Fix scrolling issue in the full widgets picker

Before this change, the widgets recommendation table handles all the
touch events. The table doesn't distinguish a touch event from a scroll
event. This change forwards the motion event to the active recycler view.
If the recycler view doesn't handle the event, it will then forward the
event back to the view hierarchy.

Test: Open the full widgets picker, then start scrolling on the
      recommended widgets UI. The full widgets picker scrolls perfectly.
      Drag-n-drop a recommended widget
Bug: 186567644
Change-Id: I89d473179796c516d2394332dd75f8e9a1d8b388

src/com/android/launcher3/widget/picker/SearchAndRecommendationsScrollController.java

@@ -15,6 +15,8 @@
  */
 package com.android.launcher3.widget.picker;
 
+import android.graphics.Point;
+import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup.MarginLayoutParams;
 import android.widget.RelativeLayout;
@@ -33,9 +35,11 @@ final class SearchAndRecommendationsScrollController implements
         RecyclerViewFastScroller.OnFastScrollChangeListener {
     private final boolean mHasWorkProfile;
     private final SearchAndRecommendationViewHolder mViewHolder;
+    private final View mSearchAndRecommendationViewParent;
     private final WidgetsRecyclerView mPrimaryRecyclerView;
     private final WidgetsRecyclerView mSearchRecyclerView;
     private final int mTabsHeight;
+    private final Point mTempOffset = new Point();
 
     // The following are only non null if mHasWorkProfile is true.
     @Nullable private final WidgetsRecyclerView mWorkRecyclerView;
@@ -62,6 +66,8 @@ final class SearchAndRecommendationsScrollController implements
      */
     private int mCollapsibleHeightForTabs = 0;
 
+    private boolean mShouldForwardToRecyclerView = false;
+
     SearchAndRecommendationsScrollController(
             boolean hasWorkProfile,
             int tabsHeight,
@@ -73,6 +79,8 @@ final class SearchAndRecommendationsScrollController implements
             @Nullable PersonalWorkPagedView primaryWorkViewPager) {
         mHasWorkProfile = hasWorkProfile;
         mViewHolder = viewHolder;
+        mViewHolder.mContainer.setSearchAndRecommendationScrollController(this);
+        mSearchAndRecommendationViewParent = (View) mViewHolder.mContainer.getParent();
         mPrimaryRecyclerView = primaryRecyclerView;
         mCurrentRecyclerView = mPrimaryRecyclerView;
         mWorkRecyclerView = workRecyclerView;
@@ -245,6 +253,43 @@ final class SearchAndRecommendationsScrollController implements
         }
     }
 
+    /**
+     * Returns {@code true} if a touch event should be intercepted by this controller.
+     */
+    public boolean onInterceptTouchEvent(MotionEvent event) {
+        calculateMotionEventOffset(mTempOffset);
+        event.offsetLocation(mTempOffset.x, mTempOffset.y);
+        try {
+            mShouldForwardToRecyclerView = mCurrentRecyclerView.onInterceptTouchEvent(event);
+            return mShouldForwardToRecyclerView;
+        } finally {
+            event.offsetLocation(-mTempOffset.x, -mTempOffset.y);
+        }
+    }
+
+    /**
+     * Returns {@code true} if this controller has intercepted and consumed a touch event.
+     */
+    public boolean onTouchEvent(MotionEvent event) {
+        if (mShouldForwardToRecyclerView) {
+            calculateMotionEventOffset(mTempOffset);
+            event.offsetLocation(mTempOffset.x, mTempOffset.y);
+            try {
+                return mCurrentRecyclerView.onTouchEvent(event);
+            } finally {
+                event.offsetLocation(-mTempOffset.x, -mTempOffset.y);
+            }
+        }
+        return false;
+    }
+
+    private void calculateMotionEventOffset(Point p) {
+        p.x = mViewHolder.mContainer.getLeft() - mCurrentRecyclerView.getLeft()
+                - mSearchAndRecommendationViewParent.getLeft();
+        p.y = mViewHolder.mContainer.getTop() - mCurrentRecyclerView.getTop()
+                - mSearchAndRecommendationViewParent.getTop();
+    }
+
     /** private the height, in pixel, + the vertical margins of a given view. */
     private static int measureHeightWithVerticalMargins(View view) {
         if (view.getVisibility() != View.VISIBLE) {