From d19d137cc18f10957b5ac64ac727d15fde57f018 Mon Sep 17 00:00:00 2001
From: Logan Daniels <logand@fb.com>
Date: Thu, 16 Nov 2017 20:03:07 -0800
Subject: [PATCH] Fix minimumViewTime in ViewabilityHelper

Reviewed By: sahrens

Differential Revision: D6350352

fbshipit-source-id: e909600875156127eb3144726981ab62e0015e6e
---
 Libraries/Lists/ViewabilityHelper.js | 21 ++++++---------------
 1 file changed, 6 insertions(+), 15 deletions(-)

diff --git a/Libraries/Lists/ViewabilityHelper.js b/Libraries/Lists/ViewabilityHelper.js
index 05f1a1bc79b435..858bb4d07e2d8a 100644
--- a/Libraries/Lists/ViewabilityHelper.js
+++ b/Libraries/Lists/ViewabilityHelper.js
@@ -74,7 +74,6 @@ export type ViewabilityConfig = {|
 class ViewabilityHelper {
   _config: ViewabilityConfig;
   _hasInteracted: boolean = false;
-  _lastUpdateTime: number = 0;
   _timers: Set<number> = new Set();
   _viewableIndices: Array<number> = [];
   _viewableItems: Map<string, ViewToken> = new Map();
@@ -170,15 +169,11 @@ class ViewabilityHelper {
     }) => void,
     renderRange?: {first: number, last: number}, // Optional optimization to reduce the scan size
   ): void {
-    const updateTime = Date.now();
-    if (this._lastUpdateTime === 0 && itemCount > 0 && getFrameMetrics(0)) {
-      // Only count updates after the first item is rendered and has a frame.
-      this._lastUpdateTime = updateTime;
-    }
-    const updateElapsed = this._lastUpdateTime
-      ? updateTime - this._lastUpdateTime
-      : 0;
-    if (this._config.waitForInteraction && !this._hasInteracted) {
+    if (
+      (this._config.waitForInteraction && !this._hasInteracted) ||
+      itemCount === 0 ||
+      !getFrameMetrics(0)
+    ) {
       return;
     }
     let viewableIndices = [];
@@ -200,11 +195,7 @@ class ViewabilityHelper {
       return;
     }
     this._viewableIndices = viewableIndices;
-    this._lastUpdateTime = updateTime;
-    if (
-      this._config.minimumViewTime &&
-      updateElapsed < this._config.minimumViewTime
-    ) {
+    if (this._config.minimumViewTime) {
       const handle = setTimeout(() => {
         this._timers.delete(handle);
         this._onUpdateSync(