Xaml 具有可绑定集合的 WinRT 自定义用户控件

Question

我正在尝试创建一个自定义用户控件，我可以在我的所有视图中重复使用它。我的 BaseViewModel 有一个名为 ViewAlerts 的属性，旨在用于在整个应用程序中一致地显示警报（例如成功的更新、失败的请求等）。我能够达到我的自定义控件是可构建的并且具有用于绑定的属性的地步，但是永远不会显示警报集合。为了测试目的，我在我的基本视图模型中静态定义了一些警报，并且无法让警报显示（似乎是 INotifyPropertyChanged 的问题，但我的可绑定属性继承自 ObservableCollection<> 所以它应该是自动处理我认为的）。

到目前为止，这是我的自定义控件：

    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="../../Resources/MMJCeoResources.xaml" />
                <ResourceDictionary>
                    <Style TargetType="TextBlock" x:Key="AlertTextStyle">
                        <Setter Property="FontSize" Value="15"></Setter>
                        <Setter Property="Margin" Value="10" />
                        <Setter Property="Padding" Value="10" />
                    </Style>
                    <DataTemplate x:Key="DangerAlert">
                        <Grid Background="LightPink">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="*" />
                                <RowDefinition Height="10*"/>
                            </Grid.RowDefinitions>
                            <Border Width="10"
                                    Height="10"
                                    BorderBrush="DarkRed"
                                    HorizontalAlignment="Right"
                                    Margin="5"
                                    Grid.Row="0">
                                    <TextBlock Text="X" />
                            </Border>
                            <TextBlock Grid.Row="1" Text="{Binding Message}" Style="{StaticResource AlertTextStyle}" Foreground="DarkRed"/>
                        </Grid>
                    </DataTemplate>
                    <DataTemplate x:Key="SuccessAlert">
                        <Grid Background="LightGreen">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="*" />
                                <RowDefinition Height="10*"/>
                            </Grid.RowDefinitions>
                            <Border Width="10"
                                    Height="10"
                                    BorderBrush="DarkGreen"
                                    HorizontalAlignment="Right"
                                    Margin="5"
                                    Grid.Row="0">
                                <TextBlock Text="X" />
                            </Border>
                            <TextBlock Grid.Row="1" Text="{Binding Message}" Style="{StaticResource AlertTextStyle}" Foreground="DarkGreen"/>
                        </Grid>
                    </DataTemplate>
                    <DataTemplate x:Key="InfoAlert">
                        <Grid Background="LightGreen">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="*" />
                                <RowDefinition Height="10*"/>
                            </Grid.RowDefinitions>
                            <Border Width="10"
                                    Height="10"
                                    BorderBrush="DarkGreen"
                                    HorizontalAlignment="Right"
                                    Margin="5"
                                    Grid.Row="0">
                                <TextBlock Text="X" />
                            </Border>
                            <TextBlock Grid.Row="1" Text="{Binding Message}" Style="{StaticResource AlertTextStyle}" Foreground="DarkGreen"/>
                        </Grid>
                    </DataTemplate>
                    <DataTemplate x:Key="WarningAlert">
                        <Grid Background="LightSalmon">
                            <Grid.RowDefinitions>
                                <RowDefinition Height="*" />
                                <RowDefinition Height="10*"/>
                            </Grid.RowDefinitions>
                            <Border Width="10"
                                    Height="10"
                                    BorderBrush="DarkOrange"
                                    HorizontalAlignment="Right"
                                    Margin="5"
                                    Grid.Row="0">
                                <TextBlock Text="X" />
                            </Border>
                            <TextBlock Grid.Row="1" Text="{Binding Message}" Style="{StaticResource AlertTextStyle}" Foreground="DarkOrange"/>
                        </Grid>
                    </DataTemplate>
                </ResourceDictionary>
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>

    <Grid>
        <ItemsControl ItemsSource="{Binding Path=Alerts}"
                      ItemTemplateSelector="{StaticResource AlertDataTemplateSelector}">

        </ItemsControl>
    </Grid>
</UserControl>

控件的隐藏代码：

public sealed partial class AlertControl : UserControl
{
    public static readonly DependencyProperty AlertsProperty = DependencyProperty.Register(
        "Alerts", typeof (ObservableList<Alert>), typeof (AlertControl), new PropertyMetadata(default(ObservableList<Alert>), OnAlertsChanged));

    public ObservableList<Alert> Alerts
    {
        get { return (ObservableList<Alert>) GetValue(AlertsProperty); }
        set { SetValue(AlertsProperty, value); }
    }
    //I was trying to adapt another tutorial to what I was trying to accomplish but only got this far
    public static void OnAlertsChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        var old = e.OldValue as ObservableList<Alert>;
        var me = sender as AlertControl;

        if (old != null)
        {
            old.CollectionChanged -= me.OnAlertCollectionChanged;
        }

        var n = e.NewValue as ObservableList<Alert>;
        if (n != null)
            n.CollectionChanged += me.OnAlertCollectionChanged;
    }

    private void OnAlertCollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
    {
        if (e.Action == NotifyCollectionChangedAction.Reset)
        {
            Alerts.Clear();
            var n = e.NewItems as ObservableList<Alert>;
            Alerts.AddRange(n);
        }


    }
    public AlertControl()
    {
        this.InitializeComponent();
        DataContext = this;

    }
}

示例实现：

 <Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">

    <StackPanel Orientation="Vertical" HorizontalAlignment="Stretch">
        <TextBlock Style="{StaticResource PageTitle}" Text="User Information" />
        <controls:AlertControl Alerts="{Binding ViewAlerts}" />

在此实现中，ViewAlerts 属性中有 4 个静态定义的警报，因此我知道应该显示一些值。

Answer 1

您应该将 DataContext 提供给内部网格而不是控件本身，因为这样外部绑定将在控件内搜索您的 ViewAlerts

<Grid x:Name="InnerGrid">
    <ItemsControl ItemsSource="{Binding Path=Alerts}"
                  ItemTemplateSelector="{StaticResource AlertDataTemplateSelector}">

    </ItemsControl>
</Grid>


public AlertControl()
{
    this.InitializeComponent();
    InnerGrid.DataContext = this;
}

之后就可以绑定到Alerts了，Alerts会绑定到InnerGrid里面的ItemsControl

Xaml 具有可绑定集合的 WinRT 自定义用户控件

Xaml WinRT Custom User Control with Bindable Collection

c#

xaml

user-controls

windows-runtime