c# - 如何在 Windows Phone 中获取父容器，例如 PhoneApplicationPage？

Question

在子控件中处理事件时，我需要调用 MainPage.xaml.cs 类中的方法。调用this.Parent不起作用，因为它只返回树中的第一个 DependencyObject，而我无法从中PhoneApplicationPage获取

我的布局如下PhoneApplicationPage：

<Grid x:Name="LayoutRoot" Background="Transparent">
    <Grid.RowDefinitions>
        <RowDefinition Height="AUTO"/>
        <RowDefinition Height="*"/>
        <RowDefinition Height="AUTO"/>
    </Grid.RowDefinitions>

    <Grid Height="85" VerticalAlignment="Top" Grid.Row="0"></Grid>

    <Grid Grid.Row="1" Name="gridContent" />

    <ug:UniformGrid Rows="1" Columns="5" Height="85" VerticalAlignment="Bottom" Grid.Row="2">
        <tabs:TabItem Name="tabOverview" TabItemText="OVERVIEW" TabItemImage="overview_64.png" />
        <tabs:TabItem Name="tabLogs" TabItemText="LOGS" TabItemImage="log_64.png"/>           
    </ug:UniformGrid>
</Grid>

使用以下代码：

public partial class MainPage : PhoneApplicationPage
{
    public MainPage()
    {
        InitializeComponent();

        gridContent.Children.Add(new OverviewUserControl());
    }

    public void UpdateContent(UserControl control)
    {
        // I need to call this method from the TabItem Tap event
        gridContent.Children.Clear();
        gridContent.Children.Add(control);
    }
}

当点击事件发生时，我需要用gridContent与用户点击对应的内容替换 的内容。这就是我处理点击事件的方式：

private void TabItem_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{

    // var parent = this.Parent; //<-- this doesn't get the PhoneApplicationPage

    var ti = sender as TabItem;
    if (ti != null)
    {
        string tab = "";
        switch (ti.Name)
        {
            case "tabOverview":
                // I need a reference to MainPage here to call
                // MainPage.UpdateContent(new LogsUserControl())
                break;
            case "tabLogs":
                // I need a reference to MainPage here to call
                // MainPage.UpdateContent(new OverviewUserControl())
                break;
        }

    }
}

问题

所以问题是如何调用MainPagefrom中的方法TabItem_Tap？

Answer 1

这做到了：

var currentPage = ((PhoneApplicationFrame)Application.Current.RootVisual).Content as MainPage;

用法：

private void TabItem_Tap(object sender, System.Windows.Input.GestureEventArgs e)
{
    var currentPage = ((PhoneApplicationFrame)Application.Current.RootVisual).Content as MainPage;

    if (ti != null)
    {
        switch (ti.Name)
        {
            case "tabOverview":
                currentPage.UpdateContent(new OverviewUserControl());
                break;
            case "tabLogs":
                currentPage.UpdateContent(new LogsUserControl());
                break;
        }
    }
}