Merge "Fix keyboard naviagation for the nested preview scrolling" into main

7 files changed, 2760 insertions, 15 deletions

diff --git a/java/res/layout/chooser_grid_scrollable_preview.xml b/java/res/layout/chooser_grid_scrollable_preview.xml
index c1bcf912..02584d27 100644
--- a/java/res/layout/chooser_grid_scrollable_preview.xml
+++ b/java/res/layout/chooser_grid_scrollable_preview.xml
@@ -78,6 +78,7 @@
     </FrameLayout>
 
     <com.android.intentresolver.widget.ChooserNestedScrollView
+        android:id="@+id/chooser_scrollable_container"
         android:layout_width="match_parent"
         android:layout_height="wrap_content">
 
diff --git a/java/res/layout/chooser_list_per_profile_wrap.xml b/java/res/layout/chooser_list_per_profile_wrap.xml
index fc0431d7..d48fcb50 100644
--- a/java/res/layout/chooser_list_per_profile_wrap.xml
+++ b/java/res/layout/chooser_list_per_profile_wrap.xml
@@ -18,14 +18,7 @@
     xmlns:androidprv="http://schemas.android.com/apk/prv/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     android:layout_width="match_parent"
-    android:layout_height="wrap_content"
-    android:descendantFocusability="blocksDescendants">
-    <!--    ^^^ Block descendants from receiving focus to prevent NestedScrollView
-    (ChooserNestedScrollView) scrolling to the focused view when switching tabs. Without it, TabHost
-    view will request focus on the newly activated tab. The RecyclerView from this layout gets
-    focused and  notifies its parents (including NestedScrollView) about it through
-    #requestChildFocus method call. NestedScrollView's view implementation of the method  will
-    scroll to the focused view. -->
+    android:layout_height="wrap_content">
 
     <androidx.recyclerview.widget.RecyclerView
         android:layout_width="match_parent"
diff --git a/java/src/com/android/intentresolver/ChooserActivity.java b/java/src/com/android/intentresolver/ChooserActivity.java
index 4441fc99..e786dc79 100644
--- a/java/src/com/android/intentresolver/ChooserActivity.java
+++ b/java/src/com/android/intentresolver/ChooserActivity.java
@@ -24,6 +24,7 @@ import static androidx.lifecycle.LifecycleKt.getCoroutineScope;
 
 import static com.android.intentresolver.ChooserActionFactory.EDIT_SOURCE;
 import static com.android.intentresolver.Flags.fixShortcutsFlashing;
+import static com.android.intentresolver.Flags.keyboardNavigationFix;
 import static com.android.intentresolver.Flags.shareouselUpdateExcludeComponentsExtra;
 import static com.android.intentresolver.Flags.unselectFinalItem;
 import static com.android.intentresolver.ext.CreationExtrasExtKt.replaceDefaultArgs;
@@ -137,6 +138,7 @@ import com.android.intentresolver.ui.ShareResultSender;
 import com.android.intentresolver.ui.ShareResultSenderFactory;
 import com.android.intentresolver.ui.viewmodel.ChooserViewModel;
 import com.android.intentresolver.widget.ActionRow;
+import com.android.intentresolver.widget.ChooserNestedScrollView;
 import com.android.intentresolver.widget.ImagePreviewView;
 import com.android.intentresolver.widget.ResolverDrawerLayout;
 import com.android.internal.annotations.VisibleForTesting;
@@ -1284,6 +1286,18 @@ public class ChooserActivity extends Hilt_ChooserActivity implements
         mTabHost = findViewById(com.android.internal.R.id.profile_tabhost);
         mViewPager = requireViewById(com.android.internal.R.id.profile_pager);
         mChooserMultiProfilePagerAdapter.setupViewPager(mViewPager);
+        ChooserNestedScrollView scrollableContainer =
+                requireViewById(R.id.chooser_scrollable_container);
+        if (keyboardNavigationFix()) {
+            scrollableContainer.setRequestChildFocusPredicate((child, focused) ->
+                    // TabHost view will request focus on the newly activated tab. The RecyclerView
+                    // from the tab gets focused and  notifies its parents (including
+                    // NestedScrollView) about it through #requestChildFocus method call.
+                    // NestedScrollView's view implementation of the method  will  scroll to the
+                    // focused view. As we don't want to change drawer's position upon tab change,
+                    // ignore focus requests from tab RecyclerViews.
+                    focused == null || focused.getId() != com.android.internal.R.id.resolver_list);
+        }
         boolean result = postRebuildList(rebuildCompleted);
         Trace.endSection();
         return result;
diff --git a/java/src/com/android/intentresolver/profiles/ChooserMultiProfilePagerAdapter.java b/java/src/com/android/intentresolver/profiles/ChooserMultiProfilePagerAdapter.java
index 9176cd35..677b6366 100644
--- a/java/src/com/android/intentresolver/profiles/ChooserMultiProfilePagerAdapter.java
+++ b/java/src/com/android/intentresolver/profiles/ChooserMultiProfilePagerAdapter.java
@@ -16,6 +16,8 @@
 
 package com.android.intentresolver.profiles;
 
+import static com.android.intentresolver.Flags.keyboardNavigationFix;
+
 import android.content.Context;
 import android.os.UserHandle;
 import android.view.LayoutInflater;
@@ -125,6 +127,9 @@ public class ChooserMultiProfilePagerAdapter extends MultiProfilePagerAdapter<
         LayoutInflater inflater = LayoutInflater.from(context);
         ViewGroup rootView =
                 (ViewGroup) inflater.inflate(R.layout.chooser_list_per_profile_wrap, null, false);
+        if (!keyboardNavigationFix()) {
+            rootView.setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
+        }
         RecyclerView recyclerView = rootView.findViewById(com.android.internal.R.id.resolver_list);
         recyclerView.setAccessibilityDelegateCompat(
                 new ChooserRecyclerViewAccessibilityDelegate(recyclerView));
diff --git a/java/src/com/android/intentresolver/widget/ChooserNestedScrollView.kt b/java/src/com/android/intentresolver/widget/ChooserNestedScrollView.kt
index e86de888..a9577cf5 100644
--- a/java/src/com/android/intentresolver/widget/ChooserNestedScrollView.kt
+++ b/java/src/com/android/intentresolver/widget/ChooserNestedScrollView.kt
@@ -25,7 +25,7 @@ import androidx.core.view.marginBottom
 import androidx.core.view.marginLeft
 import androidx.core.view.marginRight
 import androidx.core.view.marginTop
-import androidx.core.widget.NestedScrollView
+import com.android.intentresolver.Flags.keyboardNavigationFix
 
 /**
  * A narrowly tailored [NestedScrollView] to be used inside [ResolverDrawerLayout] and help to
@@ -35,13 +35,17 @@ import androidx.core.widget.NestedScrollView
  */
 class ChooserNestedScrollView : NestedScrollView {
     constructor(context: Context) : super(context)
+
     constructor(context: Context, attrs: AttributeSet?) : super(context, attrs)
+
     constructor(
         context: Context,
         attrs: AttributeSet?,
-        defStyleAttr: Int
+        defStyleAttr: Int,
     ) : super(context, attrs, defStyleAttr)
 
+    var requestChildFocusPredicate: (View?, View?) -> Boolean = DefaultChildFocusPredicate
+
     override fun onMeasure(widthMeasureSpec: Int, heightMeasureSpec: Int) {
         val content =
             getChildAt(0) as? LinearLayout ?: error("Exactly one child, LinerLayout, is expected")
@@ -55,13 +59,13 @@ class ChooserNestedScrollView : NestedScrollView {
             getChildMeasureSpec(
                 widthMeasureSpec,
                 paddingLeft + content.marginLeft + content.marginRight + paddingRight,
-                lp.width
+                lp.width,
             )
         val contentHeightSpec =
             getChildMeasureSpec(
                 heightMeasureSpec,
                 paddingTop + content.marginTop + content.marginBottom + paddingBottom,
-                lp.height
+                lp.height,
             )
         content.measure(contentWidthSpec, contentHeightSpec)
 
@@ -76,7 +80,7 @@ class ChooserNestedScrollView : NestedScrollView {
 
             content.measure(
                 contentWidthSpec,
-                MeasureSpec.makeMeasureSpec(height, MeasureSpec.getMode(heightMeasureSpec))
+                MeasureSpec.makeMeasureSpec(height, MeasureSpec.getMode(heightMeasureSpec)),
             )
         }
         setMeasuredDimension(
@@ -87,8 +91,8 @@ class ChooserNestedScrollView : NestedScrollView {
                     content.marginTop +
                     content.measuredHeight +
                     content.marginBottom +
-                    paddingBottom
-            )
+                    paddingBottom,
+            ),
         )
     }
 
@@ -103,4 +107,18 @@ class ChooserNestedScrollView : NestedScrollView {
             consumed[1] += scrollY - preScrollY
         }
     }
+
+    override fun onRequestChildFocus(child: View?, focused: View?) {
+        if (keyboardNavigationFix()) {
+            if (requestChildFocusPredicate(child, focused)) {
+                super.onRequestChildFocus(child, focused)
+            }
+        } else {
+            super.onRequestChildFocus(child, focused)
+        }
+    }
+
+    companion object {
+        val DefaultChildFocusPredicate: (View?, View?) -> Boolean = { _, _ -> true }
+    }
 }
diff --git a/java/src/com/android/intentresolver/widget/NestedScrollView.java b/java/src/com/android/intentresolver/widget/NestedScrollView.java
new file mode 100644
index 00000000..36fc7da6
--- /dev/null
+++ b/java/src/com/android/intentresolver/widget/NestedScrollView.java
@@ -0,0 +1,2611 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+package com.android.intentresolver.widget;
+
+import static androidx.annotation.RestrictTo.Scope.LIBRARY;
+
+import android.content.Context;
+import android.content.res.TypedArray;
+import android.graphics.Canvas;
+import android.graphics.Rect;
+import android.hardware.SensorManager;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.Parcel;
+import android.os.Parcelable;
+import android.util.AttributeSet;
+import android.util.Log;
+import android.util.TypedValue;
+import android.view.FocusFinder;
+import android.view.InputDevice;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+import android.view.VelocityTracker;
+import android.view.View;
+import android.view.ViewConfiguration;
+import android.view.ViewGroup;
+import android.view.ViewParent;
+import android.view.accessibility.AccessibilityEvent;
+import android.view.animation.AnimationUtils;
+import android.widget.EdgeEffect;
+import android.widget.FrameLayout;
+import android.widget.OverScroller;
+import android.widget.ScrollView;
+
+import androidx.annotation.DoNotInline;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.RequiresApi;
+import androidx.annotation.RestrictTo;
+import androidx.annotation.VisibleForTesting;
+import androidx.core.R;
+import androidx.core.view.AccessibilityDelegateCompat;
+import androidx.core.view.DifferentialMotionFlingController;
+import androidx.core.view.DifferentialMotionFlingTarget;
+import androidx.core.view.MotionEventCompat;
+import androidx.core.view.NestedScrollingChild3;
+import androidx.core.view.NestedScrollingChildHelper;
+import androidx.core.view.NestedScrollingParent3;
+import androidx.core.view.NestedScrollingParentHelper;
+import androidx.core.view.ScrollingView;
+import androidx.core.view.ViewCompat;
+import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
+import androidx.core.view.accessibility.AccessibilityRecordCompat;
+import androidx.core.widget.EdgeEffectCompat;
+
+import java.util.List;
+
+/**
+ * A copy of the {@link androidx.core.widget.NestedScrollView} (from
+ * prebuilts/sdk/current/androidx/m2repository/androidx/core/core/1.13.0-beta01/core-1.13.0-beta01-sources.jar)
+ * without any functional changes with a pure refactoring of {@link #requestChildFocus(View, View)}:
+ * the method's body is extracted into the new protected method,
+ * {@link #onRequestChildFocus(View, View)}.
+ * <p>
+ * For the exact change see NestedScrollView.java.patch file.
+ * </p>
+ */
+public class NestedScrollView extends FrameLayout implements NestedScrollingParent3,
+        NestedScrollingChild3, ScrollingView {
+    static final int ANIMATED_SCROLL_GAP = 250;
+
+    static final float MAX_SCROLL_FACTOR = 0.5f;
+
+    private static final String TAG = "NestedScrollView";
+    private static final int DEFAULT_SMOOTH_SCROLL_DURATION = 250;
+
+    /**
+     * The following are copied from OverScroller to determine how far a fling will go.
+     */
+    private static final float SCROLL_FRICTION = 0.015f;
+    private static final float INFLEXION = 0.35f; // Tension lines cross at (INFLEXION, 1)
+    private static final float DECELERATION_RATE = (float) (Math.log(0.78) / Math.log(0.9));
+    private final float mPhysicalCoeff;
+
+    /**
+     * When flinging the stretch towards scrolling content, it should destretch quicker than the
+     * fling would normally do. The visual effect of flinging the stretch looks strange as little
+     * appears to happen at first and then when the stretch disappears, the content starts
+     * scrolling quickly.
+     */
+    private static final float FLING_DESTRETCH_FACTOR = 4f;
+
+    /**
+     * Interface definition for a callback to be invoked when the scroll
+     * X or Y positions of a view change.
+     *
+     * <p>This version of the interface works on all versions of Android, back to API v4.</p>
+     *
+     * @see #setOnScrollChangeListener(OnScrollChangeListener)
+     */
+    public interface OnScrollChangeListener {
+        /**
+         * Called when the scroll position of a view changes.
+         * @param v The view whose scroll position has changed.
+         * @param scrollX Current horizontal scroll origin.
+         * @param scrollY Current vertical scroll origin.
+         * @param oldScrollX Previous horizontal scroll origin.
+         * @param oldScrollY Previous vertical scroll origin.
+         */
+        void onScrollChange(@NonNull NestedScrollView v, int scrollX, int scrollY,
+                int oldScrollX, int oldScrollY);
+    }
+
+    private long mLastScroll;
+
+    private final Rect mTempRect = new Rect();
+    private OverScroller mScroller;
+
+    @RestrictTo(LIBRARY)
+    @VisibleForTesting
+    @NonNull
+    public EdgeEffect mEdgeGlowTop;
+
+    @RestrictTo(LIBRARY)
+    @VisibleForTesting
+    @NonNull
+    public EdgeEffect mEdgeGlowBottom;
+
+    /**
+     * Position of the last motion event; only used with touch related events (usually to assist
+     * in movement changes in a drag gesture).
+     */
+    private int mLastMotionY;
+
+    /**
+     * True when the layout has changed but the traversal has not come through yet.
+     * Ideally the view hierarchy would keep track of this for us.
+     */
+    private boolean mIsLayoutDirty = true;
+    private boolean mIsLaidOut = false;
+
+    /**
+     * The child to give focus to in the event that a child has requested focus while the
+     * layout is dirty. This prevents the scroll from being wrong if the child has not been
+     * laid out before requesting focus.
+     */
+    private View mChildToScrollTo = null;
+
+    /**
+     * True if the user is currently dragging this ScrollView around. This is
+     * not the same as 'is being flinged', which can be checked by
+     * mScroller.isFinished() (flinging begins when the user lifts their finger).
+     */
+    private boolean mIsBeingDragged = false;
+
+    /**
+     * Determines speed during touch scrolling
+     */
+    private VelocityTracker mVelocityTracker;
+
+    /**
+     * When set to true, the scroll view measure its child to make it fill the currently
+     * visible area.
+     */
+    private boolean mFillViewport;
+
+    /**
+     * Whether arrow scrolling is animated.
+     */
+    private boolean mSmoothScrollingEnabled = true;
+
+    private int mTouchSlop;
+    private int mMinimumVelocity;
+    private int mMaximumVelocity;
+
+    /**
+     * ID of the active pointer. This is used to retain consistency during
+     * drags/flings if multiple pointers are used.
+     */
+    private int mActivePointerId = INVALID_POINTER;
+
+    /**
+     * Used during scrolling to retrieve the new offset within the window. Saves memory by saving
+     * x, y changes to this array (0 position = x, 1 position = y) vs. reallocating an x and y
+     * every time.
+     */
+    private final int[] mScrollOffset = new int[2];
+
+    /*
+     * Used during scrolling to retrieve the new consumed offset within the window.
+     * Uses same memory saving strategy as mScrollOffset.
+     */
+    private final int[] mScrollConsumed = new int[2];
+
+    // Used to track the position of the touch only events relative to the container.
+    private int mNestedYOffset;
+
+    private int mLastScrollerY;
+
+    /**
+     * Sentinel value for no current active pointer.
+     * Used by {@link #mActivePointerId}.
+     */
+    private static final int INVALID_POINTER = -1;
+
+    private SavedState mSavedState;
+
+    private static final AccessibilityDelegate ACCESSIBILITY_DELEGATE = new AccessibilityDelegate();
+
+    private static final int[] SCROLLVIEW_STYLEABLE = new int[] {
+            android.R.attr.fillViewport
+    };
+
+    private final NestedScrollingParentHelper mParentHelper;
+    private final NestedScrollingChildHelper mChildHelper;
+
+    private float mVerticalScrollFactor;
+
+    private OnScrollChangeListener mOnScrollChangeListener;
+
+    @VisibleForTesting
+    final DifferentialMotionFlingTargetImpl mDifferentialMotionFlingTarget =
+            new DifferentialMotionFlingTargetImpl();
+
+    @VisibleForTesting
+    DifferentialMotionFlingController mDifferentialMotionFlingController =
+            new DifferentialMotionFlingController(getContext(), mDifferentialMotionFlingTarget);
+
+    public NestedScrollView(@NonNull Context context) {
+        this(context, null);
+    }
+
+    public NestedScrollView(@NonNull Context context, @Nullable AttributeSet attrs) {
+        this(context, attrs, R.attr.nestedScrollViewStyle);
+    }
+
+    public NestedScrollView(@NonNull Context context, @Nullable AttributeSet attrs,
+            int defStyleAttr) {
+        super(context, attrs, defStyleAttr);
+        mEdgeGlowTop = EdgeEffectCompat.create(context, attrs);
+        mEdgeGlowBottom = EdgeEffectCompat.create(context, attrs);
+
+        final float ppi = context.getResources().getDisplayMetrics().density * 160.0f;
+        mPhysicalCoeff = SensorManager.GRAVITY_EARTH // g (m/s^2)
+                * 39.37f // inch/meter
+                * ppi
+                * 0.84f; // look and feel tuning
+
+        initScrollView();
+
+        final TypedArray a = context.obtainStyledAttributes(
+                attrs, SCROLLVIEW_STYLEABLE, defStyleAttr, 0);
+
+        setFillViewport(a.getBoolean(0, false));
+
+        a.recycle();
+
+        mParentHelper = new NestedScrollingParentHelper(this);
+        mChildHelper = new NestedScrollingChildHelper(this);
+
+        // ...because why else would you be using this widget?
+        setNestedScrollingEnabled(true);
+
+        ViewCompat.setAccessibilityDelegate(this, ACCESSIBILITY_DELEGATE);
+    }
+
+    // NestedScrollingChild3
+
+    @Override
+    public void dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed,
+            int dyUnconsumed, @Nullable int[] offsetInWindow, int type, @NonNull int[] consumed) {
+        mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed,
+                offsetInWindow, type, consumed);
+    }
+
+    // NestedScrollingChild2
+
+    @Override
+    public boolean startNestedScroll(int axes, int type) {
+        return mChildHelper.startNestedScroll(axes, type);
+    }
+
+    @Override
+    public void stopNestedScroll(int type) {
+        mChildHelper.stopNestedScroll(type);
+    }
+
+    @Override
+    public boolean hasNestedScrollingParent(int type) {
+        return mChildHelper.hasNestedScrollingParent(type);
+    }
+
+    @Override
+    public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed,
+            int dyUnconsumed, @Nullable int[] offsetInWindow, int type) {
+        return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed,
+                offsetInWindow, type);
+    }
+
+    @Override
+    public boolean dispatchNestedPreScroll(
+            int dx,
+            int dy,
+            @Nullable int[] consumed,
+            @Nullable int[] offsetInWindow,
+            int type
+    ) {
+        return mChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow, type);
+    }
+
+    // NestedScrollingChild
+
+    @Override
+    public void setNestedScrollingEnabled(boolean enabled) {
+        mChildHelper.setNestedScrollingEnabled(enabled);
+    }
+
+    @Override
+    public boolean isNestedScrollingEnabled() {
+        return mChildHelper.isNestedScrollingEnabled();
+    }
+
+    @Override
+    public boolean startNestedScroll(int axes) {
+        return startNestedScroll(axes, ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public void stopNestedScroll() {
+        stopNestedScroll(ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public boolean hasNestedScrollingParent() {
+        return hasNestedScrollingParent(ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed,
+            int dyUnconsumed, @Nullable int[] offsetInWindow) {
+        return mChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed,
+                offsetInWindow);
+    }
+
+    @Override
+    public boolean dispatchNestedPreScroll(int dx, int dy, @Nullable int[] consumed,
+            @Nullable int[] offsetInWindow) {
+        return dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow, ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) {
+        return mChildHelper.dispatchNestedFling(velocityX, velocityY, consumed);
+    }
+
+    @Override
+    public boolean dispatchNestedPreFling(float velocityX, float velocityY) {
+        return mChildHelper.dispatchNestedPreFling(velocityX, velocityY);
+    }
+
+    // NestedScrollingParent3
+
+    @Override
+    public void onNestedScroll(@NonNull View target, int dxConsumed, int dyConsumed,
+            int dxUnconsumed, int dyUnconsumed, int type, @NonNull int[] consumed) {
+        onNestedScrollInternal(dyUnconsumed, type, consumed);
+    }
+
+    private void onNestedScrollInternal(int dyUnconsumed, int type, @Nullable int[] consumed) {
+        final int oldScrollY = getScrollY();
+        scrollBy(0, dyUnconsumed);
+        final int myConsumed = getScrollY() - oldScrollY;
+
+        if (consumed != null) {
+            consumed[1] += myConsumed;
+        }
+        final int myUnconsumed = dyUnconsumed - myConsumed;
+
+        mChildHelper.dispatchNestedScroll(0, myConsumed, 0, myUnconsumed, null, type, consumed);
+    }
+
+    // NestedScrollingParent2
+
+    @Override
+    public boolean onStartNestedScroll(@NonNull View child, @NonNull View target, int axes,
+            int type) {
+        return (axes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
+    }
+
+    @Override
+    public void onNestedScrollAccepted(@NonNull View child, @NonNull View target, int axes,
+            int type) {
+        mParentHelper.onNestedScrollAccepted(child, target, axes, type);
+        startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, type);
+    }
+
+    @Override
+    public void onStopNestedScroll(@NonNull View target, int type) {
+        mParentHelper.onStopNestedScroll(target, type);
+        stopNestedScroll(type);
+    }
+
+    @Override
+    public void onNestedScroll(@NonNull View target, int dxConsumed, int dyConsumed,
+            int dxUnconsumed, int dyUnconsumed, int type) {
+        onNestedScrollInternal(dyUnconsumed, type, null);
+    }
+
+    @Override
+    public void onNestedPreScroll(@NonNull View target, int dx, int dy, @NonNull int[] consumed,
+            int type) {
+        dispatchNestedPreScroll(dx, dy, consumed, null, type);
+    }
+
+    // NestedScrollingParent
+
+    @Override
+    public boolean onStartNestedScroll(
+            @NonNull View child, @NonNull View target, int axes) {
+        return onStartNestedScroll(child, target, axes, ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public void onNestedScrollAccepted(
+            @NonNull View child, @NonNull View target, int axes) {
+        onNestedScrollAccepted(child, target, axes, ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public void onStopNestedScroll(@NonNull View target) {
+        onStopNestedScroll(target, ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public void onNestedScroll(@NonNull View target, int dxConsumed, int dyConsumed,
+            int dxUnconsumed, int dyUnconsumed) {
+        onNestedScrollInternal(dyUnconsumed, ViewCompat.TYPE_TOUCH, null);
+    }
+
+    @Override
+    public void onNestedPreScroll(@NonNull View target, int dx, int dy, @NonNull int[] consumed) {
+        onNestedPreScroll(target, dx, dy, consumed, ViewCompat.TYPE_TOUCH);
+    }
+
+    @Override
+    public boolean onNestedFling(
+            @NonNull View target, float velocityX, float velocityY, boolean consumed) {
+        if (!consumed) {
+            dispatchNestedFling(0, velocityY, true);
+            fling((int) velocityY);
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public boolean onNestedPreFling(@NonNull View target, float velocityX, float velocityY) {
+        return dispatchNestedPreFling(velocityX, velocityY);
+    }
+
+    @Override
+    public int getNestedScrollAxes() {
+        return mParentHelper.getNestedScrollAxes();
+    }
+
+    // ScrollView import
+
+    @Override
+    public boolean shouldDelayChildPressedState() {
+        return true;
+    }
+
+    @Override
+    protected float getTopFadingEdgeStrength() {
+        if (getChildCount() == 0) {
+            return 0.0f;
+        }
+
+        final int length = getVerticalFadingEdgeLength();
+        final int scrollY = getScrollY();
+        if (scrollY < length) {
+            return scrollY / (float) length;
+        }
+
+        return 1.0f;
+    }
+
+    @Override
+    protected float getBottomFadingEdgeStrength() {
+        if (getChildCount() == 0) {
+            return 0.0f;
+        }
+
+        View child = getChildAt(0);
+        final LayoutParams lp = (LayoutParams) child.getLayoutParams();
+        final int length = getVerticalFadingEdgeLength();
+        final int bottomEdge = getHeight() - getPaddingBottom();
+        final int span = child.getBottom() + lp.bottomMargin - getScrollY() - bottomEdge;
+        if (span < length) {
+            return span / (float) length;
+        }
+
+        return 1.0f;
+    }
+
+    /**
+     * @return The maximum amount this scroll view will scroll in response to
+     *   an arrow event.
+     */
+    public int getMaxScrollAmount() {
+        return (int) (MAX_SCROLL_FACTOR * getHeight());
+    }
+
+    private void initScrollView() {
+        mScroller = new OverScroller(getContext());
+        setFocusable(true);
+        setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
+        setWillNotDraw(false);
+        final ViewConfiguration configuration = ViewConfiguration.get(getContext());
+        mTouchSlop = configuration.getScaledTouchSlop();
+        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
+        mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
+    }
+
+    @Override
+    public void addView(@NonNull View child) {
+        if (getChildCount() > 0) {
+            throw new IllegalStateException("ScrollView can host only one direct child");
+        }
+
+        super.addView(child);
+    }
+
+    @Override
+    public void addView(View child, int index) {
+        if (getChildCount() > 0) {
+            throw new IllegalStateException("ScrollView can host only one direct child");
+        }
+
+        super.addView(child, index);
+    }
+
+    @Override
+    public void addView(View child, ViewGroup.LayoutParams params) {
+        if (getChildCount() > 0) {
+            throw new IllegalStateException("ScrollView can host only one direct child");
+        }
+
+        super.addView(child, params);
+    }
+
+    @Override
+    public void addView(View child, int index, ViewGroup.LayoutParams params) {
+        if (getChildCount() > 0) {
+            throw new IllegalStateException("ScrollView can host only one direct child");
+        }
+
+        super.addView(child, index, params);
+    }
+
+    /**
+     * Register a callback to be invoked when the scroll X or Y positions of
+     * this view change.
+     * <p>This version of the method works on all versions of Android, back to API v4.</p>
+     *
+     * @param l The listener to notify when the scroll X or Y position changes.
+     * @see View#getScrollX()
+     * @see View#getScrollY()
+     */
+    public void setOnScrollChangeListener(@Nullable OnScrollChangeListener l) {
+        mOnScrollChangeListener = l;
+    }
+
+    /**
+     * @return Returns true this ScrollView can be scrolled
+     */
+    private boolean canScroll() {
+        if (getChildCount() > 0) {
+            View child = getChildAt(0);
+            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
+            int childSize = child.getHeight() + lp.topMargin + lp.bottomMargin;
+            int parentSpace = getHeight() - getPaddingTop() - getPaddingBottom();
+            return childSize > parentSpace;
+        }
+        return false;
+    }
+
+    /**
+     * Indicates whether this ScrollView's content is stretched to fill the viewport.
+     *
+     * @return True if the content fills the viewport, false otherwise.
+     *
+     * @attr name android:fillViewport
+     */
+    public boolean isFillViewport() {
+        return mFillViewport;
+    }
+
+    /**
+     * Set whether this ScrollView should stretch its content height to fill the viewport or not.
+     *
+     * @param fillViewport True to stretch the content's height to the viewport's
+     *        boundaries, false otherwise.
+     *
+     * @attr name android:fillViewport
+     */
+    public void setFillViewport(boolean fillViewport) {
+        if (fillViewport != mFillViewport) {
+            mFillViewport = fillViewport;
+            requestLayout();
+        }
+    }
+
+    /**
+     * @return Whether arrow scrolling will animate its transition.
+     */
+    public boolean isSmoothScrollingEnabled() {
+        return mSmoothScrollingEnabled;
+    }
+
+    /**
+     * Set whether arrow scrolling will animate its transition.
+     * @param smoothScrollingEnabled whether arrow scrolling will animate its transition
+     */
+    public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {
+        mSmoothScrollingEnabled = smoothScrollingEnabled;
+    }
+
+    @Override
+    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
+        super.onScrollChanged(l, t, oldl, oldt);
+
+        if (mOnScrollChangeListener != null) {
+            mOnScrollChangeListener.onScrollChange(this, l, t, oldl, oldt);
+        }
+    }
+
+    @Override
+    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
+        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
+
+        if (!mFillViewport) {
+            return;
+        }
+
+        final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
+        if (heightMode == MeasureSpec.UNSPECIFIED) {
+            return;
+        }
+
+        if (getChildCount() > 0) {
+            View child = getChildAt(0);
+            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
+
+            int childSize = child.getMeasuredHeight();
+            int parentSpace = getMeasuredHeight()
+                    - getPaddingTop()
+                    - getPaddingBottom()
+                    - lp.topMargin
+                    - lp.bottomMargin;
+
+            if (childSize < parentSpace) {
+                int childWidthMeasureSpec = getChildMeasureSpec(widthMeasureSpec,
+                        getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin,
+                        lp.width);
+                int childHeightMeasureSpec =
+                        MeasureSpec.makeMeasureSpec(parentSpace, MeasureSpec.EXACTLY);
+                child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
+            }
+        }
+    }
+
+    @Override
+    public boolean dispatchKeyEvent(KeyEvent event) {
+        // Let the focused view and/or our descendants get the key first
+        return super.dispatchKeyEvent(event) || executeKeyEvent(event);
+    }
+
+    /**
+     * You can call this function yourself to have the scroll view perform
+     * scrolling from a key event, just as if the event had been dispatched to
+     * it by the view hierarchy.
+     *
+     * @param event The key event to execute.
+     * @return Return true if the event was handled, else false.
+     */
+    public boolean executeKeyEvent(@NonNull KeyEvent event) {
+        mTempRect.setEmpty();
+
+        if (!canScroll()) {
+            if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) {
+                View currentFocused = findFocus();
+                if (currentFocused == this) currentFocused = null;
+                View nextFocused = FocusFinder.getInstance().findNextFocus(this,
+                        currentFocused, View.FOCUS_DOWN);
+                return nextFocused != null
+                        && nextFocused != this
+                        && nextFocused.requestFocus(View.FOCUS_DOWN);
+            }
+            return false;
+        }
+
+        boolean handled = false;
+        if (event.getAction() == KeyEvent.ACTION_DOWN) {
+            switch (event.getKeyCode()) {
+                case KeyEvent.KEYCODE_DPAD_UP:
+                    if (event.isAltPressed()) {
+                        handled = fullScroll(View.FOCUS_UP);
+                    } else {
+                        handled = arrowScroll(View.FOCUS_UP);
+                    }
+                    break;
+                case KeyEvent.KEYCODE_DPAD_DOWN:
+                    if (event.isAltPressed()) {
+                        handled = fullScroll(View.FOCUS_DOWN);
+                    } else {
+                        handled = arrowScroll(View.FOCUS_DOWN);
+                    }
+                    break;
+                case KeyEvent.KEYCODE_PAGE_UP:
+                    handled = fullScroll(View.FOCUS_UP);
+                    break;
+                case KeyEvent.KEYCODE_PAGE_DOWN:
+                    handled = fullScroll(View.FOCUS_DOWN);
+                    break;
+                case KeyEvent.KEYCODE_SPACE:
+                    pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN);
+                    break;
+                case KeyEvent.KEYCODE_MOVE_HOME:
+                    pageScroll(View.FOCUS_UP);
+                    break;
+                case KeyEvent.KEYCODE_MOVE_END:
+                    pageScroll(View.FOCUS_DOWN);
+                    break;
+            }
+        }
+
+        return handled;
+    }
+
+    private boolean inChild(int x, int y) {
+        if (getChildCount() > 0) {
+            final int scrollY = getScrollY();
+            final View child = getChildAt(0);
+            return !(y < child.getTop() - scrollY
+                    || y >= child.getBottom() - scrollY
+                    || x < child.getLeft()
+                    || x >= child.getRight());
+        }
+        return false;
+    }
+
+    private void initOrResetVelocityTracker() {
+        if (mVelocityTracker == null) {
+            mVelocityTracker = VelocityTracker.obtain();
+        } else {
+            mVelocityTracker.clear();
+        }
+    }
+
+    private void initVelocityTrackerIfNotExists() {
+        if (mVelocityTracker == null) {
+            mVelocityTracker = VelocityTracker.obtain();
+        }
+    }
+
+    private void recycleVelocityTracker() {
+        if (mVelocityTracker != null) {
+            mVelocityTracker.recycle();
+            mVelocityTracker = null;
+        }
+    }
+
+    @Override
+    public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
+        if (disallowIntercept) {
+            recycleVelocityTracker();
+        }
+        super.requestDisallowInterceptTouchEvent(disallowIntercept);
+    }
+
+    @Override
+    public boolean onInterceptTouchEvent(@NonNull MotionEvent ev) {
+        /*
+         * This method JUST determines whether we want to intercept the motion.
+         * If we return true, onMotionEvent will be called and we do the actual
+         * scrolling there.
+         */
+
+        /*
+        * Shortcut the most recurring case: the user is in the dragging
+        * state and they are moving their finger.  We want to intercept this
+        * motion.
+        */
+        final int action = ev.getAction();
+        if ((action == MotionEvent.ACTION_MOVE) && mIsBeingDragged) {
+            return true;
+        }
+
+        switch (action & MotionEvent.ACTION_MASK) {
+            case MotionEvent.ACTION_MOVE: {
+                /*
+                 * mIsBeingDragged == false, otherwise the shortcut would have caught it. Check
+                 * whether the user has moved far enough from their original down touch.
+                 */
+
+                /*
+                * Locally do absolute value. mLastMotionY is set to the y value
+                * of the down event.
+                */
+                final int activePointerId = mActivePointerId;
+                if (activePointerId == INVALID_POINTER) {
+                    // If we don't have a valid id, the touch down wasn't on content.
+                    break;
+                }
+
+                final int pointerIndex = ev.findPointerIndex(activePointerId);
+                if (pointerIndex == -1) {
+                    Log.e(TAG, "Invalid pointerId=" + activePointerId
+                            + " in onInterceptTouchEvent");
+                    break;
+                }
+
+                final int y = (int) ev.getY(pointerIndex);
+                final int yDiff = Math.abs(y - mLastMotionY);
+                if (yDiff > mTouchSlop
+                        && (getNestedScrollAxes() & ViewCompat.SCROLL_AXIS_VERTICAL) == 0) {
+                    mIsBeingDragged = true;
+                    mLastMotionY = y;
+                    initVelocityTrackerIfNotExists();
+                    mVelocityTracker.addMovement(ev);
+                    mNestedYOffset = 0;
+                    final ViewParent parent = getParent();
+                    if (parent != null) {
+                        parent.requestDisallowInterceptTouchEvent(true);
+                    }
+                }
+                break;
+            }
+
+            case MotionEvent.ACTION_DOWN: {
+                final int y = (int) ev.getY();
+                if (!inChild((int) ev.getX(), y)) {
+                    mIsBeingDragged = stopGlowAnimations(ev) || !mScroller.isFinished();
+                    recycleVelocityTracker();
+                    break;
+                }
+
+                /*
+                 * Remember location of down touch.
+                 * ACTION_DOWN always refers to pointer index 0.
+                 */
+                mLastMotionY = y;
+                mActivePointerId = ev.getPointerId(0);
+
+                initOrResetVelocityTracker();
+                mVelocityTracker.addMovement(ev);
+                /*
+                 * If being flinged and user touches the screen, initiate drag;
+                 * otherwise don't. mScroller.isFinished should be false when
+                 * being flinged. We also want to catch the edge glow and start dragging
+                 * if one is being animated. We need to call computeScrollOffset() first so that
+                 * isFinished() is correct.
+                */
+                mScroller.computeScrollOffset();
+                mIsBeingDragged = stopGlowAnimations(ev) || !mScroller.isFinished();
+                startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, ViewCompat.TYPE_TOUCH);
+                break;
+            }
+
+            case MotionEvent.ACTION_CANCEL:
+            case MotionEvent.ACTION_UP:
+                /* Release the drag */
+                mIsBeingDragged = false;
+                mActivePointerId = INVALID_POINTER;
+                recycleVelocityTracker();
+                if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0, getScrollRange())) {
+                    postInvalidateOnAnimation();
+                }
+                stopNestedScroll(ViewCompat.TYPE_TOUCH);
+                break;
+            case MotionEvent.ACTION_POINTER_UP:
+                onSecondaryPointerUp(ev);
+                break;
+        }
+
+        /*
+        * The only time we want to intercept motion events is if we are in the
+        * drag mode.
+        */
+        return mIsBeingDragged;
+    }
+
+    @Override
+    public boolean onTouchEvent(@NonNull MotionEvent motionEvent) {
+        initVelocityTrackerIfNotExists();
+
+        final int actionMasked = motionEvent.getActionMasked();
+
+        if (actionMasked == MotionEvent.ACTION_DOWN) {
+            mNestedYOffset = 0;
+        }
+
+        MotionEvent velocityTrackerMotionEvent = MotionEvent.obtain(motionEvent);
+        velocityTrackerMotionEvent.offsetLocation(0, mNestedYOffset);
+
+        switch (actionMasked) {
+            case MotionEvent.ACTION_DOWN: {
+                if (getChildCount() == 0) {
+                    return false;
+                }
+
+                // If additional fingers touch the screen while a drag is in progress, this block
+                // of code will make sure the drag isn't interrupted.
+                if (mIsBeingDragged) {
+                    final ViewParent parent = getParent();
+                    if (parent != null) {
+                        parent.requestDisallowInterceptTouchEvent(true);
+                    }
+                }
+
+                /*
+                 * If being flinged and user touches, stop the fling. isFinished
+                 * will be false if being flinged.
+                 */
+                if (!mScroller.isFinished()) {
+                    abortAnimatedScroll();
+                }
+
+                initializeTouchDrag(
+                        (int) motionEvent.getY(),
+                        motionEvent.getPointerId(0)
+                );
+
+                break;
+            }
+
+            case MotionEvent.ACTION_MOVE: {
+                final int activePointerIndex = motionEvent.findPointerIndex(mActivePointerId);
+                if (activePointerIndex == -1) {
+                    Log.e(TAG, "Invalid pointerId=" + mActivePointerId + " in onTouchEvent");
+                    break;
+                }
+
+                final int y = (int) motionEvent.getY(activePointerIndex);
+                int deltaY = mLastMotionY - y;
+                deltaY -= releaseVerticalGlow(deltaY, motionEvent.getX(activePointerIndex));
+
+                // Changes to dragged state if delta is greater than the slop (and not in
+                // the dragged state).
+                if (!mIsBeingDragged && Math.abs(deltaY) > mTouchSlop) {
+                    final ViewParent parent = getParent();
+                    if (parent != null) {
+                        parent.requestDisallowInterceptTouchEvent(true);
+                    }
+                    mIsBeingDragged = true;
+                    if (deltaY > 0) {
+                        deltaY -= mTouchSlop;
+                    } else {
+                        deltaY += mTouchSlop;
+                    }
+                }
+
+                if (mIsBeingDragged) {
+                    final int x = (int) motionEvent.getX(activePointerIndex);
+                    int scrollOffset = scrollBy(deltaY, x, ViewCompat.TYPE_TOUCH, false);
+                    // Updates the global positions (used by later move events to properly scroll).
+                    mLastMotionY = y - scrollOffset;
+                    mNestedYOffset += scrollOffset;
+                }
+                break;
+            }
+
+            case MotionEvent.ACTION_UP: {
+                final VelocityTracker velocityTracker = mVelocityTracker;
+                velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
+                int initialVelocity = (int) velocityTracker.getYVelocity(mActivePointerId);
+                if ((Math.abs(initialVelocity) >= mMinimumVelocity)) {
+                    if (!edgeEffectFling(initialVelocity)
+                            && !dispatchNestedPreFling(0, -initialVelocity)) {
+                        dispatchNestedFling(0, -initialVelocity, true);
+                        fling(-initialVelocity);
+                    }
+                } else if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0,
+                        getScrollRange())) {
+                    postInvalidateOnAnimation();
+                }
+                endTouchDrag();
+                break;
+            }
+
+            case MotionEvent.ACTION_CANCEL: {
+                if (mIsBeingDragged && getChildCount() > 0) {
+                    if (mScroller.springBack(getScrollX(), getScrollY(), 0, 0, 0,
+                            getScrollRange())) {
+                        postInvalidateOnAnimation();
+                    }
+                }
+                endTouchDrag();
+                break;
+            }
+
+            case MotionEvent.ACTION_POINTER_DOWN: {
+                final int index = motionEvent.getActionIndex();
+                mLastMotionY = (int) motionEvent.getY(index);
+                mActivePointerId = motionEvent.getPointerId(index);
+                break;
+            }
+
+            case MotionEvent.ACTION_POINTER_UP: {
+                onSecondaryPointerUp(motionEvent);
+                mLastMotionY =
+                        (int) motionEvent.getY(motionEvent.findPointerIndex(mActivePointerId));
+                break;
+            }
+        }
+
+        if (mVelocityTracker != null) {
+            mVelocityTracker.addMovement(velocityTrackerMotionEvent);
+        }
+        // Returns object back to be re-used by others.
+        velocityTrackerMotionEvent.recycle();
+
+        return true;
+    }
+
+    private void initializeTouchDrag(int lastMotionY, int activePointerId) {
+        mLastMotionY = lastMotionY;
+        mActivePointerId = activePointerId;
+        startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, ViewCompat.TYPE_TOUCH);
+    }
+
+    // Ends drag in a nested scroll.
+    private void endTouchDrag() {
+        mActivePointerId = INVALID_POINTER;
+        mIsBeingDragged = false;
+
+        recycleVelocityTracker();
+        stopNestedScroll(ViewCompat.TYPE_TOUCH);
+
+        mEdgeGlowTop.onRelease();
+        mEdgeGlowBottom.onRelease();
+    }
+
+    /*
+     * Handles scroll events for both touch and non-touch events (mouse scroll wheel,
+     * rotary button, keyboard, etc.).
+     *
+     * Note: This function returns the total scroll offset for this scroll event which is required
+     * for calculating the total scroll between multiple move events (touch). This returned value
+     * is NOT needed for non-touch events since a scroll is a one time event (vs. touch where a
+     * drag may be triggered multiple times with the movement of the finger).
+     */
+    // TODO: You should rename this to nestedScrollBy() so it is different from View.scrollBy
+    private int scrollBy(
+            int verticalScrollDistance,
+            int x,
+            int touchType,
+            boolean isSourceMouseOrKeyboard
+    ) {
+        int totalScrollOffset = 0;
+
+        /*
+         * Starts nested scrolling for non-touch events (mouse scroll wheel, rotary button, etc.).
+         * This is in contrast to a touch event which would trigger the start of nested scrolling
+         * with a touch down event outside of this method, since for a single gesture scrollBy()
+         * might be called several times for a move event for a single drag gesture.
+         */
+        if (touchType == ViewCompat.TYPE_NON_TOUCH) {
+            startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, touchType);
+        }
+
+        // Dispatches scrolling delta amount available to parent (to consume what it needs).
+        // Note: The amounts the parent consumes are saved in arrays named mScrollConsumed and
+        // mScrollConsumed to save space.
+        if (dispatchNestedPreScroll(
+                0,
+                verticalScrollDistance,
+                mScrollConsumed,
+                mScrollOffset,
+                touchType)
+        ) {
+            // Deducts the scroll amount (y) consumed by the parent (x in position 0,
+            // y in position 1). Nested scroll only works with Y position (so we don't use x).
+            verticalScrollDistance -= mScrollConsumed[1];
+            totalScrollOffset += mScrollOffset[1];
+        }
+
+        // Retrieves the scroll y position (top position of this view) and scroll Y range (how far
+        // the scroll can go).
+        final int initialScrollY = getScrollY();
+        final int scrollRangeY = getScrollRange();
+
+        // Overscroll is for adding animations at the top/bottom of a view when the user scrolls
+        // beyond the beginning/end of the view. Overscroll is not used with a mouse.
+        boolean canOverscroll = canOverScroll() && !isSourceMouseOrKeyboard;
+
+        // Scrolls content in the current View, but clamps it if it goes too far.
+        boolean hitScrollBarrier =
+                overScrollByCompat(
+                        0,
+                        verticalScrollDistance,
+                        0,
+                        initialScrollY,
+                        0,
+                        scrollRangeY,
+                        0,
+                        0,
+                        true
+                ) && !hasNestedScrollingParent(touchType);
+
+        // The position may have been adjusted in the previous call, so we must revise our values.
+        final int scrollYDelta = getScrollY() - initialScrollY;
+        final int unconsumedY = verticalScrollDistance - scrollYDelta;
+
+        // Reset the Y consumed scroll to zero
+        mScrollConsumed[1] = 0;
+
+        //  Dispatch the unconsumed delta Y to the children to consume.
+        dispatchNestedScroll(
+                0,
+                scrollYDelta,
+                0,
+                unconsumedY,
+                mScrollOffset,
+                touchType,
+                mScrollConsumed
+        );
+
+        totalScrollOffset += mScrollOffset[1];
+
+        // Handle overscroll of the children.
+        verticalScrollDistance -= mScrollConsumed[1];
+        int newScrollY = initialScrollY + verticalScrollDistance;
+
+        if (newScrollY < 0) {
+            if (canOverscroll) {
+                EdgeEffectCompat.onPullDistance(
+                        mEdgeGlowTop,
+                        (float) -verticalScrollDistance / getHeight(),
+                        (float) x / getWidth()
+                );
+
+                if (!mEdgeGlowBottom.isFinished()) {
+                    mEdgeGlowBottom.onRelease();
+                }
+            }
+
+        } else if (newScrollY > scrollRangeY) {
+            if (canOverscroll) {
+                EdgeEffectCompat.onPullDistance(
+                        mEdgeGlowBottom,
+                        (float) verticalScrollDistance / getHeight(),
+                        1.f - ((float) x / getWidth())
+                );
+
+                if (!mEdgeGlowTop.isFinished()) {
+                    mEdgeGlowTop.onRelease();
+                }
+            }
+        }
+
+        if (!mEdgeGlowTop.isFinished() || !mEdgeGlowBottom.isFinished()) {
+            postInvalidateOnAnimation();
+            hitScrollBarrier = false;
+        }
+
+        if (hitScrollBarrier && (touchType == ViewCompat.TYPE_TOUCH)) {
+            // Break our velocity if we hit a scroll barrier.
+            if (mVelocityTracker != null) {
+                mVelocityTracker.clear();
+            }
+        }
+
+        /*
+         * Ends nested scrolling for non-touch events (mouse scroll wheel, rotary button, etc.).
+         * As noted above, this is in contrast to a touch event.
+         */
+        if (touchType == ViewCompat.TYPE_NON_TOUCH) {
+            stopNestedScroll(touchType);
+
+            // Required for scrolling with Rotary Device stretch top/bottom to work properly
+            mEdgeGlowTop.onRelease();
+            mEdgeGlowBottom.onRelease();
+        }
+
+        return totalScrollOffset;
+    }
+
+    /**
+     * Returns true if edgeEffect should call onAbsorb() with veclocity or false if it should
+     * animate with a fling. It will animate with a fling if the velocity will remove the
+     * EdgeEffect through its normal operation.
+     *
+     * @param edgeEffect The EdgeEffect that might absorb the velocity.
+     * @param velocity The velocity of the fling motion
+     * @return true if the velocity should be absorbed or false if it should be flung.
+     */
+    private boolean shouldAbsorb(@NonNull EdgeEffect edgeEffect, int velocity) {
+        if (velocity > 0) {
+            return true;
+        }
+        float distance = EdgeEffectCompat.getDistance(edgeEffect) * getHeight();
+
+        // This is flinging without the spring, so let's see if it will fling past the overscroll
+        float flingDistance = getSplineFlingDistance(-velocity);
+
+        return flingDistance < distance;
+    }
+
+    /**
+     * If mTopGlow or mBottomGlow is currently active and the motion will remove some of the
+     * stretch, this will consume any of unconsumedY that the glow can. If the motion would
+     * increase the stretch, or the EdgeEffect isn't a stretch, then nothing will be consumed.
+     *
+     * @param unconsumedY The vertical delta that might be consumed by the vertical EdgeEffects
+     * @return The remaining unconsumed delta after the edge effects have consumed.
+     */
+    int consumeFlingInVerticalStretch(int unconsumedY) {
+        int height = getHeight();
+        if (unconsumedY > 0 && EdgeEffectCompat.getDistance(mEdgeGlowTop) != 0f) {
+            float deltaDistance = -unconsumedY * FLING_DESTRETCH_FACTOR / height;
+            int consumed = Math.round(-height / FLING_DESTRETCH_FACTOR
+                    * EdgeEffectCompat.onPullDistance(mEdgeGlowTop, deltaDistance, 0.5f));
+            if (consumed != unconsumedY) {
+                mEdgeGlowTop.finish();
+            }
+            return unconsumedY - consumed;
+        }
+        if (unconsumedY < 0 && EdgeEffectCompat.getDistance(mEdgeGlowBottom) != 0f) {
+            float deltaDistance = unconsumedY * FLING_DESTRETCH_FACTOR / height;
+            int consumed = Math.round(height / FLING_DESTRETCH_FACTOR
+                    * EdgeEffectCompat.onPullDistance(mEdgeGlowBottom, deltaDistance, 0.5f));
+            if (consumed != unconsumedY) {
+                mEdgeGlowBottom.finish();
+            }
+            return unconsumedY - consumed;
+        }
+        return unconsumedY;
+    }
+
+    /**
+     * Copied from OverScroller, this returns the distance that a fling with the given velocity
+     * will go.
+     * @param velocity The velocity of the fling
+     * @return The distance that will be traveled by a fling of the given velocity.
+     */
+    private float getSplineFlingDistance(int velocity) {
+        final double l =
+                Math.log(INFLEXION * Math.abs(velocity) / (SCROLL_FRICTION * mPhysicalCoeff));
+        final double decelMinusOne = DECELERATION_RATE - 1.0;
+        return (float) (SCROLL_FRICTION * mPhysicalCoeff
+                * Math.exp(DECELERATION_RATE / decelMinusOne * l));
+    }
+
+    private boolean edgeEffectFling(int velocityY) {
+        boolean consumed = true;
+        if (EdgeEffectCompat.getDistance(mEdgeGlowTop) != 0) {
+            if (shouldAbsorb(mEdgeGlowTop, velocityY)) {
+                mEdgeGlowTop.onAbsorb(velocityY);
+            } else {
+                fling(-velocityY);
+            }
+        } else if (EdgeEffectCompat.getDistance(mEdgeGlowBottom) != 0) {
+            if (shouldAbsorb(mEdgeGlowBottom, -velocityY)) {
+                mEdgeGlowBottom.onAbsorb(-velocityY);
+            } else {
+                fling(-velocityY);
+            }
+        } else {
+            consumed = false;
+        }
+        return consumed;
+    }
+
+    /**
+     * This stops any edge glow animation that is currently running by applying a
+     * 0 length pull at the displacement given by the provided MotionEvent. On pre-S devices,
+     * this method does nothing, allowing any animating edge effect to continue animating and
+     * returning <code>false</code> always.
+     *
+     * @param e The motion event to use to indicate the finger position for the displacement of
+     *          the current pull.
+     * @return <code>true</code> if any edge effect had an existing effect to be drawn ond the
+     * animation was stopped or <code>false</code> if no edge effect had a value to display.
+     */
+    private boolean stopGlowAnimations(MotionEvent e) {
+        boolean stopped = false;
+        if (EdgeEffectCompat.getDistance(mEdgeGlowTop) != 0) {
+            EdgeEffectCompat.onPullDistance(mEdgeGlowTop, 0, e.getX() / getWidth());
+            stopped = true;
+        }
+        if (EdgeEffectCompat.getDistance(mEdgeGlowBottom) != 0) {
+            EdgeEffectCompat.onPullDistance(mEdgeGlowBottom, 0, 1 - e.getX() / getWidth());
+            stopped = true;
+        }
+        return stopped;
+    }
+
+    private void onSecondaryPointerUp(MotionEvent ev) {
+        final int pointerIndex = ev.getActionIndex();
+        final int pointerId = ev.getPointerId(pointerIndex);
+        if (pointerId == mActivePointerId) {
+            // This was our active pointer going up. Choose a new
+            // active pointer and adjust accordingly.
+            // TODO: Make this decision more intelligent.
+            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
+            mLastMotionY = (int) ev.getY(newPointerIndex);
+            mActivePointerId = ev.getPointerId(newPointerIndex);
+            if (mVelocityTracker != null) {
+                mVelocityTracker.clear();
+            }
+        }
+    }
+
+    @Override
+    public boolean onGenericMotionEvent(@NonNull MotionEvent motionEvent) {
+        if (motionEvent.getAction() == MotionEvent.ACTION_SCROLL && !mIsBeingDragged) {
+            final float verticalScroll;
+            final int x;
+            final int flingAxis;
+
+            if (MotionEventCompat.isFromSource(motionEvent, InputDevice.SOURCE_CLASS_POINTER)) {
+                verticalScroll = motionEvent.getAxisValue(MotionEvent.AXIS_VSCROLL);
+                x = (int) motionEvent.getX();
+                flingAxis = MotionEvent.AXIS_VSCROLL;
+            } else if (
+                    MotionEventCompat.isFromSource(motionEvent, InputDevice.SOURCE_ROTARY_ENCODER)
+            ) {
+                verticalScroll = motionEvent.getAxisValue(MotionEvent.AXIS_SCROLL);
+                // Since a Wear rotary event doesn't have a true X and we want to support proper
+                // overscroll animations, we put the x at the center of the screen.
+                x = getWidth() / 2;
+                flingAxis = MotionEvent.AXIS_SCROLL;
+            } else {
+                verticalScroll = 0;
+                x = 0;
+                flingAxis = 0;
+            }
+
+            if (verticalScroll != 0) {
+                // Rotary and Mouse scrolls are inverted from a touch scroll.
+                final int invertedDelta = (int) (verticalScroll * getVerticalScrollFactorCompat());
+
+                final boolean isSourceMouse =
+                        MotionEventCompat.isFromSource(motionEvent, InputDevice.SOURCE_MOUSE);
+
+                scrollBy(-invertedDelta, x, ViewCompat.TYPE_NON_TOUCH, isSourceMouse);
+                if (flingAxis != 0) {
+                    mDifferentialMotionFlingController.onMotionEvent(motionEvent, flingAxis);
+                }
+
+                return true;
+            }
+        }
+        return false;
+    }
+
+    /**
+     * Returns true if the NestedScrollView supports over scroll.
+     */
+    private boolean canOverScroll() {
+        final int mode = getOverScrollMode();
+        return mode == OVER_SCROLL_ALWAYS
+                || (mode == OVER_SCROLL_IF_CONTENT_SCROLLS && getScrollRange() > 0);
+    }
+
+    @VisibleForTesting
+    float getVerticalScrollFactorCompat() {
+        if (mVerticalScrollFactor == 0) {
+            TypedValue outValue = new TypedValue();
+            final Context context = getContext();
+            if (!context.getTheme().resolveAttribute(
+                    android.R.attr.listPreferredItemHeight, outValue, true)) {
+                throw new IllegalStateException(
+                        "Expected theme to define listPreferredItemHeight.");
+            }
+            mVerticalScrollFactor = outValue.getDimension(
+                    context.getResources().getDisplayMetrics());
+        }
+        return mVerticalScrollFactor;
+    }
+
+    @Override
+    protected void onOverScrolled(int scrollX, int scrollY,
+            boolean clampedX, boolean clampedY) {
+        super.scrollTo(scrollX, scrollY);
+    }
+
+    @SuppressWarnings({"SameParameterValue", "unused"})
+    boolean overScrollByCompat(int deltaX, int deltaY,
+            int scrollX, int scrollY,
+            int scrollRangeX, int scrollRangeY,
+            int maxOverScrollX, int maxOverScrollY,
+            boolean isTouchEvent) {
+
+        final int overScrollMode = getOverScrollMode();
+        final boolean canScrollHorizontal =
+                computeHorizontalScrollRange() > computeHorizontalScrollExtent();
+        final boolean canScrollVertical =
+                computeVerticalScrollRange() > computeVerticalScrollExtent();
+
+        final boolean overScrollHorizontal = overScrollMode == View.OVER_SCROLL_ALWAYS
+                || (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollHorizontal);
+        final boolean overScrollVertical = overScrollMode == View.OVER_SCROLL_ALWAYS
+                || (overScrollMode == View.OVER_SCROLL_IF_CONTENT_SCROLLS && canScrollVertical);
+
+        int newScrollX = scrollX + deltaX;
+        if (!overScrollHorizontal) {
+            maxOverScrollX = 0;
+        }
+
+        int newScrollY = scrollY + deltaY;
+        if (!overScrollVertical) {
+            maxOverScrollY = 0;
+        }
+
+        // Clamp values if at the limits and record
+        final int left = -maxOverScrollX;
+        final int right = maxOverScrollX + scrollRangeX;
+        final int top = -maxOverScrollY;
+        final int bottom = maxOverScrollY + scrollRangeY;
+
+        boolean clampedX = false;
+        if (newScrollX > right) {
+            newScrollX = right;
+            clampedX = true;
+        } else if (newScrollX < left) {
+            newScrollX = left;
+            clampedX = true;
+        }
+
+        boolean clampedY = false;
+        if (newScrollY > bottom) {
+            newScrollY = bottom;
+            clampedY = true;
+        } else if (newScrollY < top) {
+            newScrollY = top;
+            clampedY = true;
+        }
+
+        if (clampedY && !hasNestedScrollingParent(ViewCompat.TYPE_NON_TOUCH)) {
+            mScroller.springBack(newScrollX, newScrollY, 0, 0, 0, getScrollRange());
+        }
+
+        onOverScrolled(newScrollX, newScrollY, clampedX, clampedY);
+
+        return clampedX || clampedY;
+    }
+
+    int getScrollRange() {
+        int scrollRange = 0;
+        if (getChildCount() > 0) {
+            View child = getChildAt(0);
+            LayoutParams lp = (LayoutParams) child.getLayoutParams();
+            int childSize = child.getHeight() + lp.topMargin + lp.bottomMargin;
+            int parentSpace = getHeight() - getPaddingTop() - getPaddingBottom();
+            scrollRange = Math.max(0, childSize - parentSpace);
+        }
+        return scrollRange;
+    }
+
+    /**
+     * <p>
+     * Finds the next focusable component that fits in the specified bounds.
+     * </p>
+     *
+     * @param topFocus look for a candidate is the one at the top of the bounds
+     *                 if topFocus is true, or at the bottom of the bounds if topFocus is
+     *                 false
+     * @param top      the top offset of the bounds in which a focusable must be
+     *                 found
+     * @param bottom   the bottom offset of the bounds in which a focusable must
+     *                 be found
+     * @return the next focusable component in the bounds or null if none can
+     *         be found
+     */
+    private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) {
+
+        List<View> focusables = getFocusables(View.FOCUS_FORWARD);
+        View focusCandidate = null;
+
+        /*
+         * A fully contained focusable is one where its top is below the bound's
+         * top, and its bottom is above the bound's bottom. A partially
+         * contained focusable is one where some part of it is within the
+         * bounds, but it also has some part that is not within bounds.  A fully contained
+         * focusable is preferred to a partially contained focusable.
+         */
+        boolean foundFullyContainedFocusable = false;
+
+        int count = focusables.size();
+        for (int i = 0; i < count; i++) {
+            View view = focusables.get(i);
+            int viewTop = view.getTop();
+            int viewBottom = view.getBottom();
+
+            if (top < viewBottom && viewTop < bottom) {
+                /*
+                 * the focusable is in the target area, it is a candidate for
+                 * focusing
+                 */
+
+                final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom);
+
+                if (focusCandidate == null) {
+                    /* No candidate, take this one */
+                    focusCandidate = view;
+                    foundFullyContainedFocusable = viewIsFullyContained;
+                } else {
+                    final boolean viewIsCloserToBoundary =
+                            (topFocus && viewTop < focusCandidate.getTop())
+                                    || (!topFocus && viewBottom > focusCandidate.getBottom());
+
+                    if (foundFullyContainedFocusable) {
+                        if (viewIsFullyContained && viewIsCloserToBoundary) {
+                            /*
+                             * We're dealing with only fully contained views, so
+                             * it has to be closer to the boundary to beat our
+                             * candidate
+                             */
+                            focusCandidate = view;
+                        }
+                    } else {
+                        if (viewIsFullyContained) {
+                            /* Any fully contained view beats a partially contained view */
+                            focusCandidate = view;
+                            foundFullyContainedFocusable = true;
+                        } else if (viewIsCloserToBoundary) {
+                            /*
+                             * Partially contained view beats another partially
+                             * contained view if it's closer
+                             */
+                            focusCandidate = view;
+                        }
+                    }
+                }
+            }
+        }
+
+        return focusCandidate;
+    }
+
+    /**
+     * <p>Handles scrolling in response to a "page up/down" shortcut press. This
+     * method will scroll the view by one page up or down and give the focus
+     * to the topmost/bottommost component in the new visible area. If no
+     * component is a good candidate for focus, this scrollview reclaims the
+     * focus.</p>
+     *
+     * @param direction the scroll direction: {@link View#FOCUS_UP}
+     *                  to go one page up or
+     *                  {@link View#FOCUS_DOWN} to go one page down
+     * @return true if the key event is consumed by this method, false otherwise
+     */
+    public boolean pageScroll(int direction) {
+        boolean down = direction == View.FOCUS_DOWN;
+        int height = getHeight();
+
+        if (down) {
+            mTempRect.top = getScrollY() + height;
+            int count = getChildCount();
+            if (count > 0) {
+                View view = getChildAt(count - 1);
+                LayoutParams lp = (LayoutParams) view.getLayoutParams();
+                int bottom = view.getBottom() + lp.bottomMargin + getPaddingBottom();
+                if (mTempRect.top + height > bottom) {
+                    mTempRect.top = bottom - height;
+                }
+            }
+        } else {
+            mTempRect.top = getScrollY() - height;
+            if (mTempRect.top < 0) {
+                mTempRect.top = 0;
+            }
+        }
+        mTempRect.bottom = mTempRect.top + height;
+
+        return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
+    }
+
+    /**
+     * <p>Handles scrolling in response to a "home/end" shortcut press. This
+     * method will scroll the view to the top or bottom and give the focus
+     * to the topmost/bottommost component in the new visible area. If no
+     * component is a good candidate for focus, this scrollview reclaims the
+     * focus.</p>
+     *
+     * @param direction the scroll direction: {@link View#FOCUS_UP}
+     *                  to go the top of the view or
+     *                  {@link View#FOCUS_DOWN} to go the bottom
+     * @return true if the key event is consumed by this method, false otherwise
+     */
+    public boolean fullScroll(int direction) {
+        boolean down = direction == View.FOCUS_DOWN;
+        int height = getHeight();
+
+        mTempRect.top = 0;
+        mTempRect.bottom = height;
+
+        if (down) {
+            int count = getChildCount();
+            if (count > 0) {
+                View view = getChildAt(count - 1);
+                LayoutParams lp = (LayoutParams) view.getLayoutParams();
+                mTempRect.bottom = view.getBottom() + lp.bottomMargin + getPaddingBottom();
+                mTempRect.top = mTempRect.bottom - height;
+            }
+        }
+        return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
+    }
+
+    /**
+     * <p>Scrolls the view to make the area defined by <code>top</code> and
+     * <code>bottom</code> visible. This method attempts to give the focus
+     * to a component visible in this area. If no component can be focused in
+     * the new visible area, the focus is reclaimed by this ScrollView.</p>
+     *
+     * @param direction the scroll direction: {@link View#FOCUS_UP}
+     *                  to go upward, {@link View#FOCUS_DOWN} to downward
+     * @param top       the top offset of the new area to be made visible
+     * @param bottom    the bottom offset of the new area to be made visible
+     * @return true if the key event is consumed by this method, false otherwise
+     */
+    private boolean scrollAndFocus(int direction, int top, int bottom) {
+        boolean handled = true;
+
+        int height = getHeight();
+        int containerTop = getScrollY();
+        int containerBottom = containerTop + height;
+        boolean up = direction == View.FOCUS_UP;
+
+        View newFocused = findFocusableViewInBounds(up, top, bottom);
+        if (newFocused == null) {
+            newFocused = this;
+        }
+
+        if (top >= containerTop && bottom <= containerBottom) {
+            handled = false;
+        } else {
+            int delta = up ? (top - containerTop) : (bottom - containerBottom);
+            scrollBy(delta, 0, ViewCompat.TYPE_NON_TOUCH, true);
+        }
+
+        if (newFocused != findFocus()) newFocused.requestFocus(direction);
+
+        return handled;
+    }
+
+    /**
+     * Handle scrolling in response to an up or down arrow click.
+     *
+     * @param direction The direction corresponding to the arrow key that was
+     *                  pressed
+     * @return True if we consumed the event, false otherwise
+     */
+    public boolean arrowScroll(int direction) {
+        View currentFocused = findFocus();
+        if (currentFocused == this) currentFocused = null;
+
+        View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);
+
+        final int maxJump = getMaxScrollAmount();
+
+        if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) {
+            nextFocused.getDrawingRect(mTempRect);
+            offsetDescendantRectToMyCoords(nextFocused, mTempRect);
+            int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
+
+            scrollBy(scrollDelta, 0, ViewCompat.TYPE_NON_TOUCH, true);
+            nextFocused.requestFocus(direction);
+
+        } else {
+            // no new focus
+            int scrollDelta = maxJump;
+
+            if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {
+                scrollDelta = getScrollY();
+            } else if (direction == View.FOCUS_DOWN) {
+                if (getChildCount() > 0) {
+                    View child = getChildAt(0);
+                    LayoutParams lp = (LayoutParams) child.getLayoutParams();
+                    int daBottom = child.getBottom() + lp.bottomMargin;
+                    int screenBottom = getScrollY() + getHeight() - getPaddingBottom();
+                    scrollDelta = Math.min(daBottom - screenBottom, maxJump);
+                }
+            }
+            if (scrollDelta == 0) {
+                return false;
+            }
+
+            int finalScrollDelta = direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta;
+            scrollBy(finalScrollDelta, 0, ViewCompat.TYPE_NON_TOUCH, true);
+        }
+
+        if (currentFocused != null && currentFocused.isFocused()
+                && isOffScreen(currentFocused)) {
+            // previously focused item still has focus and is off screen, give
+            // it up (take it back to ourselves)
+            // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are
+            // sure to
+            // get it)
+            final int descendantFocusability = getDescendantFocusability();  // save
+            setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
+            requestFocus();
+            setDescendantFocusability(descendantFocusability);  // restore
+        }
+        return true;
+    }
+
+    /**
+     * @return whether the descendant of this scroll view is scrolled off
+     *  screen.
+     */
+    private boolean isOffScreen(View descendant) {
+        return !isWithinDeltaOfScreen(descendant, 0, getHeight());
+    }
+
+    /**
+     * @return whether the descendant of this scroll view is within delta
+     *  pixels of being on the screen.
+     */
+    private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) {
+        descendant.getDrawingRect(mTempRect);
+        offsetDescendantRectToMyCoords(descendant, mTempRect);
+
+        return (mTempRect.bottom + delta) >= getScrollY()
+                && (mTempRect.top - delta) <= (getScrollY() + height);
+    }
+
+    /**
+     * Smooth scroll by a Y delta
+     *
+     * @param delta the number of pixels to scroll by on the Y axis
+     */
+    private void doScrollY(int delta) {
+        if (delta != 0) {
+            if (mSmoothScrollingEnabled) {
+                smoothScrollBy(0, delta);
+            } else {
+                scrollBy(0, delta);
+            }
+        }
+    }
+
+    /**
+     * Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
+     *
+     * @param dx the number of pixels to scroll by on the X axis
+     * @param dy the number of pixels to scroll by on the Y axis
+     */
+    public final void smoothScrollBy(int dx, int dy) {
+        smoothScrollBy(dx, dy, DEFAULT_SMOOTH_SCROLL_DURATION, false);
+    }
+
+   /**
+     * Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
+     *
+     * @param dx the number of pixels to scroll by on the X axis
+     * @param dy the number of pixels to scroll by on the Y axis
+     * @param scrollDurationMs the duration of the smooth scroll operation in milliseconds
+     */
+    public final void smoothScrollBy(int dx, int dy, int scrollDurationMs) {
+        smoothScrollBy(dx, dy, scrollDurationMs, false);
+    }
+
+    /**
+     * Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
+     *
+     * @param dx the number of pixels to scroll by on the X axis
+     * @param dy the number of pixels to scroll by on the Y axis
+     * @param scrollDurationMs the duration of the smooth scroll operation in milliseconds
+     * @param withNestedScrolling whether to include nested scrolling operations.
+     */
+    private void smoothScrollBy(int dx, int dy, int scrollDurationMs, boolean withNestedScrolling) {
+        if (getChildCount() == 0) {
+            // Nothing to do.
+            return;
+        }
+        long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
+        if (duration > ANIMATED_SCROLL_GAP) {
+            View child = getChildAt(0);
+            LayoutParams lp = (LayoutParams) child.getLayoutParams();
+            int childSize = child.getHeight() + lp.topMargin + lp.bottomMargin;
+            int parentSpace = getHeight() - getPaddingTop() - getPaddingBottom();
+            final int scrollY = getScrollY();
+            final int maxY = Math.max(0, childSize - parentSpace);
+            dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;
+            mScroller.startScroll(getScrollX(), scrollY, 0, dy, scrollDurationMs);
+            runAnimatedScroll(withNestedScrolling);
+        } else {
+            if (!mScroller.isFinished()) {
+                abortAnimatedScroll();
+            }
+            scrollBy(dx, dy);
+        }
+        mLastScroll = AnimationUtils.currentAnimationTimeMillis();
+    }
+
+    /**
+     * Like {@link #scrollTo}, but scroll smoothly instead of immediately.
+     *
+     * @param x the position where to scroll on the X axis
+     * @param y the position where to scroll on the Y axis
+     */
+    public final void smoothScrollTo(int x, int y) {
+        smoothScrollTo(x, y, DEFAULT_SMOOTH_SCROLL_DURATION, false);
+    }
+
+    /**
+     * Like {@link #scrollTo}, but scroll smoothly instead of immediately.
+     *
+     * @param x the position where to scroll on the X axis
+     * @param y the position where to scroll on the Y axis
+     * @param scrollDurationMs the duration of the smooth scroll operation in milliseconds
+     */
+    public final void smoothScrollTo(int x, int y, int scrollDurationMs) {
+        smoothScrollTo(x, y, scrollDurationMs, false);
+    }
+
+    /**
+     * Like {@link #scrollTo}, but scroll smoothly instead of immediately.
+     *
+     * @param x the position where to scroll on the X axis
+     * @param y the position where to scroll on the Y axis
+     * @param withNestedScrolling whether to include nested scrolling operations.
+     */
+    // This should be considered private, it is package private to avoid a synthetic ancestor.
+    @SuppressWarnings("SameParameterValue")
+    void smoothScrollTo(int x, int y, boolean withNestedScrolling) {
+        smoothScrollTo(x, y, DEFAULT_SMOOTH_SCROLL_DURATION, withNestedScrolling);
+    }
+
+    /**
+     * Like {@link #scrollTo}, but scroll smoothly instead of immediately.
+     *
+     * @param x the position where to scroll on the X axis
+     * @param y the position where to scroll on the Y axis
+     * @param scrollDurationMs the duration of the smooth scroll operation in milliseconds
+     * @param withNestedScrolling whether to include nested scrolling operations.
+     */
+    // This should be considered private, it is package private to avoid a synthetic ancestor.
+    void smoothScrollTo(int x, int y, int scrollDurationMs, boolean withNestedScrolling) {
+        smoothScrollBy(x - getScrollX(), y - getScrollY(), scrollDurationMs, withNestedScrolling);
+    }
+
+    /**
+     * <p>The scroll range of a scroll view is the overall height of all of its
+     * children.</p>
+     */
+    @Override
+    public int computeVerticalScrollRange() {
+        final int count = getChildCount();
+        final int parentSpace = getHeight() - getPaddingBottom() - getPaddingTop();
+        if (count == 0) {
+            return parentSpace;
+        }
+
+        View child = getChildAt(0);
+        LayoutParams lp = (LayoutParams) child.getLayoutParams();
+        int scrollRange = child.getBottom() + lp.bottomMargin;
+        final int scrollY = getScrollY();
+        final int overscrollBottom = Math.max(0, scrollRange - parentSpace);
+        if (scrollY < 0) {
+            scrollRange -= scrollY;
+        } else if (scrollY > overscrollBottom) {
+            scrollRange += scrollY - overscrollBottom;
+        }
+
+        return scrollRange;
+    }
+
+    @Override
+    public int computeVerticalScrollOffset() {
+        return Math.max(0, super.computeVerticalScrollOffset());
+    }
+
+    @Override
+    public int computeVerticalScrollExtent() {
+        return super.computeVerticalScrollExtent();
+    }
+
+    @Override
+    public int computeHorizontalScrollRange() {
+        return super.computeHorizontalScrollRange();
+    }
+
+    @Override
+    public int computeHorizontalScrollOffset() {
+        return super.computeHorizontalScrollOffset();
+    }
+
+    @Override
+    public int computeHorizontalScrollExtent() {
+        return super.computeHorizontalScrollExtent();
+    }
+
+    @Override
+    protected void measureChild(@NonNull View child, int parentWidthMeasureSpec,
+            int parentHeightMeasureSpec) {
+        ViewGroup.LayoutParams lp = child.getLayoutParams();
+
+        int childWidthMeasureSpec;
+        int childHeightMeasureSpec;
+
+        childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, getPaddingLeft()
+                + getPaddingRight(), lp.width);
+
+        childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
+
+        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
+    }
+
+    @Override
+    protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,
+            int parentHeightMeasureSpec, int heightUsed) {
+        final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
+
+        final int childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
+                getPaddingLeft() + getPaddingRight() + lp.leftMargin + lp.rightMargin
+                        + widthUsed, lp.width);
+        final int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
+                lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);
+
+        child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
+    }
+
+    @Override
+    public void computeScroll() {
+
+        if (mScroller.isFinished()) {
+            return;
+        }
+
+        mScroller.computeScrollOffset();
+        final int y = mScroller.getCurrY();
+        int unconsumed = consumeFlingInVerticalStretch(y - mLastScrollerY);
+        mLastScrollerY = y;
+
+        // Nested Scrolling Pre Pass
+        mScrollConsumed[1] = 0;
+        dispatchNestedPreScroll(0, unconsumed, mScrollConsumed, null,
+                ViewCompat.TYPE_NON_TOUCH);
+        unconsumed -= mScrollConsumed[1];
+
+        final int range = getScrollRange();
+
+        if (unconsumed != 0) {
+            // Internal Scroll
+            final int oldScrollY = getScrollY();
+            overScrollByCompat(0, unconsumed, getScrollX(), oldScrollY, 0, range, 0, 0, false);
+            final int scrolledByMe = getScrollY() - oldScrollY;
+            unconsumed -= scrolledByMe;
+
+            // Nested Scrolling Post Pass
+            mScrollConsumed[1] = 0;
+            dispatchNestedScroll(0, scrolledByMe, 0, unconsumed, mScrollOffset,
+                    ViewCompat.TYPE_NON_TOUCH, mScrollConsumed);
+            unconsumed -= mScrollConsumed[1];
+        }
+
+        if (unconsumed != 0) {
+            final int mode = getOverScrollMode();
+            final boolean canOverscroll = mode == OVER_SCROLL_ALWAYS
+                    || (mode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0);
+            if (canOverscroll) {
+                if (unconsumed < 0) {
+                    if (mEdgeGlowTop.isFinished()) {
+                        mEdgeGlowTop.onAbsorb((int) mScroller.getCurrVelocity());
+                    }
+                } else {
+                    if (mEdgeGlowBottom.isFinished()) {
+                        mEdgeGlowBottom.onAbsorb((int) mScroller.getCurrVelocity());
+                    }
+                }
+            }
+            abortAnimatedScroll();
+        }
+
+        if (!mScroller.isFinished()) {
+            postInvalidateOnAnimation();
+        } else {
+            stopNestedScroll(ViewCompat.TYPE_NON_TOUCH);
+        }
+    }
+
+    /**
+     * If either of the vertical edge glows are currently active, this consumes part or all of
+     * deltaY on the edge glow.
+     *
+     * @param deltaY The pointer motion, in pixels, in the vertical direction, positive
+     *                         for moving down and negative for moving up.
+     * @param x The vertical position of the pointer.
+     * @return The amount of <code>deltaY</code> that has been consumed by the
+     * edge glow.
+     */
+    private int releaseVerticalGlow(int deltaY, float x) {
+        // First allow releasing existing overscroll effect:
+        float consumed = 0;
+        float displacement = x / getWidth();
+        float pullDistance = (float) deltaY / getHeight();
+        if (EdgeEffectCompat.getDistance(mEdgeGlowTop) != 0) {
+            consumed = -EdgeEffectCompat.onPullDistance(mEdgeGlowTop, -pullDistance, displacement);
+            if (EdgeEffectCompat.getDistance(mEdgeGlowTop) == 0) {
+                mEdgeGlowTop.onRelease();
+            }
+        } else if (EdgeEffectCompat.getDistance(mEdgeGlowBottom) != 0) {
+            consumed = EdgeEffectCompat.onPullDistance(mEdgeGlowBottom, pullDistance,
+                    1 - displacement);
+            if (EdgeEffectCompat.getDistance(mEdgeGlowBottom) == 0) {
+                mEdgeGlowBottom.onRelease();
+            }
+        }
+        int pixelsConsumed = Math.round(consumed * getHeight());
+        if (pixelsConsumed != 0) {
+            invalidate();
+        }
+        return pixelsConsumed;
+    }
+
+    private void runAnimatedScroll(boolean participateInNestedScrolling) {
+        if (participateInNestedScrolling) {
+            startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL, ViewCompat.TYPE_NON_TOUCH);
+        } else {
+            stopNestedScroll(ViewCompat.TYPE_NON_TOUCH);
+        }
+        mLastScrollerY = getScrollY();
+        postInvalidateOnAnimation();
+    }
+
+    private void abortAnimatedScroll() {
+        mScroller.abortAnimation();
+        stopNestedScroll(ViewCompat.TYPE_NON_TOUCH);
+    }
+
+    /**
+     * Scrolls the view to the given child.
+     *
+     * @param child the View to scroll to
+     */
+    private void scrollToChild(View child) {
+        child.getDrawingRect(mTempRect);
+
+        /* Offset from child's local coordinates to ScrollView coordinates */
+        offsetDescendantRectToMyCoords(child, mTempRect);
+
+        int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
+
+        if (scrollDelta != 0) {
+            scrollBy(0, scrollDelta);
+        }
+    }
+
+    /**
+     * If rect is off screen, scroll just enough to get it (or at least the
+     * first screen size chunk of it) on screen.
+     *
+     * @param rect      The rectangle.
+     * @param immediate True to scroll immediately without animation
+     * @return true if scrolling was performed
+     */
+    private boolean scrollToChildRect(Rect rect, boolean immediate) {
+        final int delta = computeScrollDeltaToGetChildRectOnScreen(rect);
+        final boolean scroll = delta != 0;
+        if (scroll) {
+            if (immediate) {
+                scrollBy(0, delta);
+            } else {
+                smoothScrollBy(0, delta);
+            }
+        }
+        return scroll;
+    }
+
+    /**
+     * Compute the amount to scroll in the Y direction in order to get
+     * a rectangle completely on the screen (or, if taller than the screen,
+     * at least the first screen size chunk of it).
+     *
+     * @param rect The rect.
+     * @return The scroll delta.
+     */
+    protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
+        if (getChildCount() == 0) return 0;
+
+        int height = getHeight();
+        int screenTop = getScrollY();
+        int screenBottom = screenTop + height;
+        int actualScreenBottom = screenBottom;
+
+        int fadingEdge = getVerticalFadingEdgeLength();
+
+        // TODO: screenTop should be incremented by fadingEdge * getTopFadingEdgeStrength (but for
+        // the target scroll distance).
+        // leave room for top fading edge as long as rect isn't at very top
+        if (rect.top > 0) {
+            screenTop += fadingEdge;
+        }
+
+        // TODO: screenBottom should be decremented by fadingEdge * getBottomFadingEdgeStrength (but
+        // for the target scroll distance).
+        // leave room for bottom fading edge as long as rect isn't at very bottom
+        View child = getChildAt(0);
+        final LayoutParams lp = (LayoutParams) child.getLayoutParams();
+        if (rect.bottom < child.getHeight() + lp.topMargin + lp.bottomMargin) {
+            screenBottom -= fadingEdge;
+        }
+
+        int scrollYDelta = 0;
+
+        if (rect.bottom > screenBottom && rect.top > screenTop) {
+            // need to move down to get it in view: move down just enough so
+            // that the entire rectangle is in view (or at least the first
+            // screen size chunk).
+
+            if (rect.height() > height) {
+                // just enough to get screen size chunk on
+                scrollYDelta += (rect.top - screenTop);
+            } else {
+                // get entire rect at bottom of screen
+                scrollYDelta += (rect.bottom - screenBottom);
+            }
+
+            // make sure we aren't scrolling beyond the end of our content
+            int bottom = child.getBottom() + lp.bottomMargin;
+            int distanceToBottom = bottom - actualScreenBottom;
+            scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
+
+        } else if (rect.top < screenTop && rect.bottom < screenBottom) {
+            // need to move up to get it in view: move up just enough so that
+            // entire rectangle is in view (or at least the first screen
+            // size chunk of it).
+
+            if (rect.height() > height) {
+                // screen size chunk
+                scrollYDelta -= (screenBottom - rect.bottom);
+            } else {
+                // entire rect at top
+                scrollYDelta -= (screenTop - rect.top);
+            }
+
+            // make sure we aren't scrolling any further than the top our content
+            scrollYDelta = Math.max(scrollYDelta, -getScrollY());
+        }
+        return scrollYDelta;
+    }
+
+    @Override
+    public void requestChildFocus(View child, View focused) {
+        onRequestChildFocus(child, focused);
+        super.requestChildFocus(child, focused);
+    }
+
+    protected void onRequestChildFocus(View child, View focused) {
+        if (!mIsLayoutDirty) {
+            scrollToChild(focused);
+        } else {
+            // The child may not be laid out yet, we can't compute the scroll yet
+            mChildToScrollTo = focused;
+        }
+    }
+
+
+    /**
+     * When looking for focus in children of a scroll view, need to be a little
+     * more careful not to give focus to something that is scrolled off screen.
+     *
+     * This is more expensive than the default {@link ViewGroup}
+     * implementation, otherwise this behavior might have been made the default.
+     */
+    @Override
+    protected boolean onRequestFocusInDescendants(int direction,
+            Rect previouslyFocusedRect) {
+
+        // convert from forward / backward notation to up / down / left / right
+        // (ugh).
+        if (direction == View.FOCUS_FORWARD) {
+            direction = View.FOCUS_DOWN;
+        } else if (direction == View.FOCUS_BACKWARD) {
+            direction = View.FOCUS_UP;
+        }
+
+        final View nextFocus = previouslyFocusedRect == null
+                ? FocusFinder.getInstance().findNextFocus(this, null, direction)
+                : FocusFinder.getInstance().findNextFocusFromRect(
+                        this, previouslyFocusedRect, direction);
+
+        if (nextFocus == null) {
+            return false;
+        }
+
+        if (isOffScreen(nextFocus)) {
+            return false;
+        }
+
+        return nextFocus.requestFocus(direction, previouslyFocusedRect);
+    }
+
+    @Override
+    public boolean requestChildRectangleOnScreen(@NonNull View child, Rect rectangle,
+            boolean immediate) {
+        // offset into coordinate space of this scroll view
+        rectangle.offset(child.getLeft() - child.getScrollX(),
+                child.getTop() - child.getScrollY());
+
+        return scrollToChildRect(rectangle, immediate);
+    }
+
+    @Override
+    public void requestLayout() {
+        mIsLayoutDirty = true;
+        super.requestLayout();
+    }
+
+    @Override
+    protected void onLayout(boolean changed, int l, int t, int r, int b) {
+        super.onLayout(changed, l, t, r, b);
+        mIsLayoutDirty = false;
+        // Give a child focus if it needs it
+        if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {
+            scrollToChild(mChildToScrollTo);
+        }
+        mChildToScrollTo = null;
+
+        if (!mIsLaidOut) {
+            // If there is a saved state, scroll to the position saved in that state.
+            if (mSavedState != null) {
+                scrollTo(getScrollX(), mSavedState.scrollPosition);
+                mSavedState = null;
+            } // mScrollY default value is "0"
+
+            // Make sure current scrollY position falls into the scroll range.  If it doesn't,
+            // scroll such that it does.
+            int childSize = 0;
+            if (getChildCount() > 0) {
+                View child = getChildAt(0);
+                LayoutParams lp = (LayoutParams) child.getLayoutParams();
+                childSize = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin;
+            }
+            int parentSpace = b - t - getPaddingTop() - getPaddingBottom();
+            int currentScrollY = getScrollY();
+            int newScrollY = clamp(currentScrollY, parentSpace, childSize);
+            if (newScrollY != currentScrollY) {
+                scrollTo(getScrollX(), newScrollY);
+            }
+        }
+
+        // Calling this with the present values causes it to re-claim them
+        scrollTo(getScrollX(), getScrollY());
+        mIsLaidOut = true;
+    }
+
+    @Override
+    public void onAttachedToWindow() {
+        super.onAttachedToWindow();
+
+        mIsLaidOut = false;
+    }
+
+    @Override
+    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
+        super.onSizeChanged(w, h, oldw, oldh);
+
+        View currentFocused = findFocus();
+        if (null == currentFocused || this == currentFocused) {
+            return;
+        }
+
+        // If the currently-focused view was visible on the screen when the
+        // screen was at the old height, then scroll the screen to make that
+        // view visible with the new screen height.
+        if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {
+            currentFocused.getDrawingRect(mTempRect);
+            offsetDescendantRectToMyCoords(currentFocused, mTempRect);
+            int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
+            doScrollY(scrollDelta);
+        }
+    }
+
+    /**
+     * Return true if child is a descendant of parent, (or equal to the parent).
+     */
+    private static boolean isViewDescendantOf(View child, View parent) {
+        if (child == parent) {
+            return true;
+        }
+
+        final ViewParent theParent = child.getParent();
+        return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);
+    }
+
+    /**
+     * Fling the scroll view
+     *
+     * @param velocityY The initial velocity in the Y direction. Positive
+     *                  numbers mean that the finger/cursor is moving down the screen,
+     *                  which means we want to scroll towards the top.
+     */
+    public void fling(int velocityY) {
+        if (getChildCount() > 0) {
+
+            mScroller.fling(getScrollX(), getScrollY(), // start
+                    0, velocityY, // velocities
+                    0, 0, // x
+                    Integer.MIN_VALUE, Integer.MAX_VALUE, // y
+                    0, 0); // overscroll
+            runAnimatedScroll(true);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     *
+     * <p>This version also clamps the scrolling to the bounds of our child.
+     */
+    @Override
+    public void scrollTo(int x, int y) {
+        // we rely on the fact the View.scrollBy calls scrollTo.
+        if (getChildCount() > 0) {
+            View child = getChildAt(0);
+            final LayoutParams lp = (LayoutParams) child.getLayoutParams();
+            int parentSpaceHorizontal = getWidth() - getPaddingLeft() - getPaddingRight();
+            int childSizeHorizontal = child.getWidth() + lp.leftMargin + lp.rightMargin;
+            int parentSpaceVertical = getHeight() - getPaddingTop() - getPaddingBottom();
+            int childSizeVertical = child.getHeight() + lp.topMargin + lp.bottomMargin;
+            x = clamp(x, parentSpaceHorizontal, childSizeHorizontal);
+            y = clamp(y, parentSpaceVertical, childSizeVertical);
+            if (x != getScrollX() || y != getScrollY()) {
+                super.scrollTo(x, y);
+            }
+        }
+    }
+
+    @Override
+    public void draw(@NonNull Canvas canvas) {
+        super.draw(canvas);
+        final int scrollY = getScrollY();
+        if (!mEdgeGlowTop.isFinished()) {
+            final int restoreCount = canvas.save();
+            int width = getWidth();
+            int height = getHeight();
+            int xTranslation = 0;
+            int yTranslation = Math.min(0, scrollY);
+            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP
+                    || Api21Impl.getClipToPadding(this)) {
+                width -= getPaddingLeft() + getPaddingRight();
+                xTranslation += getPaddingLeft();
+            }
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP
+                    && Api21Impl.getClipToPadding(this)) {
+                height -= getPaddingTop() + getPaddingBottom();
+                yTranslation += getPaddingTop();
+            }
+            canvas.translate(xTranslation, yTranslation);
+            mEdgeGlowTop.setSize(width, height);
+            if (mEdgeGlowTop.draw(canvas)) {
+                postInvalidateOnAnimation();
+            }
+            canvas.restoreToCount(restoreCount);
+        }
+        if (!mEdgeGlowBottom.isFinished()) {
+            final int restoreCount = canvas.save();
+            int width = getWidth();
+            int height = getHeight();
+            int xTranslation = 0;
+            int yTranslation = Math.max(getScrollRange(), scrollY) + height;
+            if (Build.VERSION.SDK_INT < Build.VERSION_CODES.LOLLIPOP
+                    || Api21Impl.getClipToPadding(this)) {
+                width -= getPaddingLeft() + getPaddingRight();
+                xTranslation += getPaddingLeft();
+            }
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP
+                    && Api21Impl.getClipToPadding(this)) {
+                height -= getPaddingTop() + getPaddingBottom();
+                yTranslation -= getPaddingBottom();
+            }
+            canvas.translate(xTranslation - width, yTranslation);
+            canvas.rotate(180, width, 0);
+            mEdgeGlowBottom.setSize(width, height);
+            if (mEdgeGlowBottom.draw(canvas)) {
+                postInvalidateOnAnimation();
+            }
+            canvas.restoreToCount(restoreCount);
+        }
+    }
+
+    private static int clamp(int n, int my, int child) {
+        if (my >= child || n < 0) {
+            /* my >= child is this case:
+             *                    |--------------- me ---------------|
+             *     |------ child ------|
+             * or
+             *     |--------------- me ---------------|
+             *            |------ child ------|
+             * or
+             *     |--------------- me ---------------|
+             *                                  |------ child ------|
+             *
+             * n < 0 is this case:
+             *     |------ me ------|
+             *                    |-------- child --------|
+             *     |-- mScrollX --|
+             */
+            return 0;
+        }
+        if ((my + n) > child) {
+            /* this case:
+             *                    |------ me ------|
+             *     |------ child ------|
+             *     |-- mScrollX --|
+             */
+            return child - my;
+        }
+        return n;
+    }
+
+    @Override
+    protected void onRestoreInstanceState(Parcelable state) {
+        if (!(state instanceof SavedState)) {
+            super.onRestoreInstanceState(state);
+            return;
+        }
+
+        SavedState ss = (SavedState) state;
+        super.onRestoreInstanceState(ss.getSuperState());
+        mSavedState = ss;
+        requestLayout();
+    }
+
+    @NonNull
+    @Override
+    protected Parcelable onSaveInstanceState() {
+        Parcelable superState = super.onSaveInstanceState();
+        SavedState ss = new SavedState(superState);
+        ss.scrollPosition = getScrollY();
+        return ss;
+    }
+
+    static class SavedState extends BaseSavedState {
+        public int scrollPosition;
+
+        SavedState(Parcelable superState) {
+            super(superState);
+        }
+
+        SavedState(Parcel source) {
+            super(source);
+            scrollPosition = source.readInt();
+        }
+
+        @Override
+        public void writeToParcel(Parcel dest, int flags) {
+            super.writeToParcel(dest, flags);
+            dest.writeInt(scrollPosition);
+        }
+
+        @NonNull
+        @Override
+        public String toString() {
+            return "HorizontalScrollView.SavedState{"
+                    + Integer.toHexString(System.identityHashCode(this))
+                    + " scrollPosition=" + scrollPosition + "}";
+        }
+
+        public static final Creator<SavedState> CREATOR =
+                new Creator<SavedState>() {
+            @Override
+            public SavedState createFromParcel(Parcel in) {
+                return new SavedState(in);
+            }
+
+            @Override
+            public SavedState[] newArray(int size) {
+                return new SavedState[size];
+            }
+        };
+    }
+
+    static class AccessibilityDelegate extends AccessibilityDelegateCompat {
+        @Override
+        public boolean performAccessibilityAction(View host, int action, Bundle arguments) {
+            if (super.performAccessibilityAction(host, action, arguments)) {
+                return true;
+            }
+            final NestedScrollView nsvHost = (NestedScrollView) host;
+            if (!nsvHost.isEnabled()) {
+                return false;
+            }
+            int height = nsvHost.getHeight();
+            Rect rect = new Rect();
+            // Gets the visible rect on the screen except for the rotation or scale cases which
+            // might affect the result.
+            if (nsvHost.getMatrix().isIdentity() && nsvHost.getGlobalVisibleRect(rect)) {
+                height = rect.height();
+            }
+            switch (action) {
+                case AccessibilityNodeInfoCompat.ACTION_SCROLL_FORWARD:
+                case android.R.id.accessibilityActionScrollDown: {
+                    final int viewportHeight = height - nsvHost.getPaddingBottom()
+                            - nsvHost.getPaddingTop();
+                    final int targetScrollY = Math.min(nsvHost.getScrollY() + viewportHeight,
+                            nsvHost.getScrollRange());
+                    if (targetScrollY != nsvHost.getScrollY()) {
+                        nsvHost.smoothScrollTo(0, targetScrollY, true);
+                        return true;
+                    }
+                }
+                return false;
+                case AccessibilityNodeInfoCompat.ACTION_SCROLL_BACKWARD:
+                case android.R.id.accessibilityActionScrollUp: {
+                    final int viewportHeight = height - nsvHost.getPaddingBottom()
+                            - nsvHost.getPaddingTop();
+                    final int targetScrollY = Math.max(nsvHost.getScrollY() - viewportHeight, 0);
+                    if (targetScrollY != nsvHost.getScrollY()) {
+                        nsvHost.smoothScrollTo(0, targetScrollY, true);
+                        return true;
+                    }
+                }
+                return false;
+            }
+            return false;
+        }
+
+        @Override
+        public void onInitializeAccessibilityNodeInfo(View host, AccessibilityNodeInfoCompat info) {
+            super.onInitializeAccessibilityNodeInfo(host, info);
+            final NestedScrollView nsvHost = (NestedScrollView) host;
+            info.setClassName(ScrollView.class.getName());
+            if (nsvHost.isEnabled()) {
+                final int scrollRange = nsvHost.getScrollRange();
+                if (scrollRange > 0) {
+                    info.setScrollable(true);
+                    if (nsvHost.getScrollY() > 0) {
+                        info.addAction(AccessibilityNodeInfoCompat.AccessibilityActionCompat
+                                .ACTION_SCROLL_BACKWARD);
+                        info.addAction(AccessibilityNodeInfoCompat.AccessibilityActionCompat
+                                .ACTION_SCROLL_UP);
+                    }
+                    if (nsvHost.getScrollY() < scrollRange) {
+                        info.addAction(AccessibilityNodeInfoCompat.AccessibilityActionCompat
+                                .ACTION_SCROLL_FORWARD);
+                        info.addAction(AccessibilityNodeInfoCompat.AccessibilityActionCompat
+                                .ACTION_SCROLL_DOWN);
+                    }
+                }
+            }
+        }
+
+        @Override
+        public void onInitializeAccessibilityEvent(View host, AccessibilityEvent event) {
+            super.onInitializeAccessibilityEvent(host, event);
+            final NestedScrollView nsvHost = (NestedScrollView) host;
+            event.setClassName(ScrollView.class.getName());
+            final boolean scrollable = nsvHost.getScrollRange() > 0;
+            event.setScrollable(scrollable);
+            event.setScrollX(nsvHost.getScrollX());
+            event.setScrollY(nsvHost.getScrollY());
+            AccessibilityRecordCompat.setMaxScrollX(event, nsvHost.getScrollX());
+            AccessibilityRecordCompat.setMaxScrollY(event, nsvHost.getScrollRange());
+        }
+    }
+
+    class DifferentialMotionFlingTargetImpl implements DifferentialMotionFlingTarget {
+        @Override
+        public boolean startDifferentialMotionFling(float velocity) {
+            if (velocity == 0) {
+                return false;
+            }
+            stopDifferentialMotionFling();
+            fling((int) velocity);
+            return true;
+        }
+
+        @Override
+        public void stopDifferentialMotionFling() {
+            mScroller.abortAnimation();
+        }
+
+        @Override
+        public float getScaledScrollFactor() {
+            return -getVerticalScrollFactorCompat();
+        }
+    }
+
+    @RequiresApi(21)
+    static class Api21Impl {
+        private Api21Impl() {
+            // This class is not instantiable.
+        }
+
+        @DoNotInline
+        static boolean getClipToPadding(ViewGroup viewGroup) {
+            return viewGroup.getClipToPadding();
+        }
+    }
+}
diff --git a/java/src/com/android/intentresolver/widget/NestedScrollView.java.patch b/java/src/com/android/intentresolver/widget/NestedScrollView.java.patch
new file mode 100644
index 00000000..913d3b1a
--- /dev/null
+++ b/java/src/com/android/intentresolver/widget/NestedScrollView.java.patch
@@ -0,0 +1,103 @@
+--- prebuilts/sdk/current/androidx/m2repository/androidx/core/core/1.13.0-beta01/core-1.13.0-beta01-sources.jar!/androidx/core/widget/NestedScrollView.java	1980-02-01 00:00:00.000000000 -0800
++++ packages/modules/IntentResolver/java/src/com/android/intentresolver/widget/NestedScrollView.java	2024-03-04 17:17:47.357059016 -0800
+@@ -1,5 +1,5 @@
+ /*
+- * Copyright (C) 2015 The Android Open Source Project
++ * Copyright 2024 The Android Open Source Project
+  *
+  * Licensed under the Apache License, Version 2.0 (the "License");
+  * you may not use this file except in compliance with the License.
+@@ -15,10 +15,9 @@
+  */
+ 
+ 
+-package androidx.core.widget;
++package com.android.intentresolver.widget;
+ 
+ import static androidx.annotation.RestrictTo.Scope.LIBRARY;
+-import static androidx.annotation.RestrictTo.Scope.LIBRARY_GROUP_PREFIX;
+ 
+ import android.content.Context;
+ import android.content.res.TypedArray;
+@@ -67,13 +66,19 @@
+ import androidx.core.view.ViewCompat;
+ import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;
+ import androidx.core.view.accessibility.AccessibilityRecordCompat;
++import androidx.core.widget.EdgeEffectCompat;
+ 
+ import java.util.List;
+ 
+ /**
+- * NestedScrollView is just like {@link ScrollView}, but it supports acting
+- * as both a nested scrolling parent and child on both new and old versions of Android.
+- * Nested scrolling is enabled by default.
++ * A copy of the {@link androidx.core.widget.NestedScrollView} (from
++ * prebuilts/sdk/current/androidx/m2repository/androidx/core/core/1.13.0-beta01/core-1.13.0-beta01-sources.jar)
++ * without any functional changes with a pure refactoring of {@link #requestChildFocus(View, View)}:
++ * the method's body is extracted into the new protected method,
++ * {@link #onRequestChildFocus(View, View)}.
++ * <p>
++ * For the exact change see NestedScrollView.java.patch file.
++ * </p>
+  */
+ public class NestedScrollView extends FrameLayout implements NestedScrollingParent3,
+         NestedScrollingChild3, ScrollingView {
+@@ -1858,7 +1863,6 @@
+      * <p>The scroll range of a scroll view is the overall height of all of its
+      * children.</p>
+      */
+-    @RestrictTo(LIBRARY_GROUP_PREFIX)
+     @Override
+     public int computeVerticalScrollRange() {
+         final int count = getChildCount();
+@@ -1881,31 +1885,26 @@
+         return scrollRange;
+     }
+ 
+-    @RestrictTo(LIBRARY_GROUP_PREFIX)
+     @Override
+     public int computeVerticalScrollOffset() {
+         return Math.max(0, super.computeVerticalScrollOffset());
+     }
+ 
+-    @RestrictTo(LIBRARY_GROUP_PREFIX)
+     @Override
+     public int computeVerticalScrollExtent() {
+         return super.computeVerticalScrollExtent();
+     }
+ 
+-    @RestrictTo(LIBRARY_GROUP_PREFIX)
+     @Override
+     public int computeHorizontalScrollRange() {
+         return super.computeHorizontalScrollRange();
+     }
+ 
+-    @RestrictTo(LIBRARY_GROUP_PREFIX)
+     @Override
+     public int computeHorizontalScrollOffset() {
+         return super.computeHorizontalScrollOffset();
+     }
+ 
+-    @RestrictTo(LIBRARY_GROUP_PREFIX)
+     @Override
+     public int computeHorizontalScrollExtent() {
+         return super.computeHorizontalScrollExtent();
+@@ -2163,13 +2162,17 @@
+ 
+     @Override
+     public void requestChildFocus(View child, View focused) {
++        onRequestChildFocus(child, focused);
++        super.requestChildFocus(child, focused);
++    }
++
++    protected void onRequestChildFocus(View child, View focused) {
+         if (!mIsLayoutDirty) {
+             scrollToChild(focused);
+         } else {
+             // The child may not be laid out yet, we can't compute the scroll yet
+             mChildToScrollTo = focused;
+         }
+-        super.requestChildFocus(child, focused);
+     }
+ 
+