如何从可执行文件而不是在 C# 中的托盘图标上打开应用程序主界面

Question

这是场景，我打开我的应用程序，然后显示托盘图标，如果我双击托盘图标，将显示主界面。如果我再次打开我的应用程序，主界面应该获得焦点，或者如果它尚未显示，那么应该显示它，而不是打开我的应用程序的另一个实例。

我的代码如下所示：

//Program.cs
.....

if(myAppIsNotRunningYet) //the program has not been open yet
{
MyTray = new MyTray();
Application.Run();
}

else //the program is already on the tray
{
//the code to give focus to the mainForm or open it up if not yet open
}

//MyTray.cs
.....
public MyTray()
{
notifyIcon = new NotifyIcon();
....
notifyIcon.Visible = true;
}

private void notifyIcon_DoubleClick(object sender, EventArgs e)
{
MainForm mainForm = new MainForm();
mainForm.ShowDialog();
}

Answer 1

编辑：好的，看来要正确覆盖 WndProc，您必须使用可见的表单。因此，下面是使用 MessageFilter< 的不同解决方案/a>.这确实有效，所以希望你能从这里开始！

 internal sealed class Program
 { 
  /// <summary>
  /// Program entry point.
  /// </summary>
  [STAThread]
  public static void Main(string[] args)
  {
    bool newMutex;
    System.Threading.Mutex mutex = new System.Threading.Mutex(true, "{9F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}", out newMutex);

     // Attempt aquire the mutex
     if(newMutex)
     {
      // If we are able to aquire the mutex, it means the application is not running.
         Application.EnableVisualStyles();
         Application.SetCompatibleTextRenderingDefault(false);

         // Create the new tray icon
         MyTray myTray = new MyTray();

         Application.AddMessageFilter(myTray);
         Application.Run();

         // Release the mutex on exit
         mutex.ReleaseMutex();
     }
     else
     {
        // If the aquire attempt fails, the application is already running
        // so we broadcast a windows message to tell it to wake up.
         NativeMethods.PostMessage((IntPtr)NativeMethods.HWND_BROADCAST, NativeMethods.WM_SHOWME, IntPtr.Zero, IntPtr.Zero);
     }
     }
 }
}

internal class NativeMethods
 {
     public const int HWND_BROADCAST = 0xffff;
     public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME");

     [DllImport("user32")]
     public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);

     [DllImport("user32")]     
     public static extern int RegisterWindowMessage(string message);
 }

 public class MyTray : IMessageFilter
 {
  private NotifyIcon notifyIcon = new NotifyIcon();
  private Form myForm = new Form();

  public MyTray()
  {
     this.notifyIcon.Icon = System.Drawing.Icon.FromHandle(new System.Drawing.Bitmap(16,16).GetHicon());
     this.notifyIcon.Visible = true;
     this.notifyIcon.DoubleClick += delegate(object sender, EventArgs e) { ShowForm(); };
  }

     void ShowForm()
     {
        this.notifyIcon.Visible = false;            
        this.myForm.ShowDialog();   
        this.notifyIcon.Visible = true;
      }

    public bool PreFilterMessage(ref Message m)
    {
       // If the message is the 'show me' message, then hide the icon and show the form.
       if(m.Msg == NativeMethods.WM_SHOWME)
       {
            if (!this.myForm.Visible)
            {
                ShowForm();
                return true; // Filter the message
            }
       }

       return false; // Forward the message
    }
 }

---

编辑：我整理了一个更接近您的场景的示例：

 internal sealed class Program
 {
  static System.Threading.Mutex mutex = new System.Threading.Mutex(true, "{8F6F0AC4-B9A1-45fd-A8CF-72F04E6BDE8F}");

  /// <summary>
  /// Program entry point.
  /// </summary>
  [STAThread]
  private static void Main(string[] args)
  {
   // Attempt aquire the mutex
         if(mutex.WaitOne(TimeSpan.Zero, true))
         {
          // If we are able to aquire the mutex, it means the application is not running.
             Application.EnableVisualStyles();
             Application.SetCompatibleTextRenderingDefault(false);

             // Create the new tray icon
             MyTray myTray = new MyTray();

             Application.Run();

             // Release the mutex on exit
             mutex.ReleaseMutex();
         }
         else
         {
            // If the aquire attempt fails, the application is already running
            // so we broadcast a windows message to tell it to wake up.
             NativeMethods.PostMessage((IntPtr)NativeMethods.HWND_BROADCAST, NativeMethods.WM_SHOWME, IntPtr.Zero, IntPtr.Zero);
         }
     }
 }

 internal class NativeMethods
 {
     public const int HWND_BROADCAST = 0xffff;
     public static readonly int WM_SHOWME = RegisterWindowMessage("WM_SHOWME");

     [DllImport("user32")]
     public static extern bool PostMessage(IntPtr hwnd, int msg, IntPtr wparam, IntPtr lparam);

     [DllImport("user32")]     
     public static extern int RegisterWindowMessage(string message);
 }

 public class MyTray : Control
 {
  private NotifyIcon notifyIcon = new NotifyIcon();

  public MyTray()
  {
   this.notifyIcon.Visible = true;
  }

  /// <summary>
  /// This method listens to all windows messages either broadcast or sent to this control
  /// </summary>
  protected override void WndProc(ref Message m)
  {
   // If the message is the 'show me' message, then hide the icon and show the form.
   if(m.Msg == NativeMethods.WM_SHOWME)
   {
    this.notifyIcon.Visible = false;
    using (Form mainForm = new Form())
    {
     mainForm.ShowDialog();
     this.notifyIcon.Visible = true;
    }  
   }
   else
   {
    base.WndProc(ref m);    
   }   
  }
 }

---

编辑：我在 C# 中找到了一个结合了互斥体和 Windows 消息的示例：

C# .NET 单实例应用程序

---

互斥体可能是最好的方法。将此与应用程序侦听的自定义 Windows 消息结合起来，使其成为焦点（请参阅 VB .NET、VB6 和 C# 通过 Window Messaging 进行进程间通信）。

查看此示例：
C# - 单个应用程序实例

Answer 2

我认为您不能在另一个应用程序的窗口上引发事件（即使它们是相同的可执行文件）。

我解决这个问题的方法是使用一些 IPC 机制 来告诉正在运行的实例打开主窗口。相同的 IPC 机制也可用于确定另一个实例是否正在运行。

Answer 3

您还可以查看 SwitchToThisWindow 函数。

当应用程序的第二个实例启动时，您可以使用第一个实例的主窗口句柄调用该函数。您可以使用 Process.MainWindowHandle 获取主窗口句柄 属性。