src/Tizen.NUI/src/internal/XamlBinding/Interactivity/AttachedCollection.cs

   1 /*
   2  * Copyright(c) 2021 Samsung Electronics Co., Ltd.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  *
  16  */
  17 using System;
  18 using System.Collections.Generic;
  19 using System.Collections.ObjectModel;
  20
  21 namespace Tizen.NUI.Binding
  22 {
  23     internal class AttachedCollection<T> : ObservableCollection<T>, ICollection<T>, IAttachedObject where T : BindableObject, IAttachedObject
  24     {
  25         readonly List<WeakReference> _associatedObjects = new List<WeakReference>();
  26
  27         public AttachedCollection()
  28         {
  29         }
  30
  31         public AttachedCollection(IEnumerable<T> collection) : base(collection)
  32         {
  33         }
  34
  35         public AttachedCollection(IList<T> list) : base(list)
  36         {
  37         }
  38
  39         public void AttachTo(BindableObject bindable)
  40         {
  41             if (bindable == null)
  42                 throw new ArgumentNullException(nameof(bindable));
  43             OnAttachedTo(bindable);
  44         }
  45
  46         public void DetachFrom(BindableObject bindable)
  47         {
  48             OnDetachingFrom(bindable);
  49         }
  50
  51         protected override void ClearItems()
  52         {
  53             foreach (WeakReference weakbindable in _associatedObjects)
  54             {
  55                 foreach (T item in this)
  56                 {
  57                     var bindable = weakbindable.Target as BindableObject;
  58                     if (bindable == null)
  59                         continue;
  60                     item?.DetachFrom(bindable);
  61                 }
  62             }
  63             base.ClearItems();
  64         }
  65
  66         protected override void InsertItem(int index, T item)
  67         {
  68             base.InsertItem(index, item);
  69             foreach (WeakReference weakbindable in _associatedObjects)
  70             {
  71                 var bindable = weakbindable.Target as BindableObject;
  72                 if (bindable == null)
  73                     continue;
  74                 item?.AttachTo(bindable);
  75             }
  76         }
  77
  78         protected virtual void OnAttachedTo(BindableObject bindable)
  79         {
  80             lock (_associatedObjects)
  81             {
  82                 _associatedObjects.Add(new WeakReference(bindable));
  83             }
  84             foreach (T item in this)
  85                 item?.AttachTo(bindable);
  86         }
  87
  88         protected virtual void OnDetachingFrom(BindableObject bindable)
  89         {
  90             foreach (T item in this)
  91                 item?.DetachFrom(bindable);
  92             lock (_associatedObjects)
  93             {
  94                 for (var i = 0; i < _associatedObjects.Count; i++)
  95                 {
  96                     object target = _associatedObjects[i].Target;
  97
  98                     if (target == null || target == bindable)
  99                     {
 100                         _associatedObjects.RemoveAt(i);
 101                         i--;
 102                     }
 103                 }
 104             }
 105         }
 106
 107         protected override void RemoveItem(int index)
 108         {
 109             T item = this[index];
 110             foreach (WeakReference weakbindable in _associatedObjects)
 111             {
 112                 var bindable = weakbindable.Target as BindableObject;
 113                 if (bindable == null)
 114                     continue;
 115                 item?.DetachFrom(bindable);
 116             }
 117
 118             base.RemoveItem(index);
 119         }
 120
 121         protected override void SetItem(int index, T item)
 122         {
 123             T old = this[index];
 124             foreach (WeakReference weakbindable in _associatedObjects)
 125             {
 126                 var bindable = weakbindable.Target as BindableObject;
 127                 if (bindable == null)
 128                     continue;
 129                 old?.DetachFrom(bindable);
 130             }
 131
 132             base.SetItem(index, item);
 133
 134             foreach (WeakReference weakbindable in _associatedObjects)
 135             {
 136                 var bindable = weakbindable.Target as BindableObject;
 137                 if (bindable == null)
 138                     continue;
 139                 item?.AttachTo(bindable);
 140             }
 141         }
 142     }
 143 }