-
Notifications
You must be signed in to change notification settings - Fork 1.7k
/
ElementTemplate.cs
103 lines (86 loc) · 2.46 KB
/
ElementTemplate.cs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
using System;
using System.Collections.Generic;
using Xamarin.Forms.Internals;
namespace Xamarin.Forms
{
#pragma warning disable 612
public class ElementTemplate : IElement, IDataTemplate
#pragma warning restore 612
{
List<Action<object, ResourcesChangedEventArgs>> _changeHandlers;
Element _parent;
bool _canRecycle; // aka IsDeclarative
internal ElementTemplate()
{
}
internal ElementTemplate(Type type) : this()
{
if (type == null)
throw new ArgumentNullException("type");
_canRecycle = true;
LoadTemplate = () => Activator.CreateInstance(type);
}
internal ElementTemplate(Func<object> loadTemplate) : this()
{
if (loadTemplate == null)
throw new ArgumentNullException("loadTemplate");
LoadTemplate = loadTemplate;
}
Func<object> LoadTemplate { get; set; }
#pragma warning disable 0612
Func<object> IDataTemplate.LoadTemplate
{
#pragma warning restore 0612
get { return LoadTemplate; }
set { LoadTemplate = value; }
}
void IElement.AddResourcesChangedListener(Action<object, ResourcesChangedEventArgs> onchanged)
{
_changeHandlers = _changeHandlers ?? new List<Action<object, ResourcesChangedEventArgs>>(1);
_changeHandlers.Add(onchanged);
}
internal bool CanRecycle => _canRecycle;
Element IElement.Parent
{
get { return _parent; }
set
{
if (_parent == value)
return;
if (_parent != null)
((IElement)_parent).RemoveResourcesChangedListener(OnResourcesChanged);
_parent = value;
if (_parent != null)
((IElement)_parent).AddResourcesChangedListener(OnResourcesChanged);
}
}
void IElement.RemoveResourcesChangedListener(Action<object, ResourcesChangedEventArgs> onchanged)
{
if (_changeHandlers == null)
return;
_changeHandlers.Remove(onchanged);
}
public object CreateContent()
{
if (LoadTemplate == null)
throw new InvalidOperationException("LoadTemplate should not be null");
if (this is DataTemplateSelector)
throw new InvalidOperationException("Cannot call CreateContent directly on a DataTemplateSelector");
object item = LoadTemplate();
SetupContent(item);
if (item is Element elem)
elem.IsTemplateRoot = true;
return item;
}
internal virtual void SetupContent(object item)
{
}
void OnResourcesChanged(object sender, ResourcesChangedEventArgs e)
{
if (_changeHandlers == null)
return;
foreach (Action<object, ResourcesChangedEventArgs> handler in _changeHandlers)
handler(this, e);
}
}
}