XLib：Windows Manager在调用XSetWMProtocols之后未发送客户端消息

Question

有很多关于如何使用XLib处理窗口关闭的示例，可以在互联网上找到：

• http://cboard.cprogramming.com/linux-programming/60466-xwindows-close-window-event.html
• https://en.wikibooks.org/wiki/X_Window_Programming/XLib
• https://john.nachtimwald.com/2009/11/01/x11-intercept-window-close-event/

还有几个。这就是说我试图在代码中实现它们，如下所示。但是，当我点击窗口一角的X时，我没有收到任何事件发送到我的消息循环。这是因为XChcekWindowEvent忽略或不处理客户端消息？如果不是这种情况，我应该寻找什么其他东西来使用SetWMProtocols从XLib集中获取消息？

m_impl->m_delete_window = XInternAtom(display, "WM_DELETE_WINDOW", False);
if (!XSetWMProtocols(display, window, &m_impl->m_delete_window, 1)) {
  std::cout << "Set Window Protocols Failed" << std::endl;
}

...

while (!terminate) {
  while (::XCheckWindowEvent(display, window, events::mask, &x_event)) {
    if (x_event.type == ClientMessage) {
      std::cout << "Client Message" << std::endl;   
      if ((Atom)x_event.xclient.data.l[0] == m_impl->m_delete_window) {
        terminate = true;
      }
    }
  }
}

Answer 1

XCheckWindowEvent（）不会返回ClientMessage。它不返回任何不可屏蔽的。解决方法：

while (XPending(display))
{
    XNextEvent(display, &event);

但是可以通过窗口创建额外的工作来过滤事件。 BR Pekka

Answer 2

如果要防止使用XNextEvent（不在实时事件循环中应用），可以使用以下基于XCheckTypedWindowEvent的代码：

// Globals

Atom wm_protocols;
Atom wm_delete_window;

// Functions

void PreventClose(Display* disp, Window& win)
{
  wm_protocols = XInternAtom(disp, "WM_PROTOCOLS", false);
  wm_delete_window = XInternAtom(disp, "WM_DELETE_WINDOW", false);
  XSetWMProtocols(disp, win, &wm_delete_window, 1);
}

bool IsClosed(Display* disp, Window& win)
{
  XEvent e;
  if (XCheckTypedWindowEvent(disp, win, ClientMessage, &e))
    if (e.xclient.message_type == wm_protocols &&
        e.xclient.data.l[0]    == wm_delete_window_)
      return true;
  return false;
}

// Usage

int main()
{
   ...
   PreventClose(disp, win);
   do {
     if (IsClosed(disp, win))
       // break, some actions, etc...
     ...
   } while(true);
   return 0;
}

有关更多信息，请参阅man 3 XCheckTypedWindowEvent