/* * Copyright 2016 Vsevolod Ganin * * 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 net.ganin.darv; import android.support.annotation.NonNull; import android.support.annotation.Nullable; import android.support.v7.widget.RecyclerView; import android.view.View; import static android.support.v7.widget.RecyclerView.NO_ID; import static android.support.v7.widget.RecyclerView.NO_POSITION; /** * Helper class that manages focus archiving for some RecyclerView. */ class FocusArchivist { private int mLastSelectedPos = NO_POSITION; private long mLastSelectedId = NO_ID; /** * Remember currently focused entity of the passed RecyclerView. If RecyclerView doesn't contain * focus, ignore archiving and stick to the former remembered entity. * * @param rv Recycler view. */ void archiveFocus(@NonNull RecyclerView rv) { if (rv.hasFocus()) { View focusedChild = rv.getFocusedChild(); archiveFocus(rv, focusedChild); } } /** * Remember some child of RecyclerView as was being focused. * * @param rv Recycler view. * @param child child of that recycler view. */ void archiveFocus(@NonNull RecyclerView rv, View child) { mLastSelectedPos = rv.getChildAdapterPosition(child); mLastSelectedId = rv.getChildItemId(child); } /** * Gets last focused view. * * @param rv Recycler view. * @return Last focused view. Returns null if no appropriate view was found. */ @Nullable View getLastFocus(@NonNull RecyclerView rv) { View lastFocused = findLastFocusedViewById(rv, mLastSelectedId); if (lastFocused != null) { return lastFocused; } return findLastFocusedViewByPos(rv, mLastSelectedPos); } /** * Find focusable view by item id. * * @param rv Recycler view. * @param id Item's id. * @return View with such id, if selection can be restored on it. Null otherwise. */ private View findLastFocusedViewById(@NonNull RecyclerView rv, long id) { RecyclerView.Adapter adapter = rv.getAdapter(); if (adapter != null && adapter.hasStableIds() && mLastSelectedId != NO_ID) { RecyclerView.ViewHolder viewHolder = rv.findViewHolderForItemId(id); if (viewHolder != null) { viewHolder.itemView.requestFocus(); return viewHolder.itemView; } } return null; } /** * Find focusable view by item position. * * @param rv Recycler view. * @param pos Item's pos. * @return View with such position, if selection can be restored on it. Null otherwise. */ private View findLastFocusedViewByPos(@NonNull RecyclerView rv, int pos) { if (pos != NO_POSITION) { RecyclerView.ViewHolder viewHolder = rv.findViewHolderForAdapterPosition(pos); if (viewHolder != null) { return viewHolder.itemView; } } return null; } }