From 54ca52e0634970fab29abcafaebc1ae534c9eeed Mon Sep 17 00:00:00 2001
From: Mark Tolmacs <mark@lazycat.hu>
Date: Mon, 22 Sep 2025 16:44:34 +0200
Subject: [PATCH] fix: Arrow eraser precision & lasso arrow selection

---
 packages/element/src/bounds.ts      | 22 +++++++++++++++++++++-
 packages/excalidraw/eraser/index.ts | 25 +++++++++++++++++--------
 2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/packages/element/src/bounds.ts b/packages/element/src/bounds.ts
index 6b190de1b7..0d57e39333 100644
--- a/packages/element/src/bounds.ts
+++ b/packages/element/src/bounds.ts
@@ -42,6 +42,7 @@ import {
   isBoundToContainer,
   isFreeDrawElement,
   isLinearElement,
+  isLineElement,
   isTextElement,
 } from "./typeChecks";
 
@@ -324,9 +325,28 @@ export const getElementLineSegments = (
     const points = curves
       .map((curve) => pointsOnBezierCurves(curve, 10))
       .flat();
-    let i = 0;
     const segments: LineSegment<GlobalPoint>[] = [];
+
+    let i = 0;
+
     while (i < points.length - 1) {
+      const p1 = pointFrom(points[i + 1][0], points[i][1]);
+      const p2 = pointFrom(points[i][0], points[i + 1][1]);
+      const alignsWithStart = pointDistance(p1, points[0] as GlobalPoint) < 1;
+      const alignsWithEnd =
+        pointDistance(p2, points[points.length - 1] as GlobalPoint) < 1;
+
+      // Avoid closing the polycurve for non-polygon lines and arrows
+      if (
+        ((isLineElement(element) && !element.polygon) ||
+          isArrowElement(element)) &&
+        alignsWithStart &&
+        alignsWithEnd
+      ) {
+        i++;
+        continue;
+      }
+
       segments.push(
         lineSegment(
           pointFrom(points[i][0], points[i][1]),
diff --git a/packages/excalidraw/eraser/index.ts b/packages/excalidraw/eraser/index.ts
index 8d09b1aafc..d587bb3811 100644
--- a/packages/excalidraw/eraser/index.ts
+++ b/packages/excalidraw/eraser/index.ts
@@ -2,10 +2,10 @@ import { arrayToMap, easeOut, THEME } from "@excalidraw/common";
 
 import {
   computeBoundTextPosition,
-  distanceToElement,
   doBoundsIntersect,
   getBoundTextElement,
   getElementBounds,
+  getElementLineSegments,
   getFreedrawOutlineAsSegments,
   getFreedrawOutlinePoints,
   intersectElementWithLineSegment,
@@ -265,19 +265,28 @@ const eraserTest = (
     }
 
     return false;
-  } else if (
-    isArrowElement(element) ||
-    (isLineElement(element) && !element.polygon)
-  ) {
+  }
+
+  const boundTextElement = getBoundTextElement(element, elementsMap);
+
+  if (isArrowElement(element) || (isLineElement(element) && !element.polygon)) {
     const tolerance = Math.max(
       element.strokeWidth,
       (element.strokeWidth * 2) / zoom,
     );
 
-    return distanceToElement(element, elementsMap, lastPoint) <= tolerance;
-  }
+    // If the eraser movement is so fast that a large distance is covered
+    // between the last two points, the distanceToElement miss, so we test
+    // agaist each segment of the linear element
+    const segments = getElementLineSegments(element, elementsMap);
+    for (const seg of segments) {
+      if (lineSegmentsDistance(seg, pathSegment) <= tolerance) {
+        return true;
+      }
+    }
 
-  const boundTextElement = getBoundTextElement(element, elementsMap);
+    return false;
+  }
 
   return (
     intersectElementWithLineSegment(element, elementsMap, pathSegment, 0, true)