From dbc23466b3ec63453ca57e6e24e1efd23c104b8f Mon Sep 17 00:00:00 2001
From: Shane Osbourne <shane.osbourne8@gmail.com>
Date: Thu, 28 Jun 2018 15:24:25 -0700
Subject: [PATCH] =?UTF-8?q?fix:=20account=20for=20`ListHeaderComponent`=20?=
 =?UTF-8?q?length=20when=20calculating=20offset=E2=80=A6=20(#17415)?=
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Summary:
… in VirtualizedList - fixes #16612

Issue is detailed in #16612

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I need `onViewableItemsChanged` to account for the length of any ListHeaderComponents

I couldn't find any tests that currently cover the use-case of a VirtualizedList + ListComponent + scroll with onViewableItemsChanged, so I have not added any tests - all previous tests pass however.

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  CATEGORY
[----------]        TYPE
[ CLI      ]   [-------------]      LOCATION
[ DOCS     ]   [ BREAKING    ]   [-------------]
[ GENERAL  ]   [ BUGFIX      ]   [-{Component}-]
[ INTERNAL ]   [ ENHANCEMENT ]   [ {File}      ]
[ IOS      ]   [ FEATURE     ]   [ {Directory} ]   |-----------|
[ ANDROID  ]   [ MINOR       ]   [ {Framework} ] - | {Message} |
[----------]   [-------------]   [-------------]   |-----------|

[CATEGORY] [TYPE] [LOCATION] - MESSAGE

 EXAMPLES:

 [IOS] [BREAKING] [FlatList] - Change a thing that breaks other things
 [ANDROID] [BUGFIX] [TextInput] - Did a thing to TextInput
 [CLI] [FEATURE] [local-cli/info/info.js] - CLI easier to do things with
 [DOCS] [BUGFIX] [GettingStarted.md] - Accidentally a thing/word
 [GENERAL] [ENHANCEMENT] [Yoga] - Added new yoga thing/position
 [INTERNAL] [FEATURE] [./scripts] - Added thing to script that nobody will see
-->

[GENERAL][BUGFIX][VirtualizedList] - account for `ListHeaderComponent` length
Closes https://github.com/facebook/react-native/pull/17415

Differential Revision: D8683555

Pulled By: hramos

fbshipit-source-id: 05df7b79c16e3c07c12468e782f3c4b0bdce7403
---
 Libraries/Lists/VirtualizedList.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Libraries/Lists/VirtualizedList.js b/Libraries/Lists/VirtualizedList.js
index 56364823f06d49..47b6b5f083e1d7 100644
--- a/Libraries/Lists/VirtualizedList.js
+++ b/Libraries/Lists/VirtualizedList.js
@@ -1217,7 +1217,9 @@ class VirtualizedList extends React.PureComponent<Props, State> {
   }
 
   _selectOffset(metrics: $ReadOnly<{x: number, y: number}>): number {
-    return !this.props.horizontal ? metrics.y : metrics.x;
+    return (
+      (!this.props.horizontal ? metrics.y : metrics.x) - this._headerLength
+    );
   }
 
   _maybeCallOnEndReached() {