FacetProviderAdapter.java

/*
 * Copyright (C) 2015 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 androidx.leanback.widget;

import androidx.recyclerview.widget.RecyclerView;

/**
 * Optional interface that implemented by {@link RecyclerView.Adapter} to
 * query {@link FacetProvider} for a given item view type within Adapter.  Note that
 * {@link RecyclerView.ViewHolder} may also implement {@link FacetProvider} which
 * has a higher priority than the one returned from{@link #getFacetProvider(int)}.
 * <p>
 * A typical use case of {@link FacetProvider} is that VerticalGridView/HorizontalGridView retrieves
 * {@link ItemAlignmentFacet} for a ViewHolder or a item view type.
 * <p>
 * App does not need implement FacetProviderAdapter when using {@link ObjectAdapter},
 * {@link Presenter} and {@link ItemBridgeAdapter}. {@link ItemBridgeAdapter} implemented
 * FacetProviderAdapter, it returns the FacetProvider implemented by {@link Presenter} which is
 * mapped to the item view type.
 * <p>
 * For example, app calls presenter.setFacet(ItemAlignmentFacet.class, itemAlignmentFacet) to
 * set alignment of the ViewHolders created by this Presenter.
 * </p>
 */
public interface FacetProviderAdapter {

    /**
     * Queries {@link FacetProvider} for a given type within Adapter.
     * @param type        type of the item.
     * @return Facet provider for the type.
     */
    public FacetProvider getFacetProvider(int type);

}