Refine AbsListView transcript mode behavior.

Make transcript mode only scroll to the bottom if the last item is
already scrolled fully to the bottom when the change occurs Before
this, transcript mode would cause a list to scroll to the bottom as
long as the last item in the adapter was visible at all. Long items
would make this behave unexpectedly.

Change-Id: Ia6a52c969ea6d50653cf2b8cd4dc30ba517cf803

1 files changed, 14 insertions, 3 deletions

diff --git a/core/java/android/widget/AbsListView.java b/core/java/android/widget/AbsListView.java
index d0ed23f..ab5ff3d 100644
--- a/core/java/android/widget/AbsListView.java
+++ b/core/java/android/widget/AbsListView.java
@@ -3856,12 +3856,23 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
                 // Update this first, since setNextSelectedPositionInt inspects it
                 mNeedSync = false;
 
-                if (mTranscriptMode == TRANSCRIPT_MODE_ALWAYS_SCROLL ||
-                        (mTranscriptMode == TRANSCRIPT_MODE_NORMAL &&
-                                mFirstPosition + getChildCount() >= mOldItemCount)) {
+                if (mTranscriptMode == TRANSCRIPT_MODE_ALWAYS_SCROLL) {
                     mLayoutMode = LAYOUT_FORCE_BOTTOM;
                     return;
                 }
+                if (mTranscriptMode == TRANSCRIPT_MODE_NORMAL) {
+                    final int childCount = getChildCount();
+                    final int listBottom = getBottom() - getPaddingBottom();
+                    final View lastChild = getChildAt(childCount - 1);
+                    final int lastBottom = lastChild != null ? lastChild.getBottom() : listBottom;
+                    if (mFirstPosition + childCount >= mOldItemCount && lastBottom <= listBottom) {
+                        mLayoutMode = LAYOUT_FORCE_BOTTOM;
+                        return;
+                    }
+                    // Something new came in and we didn't scroll; give the user a clue that
+                    // there's something new.
+                    awakenScrollBars();
+                }
 
                 switch (mSyncMode) {
                 case SYNC_SELECTED_POSITION: