From 5c8941467d7275ba553fb171639698c047666c3b Mon Sep 17 00:00:00 2001
From: zsviczian <viczian.zsolt@gmail.com>
Date: Mon, 20 Mar 2023 13:20:09 +0100
Subject: [PATCH] fix: division by zero in findFocusPointForEllipse leads to
 infinite loop in wrapText freezing Excalidraw (#6377)

* Update collision.ts

* Update textElement.ts

* Update textElement.ts

* tweak

* fix

* remove unnecessary `Math.sign`

* change check and add doc

* Add a case for negative max width and specs

* fix

---------

Co-authored-by: dwelle <luzar.david@gmail.com>
Co-authored-by: Aakansha Doshi <aakansha1216@gmail.com>
---
 src/element/collision.ts        | 7 ++++++-
 src/element/textElement.test.ts | 7 +++++++
 src/element/textElement.ts      | 7 +++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/element/collision.ts b/src/element/collision.ts
index 097b76d3..0e7257d7 100644
--- a/src/element/collision.ts
+++ b/src/element/collision.ts
@@ -786,7 +786,12 @@ export const findFocusPointForEllipse = (
       orientation * py * Math.sqrt(Math.max(0, squares - a ** 2 * b ** 2))) /
     squares;
 
-  const n = (-m * px - 1) / py;
+  let n = (-m * px - 1) / py;
+
+  if (n === 0) {
+    // if zero {-0, 0}, fall back to a same-sign value in the similar range
+    n = (Object.is(n, -0) ? -1 : 1) * 0.01;
+  }
 
   const x = -(a ** 2 * m) / (n ** 2 * b ** 2 + m ** 2 * a ** 2);
   return GA.point(x, (-m * x - 1) / n);
diff --git a/src/element/textElement.test.ts b/src/element/textElement.test.ts
index 3de96037..be6d1a8a 100644
--- a/src/element/textElement.test.ts
+++ b/src/element/textElement.test.ts
@@ -184,6 +184,13 @@ break it now`,
     expect(res).toEqual(`Hello 
 Excalidraw`);
   });
+
+  it("should return the text as is if max width is invalid", () => {
+    const text = "Hello Excalidraw";
+    expect(wrapText(text, font, NaN)).toEqual(text);
+    expect(wrapText(text, font, -1)).toEqual(text);
+    expect(wrapText(text, font, Infinity)).toEqual(text);
+  });
 });
 
 describe("Test measureText", () => {
diff --git a/src/element/textElement.ts b/src/element/textElement.ts
index 7dc11c9a..8d1b0901 100644
--- a/src/element/textElement.ts
+++ b/src/element/textElement.ts
@@ -324,6 +324,13 @@ export const getTextHeight = (text: string, font: FontString) => {
 };
 
 export const wrapText = (text: string, font: FontString, maxWidth: number) => {
+  // if maxWidth is not finite or NaN which can happen in case of bugs in
+  // computation, we need to make sure we don't continue as we'll end up
+  // in an infinite loop
+  if (!Number.isFinite(maxWidth) || maxWidth < 0) {
+    return text;
+  }
+
   const lines: Array<string> = [];
   const originalLines = text.split("\n");
   const spaceWidth = getLineWidth(" ", font);