在X11应用程序中忽略自动重复

Question

如果在启用AutoRepeat的同时按住X11中的某个键，则会连续收到KeyPress和KeyRelease事件。我知道可以使用函数XAutoRepeatOff()，禁用AutoRepeat，但这会更改整个X服务器的设置。有没有办法禁用单个应用程序的AutoRepeat，或者忽略重复的击键？

我正在寻找的是当一个键被按下时的单个KeyPress事件和当一个键被释放时的单个KeyRelease事件，而不会干扰X服务器的AutoRepeat设置。

下面是一个简单的示例(主要来自Beginner Xlib Tutorial)：

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include <X11/keysym.h>

Display *dis;
Window win;
XEvent report;

int main ()
{
  dis = XOpenDisplay (NULL);
  // XAutoRepeatOn(dis);
  win = XCreateSimpleWindow (dis, RootWindow (dis, 0), 1, 1, 500, 500,
        0, BlackPixel (dis, 0), BlackPixel (dis, 0));
  XSelectInput (dis, win, KeyPressMask | KeyReleaseMask);
  XMapWindow (dis, win);
  XFlush (dis);

  while (1)
    {
      XNextEvent (dis, &report);
      switch (report.type)
 {
 case KeyPress:
   fprintf (stdout, "key #%ld was pressed.\n",
     (long) XLookupKeysym (&report.xkey, 0));
   break;
 case KeyRelease:
   fprintf (stdout, "key #%ld was released.\n",
     (long) XLookupKeysym (&report.xkey, 0));
   break;
 }
    }

  return (0);
}

Answer 1

当你收到一个按键释放，并且下一个事件是按下相同的组合键时，它会自动重复，并且该键并没有实际释放。您可以使用这样的代码来查看下一个事件

if (event->type == KeyRelease && XEventsQueued(disp, QueuedAfterReading))
{
  XEvent nev;
  XPeekEvent(disp, &nev);
    
  if (nev.type == KeyPress && nev.xkey.time == event->xkey.time &&
      nev.xkey.keycode == event->xkey.keycode)
  {
    /* Key wasn’t actually released */
  }
}

Answer 2

您可以使用XkbSetDetectableAutorepeat函数告诉X服务器仅在用户实际释放键时发送KeyRelease事件-当您不想要自动重复事件时，则丢弃任何不匹配KeyRelease的KeyPress。

Answer 3

作为参考，这里有一个删除自动重复的KeyPress事件的工作最小示例。谢谢，kralyk！

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include <X11/keysym.h>

Display *dis;
Window win;
XEvent report;

int main ()
{
  dis = XOpenDisplay (NULL);
  // XAutoRepeatOn(dis);
  win = XCreateSimpleWindow (dis, RootWindow (dis, 0), 1, 1, 500, 500,
        0, BlackPixel (dis, 0), BlackPixel (dis, 0));
  XSelectInput (dis, win, KeyPressMask | KeyReleaseMask);
  XMapWindow (dis, win);
  XFlush (dis);

  while (1)
    {
      XNextEvent (dis, &report);
      switch (report.type)
 {
 case KeyPress:
   fprintf (stdout, "key #%ld was pressed.\n",
     (long) XLookupKeysym (&report.xkey, 0));
   break;
 case KeyRelease:
   {
     unsigned short is_retriggered = 0;

     if (XEventsQueued(dis, QueuedAfterReading))
       {
         XEvent nev;
         XPeekEvent(dis, &nev);

         if (nev.type == KeyPress && nev.xkey.time == report.xkey.time &&
             nev.xkey.keycode == report.xkey.keycode)
           {
             fprintf (stdout, "key #%ld was retriggered.\n",
               (long) XLookupKeysym (&nev.xkey, 0));

             // delete retriggered KeyPress event
             XNextEvent (dis, &report);
             is_retriggered = 1;
           }
       }

     if (!is_retriggered)
       fprintf (stdout, "key #%ld was released.\n",
         (long) XLookupKeysym (&report.xkey, 0));
   }
   break;
 }
    }

  return (0);
}