Question

以下应用程序在系统托盘图标中显示磁盘活动。它正常运行大约30-40分钟，然后终止，将图标留在桌面上。好像它被系统杀死是一项不必要的后台任务。为什么会发生这种情况，我该如何预防呢？

public partial class MainWindow : Window
{
    public System.Windows.Forms.NotifyIcon ni = new System.Windows.Forms.NotifyIcon();
    public MainWindow()
    {
        InitializeComponent();

        ni.Visible = true;
        ni.Text = "disktray"; // tooltip text show over tray icon
        CreateTextIcon("0");
        ni.DoubleClick +=
            delegate (object sender, EventArgs args)
            {
                //this.Show();
                //this.WindowState = WindowState.Normal;
                ni.Visible = false;
                ni.Dispose();
                System.Windows.Application.Current.Shutdown();
            };
    }
    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        CreateTextIcon("0");
        DispatcherTimer timer = new DispatcherTimer()
        {
            Interval = TimeSpan.FromMilliseconds(1024)
        };
        timer.Tick += Timer_Tick;
        timer.Start();

        this.Hide();
    }
    private void Timer_Tick(object sender, EventArgs e)
    {
        Diskpercent();
        string iii = diskpercentvalue.ToString();
        CreateTextIcon(iii);
    }
    public PerformanceCounter myCounter =
       new PerformanceCounter("PhysicalDisk", "% Disk Time", "_Total");
    public int diskpercentvalue = 0;
    public void Diskpercent()
    {
        var d = Convert.ToInt32(myCounter.NextValue());
        if (d > 99) d = 99; // can go over 100%
        diskpercentvalue = d;
    }

    public System.Drawing.Font fontToUse = 
        new System.Drawing.Font("Microsoft Sans Serif", 16, System.Drawing.FontStyle.Regular, GraphicsUnit.Pixel);
    public System.Drawing.Brush brushToUse = new SolidBrush(System.Drawing.Color.White);
    public Bitmap bitmapText = new Bitmap(16, 16);
    public IntPtr hIcon;
    public void CreateTextIcon(string str)
    {
        //System.Drawing.Font fontToUse = new System.Drawing.Font("Microsoft Sans Serif", 16, System.Drawing.FontStyle.Regular, GraphicsUnit.Pixel);
        //System.Drawing.Brush brushToUse = new SolidBrush(System.Drawing.Color.White);
        //Bitmap bitmapText = new Bitmap(16, 16);
        Graphics g = System.Drawing.Graphics.FromImage(bitmapText);
        //IntPtr hIcon;
        g.Clear(System.Drawing.Color.Transparent);
        g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixelGridFit;
        g.DrawString(str, fontToUse, brushToUse, -4, -2);
        hIcon = (bitmapText.GetHicon());
        ni.Icon = System.Drawing.Icon.FromHandle(hIcon);
    }

}

Answer 1

转到App.xaml.cs并按如下所示实现它。诀窍是永远不要关闭MainWindow，因为关闭的窗口不能再显示。而是取消关闭并隐藏它。

using System.ComponentModel;
using System.Windows;

namespace BackgroundApplication
{

    public partial class App : Application
    {
        private System.Windows.Forms.NotifyIcon _notifyIcon;
        private bool _isExit;

        protected override void OnStartup(StartupEventArgs e)
        {
            base.OnStartup(e);
            MainWindow = new MainWindow();
            MainWindow.Closing += MainWindow_Closing;

            _notifyIcon = new System.Windows.Forms.NotifyIcon();
            _notifyIcon.DoubleClick += (s, args) => ShowMainWindow();
            _notifyIcon.Icon = BackgroundApplication.Properties.Resources.MyIcon;
            _notifyIcon.Visible = true;

            CreateContextMenu();
        }

        private void CreateContextMenu()
        {
            _notifyIcon.ContextMenuStrip =
              new System.Windows.Forms.ContextMenuStrip();
            _notifyIcon.ContextMenuStrip.Items.Add("MainWindow...").Click += (s, e) => ShowMainWindow();
            _notifyIcon.ContextMenuStrip.Items.Add("Exit").Click += (s, e) => ExitApplication();
        }

        private void ExitApplication()
        {
            _isExit = true;
            MainWindow.Close();
            _notifyIcon.Dispose();
            _notifyIcon = null;
        }

        private void ShowMainWindow()
        {
            if (MainWindow.IsVisible)
            {
                if (MainWindow.WindowState == WindowState.Minimized)
                {
                    MainWindow.WindowState = WindowState.Normal;
                }
                MainWindow.Activate();
            }
            else
            {
                MainWindow.Show();
            }
        }

        private void MainWindow_Closing(object sender, CancelEventArgs e)
        {
            if (!_isExit)
            {
                e.Cancel = true;
                MainWindow.Hide(); // A hidden window can be shown again, a closed one not
            }
        }
    }
}

除了App.xaml之外，还要删除Startup-Uri，以便在启动应用程序时，只将NotifyIcon添加到通知区域

<Application x:Class="BackgroundApplication.App"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:local="clr-namespace:BackgroundApplication">
  <Application.Resources>

    </Application.Resources>
</Application>

取自：

https://www.thomasclaudiushuber.com/2015/08/22/creating-a-background-application-with-wpf/

注意：如果要访问变量，可以在App.xaml.cs中创建一个公共只读属性：

public System.Windows.Forms.NotifyIcon NotifyIcon { get { return      _notifyIcon; } }

然后你可以在你的MainWindow中使用它：

((App)App.Current).NotifyIcon

Answer 2

This line is causing a memory leak:

hIcon = (bitmapText.GetHicon());

hIcon needs to be destroyed:

    hIcon = (bitmapText.GetHicon());
    ni.Icon = System.Drawing.Icon.FromHandle(hIcon);
    DestroyIcon(hIcon);

Add this code to the class to define DestroyIcon:

    [DllImport("user32.dll", SetLastError = true)]
    static extern bool DestroyIcon(IntPtr hIcon);

see:

https://msdn.microsoft.com/en-us/library/system.drawing.icon.fromhandle(v=vs.110).aspx

wpf c＃托盘图标应用程序在30分钟后终止

2 个答案: