最近在做今日头条WP的过程中，遇到需要动态生成Pivot项的问题。第一个版本是把几个频道写死在xaml里了，事件绑定也写在xaml里，每个频道绑定一个ObservableCollection<ArticleItem>。xaml中一个Pivot项的代码大体如下：
<phone:PivotItem Header="热点">
<Grid Margin="12,0,0,0" >
<Grid.RowDefinitions>
<RowDefinition Height="*" />
<RowDefinition Height="Auto"/>
<RowDefinition Height="Auto"/>
</Grid.RowDefinitions>
<telerikPrimitives:RadDataBoundListBox UseOptimizedManipulationRouting="False"
DataVirtualizationMode="OnDemandAutomatic"
IsPullToRefreshEnabled="True"
EmptyContent=""
IsAsyncBalanceEnabled="True"
x:Name="radListBoxHot"
Margin="0"
CacheMode="BitmapCache" ItemsSource="{Binding ArticleItemListHot}" telerikCore:InteractionEffectManager.IsInteractionEnabled="True" ItemTemplate="{StaticResource ArticleItemDataTemplate}" >
<i:Interaction.Triggers>
<i:EventTrigger EventName="ItemTap">
<i:InvokeCommandAction Command="{Binding CommandNavToArticleDetail}" CommandParameter="{Binding SelectedItem, ElementName=radListBoxHot}" />
</i:EventTrigger>
<i:EventTrigger EventName="DataRequested">
<i:InvokeCommandAction Command="{Binding CommandDataRequestedArticle}" CommandParameter="Hot"/>
</i:EventTrigger>
<i:EventTrigger EventName="RefreshRequested" >
<i:InvokeCommandAction Command="{Binding CommandRefreshRequestedArticle}" CommandParameter="Hot"/>
</i:EventTrigger>
<ec:PropertyChangedTrigger Binding="{Binding IsUIBusy}">
<i:Interaction.Behaviors>
<ec:ConditionBehavior>
<ec:ConditionalExpression>
<ec:ComparisonCondition LeftOperand="{Binding IsUIBusy}" RightOperand="False"/>
</ec:ConditionalExpression>
</ec:ConditionBehavior>
</i:Interaction.Behaviors>
<action:StopPullToRefreshLoadingAction TargetObject="{Binding ElementName=radListBoxHot}"/>
</ec:PropertyChangedTrigger>
</i:Interaction.Triggers> <telerikPrimitives:RadDataBoundListBox.ItemAddedAnimation>
<telerikCore:RadFadeAnimation StartOpacity="0" InitialDelay="0:0:0.3" EndOpacity="1"
Duration="0:0:0.9">
<telerikCore:RadFadeAnimation.Easing>
<CubicEase EasingMode="EaseOut" />
</telerikCore:RadFadeAnimation.Easing>
</telerikCore:RadFadeAnimation>
</telerikPrimitives:RadDataBoundListBox.ItemAddedAnimation>
<telerikPrimitives:RadDataBoundListBox.ItemLoadingTemplate>
<DataTemplate>
<telerikPrimitives:RadBusyIndicator AnimationStyle="AnimationStyle9" IsRunning="{Binding IsUIBusy}" Content="努力加载ing..."/>
</DataTemplate>
</telerikPrimitives:RadDataBoundListBox.ItemLoadingTemplate>
<telerikPrimitives:RadDataBoundListBox.VirtualizationStrategyDefinition>
<telerikPrimitives:StackVirtualizationStrategyDefinition Orientation="Vertical"
/>
</telerikPrimitives:RadDataBoundListBox.VirtualizationStrategyDefinition>
</telerikPrimitives:RadDataBoundListBox> </Grid>
</phone:PivotItem>
ViewModel中要绑定几个command，实现点击项、下拉刷新、自动加载更多等，具体代码就不贴了，主要是根据CommandParameter来区分是触发哪个列表的事件。
这样实现的话，ViewModel中需要有n个ObservableCollection<ArticleItem>，代码重复的太多。
后来用户要求根据设置自定义首页频道，于是要改成后台代码生成的方式。因为首页枢轴里还有几个Pivot项不是文章列表，所以想在Page_Loaded事件中动态去生成所需的Pivot项，并手动设置绑定。
自定义频道的实体类：
/// <summary>
/// 用户固定在首页的自定义频道信息
/// </summary>
public class UserCategoryItem : BindableBase<UserCategoryItem>
{ public UserCategoryItem()
{
ArticleItemList = new ObservableCollection<ArticleListItem>();
TempArticleItemList = new List<ArticleListItem>();
} /// <summary>
/// 频道
/// </summary>
public CategoryItem CurrentCategoryItem
{
get { return _CurrentCategoryItemLocator(this).Value; }
set { _CurrentCategoryItemLocator(this).SetValueAndTryNotify(value); }
}
#region Property CategoryItem CurrentCategoryItem Setup
protected Property<CategoryItem> _CurrentCategoryItem = new Property<CategoryItem> { LocatorFunc = _CurrentCategoryItemLocator };
static Func<BindableBase, ValueContainer<CategoryItem>> _CurrentCategoryItemLocator = RegisterContainerLocator<CategoryItem>("CurrentCategoryItem", model => model.Initialize("CurrentCategoryItem", ref model._CurrentCategoryItem, ref _CurrentCategoryItemLocator, _CurrentCategoryItemDefaultValueFactory));
static Func<CategoryItem> _CurrentCategoryItemDefaultValueFactory = () => { return default(CategoryItem); };
#endregion /// <summary>
/// 上次获取数据最大时间
/// </summary>
public string MaxBehotTime
{
get { return _MaxBehotTimeLocator(this).Value; }
set { _MaxBehotTimeLocator(this).SetValueAndTryNotify(value); }
}
#region Property string MaxBehotTime Setup
protected Property<string> _MaxBehotTime = new Property<string> { LocatorFunc = _MaxBehotTimeLocator };
static Func<BindableBase, ValueContainer<string>> _MaxBehotTimeLocator = RegisterContainerLocator<string>("MaxBehotTime", model => model.Initialize("MaxBehotTime", ref model._MaxBehotTime, ref _MaxBehotTimeLocator, _MaxBehotTimeDefaultValueFactory));
static Func<string> _MaxBehotTimeDefaultValueFactory = () => { return default(string); };
#endregion /// <summary>
/// 最小获取时间
/// </summary>
public string MinBehotTime
{
get { return _MinBehotTimeLocator(this).Value; }
set { _MinBehotTimeLocator(this).SetValueAndTryNotify(value); }
}
#region Property string MinBehotTime Setup
protected Property<string> _MinBehotTime = new Property<string> { LocatorFunc = _MinBehotTimeLocator };
static Func<BindableBase, ValueContainer<string>> _MinBehotTimeLocator = RegisterContainerLocator<string>("MinBehotTime", model => model.Initialize("MinBehotTime", ref model._MinBehotTime, ref _MinBehotTimeLocator, _MinBehotTimeDefaultValueFactory));
static Func<string> _MinBehotTimeDefaultValueFactory = () => { return default(string); };
#endregion /// <summary>
/// 文章内容
/// </summary>
public ObservableCollection<ArticleListItem> ArticleItemList
{
get { return _ArticleItemListLocator(this).Value; }
set { _ArticleItemListLocator(this).SetValueAndTryNotify(value); }
}
#region Property ObservableCollection<ArticleListItem> ArticleItemList Setup
protected Property<ObservableCollection<ArticleListItem>> _ArticleItemList = new Property<ObservableCollection<ArticleListItem>> { LocatorFunc = _ArticleItemListLocator };
static Func<BindableBase, ValueContainer<ObservableCollection<ArticleListItem>>> _ArticleItemListLocator = RegisterContainerLocator<ObservableCollection<ArticleListItem>>("ArticleItemList", model => model.Initialize("ArticleItemList", ref model._ArticleItemList, ref _ArticleItemListLocator, _ArticleItemListDefaultValueFactory));
static Func<ObservableCollection<ArticleListItem>> _ArticleItemListDefaultValueFactory = () => { return new ObservableCollection<ArticleListItem>(); };
#endregion /// <summary>
/// 排序
/// </summary>
public int SortOrder
{
get { return _SortOrderLocator(this).Value; }
set { _SortOrderLocator(this).SetValueAndTryNotify(value); }
}
#region Property int SortOrder Setup
protected Property<int> _SortOrder = new Property<int> { LocatorFunc = _SortOrderLocator };
static Func<BindableBase, ValueContainer<int>> _SortOrderLocator = RegisterContainerLocator<int>("SortOrder", model => model.Initialize("SortOrder", ref model._SortOrder, ref _SortOrderLocator, _SortOrderDefaultValueFactory));
static Func<int> _SortOrderDefaultValueFactory = () => { return default(int); };
#endregion }
在程序首次运行时，如果用户还没有自定义频道，则自动添加默认的，否则从存储中读取，代码写在MainPage.xaml.cs里：
private void MVVMPage_Loaded(object sender, RoutedEventArgs e)
{
if (pivotMain.Items.Count < )
{
MainPage_Model vm = this.LayoutRoot.DataContext as MainPage_Model;
if (vm != null)
{
vm.IsUIBusy = true;
List<UserCategoryItem> listLocal = FileHelper.Open<List<UserCategoryItem>>(Constants.UserCategoryItemListDataFileName);
if(listLocal.Any())
{
listLocal.ForEach(x => vm.UserCategoryItemList.Add(x));
}
if(!vm.UserCategoryItemList.Any())
{
UserCategoryItem item1 = new UserCategoryItem { CurrentCategoryItem = new CategoryItem { Name = "推荐", Category = "" }, SortOrder = };
vm.UserCategoryItemList.Add(item1);
UserCategoryItem item2 = new UserCategoryItem { CurrentCategoryItem = new CategoryItem { Name = "热点", Category = "news_hot" }, SortOrder = };
vm.UserCategoryItemList.Add(item2);
UserCategoryItem item3 = new UserCategoryItem { CurrentCategoryItem = new CategoryItem { Name = "社会", Category = "news_society" }, SortOrder = };
vm.UserCategoryItemList.Add(item3);
UserCategoryItem item4 = new UserCategoryItem { CurrentCategoryItem = new CategoryItem { Name = "娱乐", Category = "news_entertainment" }, SortOrder = };
vm.UserCategoryItemList.Add(item4);
UserCategoryItem item5 = new UserCategoryItem { CurrentCategoryItem = new CategoryItem { Name = "体育", Category = "news_sports" }, SortOrder = };
vm.UserCategoryItemList.Add(item5);
FileHelper.Save<List<UserCategoryItem>>(Constants.UserCategoryItemListDataFileName, vm.UserCategoryItemList.ToList());
} for (int i = ; i < vm.UserCategoryItemList.Count; i++)
{
UserCategoryItem item = vm.UserCategoryItemList[i];
//userCategoryItem.CurrentCategoryItem = new CategoryItem { Category = "", Name = "推荐" };
//vm.UserCategoryItemList.Add(userCategoryItem);
//手工添加pivot项
PivotItem pivot = new PivotItem();
pivot.Header = item.CurrentCategoryItem.Name;
Grid grid = new Grid();
grid.Margin = new Thickness(, -, , );
pivot.Content = grid;
RadDataBoundListBox listBox = new RadDataBoundListBox();
listBox.Name = string.Format("listBox{0}", i);
listBox.UseOptimizedManipulationRouting = false;
listBox.DataVirtualizationMode = DataVirtualizationMode.OnDemandAutomatic;
listBox.IsPullToRefreshEnabled = true;
listBox.IsAsyncBalanceEnabled = true;
listBox.ItemsSource = item.ArticleItemList;
listBox.ItemTemplate = App.Current.Resources["ArticleItemDataTemplate"] as DataTemplate;
listBox.ItemLoadingTemplate = App.Current.Resources["CommonItemLoadingDataTemplate"] as DataTemplate;
//listBox.ListHeaderTemplate = App.Current.Resources["CommonListHeaderDataTemplate"] as DataTemplate;
listBox.SetValue(InteractionEffectManager.IsInteractionEnabledProperty, true);
//listBox.ItemAddedAnimation = App.Current.Resources["CommonItemAddesAnimation"] as RadAnimation;
listBox.VirtualizationStrategyDefinition = new StackVirtualizationStrategyDefinition { Orientation = System.Windows.Controls.Orientation.Vertical };
listBox.Margin = new Thickness(, , , );
listBox.EmptyContentTemplate = App.Current.Resources["CommonEmptyDataTemplate"] as DataTemplate;
//手动添加EventTrigger //设置目标属性
//BindingOperations.SetBinding(selectedItem, TextBlock.TextProperty, binding);
//var invokeCommandAction = new InvokeCommandAction { CommandParameter = "btnAdd" }; var triggers = Interaction.GetTriggers(listBox); //添加ItemTap事件绑定
//#region ItemTap //var itemTapInvokeCommandAction = new InvokeCommandAction(); //// create the command action and bind the command to it
//Binding itemTapParameterBinding = new Binding();
////设置源对象
//itemTapParameterBinding.Source = listBox;
////设置源属性
//itemTapParameterBinding.Path = new PropertyPath("SelectedItem");
////ElementName与Source只能用一个
////itemTapParameterBinding.ElementName = listBox.Name;
//BindingOperations.SetBinding(itemTapInvokeCommandAction, InvokeCommandAction.CommandParameterProperty, itemTapParameterBinding); //var itemTapEventBinding = new Binding { Path = new PropertyPath("CommandNavToArticleDetail") };
//BindingOperations.SetBinding(itemTapInvokeCommandAction, InvokeCommandAction.CommandProperty, itemTapEventBinding); //// create the event trigger and add the command action to it
//var itemTapEventTrigger = new System.Windows.Interactivity.EventTrigger { EventName = "ItemTap" };
//itemTapEventTrigger.Actions.Add(itemTapInvokeCommandAction); //// attach the trigger to the control
//triggers.Add(itemTapEventTrigger);
//#endregion //添加DataRequested事件绑定
#region DataRequested var dataRequestedInvokeCommandAction = new InvokeCommandAction(); // create the command action and bind the command to it
Binding dataRequestedParameterBinding = new Binding();
//设置源对象
dataRequestedParameterBinding.Source = item;
//设置源属性
dataRequestedParameterBinding.Path = new PropertyPath("CurrentCategoryItem");
//dataRequestedParameterBinding.ElementName = listBox.Name;
BindingOperations.SetBinding(dataRequestedInvokeCommandAction, InvokeCommandAction.CommandParameterProperty, dataRequestedParameterBinding); var dataRequestedEventBinding = new Binding { Path = new PropertyPath("CommandDataRequestedArticle") };
BindingOperations.SetBinding(dataRequestedInvokeCommandAction, InvokeCommandAction.CommandProperty, dataRequestedEventBinding); // create the event trigger and add the command action to it
var dataRequestedEventTrigger = new System.Windows.Interactivity.EventTrigger { EventName = "DataRequested" };
dataRequestedEventTrigger.Actions.Add(dataRequestedInvokeCommandAction); // attach the trigger to the control
triggers.Add(dataRequestedEventTrigger);
#endregion //添加RefreshRequested事件绑定
#region RefreshRequested var refreshRequestedInvokeCommandAction = new InvokeCommandAction(); // create the command action and bind the command to it
Binding refreshRequestedParameterBinding = new Binding();
//设置源对象
refreshRequestedParameterBinding.Source = item;
//设置源属性
refreshRequestedParameterBinding.Path = new PropertyPath("CurrentCategoryItem");
//refreshRequestedParameterBinding.ElementName = listBox.Name;
BindingOperations.SetBinding(refreshRequestedInvokeCommandAction, InvokeCommandAction.CommandParameterProperty, refreshRequestedParameterBinding); var refreshRequestedEventBinding = new Binding { Path = new PropertyPath("CommandRefreshRequestedArticle") };
BindingOperations.SetBinding(refreshRequestedInvokeCommandAction, InvokeCommandAction.CommandProperty, refreshRequestedEventBinding); // create the event trigger and add the command action to it
var refreshRequestedEventTrigger = new System.Windows.Interactivity.EventTrigger { EventName = "RefreshRequested" };
refreshRequestedEventTrigger.Actions.Add(refreshRequestedInvokeCommandAction); // attach the trigger to the control
triggers.Add(refreshRequestedEventTrigger);
#endregion #region 下拉刷新完成后停止
PropertyChangedTrigger stopPullToRefreshTrigger = new PropertyChangedTrigger(); Binding pullToRefreshBinding = new Binding();
pullToRefreshBinding.Path = new PropertyPath("IsUIBusy");
//stopPullToRefreshTrigger.SetValue(PropertyChangedTrigger.BindingProperty, pullToRefreshBinding);
//用下面这句不管用
BindingOperations.SetBinding(stopPullToRefreshTrigger, PropertyChangedTrigger.BindingProperty, pullToRefreshBinding); StopPullToRefreshLoadingAction stopPullToRefreshLoadingAction = new StopPullToRefreshLoadingAction();
Binding stopPullToRefreshTargetObjectBinding = new Binding();
stopPullToRefreshTargetObjectBinding.ElementName = listBox.Name;
//stopPullToRefreshLoadingAction.SetValue(StopPullToRefreshLoadingAction.TargetObjectProperty, stopPullToRefreshTargetObjectBinding);
//用下面这句不管用
BindingOperations.SetBinding(stopPullToRefreshLoadingAction, StopPullToRefreshLoadingAction.TargetObjectProperty, stopPullToRefreshTargetObjectBinding); stopPullToRefreshTrigger.Actions.Add(stopPullToRefreshLoadingAction); Binding pullToRefreshBinding2 = new Binding();
pullToRefreshBinding2.Path = new PropertyPath("IsUIBusy");
ComparisonCondition condition = new ComparisonCondition();
BindingOperations.SetBinding(condition, ComparisonCondition.LeftOperandProperty, pullToRefreshBinding2);
condition.RightOperand = false;
condition.Operator = ComparisonConditionType.Equal;
ConditionalExpression expression = new ConditionalExpression();
expression.Conditions.Add(condition);
expression.ForwardChaining = ForwardChaining.And;
ConditionBehavior conditionBehavior = new ConditionBehavior();
conditionBehavior.Condition = expression;
conditionBehavior.Attach(stopPullToRefreshTrigger); triggers.Add(stopPullToRefreshTrigger); #endregion grid.Children.Add(listBox);
this.pivotMain.Items.Insert(i, pivot);
}
vm.IsUIBusy = false; }
}
}
这里主要是用到了在代码中设置绑定的方法，一般要先初始化一个Binding,设置其Path、ElementName、Source等属性，然后调用BindingOperations.SetBinding()方法来进行绑定。主要麻烦的部分是设置EventTrigger的绑定，上面的代码基本是xaml里的绑定用后台代码翻译了一遍。
但这种方式仍然不太好，下个版本再修改一下，改成全部Pivot项都用绑定的方式。