/**
* Spacenav lib hack
* Copyright © 2019 František Kučera (Frantovo.cz, GlobalCode.info)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdint.h>
#include <dlfcn.h>
#include <stdlib.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <spnav.h>
/**
* The purpose of this hack is to enable 3D mouse in applications that use X11 protocol
* while our daemon is providing only domain socket and no X11.
*
* Usage:
* LD_PRELOAD=./spacenav-lib-hack/build/Debug/src/libspnav-lib-hack.so freecad
*
* This hack:
* 1) Pretends that spnav_x11_open() was successful.
* 2) Starts a background process (TODO: also terminate it) which reads from the domain socket
* and translates spacenav events to X11 events and sends them to the application window.
* 3) reimplements spnav_x11_event() which is needed, because Atom variables in original library
* were not initialized spnav_x11_open() and thus the library funcion is not working.
*
* This solution works and allows using e.g. FreeCAD with domain socket instead of X11, but:
* - the background process never ends and must be terminated by: killall freecad
* - is very hackish and should be reimplemented as a separate process which will work partly
* as a libspnav client and partly emulate spacenavd daemon and will bridge the domain socket
* and th X11. Other solution is to emulate the hardware and keep spacenavd and libspnav untouched.
*/
// from proto_x11.c (spacenavd)
static Atom xa_event_motion, xa_event_bpress, xa_event_brelease, xa_event_cmd;
static float x11_sens = 1.0;
/**
* This function is based on proto_x11.c (spacenavd) written by:
* Copyright (C) 2007-2019 John Tsiombikas <nuclear@member.fsf.org>
* and published under GNU GPLv3+
*
* @param ev
* @param dpy
* @param win
*/
static void send_xevent(spnav_event *ev, Display* dpy, Window win) {
int i;
XEvent xevent;
if (!dpy) return;
// if(setjmp(jbuf)) return;
xevent.type = ClientMessage;
xevent.xclient.send_event = False;
xevent.xclient.display = dpy;
xevent.xclient.window = win;
switch (ev->type) {
case SPNAV_EVENT_MOTION:
xevent.xclient.message_type = xa_event_motion;
xevent.xclient.format = 16;
for (i = 0; i < 6; i++) {
float val = (float) ev->motion.data[i] * x11_sens;
xevent.xclient.data.s[i + 2] = (short) val;
}
xevent.xclient.data.s[0] = xevent.xclient.data.s[1] = 0;
xevent.xclient.data.s[8] = ev->motion.period;
break;
case SPNAV_EVENT_BUTTON:
xevent.xclient.message_type = ev->button.press ? xa_event_bpress : xa_event_brelease;
xevent.xclient.format = 16;
xevent.xclient.data.s[2] = ev->button.bnum;
break;
default:
break;
}
XSendEvent(dpy, win, False, 0, &xevent);
XFlush(dpy);
}
static void spacenav_hack_translate_events(Window win) {
spnav_event event;
Display* dpy = XOpenDisplay(0);
while (1) {
if (spnav_wait_event(&event)) {
send_xevent(&event, dpy, win);
}
}
// FIXME: this process never ends and must be killed manually
}
int spnav_x11_open(Display* dpy, Window win) {
int result = spnav_open();
fprintf(stderr, "spnav-lib-hack: instead of spnav_x11_open(%p, 0x%lx) calling spnav_open() = %d\n", dpy, win, result);
xa_event_motion = XInternAtom(dpy, "MotionEvent", False);
xa_event_bpress = XInternAtom(dpy, "ButtonPressEvent", False);
xa_event_brelease = XInternAtom(dpy, "ButtonReleaseEvent", False);
xa_event_cmd = XInternAtom(dpy, "CommandEvent", False);
if (result == 0) {
pid_t pid = fork();
fprintf(stderr, "spnav-lib-hack: fork() = %d; PID=%d\n", pid, getpid());
if (pid == -1) return 1; // error
if (pid == 0) spacenav_hack_translate_events(win); // child
else; // parent
}
return result;
}
/**
* This function is based on proto_x11.c (spacenavd) written by:
* Copyright (C) 2007-2019 John Tsiombikas <nuclear@member.fsf.org>
* and published under GNU GPLv3+
*
* @param dpy
* @param win
* @return
*/
int spnav_x11_event(const XEvent* xev, spnav_event* event) {
/*
* Because real spnav_x11_open() was not called, the library has not initialized xa_event_*
* variables and thus will return 0 (= not a spacenav event).
*/
int i;
int xmsg_type;
if (xev->type != ClientMessage) {
return 0;
}
xmsg_type = xev->xclient.message_type;
if (xmsg_type != xa_event_motion && xmsg_type != xa_event_bpress &&
xmsg_type != xa_event_brelease) {
return 0;
}
if (xmsg_type == xa_event_motion) {
event->type = SPNAV_EVENT_MOTION;
event->motion.data = &event->motion.x;
for (i = 0; i < 6; i++) {
event->motion.data[i] = xev->xclient.data.s[i + 2];
}
event->motion.period = xev->xclient.data.s[8];
} else {
event->type = SPNAV_EVENT_BUTTON;
event->button.press = xmsg_type == xa_event_bpress ? 1 : 0;
event->button.bnum = xev->xclient.data.s[2];
}
return event->type;
// real_spnav_x11_event() is not working (see comment above):
/*
static int (*real_spnav_x11_event)(const XEvent*, spnav_event*) = NULL;
if (!real_spnav_x11_event) real_spnav_x11_event = dlsym(RTLD_NEXT, "spnav_x11_event");
int result = real_spnav_x11_event(xev, event);
if (result == SPNAV_EVENT_MOTION || result == SPNAV_EVENT_BUTTON) fprintf(stderr, "spnav-lib-hack: spnav_x11_event() = %d\n", result);
return result;
*/
}
/*
int spnav_x11_open(Display* dpy, Window win) {
static int (*real_spnav_x11_open)(Display*, Window) = NULL;
if (!real_spnav_x11_open) real_spnav_x11_open = dlsym(RTLD_NEXT, "spnav_x11_open");
int result = real_spnav_x11_open(dpy, win);
fprintf(stderr, "spnav-lib-hack: spnav_x11_open() = %d\n", result);
return result;
}
*/
/*
int spnav_open() {
static int (*real_spnav_open)() = NULL;
if (!real_spnav_open) real_spnav_open = dlsym(RTLD_NEXT, "spnav_open");
int result = real_spnav_open();
// fprintf(stderr, "spnav-lib-hack: spnav_open() = %d\n", result);
return result;
}
*/