UWP NavigationView 标题标题

Question

我正在尝试使用 NavigationView 制作 UWP 应用。我的问题是找到Header 更改当前显示页面的方法。我的应用基于 Microsoft UWP 示例“AppUIBasics”。在示例中，NavigationView 的 Header 始终显示“欢迎”，因为它是硬编码的，但我希望它根据所选页面进行更改。

MainPage.xaml：

 <NavigationView x:Name="NavView"
                ItemInvoked="NavView_ItemInvoked"
                SelectionChanged="NavView_SelectionChanged"
                Loaded="NavView_Loaded"
                Canvas.ZIndex="0">

    <NavigationView.HeaderTemplate>
        <DataTemplate>
            <Grid Margin="24,10,0,0">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition/>
                </Grid.ColumnDefinitions>
                <TextBlock x:Name="appTitle" Style="{StaticResource TitleTextBlockStyle}"
                       FontSize="28"
                       VerticalAlignment="Center"
                       Text="Welcome"/>
                <CommandBar Grid.Column="1"
                        HorizontalAlignment="Right"
                        VerticalAlignment="Top"
                        DefaultLabelPosition="Right"
                        Background="{ThemeResource SystemControlBackgroundAltHighBrush}">
                    <AppBarButton Label="Refresh" Icon="Refresh"/>
                    <AppBarButton Label="Import" Icon="Import"/>
                </CommandBar>
            </Grid>
        </DataTemplate>
    </NavigationView.HeaderTemplate>

    <NavigationView.MenuItems>
        <NavigationViewItem x:Uid="HomeNavItem" Content="" Tag="home">
            <NavigationViewItem.Icon>
                <FontIcon Glyph="&#xE10F;"/>
            </NavigationViewItem.Icon>
        </NavigationViewItem>
        <NavigationViewItemSeparator/>
        <NavigationViewItem x:Uid="ConnectionNavItem" Icon="world" Content="" Tag="connection"/>
        <NavigationViewItem x:Uid="CameraNavItem" Icon="video" Content="" Tag="camera"/>
    </NavigationView.MenuItems>

    <Frame x:Name="rootFrame" Margin="24">
        <Frame.ContentTransitions>
            <TransitionCollection>
                <NavigationThemeTransition/>
            </TransitionCollection>
        </Frame.ContentTransitions>
    </Frame>

</NavigationView>

MainPage.xaml.cs：

 public sealed partial class MainPage : Page {
    public static MainPage Current;
    public static Frame RootFrame = null;

    //private RootFrameNavigationHelper _navHelper;
    private ResourceLoader _resourceLoader = Windows.ApplicationModel.Resources.ResourceLoader.GetForCurrentView();

    public MainPage() {
        this.InitializeComponent();

        this.Loaded += (sender, args) => {
            Current = this;
            var titleBar = Windows.ApplicationModel.Core.CoreApplication.GetCurrentView().TitleBar;
        };
    }

    public Frame AppFrame { get { return this.rootFrame; } }

    private void NavView_Loaded(object sender, RoutedEventArgs e) {
        // set the initial SelectedItem 
        foreach (NavigationViewItemBase item in NavView.MenuItems) {
            if (item is NavigationViewItem && item.Tag.ToString() == "home") {
                NavView.SelectedItem = item;
                break;
            }
        }
    }

    private void NavView_ItemInvoked(NavigationView sender, NavigationViewItemInvokedEventArgs args) {

        if (args.IsSettingsInvoked) {
            rootFrame.Navigate(typeof(SettingsPage));
        } else {
            // find NavigationViewItem with Content that equals InvokedItem
            var item = sender.MenuItems.OfType<NavigationViewItem>().First(x => (string)x.Content == (string)args.InvokedItem);
            NavView_Navigate(item as NavigationViewItem);

        }
    }

    private void NavView_SelectionChanged(NavigationView sender, NavigationViewSelectionChangedEventArgs args) {
        if (args.IsSettingsSelected) {
            rootFrame.Navigate(typeof(SettingsPage));
        } else {
            NavigationViewItem item = args.SelectedItem as NavigationViewItem;
            NavView_Navigate(item);
        }
    }

    private void NavView_Navigate(NavigationViewItem item) {
        switch (item.Tag) {
            case "home":
                rootFrame.Navigate(typeof(HomePage)); break;
            case "connection":
                rootFrame.Navigate(typeof(ConnectionPage)); break;
            case "camera":
                rootFrame.Navigate(typeof(CameraPage)); break;
        }
    }
}

Answer 1

首先，您必须从模板中“取消硬编码”标题文本，而不是文本，您可以使用 {Binding}，它将提供分配给 NavigationView 的 Header 属性的值：

<NavigationView.HeaderTemplate>
    <DataTemplate>
        <Grid Margin="24,10,0,0">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="Auto"/>
                <ColumnDefinition/>
            </Grid.ColumnDefinitions>
            <TextBlock x:Name="appTitle" Style="{StaticResource TitleTextBlockStyle}"
                FontSize="28"
                VerticalAlignment="Center"
                Text="{Binding}"/>
            <CommandBar Grid.Column="1"
                HorizontalAlignment="Right"
                VerticalAlignment="Top"
                DefaultLabelPosition="Right"
                Background="{ThemeResource SystemControlBackgroundAltHighBrush}">
                <AppBarButton Label="Refresh" Icon="Refresh"/>
                <AppBarButton Label="Import" Icon="Import"/>
            </CommandBar>
        </Grid>
    </DataTemplate>
</NavigationView.HeaderTemplate>

简单的解决方案

现在有两个地方可以设置标题内容。首先是SelectionChanged事件：

private void NavView_SelectionChanged(NavigationView sender, NavigationViewSelectionChangedEventArgs args)
{
    if (args.IsSettingsSelected)
    {
        rootFrame.Navigate(typeof(SettingsPage));
        NavView.Header = "Settings";
    }
    else
    {
        NavigationViewItem item = args.SelectedItem as NavigationViewItem;
        NavView_Navigate(item);
        //just example, maybe you want to Content or something else
        NavView.Header = item.Tag.ToString(); 
    }
}

更好的解决方案

您还可以通过添加设置标头的公共方法从任何地方设置Header：

public void SetHeader(string header)
{
    NavView.Header = header;
}

然后在您认为合适的任何地方使用MainPage.Current.SetHeader( something )。

最佳解决方案

然而，最好的解决方案是创建一个其他页面将派生自的基类：

public class BasePage : Page
{
    public virtual string Header => "";
}

然后每个具体的页面都可以覆盖这个属性：

public sealed partial class HomePage : BasePage
{
    public override string Header => "Home";

    public HomePage()
    {
        this.InitializeComponent();
    }
}

注意 - 请记住，您还必须在 XAML 中更新页面的基本类型：

<local:BasePage xmlns:local="using:AppNamespace"
    x:Class="AppNamespace.HomePage" ...>
</local:BasePage>

然后在MainPage 中，我们使用数据绑定将Header 属性绑定到NavigationView 的Header：

<NavigationView x:Name="NavView"
                Header="{Binding Path=Content.Header, ElementName=rootFrame}" ...>

Answer 2

步骤 1

定义接口

interface ISubPage
{
    string NavTitile { get; }
}

第二步

在子页面中实现这个接口

public sealed partial class HomePage : Page, ISubPage
{
    public HomePage()
    {
        InitializeComponent();
    }

    public string NavTitile => "ArticlePage";
}

第三步

<NavigationView x:Name="NavView" Header="{Binding Path=Content.NavTitile, ElementName=ContentFrame}">
    <NavigationView.MenuItems>
        <NavigationViewItem Icon="Home" Tag="Home" Content="Home"/>
    </NavigationView.MenuItems>

    <Frame x:Name="ContentFrame" Margin="24"/>
</NavigationView>