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Commit 43943d8b authored by Yorke Lee's avatar Yorke Lee
Browse files

Fix nested scrolling bugs in AbsListView 

* rawDeltaY should be offset by mMotionCorrection when passing it
to dispatchNestedPreScroll
* mScrollOffset should offset the next motion event, not the current
one

Bug: 14572732

Change-Id: Ib98f27d608b91706af4537e1cf9ad42adce121ea
parent 80914669

core/java/android/widget/AbsListView.java

+13 −10
Original line number Diff line number Diff line
@@ -3305,18 +3305,22 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te 


    private void scrollIfNeeded(int y, MotionEvent vtev) {

        int rawDeltaY = y - mMotionY;

        int scrollOffsetCorrection = 0;

        int scrollConsumedCorrection = 0;

        if (mLastY == Integer.MIN_VALUE) {

            rawDeltaY -= mMotionCorrection;

        }

        if (dispatchNestedPreScroll(0, rawDeltaY, mScrollConsumed, mScrollOffset)) {

            rawDeltaY -= mScrollConsumed[1];

            mMotionCorrection -= mScrollOffset[1];

            if (mLastY != Integer.MIN_VALUE) {

                mLastY -= mScrollOffset[1] + mScrollConsumed[1];

            }

            scrollOffsetCorrection -= mScrollOffset[1];

            scrollConsumedCorrection -= mScrollConsumed[1];

            if (vtev != null) {

                vtev.offsetLocation(0, mScrollOffset[1]);

            }

        }

        final int deltaY = rawDeltaY - mMotionCorrection;

        int incrementalDeltaY = mLastY != Integer.MIN_VALUE ? y - mLastY : deltaY;

        final int deltaY = rawDeltaY;

        int incrementalDeltaY =

                mLastY != Integer.MIN_VALUE ? y - mLastY - scrollConsumedCorrection : deltaY;

        int lastYCorrection = 0;



        if (mTouchMode == TOUCH_MODE_SCROLL) {
@@ -3378,7 +3382,6 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te 
                                (motionViewRealTop - motionViewPrevTop);

                        if (dispatchNestedScroll(0, overscroll - incrementalDeltaY, 0, overscroll,

                                mScrollOffset)) {

                            mMotionCorrection -= mScrollOffset[1];

                            lastYCorrection -= mScrollOffset[1];

                            if (vtev != null) {

                                vtev.offsetLocation(0, mScrollOffset[1]);
@@ -3415,9 +3418,9 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te 
                            }

                        }

                    }

                    mMotionY = y;

                    mMotionY = y + scrollOffsetCorrection;

                }

                mLastY = y + lastYCorrection;

                mLastY = y + lastYCorrection + scrollOffsetCorrection;

            }

        } else if (mTouchMode == TOUCH_MODE_OVERSCROLL) {

            if (y != mLastY) {