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28-Jan-2015 |
Dake Gu <dake@google.com> |
Reduce memory consumption of DPAD scroll multiple column grid
Created a special SmoothScroller to handle onFocusSearchFailed
for multiple column cases. It remembers the pending movements caused
in onFocusSearchFailed and consume the pending DPAD movements when
a view is laid out in the direction. The change avoids appending
or prepending excessive views on the scroll direction which is not
within screen bounds.
Add a onLaidOut() listener for VerticalGridFragment to check if
we hit the first row. If the grid is three columns.
Previously (before introducing the special SmoothScroller) we always
prepend one row of items before fire onSelected event, so when we fire
onSelected(1), item0 is already in the tree and havePreviousViewInSameRow()
returns false. Using the special SmoothScroller, onSelected is fired at
the time a view is created. Checking hasPreviousViewInSameRow() at the
time item1 is selected will return true because item0 has not been
created yet. So VerticalGridFragment should also listen to when
item0 is added to hierarchy.
Applied a MAX_PENDING_MOVES to avoid overscroll too much.
Issue: 19150678
Change-Id: I7cf0093a4bee652f60c5f2004b799ee7c3f87fc8
/frameworks/support/v17/leanback/src/android/support/v17/leanback/widget/OnChildLaidOutListener.java
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