Question

C#Winform程序判断是否有全屏窗口程序正在运行

Answer 1

修改启动文件Program.cs
static class Program
    {
        /// <summary>
        /// 应用程序的主入口点。
        /// </summary>
        [STAThread]
        static void Main()
        {
            Process instance = RunningInstance();
            if (instance == null)
            {
                //没有实例在运行
                Application.EnableVisualStyles();
                Application.SetCompatibleTextRenderingDefault(false);
                Application.Run(new Form1());
            }
            else
            {
                //已经有一个实例在运行
                HandleRunningInstance(instance);
            }
        }
 
         private static Process RunningInstance()
         {
             Process current = Process.GetCurrentProcess();
             Process[] processes = Process.GetProcessesByName(current.ProcessName);
             //遍历与当前进程名称相同的进程列表  
             foreach (Process process in processes)
             {
                 //如果实例已经存在则忽略当前进程  
                 if (process.Id != current.Id)
                 {
                     //保证要打开的进程同已经存在的进程来自同一文件路径
                     if (Assembly.GetExecutingAssembly().Location.Replace("/", "\\") == current.MainModule.FileName)
                     {
                         //返回已经存在的进程
                         return process;
                          
                     }
                 }
             }
             return null;
         }
 
         public static void HandleRunningInstance(Process instance)
         {
             ShowWindowAsync(instance.MainWindowHandle, WS_SHOWNORMAL);
             SetForegroundWindow(instance.MainWindowHandle);
         }
         [DllImport("User32.dll")]
         private static extern bool ShowWindowAsync(IntPtr hWnd, int cmdShow);
         [DllImport("User32.dll")]
         private static extern bool SetForegroundWindow(IntPtr hWnd);
         private const int WS_SHOWNORMAL = 1;
    }

Answer 2

注册一个AppBar（什么是AppBar？Using Application Desktop Toolbars），通过SHAppBarMessage向系统注册AppBar，这样，当有程序全屏运行时系统会向我们的程序发送消息，在窗体WndProc中处理即可。

声明要使用到的API和常量：
public class APIWrapper
{
[DllImport("SHELL32", CallingConvention = CallingConvention.StdCall)]
public static extern uint SHAppBarMessage(int dwMessage, ref APPBARDATA pData);

[DllImport("User32.dll", CharSet = CharSet.Auto)]
public static extern int RegisterWindowMessage(string msg);

}

[StructLayout(LayoutKind.Sequential)]
public struct APPBARDATA
{
public int cbSize;
public IntPtr hWnd;
public int uCallbackMessage;
public int uEdge;
public RECT rc;
public IntPtr lParam;
}

public enum ABMsg : int
{
ABM_NEW = 0,
ABM_REMOVE,
ABM_QUERYPOS,
ABM_SETPOS,
ABM_GETSTATE,
ABM_GETTASKBARPOS,
ABM_ACTIVATE,
ABM_GETAUTOHIDEBAR,
ABM_SETAUTOHIDEBAR,
ABM_WINDOWPOSCHANGED,
ABM_SETSTATE
}

public enum ABNotify : int
{
ABN_STATECHANGE = 0,
ABN_POSCHANGED,
ABN_FULLSCREENAPP,
ABN_WINDOWARRANGE
}

public enum ABEdge : int
{
ABE_LEFT = 0,
ABE_TOP,
ABE_RIGHT,
ABE_BOTTOM
}

[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
public int left;
public int top;
public int right;
public int bottom;

public override string ToString()
{
return "{left=" + left.ToString() + ", " + "top=" + top.ToString() + ", " +
"right=" + right.ToString() + ", " + "bottom=" + bottom.ToString() + "}";
}
}
重载窗口消息处理函数：
protected override void WndProc(ref System.Windows.Forms.Message m)
{
if (m.Msg == uCallBackMsg)
{
switch (m.WParam.ToInt32())
{
case (int)ABNotify.ABN_FULLSCREENAPP:
{
if ((int)m.LParam == 1)
this.RunningFullScreenApp = true;
else
this.RunningFullScreenApp = false;
break;
}
default:
break;
}
}

base.WndProc(ref m);
}
在程序退出时，不要忘了Unregister我们注册的AppBar：this.RegisterAppBar(true);
以上介绍的是C# Winform程序判断是否有全屏窗口程序正在运行，希望队你有所帮助。