From 07e71a80718a7729977ea0409671e54b2dcd31c1 Mon Sep 17 00:00:00 2001
From: Aakansha Doshi <aakansha1216@gmail.com>
Date: Sat, 6 Mar 2021 19:06:42 +0530
Subject: [PATCH] fix: Reduce the scroll debounce timeout to 100ms and update
 only if offset changes (#3182)

* fix: Reduce the scroll debounce timeout to 100ms so offsets get updated faster when the container scrolled
fixes https://github.com/excalidraw/excalidraw/issues/3175

* update changelog

* update offsets only when if it changes

* up

* Update src/components/App.tsx

Co-authored-by: David Luzar <luzar.david@gmail.com>
---
 src/components/App.tsx               |  8 +++++++-
 src/constants.ts                     |  2 +-
 src/packages/excalidraw/CHANGELOG.md | 10 ++++++++++
 3 files changed, 18 insertions(+), 2 deletions(-)

diff --git a/src/components/App.tsx b/src/components/App.tsx
index ddaa552e..cb65a860 100644
--- a/src/components/App.tsx
+++ b/src/components/App.tsx
@@ -1008,7 +1008,13 @@ class App extends React.Component<ExcalidrawProps, AppState> {
   }
 
   private onScroll = debounce(() => {
-    this.setState({ ...this.getCanvasOffsets() });
+    const { offsetTop, offsetLeft } = this.getCanvasOffsets();
+    this.setState((state) => {
+      if (state.offsetLeft === offsetLeft && state.offsetTop === offsetTop) {
+        return null;
+      }
+      return { offsetTop, offsetLeft };
+    });
   }, SCROLL_TIMEOUT);
 
   // Copy/paste
diff --git a/src/constants.ts b/src/constants.ts
index 2a7c66fb..94711354 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -94,7 +94,7 @@ export const TOUCH_CTX_MENU_TIMEOUT = 500;
 export const TITLE_TIMEOUT = 10000;
 export const TOAST_TIMEOUT = 5000;
 export const VERSION_TIMEOUT = 30000;
-export const SCROLL_TIMEOUT = 500;
+export const SCROLL_TIMEOUT = 100;
 
 export const ZOOM_STEP = 0.1;
 
diff --git a/src/packages/excalidraw/CHANGELOG.md b/src/packages/excalidraw/CHANGELOG.md
index dd073044..5d0d992b 100644
--- a/src/packages/excalidraw/CHANGELOG.md
+++ b/src/packages/excalidraw/CHANGELOG.md
@@ -12,6 +12,16 @@ The change should be grouped under one of the below section and must contain PR
 Please add the latest change on the top under the correct section.
 -->
 
+## Unreleased
+
+## Excalidraw API
+
+### Fixes
+
+- Reduce the scroll debounce timeout to `100ms` so `offsets` gets updated faster if changed when container scrolled [#3182](https://github.com/excalidraw/excalidraw/pull/3182).
+
+---
+
 ## 0.4.1
 
 ## Excalidraw API