From 59cf86c13cd98391a0ea73f0b876aed713d33966 Mon Sep 17 00:00:00 2001 From: Igor Mandrigin Date: Fri, 14 Sep 2018 12:53:25 +0200 Subject: [PATCH] Workaround a wrong fling direction if FlatList or VirtualizedList is inverted. --- .../facebook/react/views/scroll/ReactScrollView.java | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java index db7844788d2cb4..e46bc5b0203eb5 100644 --- a/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java +++ b/ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java @@ -302,6 +302,16 @@ public void getClippingRect(Rect outClippingRect) { @Override public void fling(int velocityY) { + // Workaround. + // On Android P if a ScrollView is inverted, we will get a wrong sign for + // velocityY (see https://issuetracker.google.com/issues/112385925). + // At the same time, mOnScrollDispatchHelper tracks the correct velocity direction. + // + // Hence, we can use the absolute value from whatever the OS gives + // us and use the sign of what mOnScrollDispatchHelper has tracked. + velocityY = (int)(Math.abs(velocityY) * Math.signum(mOnScrollDispatchHelper.getYVelocity())); + + if (mPagingEnabled) { smoothScrollAndSnap(velocityY); } else if (mScroller != null) {