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Commit ec8e720a authored by Alan Viverette's avatar Alan Viverette
Browse files

Ensure AdapterView doesn't post selection notifications forever 

Previously we would loop forever if a selection notification was
posted after data had changed but the data changed bit was never
reset (e.g. a layout pass never occurred). This moves the pending
notification to occur as part of a layoutChildren() /
checkSelectionChanged() pass. If the client does horrible things
to prevent layout, no notification will occur -- but we won't loop
forever.

BUG: 17736536
Change-Id: I9773a769ad402c92dcbe2af7b8982d4443001961
parent 663edb8b

core/java/android/widget/AdapterView.java

+35 −9
Original line number Diff line number Diff line
@@ -215,7 +215,12 @@ public abstract class AdapterView<T extends Adapter> extends ViewGroup { 
    private boolean mDesiredFocusableState;

    private boolean mDesiredFocusableInTouchModeState;



    /** Lazily-constructed runnable for dispatching selection events. */

    private SelectionNotifier mSelectionNotifier;



    /** Selection notifier that's waiting for the next layout pass. */

    private SelectionNotifier mPendingSelectionNotifier;



    /**

     * When set to true, calls to requestLayout() will not propagate up the parent hierarchy.

     * This is used to layout the children during a layout pass.
@@ -854,37 +859,48 @@ public abstract class AdapterView<T extends Adapter> extends ViewGroup { 


    private class SelectionNotifier implements Runnable {

        public void run() {

            mPendingSelectionNotifier = null;



            if (mDataChanged) {

                // Data has changed between when this SelectionNotifier

                // was posted and now. We need to wait until the AdapterView

                // has been synched to the new data.

                // Data has changed between when this SelectionNotifier was

                // posted and now. Postpone the notification until the next

                // layout is complete and we run checkSelectionChanged().

                if (getAdapter() != null) {

                    post(this);

                    mPendingSelectionNotifier = this;

                }

            } else {

                fireOnSelected();

                performAccessibilityActionsOnSelected();

                dispatchOnItemSelected();

            }

        }

    }



    void selectionChanged() {

        // We're about to post or run the selection notifier, so we don't need

        // a pending notifier.

        mPendingSelectionNotifier = null;



        if (mOnItemSelectedListener != null

                || AccessibilityManager.getInstance(mContext).isEnabled()) {

            if (mInLayout || mBlockLayoutRequests) {

                // If we are in a layout traversal, defer notification

                // by posting. This ensures that the view tree is

                // in a consistent state and is able to accomodate

                // in a consistent state and is able to accommodate

                // new layout or invalidate requests.

                if (mSelectionNotifier == null) {

                    mSelectionNotifier = new SelectionNotifier();

                } else {

                    removeCallbacks(mSelectionNotifier);

                }

                post(mSelectionNotifier);

            } else {

                fireOnSelected();

                performAccessibilityActionsOnSelected();

                dispatchOnItemSelected();

            }

        }

    }



    private void dispatchOnItemSelected() {

        fireOnSelected();

        performAccessibilityActionsOnSelected();

    }



    private void fireOnSelected() {
@@ -1042,12 +1058,22 @@ public abstract class AdapterView<T extends Adapter> extends ViewGroup { 
        notifySubtreeAccessibilityStateChangedIfNeeded();

    }



    /**

     * Called after layout to determine whether the selection position needs to

     * be updated. Also used to fire any pending selection events.

     */

    void checkSelectionChanged() {

        if ((mSelectedPosition != mOldSelectedPosition) || (mSelectedRowId != mOldSelectedRowId)) {

            selectionChanged();

            mOldSelectedPosition = mSelectedPosition;

            mOldSelectedRowId = mSelectedRowId;

        }



        // If we have a pending selection notification -- and we won't if we

        // just fired one in selectionChanged() -- run it now.

        if (mPendingSelectionNotifier != null) {

            mPendingSelectionNotifier.run();

        }

    }



    /**