From 2dded88081cd92e342dcedb5e3604ff9ed99fbc0 Mon Sep 17 00:00:00 2001
From: Evan Hahn <69474926+EvanHahn-Signal@users.noreply.github.com>
Date: Tue, 11 Jan 2022 17:18:19 -0600
Subject: [PATCH] Add comments explaining Fabric listeners

---
 ts/mediaEditor/useFabricHistory.ts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/ts/mediaEditor/useFabricHistory.ts b/ts/mediaEditor/useFabricHistory.ts
index 9f23b61c1..0eca42700 100644
--- a/ts/mediaEditor/useFabricHistory.ts
+++ b/ts/mediaEditor/useFabricHistory.ts
@@ -186,6 +186,12 @@ export function useFabricHistory({
     }
     return fabricEffectListener(
       fabricCanvas,
+      // We want to take snapshots when objects are added, removed, and modified. The
+      //   first two are obvious. We DON'T want to take snapshots before those things
+      //   happen (like `object:moving`), and we also don't want to take redundant ones
+      //   (which is why we don't listen to both `object:modified` and `object:rotated`).
+      //
+      // See <http://fabricjs.com/docs/fabric.Canvas.html#Canvas> for the list of events.
       ['object:added', 'object:modified', 'object:removed'],
       ({ target }) => {
         if (isTimeTraveling || target?.excludeFromExport) {