忽略X11应用程序中的自动重复

Question

如果在启用AutoRepeat的同时在X11中按住某个键,则会连续收到KeyPress和KeyRelease事件.我知道,自动重复可使用功能被禁用XAutoRepeatOff(),但是这改变了整个X服务器的设置.有没有办法为单个应用程序禁用AutoRepeat或忽略重复的击键？

我正在寻找的是当按下一个键时的单个KeyPress事件和一个释放键时的单个KeyRelease事件,而不会干扰X服务器的AutoRepeat设置.

这是一个让你前进的最小例子(主要来自初学者Xlib教程):

#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

当您收到一个密钥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未被实际释放.你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密钥时发送KeyRelease事件 - 当您不想要自动重复事件时,则丢弃任何KeyPress而不匹配KeyRelease.

Answer 3

供您参考,这是一个工作的最小示例,删除自动重复的KeyPress事件. 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);
}