Wpf 在ItemsControl中插入项
以下是要求Wpf 在ItemsControl中插入项,wpf,xaml,silverlight,winrt-xaml,itemscontrol,Wpf,Xaml,Silverlight,Winrt Xaml,Itemscontrol,以下是要求 在我的代码> ITEMsStase(您可以使用 ListVIEW < /代码>,如果它有助于您考虑该场景)。我想将唯一的数据模板注入列表中的任意索引位置,而不是记录 例如,我可能希望将其插入第一个位置,索引0,或第三个位置,索引2,或者甚至可能有逻辑将其插入最后一个位置,索引count-1 我意识到,我需要子类ListView来实现这一点。也就是说,我可以很容易地创建SpecialItemTemplate、SpecialItemIndex DP属性来获得这些值 新增要求: 不需要特殊
在我的代码> ITEMsStase(您可以使用<代码> ListVIEW < /代码>,如果它有助于您考虑该场景)。我想将唯一的数据模板注入列表中的任意索引位置,而不是记录
例如,我可能希望将其插入第一个位置,索引0,或第三个位置,索引2,或者甚至可能有逻辑将其插入最后一个位置,索引count-1 我意识到,我需要子类ListView来实现这一点。也就是说,我可以很容易地创建SpecialItemTemplate、SpecialItemIndex DP属性来获得这些值 新增要求:(在WinRT中)如何完成这一壮举有什么想法吗?这里有一个解决方案,它基本上是一种
行为
,带有模板
属性,可以附加到任何项控件
。我用虚拟化和非虚拟化面板测试了它,这两种情况都适用。如果你认为代码很复杂。。。好吧,我不能不同意,前一段时间写的,我记不起我为什么要这样写
用法:
<ListBox ItemsSource="{Binding Persons}">
<Interactivity:Interaction.Behaviors>
<AlternativeItemTemplate Index="42">
<DataTemplate>
...foo...
</DataTemplate>
</AlternativeItemTemplate>
</Interactivity:Interaction.Behaviors>
<ListBox.ItemTemplate>
<DataTemplate>
...bar...
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
……福。。。
…酒吧。。。
课程包括:
[ContentProperty( "ItemTemplate" )]
public class AlternativeItemTemplate : ItemContainerDecorator
{
public DataTemplate ItemTemplate
{
get { return (DataTemplate) GetValue( ItemTemplateProperty ); }
set { SetValue( ItemTemplateProperty, value ); }
}
public static readonly DependencyProperty ItemTemplateProperty =
DependencyProperty.Register( "ItemTemplate", typeof( DataTemplate ), typeof( AlternativeItemTemplate ), new PropertyMetadata( null ) );
public int Index
{
get { return (int) GetValue( IndexProperty ); }
set { SetValue( IndexProperty, value ); }
}
public static readonly DependencyProperty IndexProperty =
DependencyProperty.Register( "Index", typeof( int ), typeof( AlternativeItemTemplate ), new PropertyMetadata( -1 ) );
protected override void OnContainersChanged()
{
if (!AssociatedObject.Items.Any() || Index < 0 || Index >= AssociatedObject.Items.Count)
{
ItemContentPresenter = null;
ItemContentControl = null;
m_overwrittenTemplate = null;
return;
}
TryUpdateItem( ItemContainerGenerator.ContainerFromItem( AssociatedObject.Items[Index] ) );
}
private ContentPresenter ItemContentPresenter { get; set; }
private ContentControl ItemContentControl { get; set; }
private DataTemplate m_overwrittenTemplate;
private void TryUpdateItem( DependencyObject itemContainer )
{
if (itemContainer == null)
{
ResetOverwrittenTemplate();
}
var containerAsPresenter = itemContainer as ContentPresenter;
if (containerAsPresenter != null) UpdateItemContentPresenter( containerAsPresenter );
else
{
var containerAsControl = itemContainer as ContentControl;
if (containerAsControl != null) UpdateItemContentControl( containerAsControl );
}
}
private void ResetOverwrittenTemplate()
{
if (ItemContentPresenter != null)
ItemContentPresenter.ContentTemplate = m_overwrittenTemplate;
if (ItemContentControl != null)
ItemContentControl.ContentTemplate = m_overwrittenTemplate;
ItemContentPresenter = null;
ItemContentControl = null;
m_overwrittenTemplate = null;
}
private void UpdateItemContentPresenter( ContentPresenter container )
{
if (ItemContentPresenter != null)
ItemContentPresenter.ContentTemplate = m_overwrittenTemplate;
ItemContentPresenter = container;
m_overwrittenTemplate = ItemContentPresenter.ContentTemplate;
ItemContentPresenter.ContentTemplate = ItemTemplate;
}
private void UpdateItemContentControl( ContentControl container )
{
if (ItemContentControl != null)
ItemContentControl.ContentTemplate = m_overwrittenTemplate;
ItemContentControl = container;
m_overwrittenTemplate = ItemContentControl.ContentTemplate;
ItemContentControl.ContentTemplate = ItemTemplate;
}
}
public abstract class ItemContainerDecorator : Behavior<ItemsControl>
{
private Dictionary<object, DependencyObject> LastKnownContainers = new Dictionary<object, DependencyObject>();
protected ItemContainerGenerator ItemContainerGenerator { get { return (AssociatedObject != null) ? AssociatedObject.ItemContainerGenerator : null; } }
protected override void OnAttached()
{
base.OnAttached();
ItemContainerGenerator.ItemsChanged += HandleItemsChangedInitially;
if (!TryAddObservers())
{
AssociatedObject.Loaded += AddObserversOnLoaded;
}
AssociatedObject.Loaded += OnItemsControlLoaded;
AssociatedObject.LayoutUpdated += OnItemsControlLayoutUpdated;
CheckContainersChanged();
}
private void OnItemsControlLayoutUpdated(object sender, EventArgs eventArgs)
{
CheckContainersChanged();
}
private void OnItemsControlLoaded(object sender, RoutedEventArgs e)
{
CheckContainersChanged();
}
private void AddObserversOnLoaded( object sender, RoutedEventArgs e )
{
AssociatedObject.Loaded -= AddObserversOnLoaded;
TryAddObservers();
}
private bool TryAddObservers()
{
const bool success = true;
Panel itemsHost =
AssociatedObject.GetVisualDescendants().OfType<Panel>().FirstOrDefault( panel => panel.IsItemsHost );
if (itemsHost != null)
{
var virtualizingItemsHost = itemsHost as VirtualizingPanel;
if (virtualizingItemsHost != null)
{
virtualizingItemsHost.LayoutUpdated += OnVirtualizingItemsHostLayoutUpdated;
m_virtualizingItemsHost = virtualizingItemsHost;
}
return success;
}
return !success;
}
private VirtualizingPanel m_virtualizingItemsHost;
private bool LayoutUpdatedOccurredFirst;
private void OnVirtualizingItemsHostLayoutUpdated( object sender, EventArgs eventArgs )
{
LayoutUpdatedOccurredFirst = true;
CheckContainersChanged();
}
protected override void OnDetaching()
{
ItemContainerGenerator.ItemsChanged -= HandleItemsChangedInitially;
ItemContainerGenerator.ItemsChanged -= HandleItemsChanged;
AssociatedObject.Loaded -= OnItemsControlLoaded;
AssociatedObject.LayoutUpdated -= OnItemsControlLayoutUpdated;
AssociatedObject.Loaded -= AddObserversOnLoaded;
if (m_virtualizingItemsHost != null) m_virtualizingItemsHost.LayoutUpdated -= OnVirtualizingItemsHostLayoutUpdated;
m_virtualizingItemsHost = null;
base.OnDetaching();
}
private void HandleItemsChangedInitially( object sender, ItemsChangedEventArgs e )
{
ItemContainerGenerator.ItemsChanged -= HandleItemsChangedInitially;
if (!LayoutUpdatedOccurredFirst)
{
//sometimes calling UpdateLayout throws an ArgumentException
//don't know why so we just swallow it
//it's not particularly important
try
{
AssociatedObject.UpdateLayout();
}
catch (ArgumentException) { }
}
ItemContainerGenerator.ItemsChanged += HandleItemsChanged;
CheckContainersChanged();
}
private void HandleItemsChanged( object sender, ItemsChangedEventArgs e )
{
CheckContainersChanged();
}
private void CheckContainersChanged()
{
var newestContainers = new Dictionary<object, DependencyObject>();
foreach (var item in AssociatedObject.Items)
{
newestContainers[item] = ItemContainerGenerator.ContainerFromItem( item );
}
if (!LastKnownContainers.SequenceEqual( newestContainers ))
{
LastKnownContainers = newestContainers;
OnContainersChanged();
}
}
protected abstract void OnContainersChanged();
}
[ContentProperty(“ItemTemplate”)]
公共类AlternativeItemTemplate:ItemContainerDecorator
{
公共数据模板ItemTemplate
{
获取{return(DataTemplate)GetValue(ItemTemplateProperty);}
set{SetValue(ItemTemplateProperty,value);}
}
公共静态只读DependencyProperty ItemTemplateProperty=
DependencyProperty.Register(“ItemTemplate”、typeof(DataTemplate)、typeof(AlternativeItemTemplate)、new PropertyMetadata(null));
公共整数索引
{
获取{return(int)GetValue(IndexProperty);}
set{SetValue(IndexProperty,value);}
}
公共静态只读从属属性IndexProperty=
DependencyProperty.Register(“索引”、typeof(int)、typeof(AlternativeItemTemplate)、新PropertyMetadata(-1));
受保护的覆盖无效OnContainersChanged()
{
如果(!AssociatedObject.Items.Any()| | Index<0 | | Index>=AssociatedObject.Items.Count)
{
ItemContentPresenter=null;
ItemContentControl=null;
m_OverwriteTemplate=null;
返回;
}
TryUpdateItem(ItemContainerGenerator.ContainerFromItem(AssociatedObject.Items[Index]);
}
私有ContentPresenter项ContentPresenter{get;set;}
私有ContentControl项ContentControl{get;set;}
私有数据模板m_OverwriteTemplate;
私有void TryUpdateItem(DependencyObject itemContainer)
{
if(itemContainer==null)
{
重置模板();
}
var containerAsPresenter=作为ContentPresenter的itemContainer;
if(containerAsPresenter!=null)UpdateItemContentPresenter(containerAsPresenter);
其他的
{
var containerAsControl=itemContainer作为ContentControl;
if(containerAsControl!=null)UpdateItemContentControl(containerAsControl);
}
}
私有void resetOverwriteTemplate()
{
if(ItemContentPresenter!=null)
ItemContentPresenter.ContentTemplate=m_OverwriteTemplate;
if(ItemContentControl!=null)
ItemContentControl.ContentTemplate=m_OverwriteTemplate;
ItemContentPresenter=null;
ItemContentControl=null;
m_OverwriteTemplate=null;
}
私有void UpdateItemContentPresenter(ContentPresenter容器)
{
if(ItemContentPresenter!=null)
ItemContentPresenter.ContentTemplate=m_OverwriteTemplate;
ItemContentPresenter=容器;
m_OverwriteTemplate=ItemContentPresenter.ContentTemplate;
ItemContentPresenter.ContentTemplate=ItemTemplate;
}
私有void UpdateItemContentControl(ContentControl容器)
{
if(ItemContentControl!=null)
ItemContentControl.ContentTemplate=m_OverwriteTemplate;
ItemContentControl=容器;
m_OverwriteTemplate=ItemContentControl.ContentTemplate;
ItemContentControl.ContentTemplate=ItemTemplate;
}
}
公共抽象类ItemContainerDecorator:行为
{
private Dictionary LastKnownContainers=新字典();
受保护的ItemContainerGenerator ItemContainerGenerator{get{return(AssociatedObject!=null)?AssociatedObject.ItemContainerGenerator:null;}}
受保护的覆盖无效附加()
{
base.onatached();
ItemContainerGenerator.ItemsChanged+=初始的HandleItemsChanged;
如果(!tryaddobserver())
{
AssociatedObject.Loaded+=AddObserversOnLoaded;
}
AssociatedObject.Loaded+=OnItemsControlled;
AssociatedObject.LayoutUpdated+=OnItemControlLayoutUpdated;
CheckContainersChanged();
}
private void OnItemControl LayoutUpdated(对象发送方,EventArgs EventArgs)
{
CheckContainersChanged();
}
已控制私有服务器(对象发送方,路由目标)
{
CheckContainersChanged();
}
private void AddObserversOnLoaded(对象发送方,RoutedEventArgs e)
{
AssociatedObject.Loaded-=AddObserversOnLoaded;
tryaddobserver();
}
私有bool-tryaddobserver()
{
const bool success=true;
小组项目=
AssociatedObject.GetVisualDescendats().OfType().FirstOrDefault(panel=>panel.IsItemsHost);
如果(itemsHost!=null)
{
var-ZingItemshost=