C#學習筆記-WinForm

1，檢查窗體是否被創建
方法

  foreach (var FormItem in Application.OpenForms)
  {
      var vForm = FormItem as 窗體類型名;
      if (vForm != null)
      {
          vForm.Activate();
          return;
      }
  }

2，父子窗體的設置
父窗體屬性IsMdiContainer屬性設置爲true
類型 childWin= new 子窗體類型();
childWin.MdiParent = this;
childWin.Show();
childWin.WindowState = FormWindowState.Maximized;

3，判斷程序是否運行實例
將Program.cs修改一下，添加一個互斥量
方法1：

 static void Main()
 {
     Application.EnableVisualStyles();
     Application.SetCompatibleTextRenderingDefault(false);
     System.Threading.Mutex mutex = new System.Threading.Mutex(true, "OnlyRun");
     if (mutex.WaitOne(0, false))
     {
         Application.Run(new Form1());
     }
     else
     {
         MessageBox.Show("程序已經在運行！", "提示");
         Application.Exit();
     }
 }

方法2：

[DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr OpenMutex(uint dwDesiredAccess, int bInheritHandle, string lpName);

[DllImport("Kernel32.dll", CharSet = CharSet.Auto)]
private static extern IntPtr CreateMutex(IntPtr lpMutexAttributes, int bInitialOwner, string lpName);