From 0256559b6809b7ced580d4123311276a11a4e9ed Mon Sep 17 00:00:00 2001
From: dwelle <5153846+dwelle@users.noreply.github.com>
Date: Fri, 3 Apr 2026 19:51:41 +0200
Subject: [PATCH] improve balls

---
 packages/element/src/shape.ts        | 49 ++++++++++++++++++++++++++--
 packages/element/tests/shape.test.ts | 26 +++++++++++++++
 2 files changed, 72 insertions(+), 3 deletions(-)

diff --git a/packages/element/src/shape.ts b/packages/element/src/shape.ts
index a74610bad4..6ee1b0f5ec 100644
--- a/packages/element/src/shape.ts
+++ b/packages/element/src/shape.ts
@@ -1233,6 +1233,11 @@ const roundPoint = (point: readonly number[]) =>
 const averagePoint = (A: readonly number[], B: readonly number[]) =>
   `${round((A[0] + B[0]) / 2, 2)},${round((A[1] + B[1]) / 2, 2)} `;
 
+const getReadonlyPointDistance = (
+  pointA: readonly number[],
+  pointB: readonly number[],
+) => Math.hypot(pointA[0] - pointB[0], pointA[1] - pointB[1]);
+
 // Trim SVG path data so number are each two decimal points. This
 // improves SVG exports, and prevents rendering errors on points
 // with long decimals.
@@ -1263,6 +1268,9 @@ const FIXED_FREEDRAW_MIN_CORNER_ROUNDING = 0.75;
 const FIXED_FREEDRAW_MAX_CORNER_ROUNDING = 6;
 const FIXED_FREEDRAW_CORNER_ROUNDING_FACTOR = 0.35;
 const FIXED_FREEDRAW_CORNER_ROUNDING_WIDTH_FACTOR = 1.5;
+const FIXED_FREEDRAW_MIN_TERMINAL_STUB = 0.75;
+const FIXED_FREEDRAW_MAX_TERMINAL_STUB = 2.5;
+const FIXED_FREEDRAW_TERMINAL_STUB_WIDTH_FACTOR = 1.5;
 
 const shouldSmoothFixedFreeDrawPoint = (
   previousPoint: readonly number[],
@@ -1344,6 +1352,15 @@ const getFixedFreeDrawRoundedCorner = (
   };
 };
 
+const getFixedFreeDrawTerminalStubThreshold = (strokeWidth: number) =>
+  Math.min(
+    Math.max(
+      strokeWidth * FIXED_FREEDRAW_TERMINAL_STUB_WIDTH_FACTOR,
+      FIXED_FREEDRAW_MIN_TERMINAL_STUB,
+    ),
+    FIXED_FREEDRAW_MAX_TERMINAL_STUB,
+  );
+
 const getSvgPathFromFixedFreeDrawPoints = (
   points: ReadonlyArray<readonly number[]>,
   strokeWidth: number,
@@ -1359,11 +1376,17 @@ const getSvgPathFromFixedFreeDrawPoints = (
   }
 
   let path = `M${roundPoint(points[0])}`;
+  const lastPoint = points[len - 1];
+  let endsAtLastPoint = false;
 
   for (let index = 1; index < len - 1; index++) {
     const previousPoint = points[index - 1];
     const currentPoint = points[index];
     const nextPoint = points[index + 1];
+    const isLastCurveSegment = index === len - 2;
+    const terminalStubThreshold = getFixedFreeDrawTerminalStubThreshold(
+      strokeWidth,
+    );
     const shouldSmooth = shouldSmoothFixedFreeDrawPoint(
       previousPoint,
       currentPoint,
@@ -1377,17 +1400,37 @@ const getSvgPathFromFixedFreeDrawPoints = (
           nextPoint,
           strokeWidth,
         );
+    const shouldCollapseSmoothTerminalStub =
+      isLastCurveSegment &&
+      shouldSmooth &&
+      getReadonlyPointDistance(currentPoint, nextPoint) / 2 <=
+        terminalStubThreshold;
+    const shouldCollapseRoundedTerminalStub =
+      isLastCurveSegment &&
+      !!roundedCorner &&
+      getReadonlyPointDistance(roundedCorner.exitPoint, lastPoint) <=
+        terminalStubThreshold;
 
     path += shouldSmooth
-      ? `Q${roundPoint(currentPoint)}${averagePoint(currentPoint, nextPoint)}`
+      ? `Q${roundPoint(currentPoint)}${
+          shouldCollapseSmoothTerminalStub
+            ? roundPoint(lastPoint)
+            : averagePoint(currentPoint, nextPoint)
+        }`
       : roundedCorner
         ? `L${roundPoint(roundedCorner.entryPoint)}Q${roundPoint(
             currentPoint,
-          )}${roundPoint(roundedCorner.exitPoint)}`
+          )}${
+            shouldCollapseRoundedTerminalStub
+              ? roundPoint(lastPoint)
+              : roundPoint(roundedCorner.exitPoint)
+          }`
         : `L${roundPoint(currentPoint)}`;
+    endsAtLastPoint =
+      shouldCollapseSmoothTerminalStub || shouldCollapseRoundedTerminalStub;
   }
 
-  return `${path}L${roundPoint(points[len - 1])}`;
+  return endsAtLastPoint ? path : `${path}L${roundPoint(lastPoint)}`;
 };
 
 const getSvgPathFromStroke = (
diff --git a/packages/element/tests/shape.test.ts b/packages/element/tests/shape.test.ts
index ff606173e4..3acbf4adfb 100644
--- a/packages/element/tests/shape.test.ts
+++ b/packages/element/tests/shape.test.ts
@@ -56,6 +56,32 @@ describe("freedraw stroke shape", () => {
     expect(path).toBe("M0,0 L10,0 L9,1 ");
   });
 
+  it("curves directly to the endpoint for tiny final smooth segments", () => {
+    const element = API.createElement({
+      type: "freedraw",
+      strokeShape: "fixed",
+      strokeWidth: 1,
+      points: [pointFrom(0, 0), pointFrom(0.5, 0.1), pointFrom(0.8, 0.3)],
+    });
+
+    const [path] = ShapeCache.generateElementShape(element, null);
+
+    expect(path).toBe("M0,0 Q0.5,0.1 0.8,0.3 ");
+  });
+
+  it("curves directly to the endpoint for tiny final rounded corners", () => {
+    const element = API.createElement({
+      type: "freedraw",
+      strokeShape: "fixed",
+      strokeWidth: 1,
+      points: [pointFrom(0, 0), pointFrom(10, 0), pointFrom(10, 1)],
+    });
+
+    const [path] = ShapeCache.generateElementShape(element, null);
+
+    expect(path).toBe("M0,0 L9.65,0 Q10,0 10,1 ");
+  });
+
   it("smooths dense fixed stroke points without dropping them", () => {
     const element = API.createElement({
       type: "freedraw",