Question

我为我的Windows Phone 8开发了UserControl，如下所示。

<UserControl x:Class="SpinrWindowsMobile.UserControls.ProgressiveLongListSelector"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    d:DesignHeight="480" d:DesignWidth="480">

    <Grid x:Name="LayoutRoot" Background="{StaticResource PhoneChromeBrush}">
        <Grid.RowDefinitions>
            <RowDefinition Height="*"></RowDefinition>
            <RowDefinition Height="Auto"></RowDefinition>
        </Grid.RowDefinitions>
        <phone:LongListSelector Grid.Row="0"  Name="longlistselector">
        </phone:LongListSelector>
        <StackPanel Grid.Row="1">
            <ProgressBar Name="listProress" IsIndeterminate="True"></ProgressBar>
            <TextBlock Name="ProgressText" Text="Loading..."></TextBlock>
        </StackPanel>
    </Grid>
</UserControl>

正如您在上面的xaml中看到的，我在Grid Control中使用了 LongListSelector和StackPanel 。我在我的MainPage.xaml中使用此控件，如下所示。

<phone:PhoneApplicationPage
    x:Class="SpinrWindowsMobile.MainPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:phone="clr-namespace:Microsoft.Phone.Controls;assembly=Microsoft.Phone"
    xmlns:shell="clr-namespace:Microsoft.Phone.Shell;assembly=Microsoft.Phone"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:UserControls="clr-namespace:SpinrWindowsMobile.UserControls"
    mc:Ignorable="d"
    FontFamily="{StaticResource PhoneFontFamilyNormal}"
    FontSize="{StaticResource PhoneFontSizeNormal}"
    Foreground="{StaticResource PhoneForegroundBrush}"
    SupportedOrientations="Portrait" Orientation="Portrait"
    shell:SystemTray.IsVisible="True">
    <!--LayoutRoot is the root grid where all page content is placed-->
    <Grid x:Name="LayoutRoot" Background="Transparent">     
            <UserControls:ProgressiveLongListSelector>

            </UserControls:ProgressiveLongListSelector>

     </Grid>    
</phone:PhoneApplicationPage>

到目前为止，这很好，但我想做一些如下的事情。

  <UserControls:ProgressiveLongListSelector>
                  <UserControls:ProgressiveLongListSelector.longlistselector 
                 ItemsSource="Binding" ItemTemplate="{staticresource myTemplate}">
                  </UserControls:ProgressiveLongListSelector.longlistselector>
    </UserControls:ProgressiveLongListSelector>

如何访问用户控件的 longlistselector，它是 UserControl 的元素/组件？这样做的好处是I can directly set the LongListSelector Properties in the xaml(in which i am embedding My usercontrol) itself。对我来说，这种东西是今天的要求。

任何人都可以指导我如何做到这一点吗？

Answer 1

由于您正在扩展和修改LongListSelector，我建议继承并重新设置LongListSelector而不是将其放在UserControl中。这将允许您访问LongListSelector上的所有现有属性和方法，并使用新的ProgressiveLongListSelector，就像使用LongListSelector一样。

首先，您可以创建一个子类LongListSelector的新类：

public class ProgressiveLongListSelector : LongListSelector {

    public ProgressiveLongListSelector() {
        DefaultStyleKey = typeof(ProgressiveLongListSelector);
    }
}

请注意 DefaultStyleKey 。这就是新控件模板的来源。

现在，您可以在App.xaml资源中放置以下样式。请注意， TargetType 是 ProgressiveLongListSelector 。这就是 DefaultStyleKey 将找到您的新默认样式的方式。

    <Style TargetType="phoneApp2:ProgressiveLongListSelector">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="phoneApp2:ProgressiveLongListSelector">
                    <Grid Background="{TemplateBinding Background}" d:DesignWidth="480" d:DesignHeight="800">
                        <VisualStateManager.VisualStateGroups>
                            <VisualStateGroup x:Name="ScrollStates">
                                <VisualStateGroup.Transitions>
                                    <VisualTransition GeneratedDuration="00:00:00.5" />
                                </VisualStateGroup.Transitions>
                                <VisualState x:Name="Scrolling">
                                    <Storyboard>
                                        <DoubleAnimation Duration="0" To="1" Storyboard.TargetProperty="Opacity" Storyboard.TargetName="VerticalScrollBar" />
                                    </Storyboard>
                                </VisualState>
                                <VisualState x:Name="NotScrolling" />
                            </VisualStateGroup>
                        </VisualStateManager.VisualStateGroups>
                        <Grid Margin="{TemplateBinding Padding}">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="*" />
                                <ColumnDefinition Width="auto" />
                            </Grid.ColumnDefinitions>
                            <ViewportControl x:Name="ViewportControl" HorizontalContentAlignment="Stretch" VerticalAlignment="Top" />
                            <ScrollBar x:Name="VerticalScrollBar" Grid.Column="1" Margin="4,0,4,0" Opacity="0" Orientation="Vertical" />
                        </Grid>
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>

此样式/模板是默认LongListSelector模板的副本（从Blend中提取）。从这里，您可以将UserControl中的其他元素（例如ProgressBar和TextBlock）添加到模板中。

Answer 2

您可以做的是使用DependencyProperty机制公开UserContorl的属性。然后，您可以在使用该UserControl的Page的XAML中设置它们。我不确定你是否想暴露你的VisualTree的所有部分，因为这可能在未来发生变化。但是您可以间接地暴露一些影响UserControl行为的属性。

以下是一个如何做到这一点的例子：

（这个例子取自我的代码，但我想你可以弄清楚如何调整它）

首先在UserControl中声明DependencyProperty：

public partial class MyUserControl : UserControl
{
    public bool IsEditingMode
    {
        get { return (bool)GetValue(IsEditingModeProperty); }
        set { SetValue(IsEditingModeProperty, value); }
    }

    public static readonly DependencyProperty IsEditingModeProperty =
        DependencyProperty.Register("IsEditingMode", typeof(bool), typeof(MyUserControl), new PropertyMetadata(false, IsEditingModeChanged));
}

private static void IsEditingModeChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    // this will be called when someone would set the exposed property to some new value
}

接下来，将MyUserControl添加到某个页面并设置该属性：

<phone:PivotItem Header="{Binding Path=LocalizedResources.MyPivotHeader, Source={StaticResource LocalizedStrings}}" Margin="0">
    <my:MyUserControl x:Name="People" IsEditingMode="True"/>
</phone:PivotItem>

注意如何在XAML中设置IsEditingMode。当然，您也可以使用public bool IsEditingMode周围的IsEditingModeProperty属性包装器从代码中设置它。

如何在Windows Phone 8中访问UserControl的组件/元素

2 个答案: