Fix a bug with deferred position scrolling in lists while data changes

are pending

Save the pending position scroll until the data change is actually
serviced before posting it to run. This avoids handler loops on
GONE subtrees or when the view is detached.

Bug 6547649

Change-Id: Iab108cfcb7dd11ece703762d311a5f5985f38c3b

Author: adamp

core/java/android/widget/AbsListView.java

@@ -579,6 +579,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
     private InputConnectionWrapper mPublicInputConnection;
 
     private Runnable mClearScrollingCache;
+    Runnable mPositionScrollAfterLayout;
     private int mMinimumVelocity;
     private int mMaximumVelocity;
     private float mVelocityScale = 1.0f;
@@ -1910,6 +1911,7 @@ void resetList() {
         removeAllViewsInLayout();
         mFirstPosition = 0;
         mDataChanged = false;
+        mPositionScrollAfterLayout = null;
         mNeedSync = false;
         mOldSelectedPosition = INVALID_POSITION;
         mOldSelectedRowId = INVALID_ROW_ID;
@@ -4248,11 +4250,11 @@ void start(final int position) {
 
             if (mDataChanged) {
                 // Wait until we're back in a stable state to try this.
-                post(new Runnable() {
+                mPositionScrollAfterLayout = new Runnable() {
                     @Override public void run() {
                         start(position);
                     }
-                });
+                };
                 return;
             }
 
@@ -4299,11 +4301,11 @@ void start(final int position, final int boundPosition) {
 
             if (mDataChanged) {
                 // Wait until we're back in a stable state to try this.
-                post(new Runnable() {
+                mPositionScrollAfterLayout = new Runnable() {
                     @Override public void run() {
                         start(position, boundPosition);
                     }
-                });
+                };
                 return;
             }
 
@@ -4376,11 +4378,11 @@ void startWithOffset(final int position, int offset, final int duration) {
             if (mDataChanged) {
                 // Wait until we're back in a stable state to try this.
                 final int postOffset = offset;
-                post(new Runnable() {
+                mPositionScrollAfterLayout = new Runnable() {
                     @Override public void run() {
                         startWithOffset(position, postOffset, duration);
                     }
-                });
+                };
                 return;
             }
 

core/java/android/widget/GridView.java

@@ -1275,6 +1275,10 @@ protected void layoutChildren() {
 
             mLayoutMode = LAYOUT_NORMAL;
             mDataChanged = false;
+            if (mPositionScrollAfterLayout != null) {
+                post(mPositionScrollAfterLayout);
+                mPositionScrollAfterLayout = null;
+            }
             mNeedSync = false;
             setNextSelectedPositionInt(mSelectedPosition);
 

core/java/android/widget/ListView.java

@@ -1691,6 +1691,10 @@ protected void layoutChildren() {
 
             mLayoutMode = LAYOUT_NORMAL;
             mDataChanged = false;
+            if (mPositionScrollAfterLayout != null) {
+                post(mPositionScrollAfterLayout);
+                mPositionScrollAfterLayout = null;
+            }
             mNeedSync = false;
             setNextSelectedPositionInt(mSelectedPosition);