src/Tizen.NUI.Components/Controls/RecyclerView/SelectionList.cs

   1 /* Copyright (c) 2021 Samsung Electronics Co., Ltd.
   2  *
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * 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
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  *
  15  */
  16
  17 using System;
  18 using System.Collections;
  19 using System.Collections.Generic;
  20 using System.Collections.Specialized;
  21
  22 namespace Tizen.NUI.Components
  23 {
  24     // Used by the CollectionView to keep track of (and respond to changes in) the SelectedItems property
  25     internal class SelectionList : IList<object>
  26     {
  27         static readonly IList<object> selectEmpty = new List<object>(0);
  28         readonly CollectionView ColView;
  29         readonly IList<object> internalList;
  30         IList<object> shadowList;
  31         bool externalChange;
  32
  33         public SelectionList(CollectionView colView, IList<object> items = null)
  34         {
  35             ColView = colView ?? throw new ArgumentNullException(nameof(colView));
  36             internalList = items ?? new List<object>();
  37             shadowList = Copy();
  38
  39             if (items is INotifyCollectionChanged incc)
  40             {
  41                 incc.CollectionChanged += OnCollectionChanged;
  42             }
  43         }
  44
  45         public object this[int index] { get => internalList[index]; set => internalList[index] = value; }
  46
  47         public int Count => internalList.Count;
  48
  49         public bool IsReadOnly => false;
  50
  51         public void Add(object item)
  52         {
  53             externalChange = true;
  54             internalList.Add(item);
  55             externalChange = false;
  56
  57             ColView.SelectedItemsPropertyChanged(shadowList, internalList);
  58             shadowList.Add(item);
  59         }
  60
  61         public void Clear()
  62         {
  63             externalChange = true;
  64             internalList.Clear();
  65             externalChange = false;
  66
  67             ColView.SelectedItemsPropertyChanged(shadowList, selectEmpty);
  68             shadowList.Clear();
  69         }
  70
  71         public bool Contains(object item)
  72         {
  73             return internalList.Contains(item);
  74         }
  75
  76         public void CopyTo(object[] array, int arrayIndex)
  77         {
  78             internalList.CopyTo(array, arrayIndex);
  79         }
  80
  81         public IEnumerator<object> GetEnumerator()
  82         {
  83             return internalList.GetEnumerator();
  84         }
  85
  86         public int IndexOf(object item)
  87         {
  88             return internalList.IndexOf(item);
  89         }
  90
  91         public void Insert(int index, object item)
  92         {
  93             externalChange = true;
  94             internalList.Insert(index, item);
  95             externalChange = false;
  96
  97             ColView.SelectedItemsPropertyChanged(shadowList, internalList);
  98             shadowList.Insert(index, item);
  99         }
 100
 101         public bool Remove(object item)
 102         {
 103             externalChange = true;
 104             var removed = internalList.Remove(item);
 105             externalChange = false;
 106
 107             if (removed)
 108             {
 109                 ColView.SelectedItemsPropertyChanged(shadowList, internalList);
 110                 shadowList.Remove(item);
 111             }
 112
 113             return removed;
 114         }
 115
 116         public void RemoveAt(int index)
 117         {
 118             externalChange = true;
 119             internalList.RemoveAt(index);
 120             externalChange = false;
 121
 122             ColView.SelectedItemsPropertyChanged(shadowList, internalList);
 123             shadowList.RemoveAt(index);
 124         }
 125
 126         IEnumerator IEnumerable.GetEnumerator()
 127         {
 128             return internalList.GetEnumerator();
 129         }
 130
 131         List<object> Copy()
 132         {
 133             var items = new List<object>();
 134             for (int n = 0; n < internalList.Count; n++)
 135             {
 136                 items.Add(internalList[n]);
 137             }
 138
 139             return items;
 140         }
 141
 142         void OnCollectionChanged(object sender, NotifyCollectionChangedEventArgs args)
 143         {
 144             if (externalChange)
 145             {
 146                 // If this change was initiated by a renderer or direct manipulation of ColllectionView.SelectedItems,
 147                 // we don't need to send a selection change notification
 148                 return;
 149             }
 150
 151             // This change is coming from a bound viewmodel property
 152             // Emit a selection change notification, then bring the shadow copy up-to-date
 153             ColView.SelectedItemsPropertyChanged(shadowList, internalList);
 154             shadowList = Copy();
 155         }
 156     }
 157 }