feat: Precise hit testing (#9488)

packages/element/src/collision.ts

@@ -2,51 +2,60 @@ import { isTransparent, elementCenterPoint } from "@excalidraw/common";
 import {
   curveIntersectLineSegment,
   isPointWithinBounds,
-  line,
   lineSegment,
   lineSegmentIntersectionPoints,
   pointFrom,
+  pointFromVector,
   pointRotateRads,
   pointsEqual,
+  vectorFromPoint,
+  vectorNormalize,
+  vectorScale,
 } from "@excalidraw/math";
 
 import {
   ellipse,
-  ellipseLineIntersectionPoints,
+  ellipseSegmentInterceptPoints,
 } from "@excalidraw/math/ellipse";
 
-import { isPointInShape, isPointOnShape } from "@excalidraw/utils/collision";
-import { type GeometricShape, getPolygonShape } from "@excalidraw/utils/shape";
-
-import type {
-  GlobalPoint,
-  LineSegment,
-  LocalPoint,
-  Polygon,
-  Radians,
-} from "@excalidraw/math";
+import type { GlobalPoint, LineSegment, Radians } from "@excalidraw/math";
 
 import type { FrameNameBounds } from "@excalidraw/excalidraw/types";
 
-import { getBoundTextShape, isPathALoop } from "./shapes";
-import { getElementBounds } from "./bounds";
+import { isPathALoop } from "./shapes";
+import {
+  type Bounds,
+  doBoundsIntersect,
+  getCenterForBounds,
+  getElementBounds,
+} from "./bounds";
 import {
   hasBoundTextElement,
+  isFreeDrawElement,
   isIframeLikeElement,
   isImageElement,
+  isLinearElement,
   isTextElement,
 } from "./typeChecks";
 import {
   deconstructDiamondElement,
+  deconstructLinearOrFreeDrawElement,
   deconstructRectanguloidElement,
 } from "./utils";
 
+import { getBoundTextElement } from "./textElement";
+
+import { LinearElementEditor } from "./linearElementEditor";
+
+import { distanceToElement } from "./distance";
+
 import type {
   ElementsMap,
   ExcalidrawDiamondElement,
   ExcalidrawElement,
   ExcalidrawEllipseElement,
-  ExcalidrawRectangleElement,
+  ExcalidrawFreeDrawElement,
+  ExcalidrawLinearElement,
   ExcalidrawRectanguloidElement,
 } from "./types";
 
@@ -72,45 +81,64 @@ export const shouldTestInside = (element: ExcalidrawElement) => {
   return isDraggableFromInside || isImageElement(element);
 };
 
-export type HitTestArgs<Point extends GlobalPoint | LocalPoint> = {
-  x: number;
-  y: number;
+export type HitTestArgs = {
+  point: GlobalPoint;
   element: ExcalidrawElement;
-  shape: GeometricShape<Point>;
-  threshold?: number;
+  threshold: number;
+  elementsMap: ElementsMap;
   frameNameBound?: FrameNameBounds | null;
 };
 
-export const hitElementItself = <Point extends GlobalPoint | LocalPoint>({
-  x,
-  y,
+export const hitElementItself = ({
+  point,
   element,
-  shape,
-  threshold = 10,
+  threshold,
+  elementsMap,
   frameNameBound = null,
-}: HitTestArgs<Point>) => {
-  let hit = shouldTestInside(element)
-    ? // Since `inShape` tests STRICTLY againt the insides of a shape
-      // we would need `onShape` as well to include the "borders"
-      isPointInShape(pointFrom(x, y), shape) ||
-      isPointOnShape(pointFrom(x, y), shape, threshold)
-    : isPointOnShape(pointFrom(x, y), shape, threshold);
+}: HitTestArgs) => {
+  // Hit test against a frame's name
+  const hitFrameName = frameNameBound
+    ? isPointWithinBounds(
+        pointFrom(frameNameBound.x - threshold, frameNameBound.y - threshold),
+        point,
+        pointFrom(
+          frameNameBound.x + frameNameBound.width + threshold,
+          frameNameBound.y + frameNameBound.height + threshold,
+        ),
+      )
+    : false;
 
-  // hit test against a frame's name
-  if (!hit && frameNameBound) {
-    hit = isPointInShape(pointFrom(x, y), {
-      type: "polygon",
-      data: getPolygonShape(frameNameBound as ExcalidrawRectangleElement)
-        .data as Polygon<Point>,
-    });
+  // Hit test against the extended, rotated bounding box of the element first
+  const bounds = getElementBounds(element, elementsMap, true);
+  const hitBounds = isPointWithinBounds(
+    pointFrom(bounds[0] - threshold, bounds[1] - threshold),
+    pointRotateRads(
+      point,
+      getCenterForBounds(bounds),
+      -element.angle as Radians,
+    ),
+    pointFrom(bounds[2] + threshold, bounds[3] + threshold),
+  );
+
+  // PERF: Bail out early if the point is not even in the
+  // rotated bounding box or not hitting the frame name (saves 99%)
+  if (!hitBounds && !hitFrameName) {
+    return false;
   }
 
-  return hit;
+  // Do the precise (and relatively costly) hit test
+  const hitElement = shouldTestInside(element)
+    ? // Since `inShape` tests STRICTLY againt the insides of a shape
+      // we would need `onShape` as well to include the "borders"
+      isPointInElement(point, element, elementsMap) ||
+      isPointOnElementOutline(point, element, elementsMap, threshold)
+    : isPointOnElementOutline(point, element, elementsMap, threshold);
+
+  return hitElement || hitFrameName;
 };
 
 export const hitElementBoundingBox = (
-  x: number,
-  y: number,
+  point: GlobalPoint,
   element: ExcalidrawElement,
   elementsMap: ElementsMap,
   tolerance = 0,
@@ -120,37 +148,42 @@ export const hitElementBoundingBox = (
   y1 -= tolerance;
   x2 += tolerance;
   y2 += tolerance;
-  return isPointWithinBounds(
-    pointFrom(x1, y1),
-    pointFrom(x, y),
-    pointFrom(x2, y2),
-  );
+  return isPointWithinBounds(pointFrom(x1, y1), point, pointFrom(x2, y2));
 };
 
-export const hitElementBoundingBoxOnly = <
-  Point extends GlobalPoint | LocalPoint,
->(
-  hitArgs: HitTestArgs<Point>,
+export const hitElementBoundingBoxOnly = (
+  hitArgs: HitTestArgs,
   elementsMap: ElementsMap,
-) => {
-  return (
-    !hitElementItself(hitArgs) &&
-    // bound text is considered part of the element (even if it's outside the bounding box)
-    !hitElementBoundText(
-      hitArgs.x,
-      hitArgs.y,
-      getBoundTextShape(hitArgs.element, elementsMap),
-    ) &&
-    hitElementBoundingBox(hitArgs.x, hitArgs.y, hitArgs.element, elementsMap)
-  );
-};
+) =>
+  !hitElementItself(hitArgs) &&
+  // bound text is considered part of the element (even if it's outside the bounding box)
+  !hitElementBoundText(hitArgs.point, hitArgs.element, elementsMap) &&
+  hitElementBoundingBox(hitArgs.point, hitArgs.element, elementsMap);
 
-export const hitElementBoundText = <Point extends GlobalPoint | LocalPoint>(
-  x: number,
-  y: number,
-  textShape: GeometricShape<Point> | null,
+export const hitElementBoundText = (
+  point: GlobalPoint,
+  element: ExcalidrawElement,
+  elementsMap: ElementsMap,
 ): boolean => {
-  return !!textShape && isPointInShape(pointFrom(x, y), textShape);
+  const boundTextElementCandidate = getBoundTextElement(element, elementsMap);
+
+  if (!boundTextElementCandidate) {
+    return false;
+  }
+  const boundTextElement = isLinearElement(element)
+    ? {
+        ...boundTextElementCandidate,
+        // arrow's bound text accurate position is not stored in the element's property
+        // but rather calculated and returned from the following static method
+        ...LinearElementEditor.getBoundTextElementPosition(
+          element,
+          boundTextElementCandidate,
+          elementsMap,
+        ),
+      }
+    : boundTextElementCandidate;
+
+  return isPointInElement(point, boundTextElement, elementsMap);
 };
 
 /**
@@ -163,9 +196,26 @@ export const hitElementBoundText = <Point extends GlobalPoint | LocalPoint>(
  */
 export const intersectElementWithLineSegment = (
   element: ExcalidrawElement,
+  elementsMap: ElementsMap,
   line: LineSegment<GlobalPoint>,
   offset: number = 0,
+  onlyFirst = false,
 ): GlobalPoint[] => {
+  // First check if the line intersects the element's axis-aligned bounding box
+  // as it is much faster than checking intersection against the element's shape
+  const intersectorBounds = [
+    Math.min(line[0][0] - offset, line[1][0] - offset),
+    Math.min(line[0][1] - offset, line[1][1] - offset),
+    Math.max(line[0][0] + offset, line[1][0] + offset),
+    Math.max(line[0][1] + offset, line[1][1] + offset),
+  ] as Bounds;
+  const elementBounds = getElementBounds(element, elementsMap);
+
+  if (!doBoundsIntersect(intersectorBounds, elementBounds)) {
+    return [];
+  }
+
+  // Do the actual intersection test against the element's shape
   switch (element.type) {
     case "rectangle":
     case "image":
@@ -173,23 +223,88 @@ export const intersectElementWithLineSegment = (
     case "iframe":
     case "embeddable":
     case "frame":
+    case "selection":
     case "magicframe":
-      return intersectRectanguloidWithLineSegment(element, line, offset);
+      return intersectRectanguloidWithLineSegment(
+        element,
+        elementsMap,
+        line,
+        offset,
+        onlyFirst,
+      );
     case "diamond":
-      return intersectDiamondWithLineSegment(element, line, offset);
+      return intersectDiamondWithLineSegment(
+        element,
+        elementsMap,
+        line,
+        offset,
+        onlyFirst,
+      );
     case "ellipse":
-      return intersectEllipseWithLineSegment(element, line, offset);
-    default:
-      throw new Error(`Unimplemented element type '${element.type}'`);
+      return intersectEllipseWithLineSegment(
+        element,
+        elementsMap,
+        line,
+        offset,
+      );
+    case "line":
+    case "freedraw":
+    case "arrow":
+      return intersectLinearOrFreeDrawWithLineSegment(
+        element,
+        elementsMap,
+        line,
+        onlyFirst,
+      );
   }
 };
 
+const intersectLinearOrFreeDrawWithLineSegment = (
+  element: ExcalidrawLinearElement | ExcalidrawFreeDrawElement,
+  elementsMap: ElementsMap,
+  segment: LineSegment<GlobalPoint>,
+  onlyFirst = false,
+): GlobalPoint[] => {
+  const [lines, curves] = deconstructLinearOrFreeDrawElement(
+    element,
+    elementsMap,
+  );
+  const intersections = [];
+
+  for (const l of lines) {
+    const intersection = lineSegmentIntersectionPoints(l, segment);
+    if (intersection) {
+      intersections.push(intersection);
+
+      if (onlyFirst) {
+        return intersections;
+      }
+    }
+  }
+
+  for (const c of curves) {
+    const hits = curveIntersectLineSegment(c, segment);
+
+    if (hits.length > 0) {
+      intersections.push(...hits);
+
+      if (onlyFirst) {
+        return intersections;
+      }
+    }
+  }
+
+  return intersections;
+};
+
 const intersectRectanguloidWithLineSegment = (
   element: ExcalidrawRectanguloidElement,
+  elementsMap: ElementsMap,
   l: LineSegment<GlobalPoint>,
   offset: number = 0,
+  onlyFirst = false,
 ): GlobalPoint[] => {
-  const center = elementCenterPoint(element);
+  const center = elementCenterPoint(element, elementsMap);
   // To emulate a rotated rectangle we rotate the point in the inverse angle
   // instead. It's all the same distance-wise.
   const rotatedA = pointRotateRads<GlobalPoint>(
@@ -206,34 +321,37 @@ const intersectRectanguloidWithLineSegment = (
   // Get the element's building components we can test against
   const [sides, corners] = deconstructRectanguloidElement(element, offset);
 
-  return (
-    // Test intersection against the sides, keep only the valid
-    // intersection points and rotate them back to scene space
-    sides
-      .map((s) =>
-        lineSegmentIntersectionPoints(
-          lineSegment<GlobalPoint>(rotatedA, rotatedB),
-          s,
-        ),
-      )
-      .filter((x) => x != null)
-      .map((j) => pointRotateRads<GlobalPoint>(j!, center, element.angle))
-      // Test intersection against the corners which are cubic bezier curves,
-      // keep only the valid intersection points and rotate them back to scene
-      // space
-      .concat(
-        corners
-          .flatMap((t) =>
-            curveIntersectLineSegment(t, lineSegment(rotatedA, rotatedB)),
-          )
-          .filter((i) => i != null)
-          .map((j) => pointRotateRads(j, center, element.angle)),
-      )
-      // Remove duplicates
-      .filter(
-        (p, idx, points) => points.findIndex((d) => pointsEqual(p, d)) === idx,
-      )
-  );
+  const intersections: GlobalPoint[] = [];
+
+  for (const s of sides) {
+    const intersection = lineSegmentIntersectionPoints(
+      lineSegment(rotatedA, rotatedB),
+      s,
+    );
+    if (intersection) {
+      intersections.push(pointRotateRads(intersection, center, element.angle));
+
+      if (onlyFirst) {
+        return intersections;
+      }
+    }
+  }
+
+  for (const t of corners) {
+    const hits = curveIntersectLineSegment(t, lineSegment(rotatedA, rotatedB));
+
+    if (hits.length > 0) {
+      for (const j of hits) {
+        intersections.push(pointRotateRads(j, center, element.angle));
+      }
+
+      if (onlyFirst) {
+        return intersections;
+      }
+    }
+  }
+
+  return intersections;
 };
 
 /**
@@ -245,43 +363,51 @@ const intersectRectanguloidWithLineSegment = (
  */
 const intersectDiamondWithLineSegment = (
   element: ExcalidrawDiamondElement,
+  elementsMap: ElementsMap,
   l: LineSegment<GlobalPoint>,
   offset: number = 0,
+  onlyFirst = false,
 ): GlobalPoint[] => {
-  const center = elementCenterPoint(element);
+  const center = elementCenterPoint(element, elementsMap);
 
   // Rotate the point to the inverse direction to simulate the rotated diamond
   // points. It's all the same distance-wise.
   const rotatedA = pointRotateRads(l[0], center, -element.angle as Radians);
   const rotatedB = pointRotateRads(l[1], center, -element.angle as Radians);
 
-  const [sides, curves] = deconstructDiamondElement(element, offset);
+  const [sides, corners] = deconstructDiamondElement(element, offset);
 
-  return (
-    sides
-      .map((s) =>
-        lineSegmentIntersectionPoints(
-          lineSegment<GlobalPoint>(rotatedA, rotatedB),
-          s,
-        ),
-      )
-      .filter((p): p is GlobalPoint => p != null)
-      // Rotate back intersection points
-      .map((p) => pointRotateRads<GlobalPoint>(p!, center, element.angle))
-      .concat(
-        curves
-          .flatMap((p) =>
-            curveIntersectLineSegment(p, lineSegment(rotatedA, rotatedB)),
-          )
-          .filter((p) => p != null)
-          // Rotate back intersection points
-          .map((p) => pointRotateRads(p, center, element.angle)),
-      )
-      // Remove duplicates
-      .filter(
-        (p, idx, points) => points.findIndex((d) => pointsEqual(p, d)) === idx,
-      )
-  );
+  const intersections: GlobalPoint[] = [];
+
+  for (const s of sides) {
+    const intersection = lineSegmentIntersectionPoints(
+      lineSegment(rotatedA, rotatedB),
+      s,
+    );
+    if (intersection) {
+      intersections.push(pointRotateRads(intersection, center, element.angle));
+
+      if (onlyFirst) {
+        return intersections;
+      }
+    }
+  }
+
+  for (const t of corners) {
+    const hits = curveIntersectLineSegment(t, lineSegment(rotatedA, rotatedB));
+
+    if (hits.length > 0) {
+      for (const j of hits) {
+        intersections.push(pointRotateRads(j, center, element.angle));
+      }
+
+      if (onlyFirst) {
+        return intersections;
+      }
+    }
+  }
+
+  return intersections;
 };
 
 /**
@@ -293,16 +419,76 @@ const intersectDiamondWithLineSegment = (
  */
 const intersectEllipseWithLineSegment = (
   element: ExcalidrawEllipseElement,
+  elementsMap: ElementsMap,
   l: LineSegment<GlobalPoint>,
   offset: number = 0,
 ): GlobalPoint[] => {
-  const center = elementCenterPoint(element);
+  const center = elementCenterPoint(element, elementsMap);
 
   const rotatedA = pointRotateRads(l[0], center, -element.angle as Radians);
   const rotatedB = pointRotateRads(l[1], center, -element.angle as Radians);
 
-  return ellipseLineIntersectionPoints(
+  return ellipseSegmentInterceptPoints(
     ellipse(center, element.width / 2 + offset, element.height / 2 + offset),
-    line(rotatedA, rotatedB),
+    lineSegment(rotatedA, rotatedB),
   ).map((p) => pointRotateRads(p, center, element.angle));
 };
+
+/**
+ * Check if the given point is considered on the given shape's border
+ *
+ * @param point
+ * @param element
+ * @param tolerance
+ * @returns
+ */
+const isPointOnElementOutline = (
+  point: GlobalPoint,
+  element: ExcalidrawElement,
+  elementsMap: ElementsMap,
+  tolerance = 1,
+) => distanceToElement(element, elementsMap, point) <= tolerance;
+
+/**
+ * Check if the given point is considered inside the element's border
+ *
+ * @param point
+ * @param element
+ * @returns
+ */
+export const isPointInElement = (
+  point: GlobalPoint,
+  element: ExcalidrawElement,
+  elementsMap: ElementsMap,
+) => {
+  if (
+    (isLinearElement(element) || isFreeDrawElement(element)) &&
+    !isPathALoop(element.points)
+  ) {
+    // There isn't any "inside" for a non-looping path
+    return false;
+  }
+
+  const [x1, y1, x2, y2] = getElementBounds(element, elementsMap);
+
+  if (!isPointWithinBounds(pointFrom(x1, y1), point, pointFrom(x2, y2))) {
+    return false;
+  }
+
+  const center = pointFrom<GlobalPoint>((x1 + x2) / 2, (y1 + y2) / 2);
+  const otherPoint = pointFromVector(
+    vectorScale(
+      vectorNormalize(vectorFromPoint(point, center, 0.1)),
+      Math.max(element.width, element.height) * 2,
+    ),
+    center,
+  );
+  const intersector = lineSegment(point, otherPoint);
+  const intersections = intersectElementWithLineSegment(
+    element,
+    elementsMap,
+    intersector,
+  ).filter((p, pos, arr) => arr.findIndex((q) => pointsEqual(q, p)) === pos);
+
+  return intersections.length % 2 === 1;
+};