初识 WPF

这两天简单学习了一下 WPF、XAML、MVVM，正在决定是否基于 WPF 重新开发高考倒计时，目前已经完成了 0.5% (🤣)，只是完成了一点点设计，主要代码还没开始。

先说说我对 WPF 的第一印象吧：

• 排在第一肯定是内存占用，我不李姐为什么一个空窗口都能占 50MB 内存，那以后代码量增多了不得冲个100MB或者是更多？这确实是一件难以置信的事，不过现在大多数的电脑运行内存都较大，应该也不会太过在意内存占用的问题。这点可以暂时忽略。
• 通过数据绑定更改控件属性也太麻烦了吧，尽管可以使用纯 C# 代码控制控件属性，可这显然不符合 WPF 的设计理念。这一点上不如 WinForms (如果微软能花更多心思在 WinForms 上就好了，结合一下两者的优点)。

另外，由于高考完后时间确实很紧以及其他原因，以后 (已更新) 可能会放弃此次决定，特别是当前 WinForms 对于一个高考倒计时来说已经完全足够了的情况。

部分代码预览

MainWindow.xaml

<Window
        x:Class="WangHaonie.CEETimer.Windows.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:reactiveui="http://reactiveui.net"
        xmlns:local="clr-namespace:WangHaonie.CEETimer.Windows"
        mc:Ignorable="d"
        Title="高考倒计时"
        Height="37"
        Width="162"
        ResizeMode="NoResize"
        SizeToContent="WidthAndHeight"
        Topmost="True"
        Background="Transparent"
        AllowsTransparency="True"
        WindowStyle="None">
    <Border x:Name="WindowBorder" Padding="2,1,2,1" Background="Black">
        <Grid>
            <TextBlock x:Name="TextBlockCountdown" Background="Black" Foreground="White" FontSize="28" FontFamily="Noto Sans SC" VerticalAlignment="Top" HorizontalAlignment="Left">
                <TextBlock.ContextMenu>
                    <ContextMenu FontFamily="Microsoft YaHei" >
                        <MenuItem x:Name="ContextOptions" Header="选项" />
                        <Separator Margin="0" />
                        <MenuItem x:Name="ContextOpenDir" Header="安装目录" />
                    </ContextMenu>
                </TextBlock.ContextMenu>
            </TextBlock>
        </Grid>
    </Border>
</Window>

MainWindow.xaml.cs

using ReactiveUI;
using System;
using System.ComponentModel;
using System.Reactive.Disposables;
using System.Windows;
using System.Windows.Input;
using System.Windows.Interop;
using System.Windows.Media;
using WangHaonie.CEETimer.Modules;
using WangHaonie.CEETimer.ViewModels;

namespace WangHaonie.CEETimer.Windows
{
    public partial class MainWindow : IViewFor<MainWindowViewModel>
    {
        public static readonly DependencyProperty ViewModelProperty = DependencyProperty
        .Register(nameof(ViewModel), typeof(MainWindowViewModel), typeof(MainWindow));

        public MainWindowViewModel ViewModel
        {
            get => (MainWindowViewModel)GetValue(ViewModelProperty);
            set => SetValue(ViewModelProperty, value);
        }

        object IViewFor.ViewModel
        {
            get => ViewModel;
            set => ViewModel = (MainWindowViewModel)value;
        }

        public MainWindow()
        {
            InitializeComponent();
            ApplyRoundedCorners();
            BindData();
            BindEvents();
        }

        private void ApplyRoundedCorners()
        {
            if (Environment.OSVersion.Platform == PlatformID.Win32NT && Environment.OSVersion.Version > new Version(10, 0, 21999, 0))
            {
                var preference = Natives.DWM_WINDOW_CORNER_PREFERENCE.DWMWCP_ROUND;
                Natives.DwmSetWindowAttribute(new WindowInteropHelper(GetWindow(this)).EnsureHandle(), Natives.DWMWINDOWATTRIBUTE.DWMWA_WINDOW_CORNER_PREFERENCE, ref preference, sizeof(uint));
            }
            else
            {
                WindowBorder.CornerRadius = new(8);
                WindowBorder.BorderBrush = Brushes.Gray;
                WindowBorder.BorderThickness = new(1);
            }

        }

        private void BindData()
        {
            ViewModel = new MainWindowViewModel();

            this.WhenActivated(d =>
            {
                this.Bind(ViewModel, x => x.CountdownText, x => x.TextBlockCountdown.Text).DisposeWith(d);
            });
        }

        private void BindEvents()
        {
            ContextOptions.Click += ContextOptions_Click;
            ContextOpenDir.Click += ContextOpenDir_Click;
            TextBlockCountdown.MouseLeftButtonDown += TextBlockCountdown_MouseLeftButtonDown;
            TextBlockCountdown.MouseMove += TextBlockCountdown_MouseMove;
            TextBlockCountdown.MouseLeftButtonUp += TextBlockCountdown_MouseLeftButtonUp;
            Closing += MainWindow_Closing;
        }

        private void TextBlockCountdown_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                Cursor = Cursors.SizeAll;
                DragMove();
            }
        }

        private void TextBlockCountdown_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.LeftButton == MouseButtonState.Pressed)
            {
                Cursor = Cursors.SizeAll;
            }
            else
            {
                Cursor = Cursors.Arrow;
            }
        }

        private void TextBlockCountdown_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
        {
            Cursor = Cursors.Arrow;
        }

        private void ContextOptions_Click(object sender, RoutedEventArgs e)
        {
            SingletonHelper<OptionsWindow>.ShowWindow();
        }

        private void ContextOpenDir_Click(object sender, RoutedEventArgs e)
        {
            App.OpenInstallDir();
        }

        private void MainWindow_Closing(object sender, CancelEventArgs e)
        {
            e.Cancel = true;
        }
    }
}

MainWindowViewModel.cs

using ReactiveUI;
using ReactiveUI.Fody.Helpers;
using System;
using System.Timers;
using System.Windows;

namespace WangHaonie.CEETimer.ViewModels
{
    public class MainWindowViewModel : ReactiveObject
    {
        [Reactive]
        public DateTime ExamStartTime { get; set; } = new(2025, 6, 7, 9, 0, 0);

        [Reactive]
        public string CountdownText { get; private set; }

        public MainWindowViewModel()
        {
            var CountdownTimer = new Timer(1000);

            CountdownTimer.Elapsed += CountdownTimer_Tick;
            CountdownTimer.AutoReset = true;
            CountdownTimer.Start();
        }

        private void CountdownTimer_Tick(object sender, ElapsedEventArgs e)
        {
            Application.Current.Dispatcher.BeginInvoke(() =>
            {
                CountdownText = $"{DateTime.Now:yyyy-MM-dd dddd HH:mm:ss}";
            });
        }
    }
}