wpf Frame.Navigate两次调用时无法推送堆栈

Question

    Page1 page1 = new Page1();
    Page2 page2 = new Page2();
    Page3 page3 = new Page3();
    private void btnNextClick(object sender, RoutedEventArgs e)
    {
        navi.Navigate(page1);
        navi.Navigate(page2);
    }

As shown in the code above, I want the Frame first to navigate to "page1",and then to navigate to "page2".

As a result,it did navigate to "page2",but I have't see "page1" in Fram.BackStack . So I can't navigate back. And I found Frame.Navigating event trigged twice, and Frame.Navigated trigged once. It seems the first navigate was canceled, and I want know why?

And, Is there another way to achieve this effect?(navigate to page1 and quickly navigate to page2--->then navigate back to page1)

Additional information：

my full c# code:

 public partial class MainWindow : Window
{
    Page1 page1 = new Page1();
    Page2 page2 = new Page2();
    Page3 page3 = new Page3();
    public MainWindow()
    {
        InitializeComponent();
        navi.Navigated += Navi_Navigated;
        navi.Navigating += Navi_Navigating;
    }

    private void Navi_Navigating(object sender, NavigatingCancelEventArgs e)
    {
    }

    private void Navi_Navigated(object sender, NavigationEventArgs e)
    {

    }

    private void btnPreviousPageClick(object sender, RoutedEventArgs e)
    {
        if (navi.CanGoBack)
        {
            navi.GoBack();
        }
    }

    private void btnNextClick(object sender, RoutedEventArgs e)
    {
        navi.Navigate(page1);
        navi.Navigate(page2);
    }

    private void btnNextClick2(object sender, RoutedEventArgs e)
    {
        navi.Navigate(page2);
    }

    private void btnNextClick3(object sender, RoutedEventArgs e)
    {
        navi.Navigate(page3);
    }
}

and my xaml code:

<Window x:Class="mmNavigate.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    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"
    xmlns:local="clr-namespace:mmNavigate"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">
<StackPanel>
    <Frame JournalOwnership="OwnsJournal" NavigationUIVisibility="Visible" x:Name="navi" Height="280"></Frame>
    <StackPanel Orientation="Horizontal">
        <Button Content="Previous" Click="btnPreviousPageClick"/>
        <Button Content="Page1" Margin="20,0,0,0" Click="btnNextClick"/>
        <Button Content="Page2" Margin="20,0,0,0" Click="btnNextClick2"/>
        <Button Content="Page3" Margin="20,0,0,0" Click="btnNextClick3"/>
    </StackPanel>
</StackPanel>

Answer 1

You should wait to navigate to Page2 until the navigation to Page1 has been completed by handling the Navigated event:

private void btnNextClick(object sender, RoutedEventArgs e)
{
    navi.Navigated += Navi_Navigated1; ;
    navi.Navigate(page1);
}

private void Navi_Navigated1(object sender, NavigationEventArgs e)
{
    navi.Navigated -= Navi_Navigated1;
    navi.Navigate(page2);
}