From ea6b541a4e3d85d515c4d51af522643ec2be65c1 Mon Sep 17 00:00:00 2001
From: Wincent <3088566+davidwincent@users.noreply.github.com>
Date: Fri, 5 Mar 2021 16:42:21 +0100
Subject: [PATCH] feat: Add measure method, issue #31 (#55)

* feat: Add measure method, issue #31

* refactor: measure method

Reduce roundtrips

* Fix: virtualItems should not depend on state

* Fix: remove eslint-disable-next-line react-hooks/exhaustive-deps

Co-authored-by: David Wincent <david.wincent@decerno.se>
Co-authored-by: David Wincent <davidwincent@users.noreply.github.com>
---
 src/index.js     | 6 ++++++
 types/index.d.ts | 1 +
 2 files changed, 7 insertions(+)

diff --git a/src/index.js b/src/index.js
index 6f5e0a5f..31f98aa5 100644
--- a/src/index.js
+++ b/src/index.js
@@ -47,6 +47,11 @@ export function useVirtual({
 
   const [measuredCache, setMeasuredCache] = React.useState({})
 
+  const measure = React.useCallback(
+    () => setMeasuredCache({}),
+    []
+  )
+
   const measurements = React.useMemo(() => {
     const measurements = []
     for (let i = 0; i < size; i++) {
@@ -215,6 +220,7 @@ export function useVirtual({
     totalSize,
     scrollToOffset,
     scrollToIndex,
+    measure,
   }
 }
 
diff --git a/types/index.d.ts b/types/index.d.ts
index 7490c40c..7ce67e3b 100644
--- a/types/index.d.ts
+++ b/types/index.d.ts
@@ -39,6 +39,7 @@ declare function useVirtual<T>(options: {
   totalSize: number
   scrollToOffset: (index: number, options?: ScrollToOffsetOptions) => void
   scrollToIndex: (index: number, options?: ScrollToIndexOptions) => void
+  measure: () => void
 }
 
 export { useVirtual }