From 2a93911b87f7aac6d0dcceabc5983e81befeeda5 Mon Sep 17 00:00:00 2001 From: Adam Powell Date: Thu, 21 Mar 2013 17:08:38 -0700 Subject: Fix a stability regression in ListView arrow scrolling The earlier patch 3cf7b3c59 introduced a stability regression. Perform the appropriate bounds checking alongside the fix it implements. Bug 8264185 Change-Id: I943d6c05bacdd777f89243fdac97788b16639dc6 --- core/java/android/widget/ListView.java | 32 +++++++++++++++++++++++++++++--- 1 file changed, 29 insertions(+), 3 deletions(-) diff --git a/core/java/android/widget/ListView.java b/core/java/android/widget/ListView.java index 38550a261120..4b62c2d2450f 100644 --- a/core/java/android/widget/ListView.java +++ b/core/java/android/widget/ListView.java @@ -2416,6 +2416,34 @@ public class ListView extends AbsListView { } } + /** + * Used by {@link #arrowScrollImpl(int)} to help determine the next selected position + * to move to. This can return a position currently not represented by a view on screen + * but only in the direction given. + * + * @param selectedPos Current selected position to move from + * @param direction Direction to move in + * @return Desired selected position after moving in the given direction + */ + private final int nextSelectedPositionForDirection(int selectedPos, int direction) { + int nextSelected; + if (direction == View.FOCUS_DOWN) { + nextSelected = selectedPos != INVALID_POSITION && selectedPos >= mFirstPosition ? + selectedPos + 1 : + mFirstPosition; + } else { + final int lastPos = mFirstPosition + getChildCount() - 1; + nextSelected = selectedPos != INVALID_POSITION && selectedPos < lastPos? + selectedPos - 1 : + lastPos; + } + + if (nextSelected < 0 || nextSelected >= mAdapter.getCount()) { + return INVALID_POSITION; + } + return lookForSelectablePosition(nextSelected, direction == View.FOCUS_DOWN); + } + /** * Handle an arrow scroll going up or down. Take into account whether items are selectable, * whether there are focusable items etc. @@ -2431,9 +2459,7 @@ public class ListView extends AbsListView { View selectedView = getSelectedView(); int selectedPos = mSelectedPosition; - int nextSelectedPosition = (direction == View.FOCUS_DOWN) ? - lookForSelectablePosition(selectedPos + 1, true) : - lookForSelectablePosition(selectedPos - 1, false); + int nextSelectedPosition = nextSelectedPositionForDirection(selectedPos, direction); int amountToScroll = amountToScroll(direction, nextSelectedPosition); // if we are moving focus, we may OVERRIDE the default behavior -- cgit v1.2.3-59-g8ed1b