Better estimate the height of widget recycler view

Test: Expand and collapse apps in the widgets picker. Then, observe
      the height of the fast scroller is correctly displayed.

Bug: 181629430
Change-Id: I9efcf902f8548fc5c8a398609758d43123228e5e

res/layout/widgets_list_row_header.xml

@@ -19,7 +19,7 @@
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
     android:background="?android:attr/selectableItemBackground"
-    android:paddingVertical="20dp"
+    android:paddingVertical="@dimen/widget_list_header_view_vertical_padding"
     android:orientation="horizontal">
 
     <ImageView

res/values/dimens.xml

@@ -108,6 +108,8 @@
     <dimen name="widget_cell_vertical_padding">8dp</dimen>
     <dimen name="widget_cell_horizontal_padding">16dp</dimen>
 
+    <dimen name="widget_list_header_view_vertical_padding">20dp</dimen>
+
     <dimen name="widget_preview_shadow_blur">0.5dp</dimen>
     <dimen name="widget_preview_key_shadow_distance">1dp</dimen>
     <dimen name="widget_preview_corner_radius">2dp</dimen>

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

@@ -385,14 +385,16 @@ public class WidgetsFullSheet extends BaseWidgetSheet
 
     @Override
     public int getHeaderViewHeight() {
-        // No need to check work profile here because mInitialTabHeight is always 0 if there is no
-        // work profile.
-        return mInitialTabsHeight
-                + measureHeightWithVerticalMargins(mSearchAndRecommendationViewHolder.mContainer);
+        return measureHeightWithVerticalMargins(mSearchAndRecommendationViewHolder.mCollapseHandle)
+                + measureHeightWithVerticalMargins(mSearchAndRecommendationViewHolder.mHeaderTitle)
+                + measureHeightWithVerticalMargins(mSearchAndRecommendationViewHolder.mSearchBar);
     }
 
     /** private the height, in pixel, + the vertical margins of a given view. */
     private static int measureHeightWithVerticalMargins(View view) {
+        if (view.getVisibility() != VISIBLE) {
+            return 0;
+        }
         MarginLayoutParams marginLayoutParams = (MarginLayoutParams) view.getLayoutParams();
         return view.getMeasuredHeight() + marginLayoutParams.bottomMargin
                 + marginLayoutParams.topMargin;

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

@@ -122,6 +122,11 @@ public class WidgetsListAdapter extends Adapter<ViewHolder> implements OnHeaderC
         return mVisibleEntries.size();
     }
 
+    /** Returns all items that will be drawn in a recycler view. */
+    public List<WidgetsListBaseEntry> getItems() {
+        return mVisibleEntries;
+    }
+
     /** Gets the section name for {@link com.android.launcher3.views.RecyclerViewFastScroller}. */
     public String getSectionName(int pos) {
         return mVisibleEntries.get(pos).mTitleSectionName;

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

@@ -21,13 +21,19 @@ import android.graphics.Point;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
+import android.widget.TableLayout;
 
 import androidx.recyclerview.widget.LinearLayoutManager;
 import androidx.recyclerview.widget.RecyclerView;
 import androidx.recyclerview.widget.RecyclerView.OnItemTouchListener;
 
 import com.android.launcher3.BaseRecyclerView;
+import com.android.launcher3.DeviceProfile;
 import com.android.launcher3.R;
+import com.android.launcher3.views.ActivityContext;
+import com.android.launcher3.widget.model.WidgetsListBaseEntry;
+import com.android.launcher3.widget.model.WidgetsListContentEntry;
+import com.android.launcher3.widget.model.WidgetsListHeaderEntry;
 
 /**
  * The widgets recycler view.
@@ -39,8 +45,10 @@ public class WidgetsRecyclerView extends BaseRecyclerView implements OnItemTouch
     private final int mScrollbarTop;
 
     private final Point mFastScrollerOffset = new Point();
+    private final int mEstimatedWidgetListHeaderHeight;
     private boolean mTouchDownOnScroller;
     private HeaderViewDimensionsProvider mHeaderViewDimensionsProvider;
+    private int mLastVisibleWidgetContentTableHeight = 0;
 
     public WidgetsRecyclerView(Context context) {
         this(context, null);
@@ -55,6 +63,12 @@ public class WidgetsRecyclerView extends BaseRecyclerView implements OnItemTouch
         super(context, attrs, defStyleAttr);
         mScrollbarTop = getResources().getDimensionPixelSize(R.dimen.dynamic_grid_edge_margin);
         addOnItemTouchListener(this);
+
+        ActivityContext activity = ActivityContext.lookupContext(getContext());
+        DeviceProfile grid = activity.getDeviceProfile();
+        mEstimatedWidgetListHeaderHeight = grid.iconSizePx
+                + 2 * context.getResources().getDimensionPixelSize(
+                        R.dimen.widget_list_header_view_vertical_padding);
     }
 
     @Override
@@ -123,21 +137,32 @@ public class WidgetsRecyclerView extends BaseRecyclerView implements OnItemTouch
 
         View child = getChildAt(0);
         int rowIndex = getChildPosition(child);
-        int y = (child.getMeasuredHeight() * rowIndex);
+        for (int i = 0; i < getChildCount(); i++) {
+            View view = getChildAt(i);
+            if (view instanceof TableLayout) {
+                // This assumes there is ever only one content shown in this recycler view.
+                mLastVisibleWidgetContentTableHeight = view.getMeasuredHeight();
+            }
+        }
+
+        int scrollPosition = getItemsHeight(rowIndex);
         int offset = getLayoutManager().getDecoratedTop(child);
 
-        return getPaddingTop() + y - offset;
+        return getPaddingTop() + scrollPosition - offset;
     }
 
     /**
-     * Returns the available scroll height:
-     *   AvailableScrollHeight = Total height of the all items - last page height
+     * Returns the available scroll height, in pixel.
+     *
+     * <p>If the recycler view can't be scrolled, returns 0.
      */
     @Override
     protected int getAvailableScrollHeight() {
-        View child = getChildAt(0);
-        return child.getMeasuredHeight() * mAdapter.getItemCount() + getScrollBarTop()
-                + getPaddingBottom() - mScrollbar.getHeight();
+        // AvailableScrollHeight = Total height of the all items - first page height
+        int firstPageHeight = getMeasuredHeight() - getPaddingTop() - getPaddingBottom();
+        int totalHeightOfAllItems = getItemsHeight(/* untilIndex= */ mAdapter.getItemCount());
+        int availableScrollHeight = totalHeightOfAllItems - firstPageHeight;
+        return Math.max(0, availableScrollHeight);
     }
 
     private boolean isModelNotReady() {
@@ -180,6 +205,31 @@ public class WidgetsRecyclerView extends BaseRecyclerView implements OnItemTouch
         mHeaderViewDimensionsProvider = headerViewDimensionsProvider;
     }
 
+    /**
+     * Returns the sum of the height, in pixels, of this list adapter's items from index 0 until
+     * {@code untilIndex}.
+     *
+     * <p>If the untilIndex is larger than the total number of items in this adapter, returns the
+     * sum of all items' height.
+     */
+    private int getItemsHeight(int untilIndex) {
+        if (untilIndex > mAdapter.getItems().size()) {
+            untilIndex = mAdapter.getItems().size();
+        }
+        int totalItemsHeight = 0;
+        for (int i = 0; i < untilIndex; i++) {
+            WidgetsListBaseEntry entry = mAdapter.getItems().get(i);
+            if (entry instanceof WidgetsListHeaderEntry) {
+                totalItemsHeight += mEstimatedWidgetListHeaderHeight;
+            } else if (entry instanceof WidgetsListContentEntry) {
+                totalItemsHeight += mLastVisibleWidgetContentTableHeight;
+            } else {
+                throw new UnsupportedOperationException("Can't estimate height for " + entry);
+            }
+        }
+        return totalItemsHeight;
+    }
+
     /**
      * Provides dimensions of the header view that is shown at the top of a
      * {@link WidgetsRecyclerView}.