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Commit d2cbe50f authored by George Mount's avatar George Mount
Browse files

Fix overscroll doesn't affect scrolling when released 

Bug: 188531406

When an EdgeEffect is flung past 0 into negative values, it
shows a stretch from the other side. To prevent this, the EdgeEffect
animation is now terminated when it reaches 0. I also made it so
that dragging to a value of 0 releases the EdgeEffect.

I also fixed the nested scrolling so that the stretch release
of ListView occurs before the onNestedPreScroll().

Test: new tests and manual testing
Change-Id: Ia20a6b96d25cf31ef143511828ddce5c33cee804
parent 265c3377

core/java/android/widget/AbsListView.java

+8 −9
Original line number Diff line number Diff line
@@ -3574,28 +3574,27 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te 
    private void scrollIfNeeded(int x, int y, MotionEvent vtev) {

        int rawDeltaY = y - mMotionY;

        int scrollOffsetCorrection = 0;

        int scrollConsumedCorrection = 0;

        if (mLastY == Integer.MIN_VALUE) {

            rawDeltaY -= mMotionCorrection;

        }

        if (dispatchNestedPreScroll(0, mLastY != Integer.MIN_VALUE ? mLastY - y : -rawDeltaY,

                mScrollConsumed, mScrollOffset)) {



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



        // First allow releasing existing overscroll effect:

        incrementalDeltaY = releaseGlow(incrementalDeltaY, x);



        if (dispatchNestedPreScroll(0, -incrementalDeltaY, mScrollConsumed, mScrollOffset)) {

            rawDeltaY += mScrollConsumed[1];

            scrollOffsetCorrection = -mScrollOffset[1];

            scrollConsumedCorrection = mScrollConsumed[1];

            incrementalDeltaY += mScrollConsumed[1];

            if (vtev != null) {

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

                mNestedYOffset += mScrollOffset[1];

            }

        }

        final int deltaY = rawDeltaY;

        int incrementalDeltaY =

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

        int lastYCorrection = 0;



        // First allow releasing existing overscroll effect:

        incrementalDeltaY = releaseGlow(incrementalDeltaY, x);



        if (mTouchMode == TOUCH_MODE_SCROLL) {

            if (PROFILE_SCROLLING) {

                if (!mScrollProfilingStarted) {

core/java/android/widget/EdgeEffect.java

+9 −2
Original line number Diff line number Diff line
@@ -342,6 +342,9 @@ public class EdgeEffect { 


        mGlowAlphaFinish = mGlowAlpha;

        mGlowScaleYFinish = mGlowScaleY;

        if (mEdgeEffectType == TYPE_STRETCH && mDistance == 0) {

            mState = STATE_IDLE;

        }

    }



    /**
@@ -739,8 +742,12 @@ public class EdgeEffect { 
    private boolean isAtEquilibrium() {

        double displacement = mDistance * mHeight; // in pixels

        double velocity = mVelocity;

        return Math.abs(velocity) < VELOCITY_THRESHOLD

                && Math.abs(displacement) < VALUE_THRESHOLD;



        // Don't allow displacement to drop below 0. We don't want it stretching the opposite

        // direction if it is flung that way. We also want to stop the animation as soon as

        // it gets very close to its destination.

        return displacement < 0 || (Math.abs(velocity) < VELOCITY_THRESHOLD

                && displacement < VALUE_THRESHOLD);

    }



    private float dampStretchVector(float normalizedVec) {