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      1 /*
      2  * Copyright (C) 2014 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
      5  * in compliance with the License. You may obtain a copy of the License at
      6  *
      7  * http://www.apache.org/licenses/LICENSE-2.0
      8  *
      9  * Unless required by applicable law or agreed to in writing, software distributed under the License
     10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
     11  * or implied. See the License for the specific language governing permissions and limitations under
     12  * the License.
     13  */
     14 package androidx.leanback.widget;
     15 
     16 import static androidx.leanback.widget.ObjectAdapter.NO_ID;
     17 
     18 /**
     19  * The base class for all rows.  A commonly used subclass is the {@link ListRow}.  Custom
     20  * subclasses may define other types of rows.
     21  */
     22 public class Row {
     23 
     24     private static final int FLAG_ID_USE_MASK = 1;
     25     private static final int FLAG_ID_USE_HEADER = 1;
     26     private static final int FLAG_ID_USE_ID = 0;
     27 
     28     private int mFlags = FLAG_ID_USE_HEADER;
     29     private HeaderItem mHeaderItem;
     30     private long mId = NO_ID;
     31 
     32     /**
     33      * Constructor for a Row.
     34      *
     35      * @param id The id of the row.
     36      * @param headerItem The {@link HeaderItem} for this Row, or null if there
     37      *        is no header.
     38      */
     39     public Row(long id, HeaderItem headerItem) {
     40         setId(id);
     41         setHeaderItem(headerItem);
     42     }
     43 
     44     /**
     45      * Constructor for a Row.
     46      *
     47      * @param headerItem The {@link HeaderItem} for this Row, or null if there
     48      *        is no header.
     49      */
     50     public Row(HeaderItem headerItem) {
     51         setHeaderItem(headerItem);
     52     }
     53 
     54     /**
     55      * Constructor for a Row.
     56      */
     57     public Row() {
     58     }
     59 
     60     /**
     61      * Returns the {@link HeaderItem} that represents metadata for the row.
     62      *
     63      * @return The HeaderItem for this row, or null if unset.
     64      */
     65     public final HeaderItem getHeaderItem() {
     66         return mHeaderItem;
     67     }
     68 
     69     /**
     70      * Sets the {@link HeaderItem} that represents metadata for the row.
     71      *
     72      * @param headerItem The HeaderItem for this Row, or null if there is no
     73      *        header.
     74      */
     75     public final void setHeaderItem(HeaderItem headerItem) {
     76         mHeaderItem = headerItem;
     77     }
     78 
     79     /**
     80      * Sets the id for this row.
     81      *
     82      * @param id The id of the row.
     83      */
     84     public final void setId(long id) {
     85         mId = id;
     86         setFlags(FLAG_ID_USE_ID, FLAG_ID_USE_MASK);
     87     }
     88 
     89     /**
     90      * Returns a unique identifier for this row. This id can come from one of
     91      * three places:
     92      * <ul>
     93      *   <li>If {@link #setId(long)} is ever called on this row, it will return
     94      *   this id.
     95      *   <li>If {@link #setId(long)} has not been called but the header item is
     96      *   not null, the result of {@link HeaderItem#getId()} is returned.
     97      *   <li>Otherwise {@link ObjectAdapter#NO_ID NO_ID} is returned.
     98      * </ul>
     99      */
    100     public final long getId() {
    101         if ( (mFlags & FLAG_ID_USE_MASK) == FLAG_ID_USE_HEADER) {
    102             HeaderItem header = getHeaderItem();
    103             if (header != null) {
    104                 return header.getId();
    105             }
    106             return NO_ID;
    107         } else {
    108             return mId;
    109         }
    110     }
    111 
    112     final void setFlags(int flags, int mask) {
    113         mFlags = (mFlags & ~mask) | (flags & mask);
    114     }
    115 
    116     final int getFlags() {
    117         return mFlags;
    118     }
    119 
    120     /**
    121      * Returns true if this Row can be rendered in a visible row view, false otherwise.  For example
    122      * {@link ListRow} is rendered by {@link ListRowPresenter}.  {@link PageRow},
    123      * {@link SectionRow}, {@link DividerRow} are rendered as invisible row views.
    124      * @return True if this Row can be rendered in a visible row view, false otherwise.
    125      */
    126     public boolean isRenderedAsRowView() {
    127         return true;
    128     }
    129 }
    130