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monitor active window and its pid using X11 lib
// monitor active window and its pid using X11 lib
// compile hint: install xlib-dev and then use g++ ./xxx.cpp -lX11
#include <X11/Xlib.h>
#include <cstring>
#include <iostream>
#define MAXSTR 1000
using namespace std;
Display *display;
unsigned char *prop;
void check_status(int status, Window window)
{
if (status == BadWindow)
{
printf("window id # 0x%lx does not exists!\n", window);
}
if (status != Success)
{
printf("XGetWindowProperty failed!\n");
}
}
unsigned char *get_string_property(const char *property_name, Window window)
{
if (window == 0)
return 0;
Atom actual_type, filter_atom;
int actual_format, status;
unsigned long nitems, bytes_after;
filter_atom = XInternAtom(display, property_name, True);
status = XGetWindowProperty(display, window, filter_atom, 0, MAXSTR, False, AnyPropertyType,
&actual_type, &actual_format, &nitems, &bytes_after, &prop);
check_status(status, window);
return prop;
}
unsigned long get_long_property(const char *property_name, Window window)
{
if (window == 0)
return 0;
get_string_property(property_name, window);
unsigned long long_property = static_cast<unsigned long>(prop[0] + (prop[1] << 8) + (prop[2] << 16) + (prop[3] << 24));
return long_property;
}
unsigned long getActiveWindowPID(Window root_window)
{
unsigned long window;
window = get_long_property("_NET_ACTIVE_WINDOW", root_window);
return get_long_property(("_NET_WM_PID"), window);
}
char *getActiveWindowName(Window root_window)
{
unsigned long window;
window = get_long_property("_NET_ACTIVE_WINDOW", root_window);
get_string_property("_NET_WM_NAME", window);
return reinterpret_cast<char *>(prop);
}
int main()
{
Display *d;
Window w;
XEvent e;
d = XOpenDisplay(0);
if (!d)
{
cerr << "Could not open display" << endl;
return 1;
}
display = d;
w = DefaultRootWindow(d);
XSelectInput(d, w, PropertyChangeMask);
pid_t window_pid;
window_pid = getActiveWindowPID(w);
if (window_pid != 0)
{
cout << "Active Window Name: " << getActiveWindowName(w);
cout << " , PID: " << window_pid << endl;
}
for (;;)
{
XNextEvent(d, &e);
if (e.type == PropertyNotify)
{
if (!strcmp(XGetAtomName(d, e.xproperty.atom), "_NET_ACTIVE_WINDOW"))
{
window_pid = getActiveWindowPID(w);
if (window_pid != 0)
{
cout << "Active Window Name: " << getActiveWindowName(w);
cout << " , PID: " << window_pid << endl;
}
}
}
}
return 0;
}
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