Better-Seewo/Installer/MainWindow.xaml.cs

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using BetterSeewoInstaller.Pages;

namespace BetterSeewoInstaller;

public partial class MainWindow : Window
{
    private int _currentPageIndex;
    private readonly Page[] _pages;

    public MainWindow()
    {
        InitializeComponent();

        _pages = new Page[]
        {
            new WelcomePage(),
            new InstallPage(),
            new CompletePage()
        };

        NavigateToPage(0);
    }

    private void TitleBar_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        if (e.ClickCount == 1) DragMove();
    }

    private void BtnClose_Click(object sender, RoutedEventArgs e) => Close();

    private void BtnBack_Click(object sender, RoutedEventArgs e)
    {
        if (_currentPageIndex > 0) NavigateToPage(_currentPageIndex - 1);
    }

    private void BtnNext_Click(object sender, RoutedEventArgs e)
    {
        if (_currentPageIndex < _pages.Length - 1)
            NavigateToPage(_currentPageIndex + 1);
    }

    private void NavigateToPage(int index)
    {
        _currentPageIndex = index;

        var oldContent = PageContent.Content;
        var newContent = _pages[index];

        // 淡出旧页面
        var fadeOut = new DoubleAnimation(1, 0, TimeSpan.FromMilliseconds(150));
        fadeOut.Completed += (_, _) =>
        {
            PageContent.Content = newContent;

            // 淡入新页面
            var fadeIn = new DoubleAnimation(0, 1, TimeSpan.FromMilliseconds(200));
            PageContent.BeginAnimation(OpacityProperty, fadeIn);

            UpdateButtons();
        };
        PageContent.BeginAnimation(OpacityProperty, fadeOut);
    }

    private void UpdateButtons()
    {
        StepText.Text = $"第 {_currentPageIndex + 1} 步，共 {_pages.Length} 步";
        BtnBack.Visibility = _currentPageIndex > 0 ? Visibility.Visible : Visibility.Collapsed;

        if (_currentPageIndex == _pages.Length - 1)
        {
            BtnNext.Content = "完成";
        }
        else if (_currentPageIndex == 1)
        {
            BtnNext.Content = "安装";
        }
        else
        {
            BtnNext.Content = "下一步";
        }
    }
}