feat: Precise hit testing (#9488)

packages/element/src/binding.ts

@@ -27,8 +27,6 @@ import {
   PRECISION,
 } from "@excalidraw/math";
 
-import { isPointOnShape } from "@excalidraw/utils/collision";
-
 import type { LocalPoint, Radians } from "@excalidraw/math";
 
 import type { AppState } from "@excalidraw/excalidraw/types";
@@ -41,7 +39,7 @@ import {
   doBoundsIntersect,
 } from "./bounds";
 import { intersectElementWithLineSegment } from "./collision";
-import { distanceToBindableElement } from "./distance";
+import { distanceToElement } from "./distance";
 import {
   headingForPointFromElement,
   headingIsHorizontal,
@@ -63,7 +61,7 @@ import {
   isTextElement,
 } from "./typeChecks";
 
-import { aabbForElement, getElementShape, pointInsideBounds } from "./shapes";
+import { aabbForElement } from "./shapes";
 import { updateElbowArrowPoints } from "./elbowArrow";
 
 import type { Scene } from "./Scene";
@@ -109,7 +107,6 @@ export const isBindingEnabled = (appState: AppState): boolean => {
 
 export const FIXED_BINDING_DISTANCE = 5;
 export const BINDING_HIGHLIGHT_THICKNESS = 10;
-export const BINDING_HIGHLIGHT_OFFSET = 4;
 
 const getNonDeletedElements = (
   scene: Scene,
@@ -131,6 +128,7 @@ export const bindOrUnbindLinearElement = (
   endBindingElement: ExcalidrawBindableElement | null | "keep",
   scene: Scene,
 ): void => {
+  const elementsMap = scene.getNonDeletedElementsMap();
   const boundToElementIds: Set<ExcalidrawBindableElement["id"]> = new Set();
   const unboundFromElementIds: Set<ExcalidrawBindableElement["id"]> = new Set();
   bindOrUnbindLinearElementEdge(
@@ -141,6 +139,7 @@ export const bindOrUnbindLinearElement = (
     boundToElementIds,
     unboundFromElementIds,
     scene,
+    elementsMap,
   );
   bindOrUnbindLinearElementEdge(
     linearElement,
@@ -150,6 +149,7 @@ export const bindOrUnbindLinearElement = (
     boundToElementIds,
     unboundFromElementIds,
     scene,
+    elementsMap,
   );
 
   const onlyUnbound = Array.from(unboundFromElementIds).filter(
@@ -176,6 +176,7 @@ const bindOrUnbindLinearElementEdge = (
   // Is mutated
   unboundFromElementIds: Set<ExcalidrawBindableElement["id"]>,
   scene: Scene,
+  elementsMap: ElementsMap,
 ): void => {
   // "keep" is for method chaining convenience, a "no-op", so just bail out
   if (bindableElement === "keep") {
@@ -216,43 +217,29 @@ const bindOrUnbindLinearElementEdge = (
   }
 };
 
-const getOriginalBindingIfStillCloseOfLinearElementEdge = (
-  linearElement: NonDeleted<ExcalidrawLinearElement>,
-  edge: "start" | "end",
-  elementsMap: NonDeletedSceneElementsMap,
-  zoom?: AppState["zoom"],
-): NonDeleted<ExcalidrawElement> | null => {
-  const coors = getLinearElementEdgeCoors(linearElement, edge, elementsMap);
-  const elementId =
-    edge === "start"
-      ? linearElement.startBinding?.elementId
-      : linearElement.endBinding?.elementId;
-  if (elementId) {
-    const element = elementsMap.get(elementId);
-    if (
-      isBindableElement(element) &&
-      bindingBorderTest(element, coors, elementsMap, zoom)
-    ) {
-      return element;
-    }
-  }
-
-  return null;
-};
-
 const getOriginalBindingsIfStillCloseToArrowEnds = (
   linearElement: NonDeleted<ExcalidrawLinearElement>,
   elementsMap: NonDeletedSceneElementsMap,
   zoom?: AppState["zoom"],
 ): (NonDeleted<ExcalidrawElement> | null)[] =>
-  ["start", "end"].map((edge) =>
-    getOriginalBindingIfStillCloseOfLinearElementEdge(
-      linearElement,
-      edge as "start" | "end",
-      elementsMap,
-      zoom,
-    ),
-  );
+  (["start", "end"] as const).map((edge) => {
+    const coors = getLinearElementEdgeCoors(linearElement, edge, elementsMap);
+    const elementId =
+      edge === "start"
+        ? linearElement.startBinding?.elementId
+        : linearElement.endBinding?.elementId;
+    if (elementId) {
+      const element = elementsMap.get(elementId);
+      if (
+        isBindableElement(element) &&
+        bindingBorderTest(element, coors, elementsMap, zoom)
+      ) {
+        return element;
+      }
+    }
+
+    return null;
+  });
 
 const getBindingStrategyForDraggingArrowEndpoints = (
   selectedElement: NonDeleted<ExcalidrawLinearElement>,
@@ -268,7 +255,7 @@ const getBindingStrategyForDraggingArrowEndpoints = (
   const endDragged = draggingPoints.findIndex((i) => i === endIdx) > -1;
   const start = startDragged
     ? isBindingEnabled
-      ? getElligibleElementForBindingElement(
+      ? getEligibleElementForBindingElement(
           selectedElement,
           "start",
           elementsMap,
@@ -279,7 +266,7 @@ const getBindingStrategyForDraggingArrowEndpoints = (
     : "keep";
   const end = endDragged
     ? isBindingEnabled
-      ? getElligibleElementForBindingElement(
+      ? getEligibleElementForBindingElement(
           selectedElement,
           "end",
           elementsMap,
@@ -311,7 +298,7 @@ const getBindingStrategyForDraggingArrowOrJoints = (
   );
   const start = startIsClose
     ? isBindingEnabled
-      ? getElligibleElementForBindingElement(
+      ? getEligibleElementForBindingElement(
           selectedElement,
           "start",
           elementsMap,
@@ -322,7 +309,7 @@ const getBindingStrategyForDraggingArrowOrJoints = (
     : null;
   const end = endIsClose
     ? isBindingEnabled
-      ? getElligibleElementForBindingElement(
+      ? getEligibleElementForBindingElement(
           selectedElement,
           "end",
           elementsMap,
@@ -441,22 +428,13 @@ export const maybeBindLinearElement = (
 const normalizePointBinding = (
   binding: { focus: number; gap: number },
   hoveredElement: ExcalidrawBindableElement,
-) => {
-  let gap = binding.gap;
-  const maxGap = maxBindingGap(
-    hoveredElement,
-    hoveredElement.width,
-    hoveredElement.height,
-  );
-
-  if (gap > maxGap) {
-    gap = BINDING_HIGHLIGHT_THICKNESS + BINDING_HIGHLIGHT_OFFSET;
-  }
-  return {
-    ...binding,
-    gap,
-  };
-};
+) => ({
+  ...binding,
+  gap: Math.min(
+    binding.gap,
+    maxBindingGap(hoveredElement, hoveredElement.width, hoveredElement.height),
+  ),
+});
 
 export const bindLinearElement = (
   linearElement: NonDeleted<ExcalidrawLinearElement>,
@@ -488,6 +466,7 @@ export const bindLinearElement = (
         linearElement,
         hoveredElement,
         startOrEnd,
+        scene.getNonDeletedElementsMap(),
       ),
     };
   }
@@ -703,8 +682,13 @@ const calculateFocusAndGap = (
   );
 
   return {
-    focus: determineFocusDistance(hoveredElement, adjacentPoint, edgePoint),
-    gap: Math.max(1, distanceToBindableElement(hoveredElement, edgePoint)),
+    focus: determineFocusDistance(
+      hoveredElement,
+      elementsMap,
+      adjacentPoint,
+      edgePoint,
+    ),
+    gap: Math.max(1, distanceToElement(hoveredElement, elementsMap, edgePoint)),
   };
 };
 
@@ -874,6 +858,7 @@ export const getHeadingForElbowArrowSnap = (
   bindableElement: ExcalidrawBindableElement | undefined | null,
   aabb: Bounds | undefined | null,
   origPoint: GlobalPoint,
+  elementsMap: ElementsMap,
   zoom?: AppState["zoom"],
 ): Heading => {
   const otherPointHeading = vectorToHeading(vectorFromPoint(otherPoint, p));
@@ -882,11 +867,16 @@ export const getHeadingForElbowArrowSnap = (
     return otherPointHeading;
   }
 
-  const distance = getDistanceForBinding(origPoint, bindableElement, zoom);
+  const distance = getDistanceForBinding(
+    origPoint,
+    bindableElement,
+    elementsMap,
+    zoom,
+  );
 
   if (!distance) {
     return vectorToHeading(
-      vectorFromPoint(p, elementCenterPoint(bindableElement)),
+      vectorFromPoint(p, elementCenterPoint(bindableElement, elementsMap)),
     );
   }
 
@@ -896,9 +886,10 @@ export const getHeadingForElbowArrowSnap = (
 const getDistanceForBinding = (
   point: Readonly<GlobalPoint>,
   bindableElement: ExcalidrawBindableElement,
+  elementsMap: ElementsMap,
   zoom?: AppState["zoom"],
 ) => {
-  const distance = distanceToBindableElement(bindableElement, point);
+  const distance = distanceToElement(bindableElement, elementsMap, point);
   const bindDistance = maxBindingGap(
     bindableElement,
     bindableElement.width,
@@ -913,12 +904,13 @@ export const bindPointToSnapToElementOutline = (
   arrow: ExcalidrawElbowArrowElement,
   bindableElement: ExcalidrawBindableElement,
   startOrEnd: "start" | "end",
+  elementsMap: ElementsMap,
 ): GlobalPoint => {
   if (isDevEnv() || isTestEnv()) {
     invariant(arrow.points.length > 1, "Arrow should have at least 2 points");
   }
 
-  const aabb = aabbForElement(bindableElement);
+  const aabb = aabbForElement(bindableElement, elementsMap);
   const localP =
     arrow.points[startOrEnd === "start" ? 0 : arrow.points.length - 1];
   const globalP = pointFrom<GlobalPoint>(
@@ -926,7 +918,7 @@ export const bindPointToSnapToElementOutline = (
     arrow.y + localP[1],
   );
   const edgePoint = isRectanguloidElement(bindableElement)
-    ? avoidRectangularCorner(bindableElement, globalP)
+    ? avoidRectangularCorner(bindableElement, elementsMap, globalP)
     : globalP;
   const elbowed = isElbowArrow(arrow);
   const center = getCenterForBounds(aabb);
@@ -945,26 +937,31 @@ export const bindPointToSnapToElementOutline = (
     const isHorizontal = headingIsHorizontal(
       headingForPointFromElement(bindableElement, aabb, globalP),
     );
+    const snapPoint = snapToMid(bindableElement, elementsMap, edgePoint);
     const otherPoint = pointFrom<GlobalPoint>(
-      isHorizontal ? center[0] : edgePoint[0],
-      !isHorizontal ? center[1] : edgePoint[1],
+      isHorizontal ? center[0] : snapPoint[0],
+      !isHorizontal ? center[1] : snapPoint[1],
+    );
+    const intersector = lineSegment(
+      otherPoint,
+      pointFromVector(
+        vectorScale(
+          vectorNormalize(vectorFromPoint(snapPoint, otherPoint)),
+          Math.max(bindableElement.width, bindableElement.height) * 2,
+        ),
+        otherPoint,
+      ),
     );
     intersection = intersectElementWithLineSegment(
       bindableElement,
-      lineSegment(
-        otherPoint,
-        pointFromVector(
-          vectorScale(
-            vectorNormalize(vectorFromPoint(edgePoint, otherPoint)),
-            Math.max(bindableElement.width, bindableElement.height) * 2,
-          ),
-          otherPoint,
-        ),
-      ),
-    )[0];
+      elementsMap,
+      intersector,
+      FIXED_BINDING_DISTANCE,
+    ).sort(pointDistanceSq)[0];
   } else {
     intersection = intersectElementWithLineSegment(
       bindableElement,
+      elementsMap,
       lineSegment(
         adjacentPoint,
         pointFromVector(
@@ -991,31 +988,15 @@ export const bindPointToSnapToElementOutline = (
     return edgePoint;
   }
 
-  if (elbowed) {
-    const scalar =
-      pointDistanceSq(edgePoint, center) -
-        pointDistanceSq(intersection, center) >
-      0
-        ? FIXED_BINDING_DISTANCE
-        : -FIXED_BINDING_DISTANCE;
-
-    return pointFromVector(
-      vectorScale(
-        vectorNormalize(vectorFromPoint(edgePoint, intersection)),
-        scalar,
-      ),
-      intersection,
-    );
-  }
-
-  return edgePoint;
+  return elbowed ? intersection : edgePoint;
 };
 
 export const avoidRectangularCorner = (
   element: ExcalidrawBindableElement,
+  elementsMap: ElementsMap,
   p: GlobalPoint,
 ): GlobalPoint => {
-  const center = elementCenterPoint(element);
+  const center = elementCenterPoint(element, elementsMap);
   const nonRotatedPoint = pointRotateRads(p, center, -element.angle as Radians);
 
   if (nonRotatedPoint[0] < element.x && nonRotatedPoint[1] < element.y) {
@@ -1108,35 +1089,34 @@ export const avoidRectangularCorner = (
 
 export const snapToMid = (
   element: ExcalidrawBindableElement,
+  elementsMap: ElementsMap,
   p: GlobalPoint,
   tolerance: number = 0.05,
 ): GlobalPoint => {
   const { x, y, width, height, angle } = element;
-
-  const center = elementCenterPoint(element, -0.1, -0.1);
-
+  const center = elementCenterPoint(element, elementsMap, -0.1, -0.1);
   const nonRotated = pointRotateRads(p, center, -angle as Radians);
 
   // snap-to-center point is adaptive to element size, but we don't want to go
   // above and below certain px distance
-  const verticalThrehsold = clamp(tolerance * height, 5, 80);
-  const horizontalThrehsold = clamp(tolerance * width, 5, 80);
+  const verticalThreshold = clamp(tolerance * height, 5, 80);
+  const horizontalThreshold = clamp(tolerance * width, 5, 80);
 
   if (
     nonRotated[0] <= x + width / 2 &&
-    nonRotated[1] > center[1] - verticalThrehsold &&
-    nonRotated[1] < center[1] + verticalThrehsold
+    nonRotated[1] > center[1] - verticalThreshold &&
+    nonRotated[1] < center[1] + verticalThreshold
   ) {
     // LEFT
-    return pointRotateRads(
+    return pointRotateRads<GlobalPoint>(
       pointFrom(x - FIXED_BINDING_DISTANCE, center[1]),
       center,
       angle,
     );
   } else if (
     nonRotated[1] <= y + height / 2 &&
-    nonRotated[0] > center[0] - horizontalThrehsold &&
-    nonRotated[0] < center[0] + horizontalThrehsold
+    nonRotated[0] > center[0] - horizontalThreshold &&
+    nonRotated[0] < center[0] + horizontalThreshold
   ) {
     // TOP
     return pointRotateRads(
@@ -1146,8 +1126,8 @@ export const snapToMid = (
     );
   } else if (
     nonRotated[0] >= x + width / 2 &&
-    nonRotated[1] > center[1] - verticalThrehsold &&
-    nonRotated[1] < center[1] + verticalThrehsold
+    nonRotated[1] > center[1] - verticalThreshold &&
+    nonRotated[1] < center[1] + verticalThreshold
   ) {
     // RIGHT
     return pointRotateRads(
@@ -1157,8 +1137,8 @@ export const snapToMid = (
     );
   } else if (
     nonRotated[1] >= y + height / 2 &&
-    nonRotated[0] > center[0] - horizontalThrehsold &&
-    nonRotated[0] < center[0] + horizontalThrehsold
+    nonRotated[0] > center[0] - horizontalThreshold &&
+    nonRotated[0] < center[0] + horizontalThreshold
   ) {
     // DOWN
     return pointRotateRads(
@@ -1167,7 +1147,7 @@ export const snapToMid = (
       angle,
     );
   } else if (element.type === "diamond") {
-    const distance = FIXED_BINDING_DISTANCE - 1;
+    const distance = FIXED_BINDING_DISTANCE;
     const topLeft = pointFrom<GlobalPoint>(
       x + width / 4 - distance,
       y + height / 4 - distance,
@@ -1184,27 +1164,28 @@ export const snapToMid = (
       x + (3 * width) / 4 + distance,
       y + (3 * height) / 4 + distance,
     );
+
     if (
       pointDistance(topLeft, nonRotated) <
-      Math.max(horizontalThrehsold, verticalThrehsold)
+      Math.max(horizontalThreshold, verticalThreshold)
     ) {
       return pointRotateRads(topLeft, center, angle);
     }
     if (
       pointDistance(topRight, nonRotated) <
-      Math.max(horizontalThrehsold, verticalThrehsold)
+      Math.max(horizontalThreshold, verticalThreshold)
     ) {
       return pointRotateRads(topRight, center, angle);
     }
     if (
       pointDistance(bottomLeft, nonRotated) <
-      Math.max(horizontalThrehsold, verticalThrehsold)
+      Math.max(horizontalThreshold, verticalThreshold)
     ) {
       return pointRotateRads(bottomLeft, center, angle);
     }
     if (
       pointDistance(bottomRight, nonRotated) <
-      Math.max(horizontalThrehsold, verticalThrehsold)
+      Math.max(horizontalThreshold, verticalThreshold)
     ) {
       return pointRotateRads(bottomRight, center, angle);
     }
@@ -1239,8 +1220,9 @@ const updateBoundPoint = (
         linearElement,
         bindableElement,
         startOrEnd === "startBinding" ? "start" : "end",
+        elementsMap,
       ).fixedPoint;
-    const globalMidPoint = elementCenterPoint(bindableElement);
+    const globalMidPoint = elementCenterPoint(bindableElement, elementsMap);
     const global = pointFrom<GlobalPoint>(
       bindableElement.x + fixedPoint[0] * bindableElement.width,
       bindableElement.y + fixedPoint[1] * bindableElement.height,
@@ -1266,6 +1248,7 @@ const updateBoundPoint = (
   );
   const focusPointAbsolute = determineFocusPoint(
     bindableElement,
+    elementsMap,
     binding.focus,
     adjacentPoint,
   );
@@ -1284,7 +1267,7 @@ const updateBoundPoint = (
         elementsMap,
       );
 
-    const center = elementCenterPoint(bindableElement);
+    const center = elementCenterPoint(bindableElement, elementsMap);
     const interceptorLength =
       pointDistance(adjacentPoint, edgePointAbsolute) +
       pointDistance(adjacentPoint, center) +
@@ -1292,6 +1275,7 @@ const updateBoundPoint = (
     const intersections = [
       ...intersectElementWithLineSegment(
         bindableElement,
+        elementsMap,
         lineSegment<GlobalPoint>(
           adjacentPoint,
           pointFromVector(
@@ -1342,6 +1326,7 @@ export const calculateFixedPointForElbowArrowBinding = (
   linearElement: NonDeleted<ExcalidrawElbowArrowElement>,
   hoveredElement: ExcalidrawBindableElement,
   startOrEnd: "start" | "end",
+  elementsMap: ElementsMap,
 ): { fixedPoint: FixedPoint } => {
   const bounds = [
     hoveredElement.x,
@@ -1353,6 +1338,7 @@ export const calculateFixedPointForElbowArrowBinding = (
     linearElement,
     hoveredElement,
     startOrEnd,
+    elementsMap,
   );
   const globalMidPoint = pointFrom(
     bounds[0] + (bounds[2] - bounds[0]) / 2,
@@ -1396,7 +1382,7 @@ const maybeCalculateNewGapWhenScaling = (
   return { ...currentBinding, gap: newGap };
 };
 
-const getElligibleElementForBindingElement = (
+const getEligibleElementForBindingElement = (
   linearElement: NonDeleted<ExcalidrawLinearElement>,
   startOrEnd: "start" | "end",
   elementsMap: NonDeletedSceneElementsMap,
@@ -1548,14 +1534,38 @@ export const bindingBorderTest = (
   zoom?: AppState["zoom"],
   fullShape?: boolean,
 ): boolean => {
+  const p = pointFrom<GlobalPoint>(x, y);
   const threshold = maxBindingGap(element, element.width, element.height, zoom);
+  const shouldTestInside =
+    // disable fullshape snapping for frame elements so we
+    // can bind to frame children
+    (fullShape || !isBindingFallthroughEnabled(element)) &&
+    !isFrameLikeElement(element);
 
-  const shape = getElementShape(element, elementsMap);
-  return (
-    isPointOnShape(pointFrom(x, y), shape, threshold) ||
-    (fullShape === true &&
-      pointInsideBounds(pointFrom(x, y), aabbForElement(element)))
+  // PERF: Run a cheap test to see if the binding element
+  // is even close to the element
+  const bounds = [
+    x - threshold,
+    y - threshold,
+    x + threshold,
+    y + threshold,
+  ] as Bounds;
+  const elementBounds = getElementBounds(element, elementsMap);
+  if (!doBoundsIntersect(bounds, elementBounds)) {
+    return false;
+  }
+
+  // Do the intersection test against the element since it's close enough
+  const intersections = intersectElementWithLineSegment(
+    element,
+    elementsMap,
+    lineSegment(elementCenterPoint(element, elementsMap), p),
   );
+  const distance = distanceToElement(element, elementsMap, p);
+
+  return shouldTestInside
+    ? intersections.length === 0 || distance <= threshold
+    : intersections.length > 0 && distance <= threshold;
 };
 
 export const maxBindingGap = (
@@ -1575,7 +1585,7 @@ export const maxBindingGap = (
     // bigger bindable boundary for bigger elements
     Math.min(0.25 * smallerDimension, 32),
     // keep in sync with the zoomed highlight
-    BINDING_HIGHLIGHT_THICKNESS / zoomValue + BINDING_HIGHLIGHT_OFFSET,
+    BINDING_HIGHLIGHT_THICKNESS / zoomValue + FIXED_BINDING_DISTANCE,
   );
 };
 
@@ -1586,12 +1596,13 @@ export const maxBindingGap = (
 // of the element.
 const determineFocusDistance = (
   element: ExcalidrawBindableElement,
+  elementsMap: ElementsMap,
   // Point on the line, in absolute coordinates
   a: GlobalPoint,
   // Another point on the line, in absolute coordinates (closer to element)
   b: GlobalPoint,
 ): number => {
-  const center = elementCenterPoint(element);
+  const center = elementCenterPoint(element, elementsMap);
 
   if (pointsEqual(a, b)) {
     return 0;
@@ -1716,12 +1727,13 @@ const determineFocusDistance = (
 
 const determineFocusPoint = (
   element: ExcalidrawBindableElement,
+  elementsMap: ElementsMap,
   // The oriented, relative distance from the center of `element` of the
   // returned focusPoint
   focus: number,
   adjacentPoint: GlobalPoint,
 ): GlobalPoint => {
-  const center = elementCenterPoint(element);
+  const center = elementCenterPoint(element, elementsMap);
 
   if (focus === 0) {
     return center;
@@ -2144,6 +2156,7 @@ export class BindableElement {
 export const getGlobalFixedPointForBindableElement = (
   fixedPointRatio: [number, number],
   element: ExcalidrawBindableElement,
+  elementsMap: ElementsMap,
 ): GlobalPoint => {
   const [fixedX, fixedY] = normalizeFixedPoint(fixedPointRatio);
 
@@ -2152,7 +2165,7 @@ export const getGlobalFixedPointForBindableElement = (
       element.x + element.width * fixedX,
       element.y + element.height * fixedY,
     ),
-    elementCenterPoint(element),
+    elementCenterPoint(element, elementsMap),
     element.angle,
   );
 };
@@ -2176,6 +2189,7 @@ export const getGlobalFixedPoints = (
       ? getGlobalFixedPointForBindableElement(
           arrow.startBinding.fixedPoint,
           startElement as ExcalidrawBindableElement,
+          elementsMap,
         )
       : pointFrom<GlobalPoint>(
           arrow.x + arrow.points[0][0],
@@ -2186,6 +2200,7 @@ export const getGlobalFixedPoints = (
       ? getGlobalFixedPointForBindableElement(
           arrow.endBinding.fixedPoint,
           endElement as ExcalidrawBindableElement,
+          elementsMap,
         )
       : pointFrom<GlobalPoint>(
           arrow.x + arrow.points[arrow.points.length - 1][0],