C#判断是否有全屏程序正在运行

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：

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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 RECT

{

public int left;

public int top;

public int right;

public int bottom;

}

[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

}

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 RECT
{
public int left;
public int top;
public int right;
public int bottom;
}
[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
}

在窗口Load事件中注册AppBar：

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private void RegisterAppBar(bool registered)

{

APPBARDATA abd = new APPBARDATA();

abd.cbSize = Marshal.SizeOf(abd);

abd.hWnd = this.Handle;

if(!registered)

{

//register

uCallBackMsg = APIWrapper.RegisterWindowMessage("APPBARMSG_CSDN_HELPER");

abd.uCallbackMessage = uCallBackMsg;

uint ret = APIWrapper.SHAppBarMessage((int)ABMsg.ABM_NEW, ref abd);

}

else

{

APIWrapper.SHAppBarMessage((int)ABMsg.ABM_REMOVE, ref abd);

}

}

private void Form1_Load(object sender, EventArgs e)

{

this.RegisterAppBar(false);

}

private void RegisterAppBar(bool registered)
{
APPBARDATA abd = new APPBARDATA();
abd.cbSize = Marshal.SizeOf(abd);
abd.hWnd = this.Handle;
if(!registered)
{
//register
uCallBackMsg = APIWrapper.RegisterWindowMessage("APPBARMSG_CSDN_HELPER");
abd.uCallbackMessage = uCallBackMsg;
uint ret = APIWrapper.SHAppBarMessage((int)ABMsg.ABM_NEW, ref abd);
}
else
{
APIWrapper.SHAppBarMessage((int)ABMsg.ABM_REMOVE, ref abd);
}
}
private void Form1_Load(object sender, EventArgs e)
{
this.RegisterAppBar(false);
}

重载窗口消息处理函数：

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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);

}

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：

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this.RegisterAppBar(true);