看起来你不会得到KeyRelease
事件(如果您在按下该键后已注册对此感兴趣)。
我可以想到两种不同的方法来解决这个问题。
- Select
KeyReleaseMask
for all窗口(并跟踪出现和消失的窗口);or
- 一旦您知道 Alt 被按下,请使用以下命令轮询键盘状态
XQueryKeyboard
每 0.1 秒左右一次,直到释放。
我已经测试了第一种方法,它似乎有效:
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <stdbool.h>
#include <stdio.h>
void dowin (Display* dpy, Window win, int reg)
{
Window root, parent;
Window* children;
int nchildren, i;
XSelectInput (dpy, win, reg ? KeyReleaseMask|SubstructureNotifyMask : 0);
XQueryTree (dpy, win, &root, &parent, &children, &nchildren);
for (i = 0; i < nchildren; ++i)
{
dowin (dpy, children[i], reg);
}
XFree(children);
}
int main()
{
Display* dpy = XOpenDisplay(0);
Window win = DefaultRootWindow(dpy);
XEvent ev;
unsigned int alt_modmask = Mod1Mask;
unsigned int ignored_modmask = 0; // stub
KeyCode tab_keycode = XKeysymToKeycode(dpy,XK_Tab);
KeyCode alt_keycode = XKeysymToKeycode(dpy,XK_Alt_L);
dowin (dpy, win, True);
XGrabKey (dpy,
tab_keycode,
alt_modmask | ignored_modmask,
win,
True,
GrabModeAsync, GrabModeAsync);
while(true)
{
ev.xkey.keycode = 0;
ev.xkey.state = 0;
ev.xkey.type = 0;
XNextEvent(dpy, &ev);
switch(ev.type)
{
case KeyPress:
printf ("Press %x: d-%d\n", ev.xkey.window, ev.xkey.state, ev.xkey.keycode);
break;
case KeyRelease:
printf ("Release %x: %d-%d\n", ev.xkey.window, ev.xkey.state, ev.xkey.keycode);
break;
case MapNotify:
printf ("Mapped %x\n", ev.xmap.window);
dowin (dpy, ev.xmap.window, True);
break;
case UnmapNotify:
printf ("Unmapped %x\n", ev.xunmap.window);
dowin (dpy, ev.xunmap.window, False);
break;
default:
printf ("Event type %d\n", ev.type);
break;
}
}
XCloseDisplay(dpy);
return 0;
}