1 files changed, 228 insertions, 0 deletions
diff --git a/packages/utils/withinBounds.ts b/packages/utils/withinBounds.ts
new file mode 100644
index 0000000..8d52eb3
--- /dev/null
+++ b/packages/utils/withinBounds.ts
@@ -0,0 +1,228 @@
+import type {
+  ExcalidrawElement,
+  ExcalidrawFreeDrawElement,
+  ExcalidrawLinearElement,
+  NonDeletedExcalidrawElement,
+} from "@excalidraw/excalidraw/element/types";
+import {
+  isArrowElement,
+  isExcalidrawElement,
+  isFreeDrawElement,
+  isLinearElement,
+  isTextElement,
+} from "@excalidraw/excalidraw/element/typeChecks";
+import type { Bounds } from "@excalidraw/excalidraw/element/bounds";
+import { getElementBounds } from "@excalidraw/excalidraw/element/bounds";
+import { arrayToMap } from "@excalidraw/excalidraw/utils";
+import type { LocalPoint } from "@excalidraw/math";
+import {
+  rangeIncludesValue,
+  pointFrom,
+  pointRotateRads,
+  rangeInclusive,
+} 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));
+};