/
DataTemplateSelector.cs
41 lines (32 loc) · 1.26 KB
/
DataTemplateSelector.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
using System;
using System.Collections.Generic;
namespace Xamarin.Forms
{
public abstract class DataTemplateSelector : DataTemplate
{
Dictionary<Type, DataTemplate> _dataTemplates = new Dictionary<Type, DataTemplate>();
public DataTemplate SelectTemplate(object item, BindableObject container)
{
var listView = container as ListView;
var recycle = listView == null ? false :
(listView.CachingStrategy & ListViewCachingStrategy.RecycleElementAndDataTemplate) ==
ListViewCachingStrategy.RecycleElementAndDataTemplate;
DataTemplate dataTemplate = null;
if (recycle && _dataTemplates.TryGetValue(item.GetType(), out dataTemplate))
return dataTemplate;
dataTemplate = OnSelectTemplate(item, container);
if (dataTemplate is DataTemplateSelector)
throw new NotSupportedException(
"DataTemplateSelector.OnSelectTemplate must not return another DataTemplateSelector");
if (recycle)
{
if (!dataTemplate.CanRecycle)
throw new NotSupportedException(
"RecycleElementAndDataTemplate requires DataTemplate activated with ctor taking a type.");
_dataTemplates[item.GetType()] = dataTemplate;
}
return dataTemplate;
}
protected abstract DataTemplate OnSelectTemplate(object item, BindableObject container);
}
}