

export const getCurvePathOps = (shape: Drawable): Op[] => {
  for (const set of shape.sets) {
    if (set.type === "path") {
      return set.ops;
    }
  }
  return shape.sets[0].ops;
};

// reference: https://eliot-jones.com/2019/12/cubic-bezier-curve-bounding-boxes
const getBezierValueForT = (
  t: number,
  p0: number,
  p1: number,
  p2: number,
  p3: number,
) => {
  const oneMinusT = 1 - t;
  return (
    Math.pow(oneMinusT, 3) * p0 +
    3 * Math.pow(oneMinusT, 2) * t * p1 +
    3 * oneMinusT * Math.pow(t, 2) * p2 +
    Math.pow(t, 3) * p3
  );
};

const solveQuadratic = (
  p0: number,
  p1: number,
  p2: number,
  p3: number,
): MaybeQuadraticSolution => {
  const i = p1 - p0;
  const j = p2 - p1;
  const k = p3 - p2;

  const a = 3 * i - 6 * j + 3 * k;
  const b = 6 * j - 6 * i;
  const c = 3 * i;

  const sqrtPart = b * b - 4 * a * c;
  const hasSolution = sqrtPart >= 0;

  if (!hasSolution) {
    return false;
  }

  let s1 = null;
  let s2 = null;

  let t1 = Infinity;
  let t2 = Infinity;

  if (a === 0) {
    t1 = t2 = -c / b;
  } else {
    t1 = (-b + Math.sqrt(sqrtPart)) / (2 * a);
    t2 = (-b - Math.sqrt(sqrtPart)) / (2 * a);
  }

  if (t1 >= 0 && t1 <= 1) {
    s1 = getBezierValueForT(t1, p0, p1, p2, p3);
  }

  if (t2 >= 0 && t2 <= 1) {
    s2 = getBezierValueForT(t2, p0, p1, p2, p3);
  }

  return [s1, s2];
};

const getCubicBezierCurveBound = (
  p0: Point,
  p1: Point,
  p2: Point,
  p3: Point,
): Bounds => {
  const solX = solveQuadratic(p0[0], p1[0], p2[0], p3[0]);
  const solY = solveQuadratic(p0[1], p1[1], p2[1], p3[1]);

  let minX = Math.min(p0[0], p3[0]);
  let maxX = Math.max(p0[0], p3[0]);

  if (solX) {
    const xs = solX.filter((x) => x !== null) as number[];
    minX = Math.min(minX, ...xs);
    maxX = Math.max(maxX, ...xs);
  }

  let minY = Math.min(p0[1], p3[1]);
  let maxY = Math.max(p0[1], p3[1]);
  if (solY) {
    const ys = solY.filter((y) => y !== null) as number[];
    minY = Math.min(minY, ...ys);
    maxY = Math.max(maxY, ...ys);
  }
  return [minX, minY, maxX, maxY];
};

export const getMinMaxXYFromCurvePathOps = (
  ops: Op[],
  transformXY?: (x: number, y: number) => [number, number],
): Bounds => {
  let currentP: Point = [0, 0];

  const { minX, minY, maxX, maxY } = ops.reduce(
    (limits, { op, data }) => {
      // There are only four operation types:
      // move, bcurveTo, lineTo, and curveTo
      if (op === "move") {
        // change starting point
        currentP = data as unknown as Point;
        // move operation does not draw anything; so, it always
        // returns false
      } else if (op === "bcurveTo") {
        const _p1 = [data[0], data[1]] as Point;
        const _p2 = [data[2], data[3]] as Point;
        const _p3 = [data[4], data[5]] as Point;

        const p1 = transformXY ? transformXY(..._p1) : _p1;
        const p2 = transformXY ? transformXY(..._p2) : _p2;
        const p3 = transformXY ? transformXY(..._p3) : _p3;

        const p0 = transformXY ? transformXY(...currentP) : currentP;
        currentP = _p3;

        const [minX, minY, maxX, maxY] = getCubicBezierCurveBound(
          p0,
          p1,
          p2,
          p3,
        );

        limits.minX = Math.min(limits.minX, minX);
        limits.minY = Math.min(limits.minY, minY);

        limits.maxX = Math.max(limits.maxX, maxX);
        limits.maxY = Math.max(limits.maxY, maxY);
      } else if (op === "lineTo") {
        // TODO: Implement this
      } else if (op === "qcurveTo") {
        // TODO: Implement this
      }
      return limits;
    },
    { minX: Infinity, minY: Infinity, maxX: -Infinity, maxY: -Infinity },
  );
  return [minX, minY, maxX, maxY];
};

export const getBoundsFromPoints = (
  points: ExcalidrawFreeDrawElement["points"],
): Bounds => {
  let minX = Infinity;
  let minY = Infinity;
  let maxX = -Infinity;
  let maxY = -Infinity;

  for (const [x, y] of points) {
    minX = Math.min(minX, x);
    minY = Math.min(minY, y);
    maxX = Math.max(maxX, x);
    maxY = Math.max(maxY, y);
  }

  return [minX, minY, maxX, maxY];
};

const getFreeDrawElementAbsoluteCoords = (
  element: ExcalidrawFreeDrawElement,
): [number, number, number, number, number, number] => {
  const [minX, minY, maxX, maxY] = getBoundsFromPoints(element.points);
  const x1 = minX + element.x;
  const y1 = minY + element.y;
  const x2 = maxX + element.x;
  const y2 = maxY + element.y;
  return [x1, y1, x2, y2, (x1 + x2) / 2, (y1 + y2) / 2];
};

/** @returns number in pixels */
export const getArrowheadSize = (arrowhead: Arrowhead): number => {
  switch (arrowhead) {
    case "arrow":
      return 25;
    case "diamond":
    case "diamond_outline":
      return 12;
    default:
      return 15;
  }
};

/** @returns number in degrees */
export const getArrowheadAngle = (arrowhead: Arrowhead): number => {
  switch (arrowhead) {
    case "bar":
      return 90;
    case "arrow":
      return 20;
    default:
      return 25;
  }
};

export const getArrowheadPoints = (
  element: ExcalidrawLinearElement,
  shape: Drawable[],
  position: "start" | "end",
  arrowhead: Arrowhead,
) => {
  const ops = getCurvePathOps(shape[0]);
  if (ops.length < 1) {
    return null;
  }

  // The index of the bCurve operation to examine.
  const index = position === "start" ? 1 : ops.length - 1;

  const data = ops[index].data;
  const p3 = [data[4], data[5]] as Point;
  const p2 = [data[2], data[3]] as Point;
  const p1 = [data[0], data[1]] as Point;

  // We need to find p0 of the bezier curve.
  // It is typically the last point of the previous
  // curve; it can also be the position of moveTo operation.
  const prevOp = ops[index - 1];
  let p0: Point = [0, 0];
  if (prevOp.op === "move") {
    p0 = prevOp.data as unknown as Point;
  } else if (prevOp.op === "bcurveTo") {
    p0 = [prevOp.data[4], prevOp.data[5]];
  }

  // B(t) = p0 * (1-t)^3 + 3p1 * t * (1-t)^2 + 3p2 * t^2 * (1-t) + p3 * t^3
  const equation = (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);

  // Ee know the last point of the arrow (or the first, if start arrowhead).
  const [x2, y2] = position === "start" ? p0 : p3;

  // By using cubic bezier equation (B(t)) and the given parameters,
  // we calculate a point that is closer to the last point.
  // The value 0.3 is chosen arbitrarily and it works best for all
  // the tested cases.
  const [x1, y1] = [equation(0.3, 0), equation(0.3, 1)];

  // Find the normalized direction vector based on the
  // previously calculated points.
  const distance = Math.hypot(x2 - x1, y2 - y1);
  const nx = (x2 - x1) / distance;
  const ny = (y2 - y1) / distance;

  const size = getArrowheadSize(arrowhead);

  let length = 0;

  {
    // Length for -> arrows is based on the length of the last section
    const [cx, cy] =
      position === "end"
        ? element.points[element.points.length - 1]
        : element.points[0];
    const [px, py] =
      element.points.length > 1
        ? position === "end"
          ? element.points[element.points.length - 2]
          : element.points[1]
        : [0, 0];

    length = Math.hypot(cx - px, cy - py);
  }

  // Scale down the arrowhead until we hit a certain size so that it doesn't look weird.
  // This value is selected by minimizing a minimum size with the last segment of the arrowhead
  const lengthMultiplier =
    arrowhead === "diamond" || arrowhead === "diamond_outline" ? 0.25 : 0.5;
  const minSize = Math.min(size, length * lengthMultiplier);
  const xs = x2 - nx * minSize;
  const ys = y2 - ny * minSize;

  if (
    arrowhead === "dot" ||
    arrowhead === "circle" ||
    arrowhead === "circle_outline"
  ) {
    const diameter = Math.hypot(ys - y2, xs - x2) + element.strokeWidth - 2;
    return [x2, y2, diameter];
  }

  const angle = getArrowheadAngle(arrowhead);

  // Return points
  const [x3, y3] = rotate(xs, ys, x2, y2, (-angle * Math.PI) / 180);
  const [x4, y4] = rotate(xs, ys, x2, y2, (angle * Math.PI) / 180);

  if (arrowhead === "diamond" || arrowhead === "diamond_outline") {
    // point opposite to the arrowhead point
    let ox;
    let oy;

    if (position === "start") {
      const [px, py] = element.points.length > 1 ? element.points[1] : [0, 0];

      [ox, oy] = rotate(
        x2 + minSize * 2,
        y2,
        x2,
        y2,
        Math.atan2(py - y2, px - x2),
      );
    } else {
      const [px, py] =
        element.points.length > 1
          ? element.points[element.points.length - 2]
          : [0, 0];

      [ox, oy] = rotate(
        x2 - minSize * 2,
        y2,
        x2,
        y2,
        Math.atan2(y2 - py, x2 - px),
      );
    }

    return [x2, y2, x3, y3, ox, oy, x4, y4];
  }

  return [x2, y2, x3, y3, x4, y4];
};

const generateLinearElementShape = (
  element: ExcalidrawLinearElement,
): Drawable => {
  const generator = rough.generator();
  const options = generateRoughOptions(element);

  const method = (() => {
    if (element.roundness) {
      return "curve";
    }
    if (options.fill) {
      return "polygon";
    }
    return "linearPath";
  })();

  return generator[method](element.points as Mutable<Point>[], options);
};

const getLinearElementRotatedBounds = (
  element: ExcalidrawLinearElement,
  cx: number,
  cy: number,
): Bounds => {
  if (element.points.length < 2) {
    const [pointX, pointY] = element.points[0];
    const [x, y] = rotate(
      element.x + pointX,
      element.y + pointY,
      cx,
      cy,
      element.angle,
    );

    let coords: Bounds = [x, y, x, y];
    const boundTextElement = getBoundTextElement(element);
    if (boundTextElement) {
      const coordsWithBoundText = LinearElementEditor.getMinMaxXYWithBoundText(
        element,
        [x, y, x, y],
        boundTextElement,
      );
      coords = [
        coordsWithBoundText[0],
        coordsWithBoundText[1],
        coordsWithBoundText[2],
        coordsWithBoundText[3],
      ];
    }
    return coords;
  }

  // first element is always the curve
  const cachedShape = ShapeCache.get(element)?.[0];
  const shape = cachedShape ?? generateLinearElementShape(element);
  const ops = getCurvePathOps(shape);
  const transformXY = (x: number, y: number) =>
    rotate(element.x + x, element.y + y, cx, cy, element.angle);
  const res = getMinMaxXYFromCurvePathOps(ops, transformXY);
  let coords: Bounds = [res[0], res[1], res[2], res[3]];
  const boundTextElement = getBoundTextElement(element);
  if (boundTextElement) {
    const coordsWithBoundText = LinearElementEditor.getMinMaxXYWithBoundText(
      element,
      coords,
      boundTextElement,
    );
    coords = [
      coordsWithBoundText[0],
      coordsWithBoundText[1],
      coordsWithBoundText[2],
      coordsWithBoundText[3],
    ];
  }
  return coords;
};

export const getElementBounds = (element: ExcalidrawElement): Bounds => {
  return ElementBounds.getBounds(element);
};
export const getCommonBounds = (
  elements: readonly ExcalidrawElement[],
): Bounds => {
  if (!elements.length) {
    return [0, 0, 0, 0];
  }

  let minX = Infinity;
  let maxX = -Infinity;
  let minY = Infinity;
  let maxY = -Infinity;

  elements.forEach((element) => {
    const [x1, y1, x2, y2] = getElementBounds(element);
    minX = Math.min(minX, x1);
    minY = Math.min(minY, y1);
    maxX = Math.max(maxX, x2);
    maxY = Math.max(maxY, y2);
  });

  return [minX, minY, maxX, maxY];
};

export const getDraggedElementsBounds = (
  elements: ExcalidrawElement[],
  dragOffset: { x: number; y: number },
) => {
  const [minX, minY, maxX, maxY] = getCommonBounds(elements);
  return [
    minX + dragOffset.x,
    minY + dragOffset.y,
    maxX + dragOffset.x,
    maxY + dragOffset.y,
  ];
};

export const getResizedElementAbsoluteCoords = (
  element: ExcalidrawElement,
  nextWidth: number,
  nextHeight: number,
  normalizePoints: boolean,
): Bounds => {
  if (!(isLinearElement(element) || isFreeDrawElement(element))) {
    return [
      element.x,
      element.y,
      element.x + nextWidth,
      element.y + nextHeight,
    ];
  }

  const points = rescalePoints(
    0,
    nextWidth,
    rescalePoints(1, nextHeight, element.points, normalizePoints),
    normalizePoints,
  );

  let bounds: Bounds;

  if (isFreeDrawElement(element)) {
    // Free Draw
    bounds = getBoundsFromPoints(points);
  } else {
    // Line
    const gen = rough.generator();
    const curve = !element.roundness
      ? gen.linearPath(
          points as [number, number][],
          generateRoughOptions(element),
        )
      : gen.curve(points as [number, number][], generateRoughOptions(element));

    const ops = getCurvePathOps(curve);
    bounds = getMinMaxXYFromCurvePathOps(ops);
  }

  const [minX, minY, maxX, maxY] = bounds;
  return [
    minX + element.x,
    minY + element.y,
    maxX + element.x,
    maxY + element.y,
  ];
};

export const getElementPointsCoords = (
  element: ExcalidrawLinearElement,
  points: readonly (readonly [number, number])[],
): Bounds => {
  // This might be computationally heavey
  const gen = rough.generator();
  const curve =
    element.roundness == null
      ? gen.linearPath(
          points as [number, number][],
          generateRoughOptions(element),
        )
      : gen.curve(points as [number, number][], generateRoughOptions(element));
  const ops = getCurvePathOps(curve);
  const [minX, minY, maxX, maxY] = getMinMaxXYFromCurvePathOps(ops);
  return [
    minX + element.x,
    minY + element.y,
    maxX + element.x,
    maxY + element.y,
  ];
};

export const getClosestElementBounds = (
  elements: readonly ExcalidrawElement[],
  from: { x: number; y: number },
): Bounds => {
  if (!elements.length) {
    return [0, 0, 0, 0];
  }

  let minDistance = Infinity;
  let closestElement = elements[0];

  elements.forEach((element) => {
    const [x1, y1, x2, y2] = getElementBounds(element);
    const distance = distance2d((x1 + x2) / 2, (y1 + y2) / 2, from.x, from.y);

    if (distance < minDistance) {
      minDistance = distance;
      closestElement = element;
    }
  });

  return getElementBounds(closestElement);
};

export interface BoundingBox {
  minX: number;
  minY: number;
  maxX: number;
  maxY: number;
  midX: number;
  midY: number;
  width: number;
  height: number;
}

export const getCommonBoundingBox = (
  elements: ExcalidrawElement[] | readonly NonDeleted<ExcalidrawElement>[],
): BoundingBox => {
  const [minX, minY, maxX, maxY] = getCommonBounds(elements);
  return {
    minX,
    minY,
    maxX,
    maxY,
    width: maxX - minX,
    height: maxY - minY,
    midX: (minX + maxX) / 2,
    midY: (minY + maxY) / 2,
  };
};

/**
 * returns scene coords of user's editor viewport (visible canvas area) bounds
 */
export const getVisibleSceneBounds = ({
  scrollX,
  scrollY,
  width,
  height,
  zoom,
}: AppState): SceneBounds => {
  return [
    -scrollX,
    -scrollY,
    -scrollX + width / zoom.value,
    -scrollY + height / zoom.value,
  ];
};