从进程PID查找X Window ID

风行水上 @ 2011-12-31 16:11:46

标签： gui

下面的代码用来查找与特定进程的PID对应的X Window窗口。关键部分是递归查找窗口的_NET_WM_PID属性。

一个进程PID可能会对应多个窗口，即使你在屏幕上只看到了一个窗口。

除了程序主窗口外，还可能有程序的“关于”等窗口。这类窗口虽然逻辑上（比如在Qt库中）应该从属于主窗口，但作为一个X Window来说，却有可能并不从属于主窗口。

#include <X11/X.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xproto.h>
#include <X11/Xatom.h>

#include <iostream>
#include <list>

/* Find X Window From PID
*
* Reference:
*  http://stackoverflow.com/questions/151407/how-to-get-an-x11-window-from-a-process-id
*/
class XWindowFinder {
public:
  XWindowFinder(unsigned long pid, Display *display=NULL): _display(display), _pid(pid) {
    if(_display==NULL) _display = XOpenDisplay(NULL);

    _atomPID = XInternAtom(_display, "_NET_WM_PID", True);
    if(_atomPID == None) {
      std::cout << "No such atom" << std::endl;
      return;
    }

    Window wRoot = XDefaultRootWindow(_display);
    this->search(wRoot);
  }

  const std::vector<Window> &result() const { return _result; }

  void print(){
    for(std::vector<Window>::const_iterator it=_result.begin(); it !=_result.end(); it++)
      std::cout << "Window #" << (unsigned long)(*it) << std::endl;
  }

private:
    unsigned long  _pid;
    Atom           _atomPID;
    Display       *_display;
    std::vector<Window>   _result;

    unsigned long getPid(Window w){
    	Atom           type;
    	int            format;
    	unsigned long  nItems;
    	unsigned long  bytesAfter;
    	unsigned char *propPID = 0;

    	if(Success == XGetWindowProperty(_display, w, _atomPID, 0, 1, False, XA_CARDINAL,
    	                                 &type, &format, &nItems, &bytesAfter, &propPID))
    	{
    	    if(propPID != 0) {
              unsigned long pid = *((unsigned long *)propPID);
    	      XFree(propPID);
              return pid;
            }
        }
        return 0;
    }

    bool search(Window w) {
      bool found = false;

      unsigned long propPID = this->getPid(w);
      if(_pid == propPID){
        _result.push_back(w);
        return true;
      }

      // Recurse into child windows.
      Window    wRoot;
      Window    wParent;
      Window   *wChild;
      unsigned  nChildren;
      if(0 != XQueryTree(_display, w, &wRoot, &wParent, &wChild, &nChildren)) {
        for(unsigned i = 0; i < nChildren; i++){
          found = search(wChild[i]) || found;
          // found = found || search(wChild[i]);
          //if(found) break;
        }
      }
      return found;
    }
};

int main(int argc, char **argv){

  if(argc>=3 && strcmp(argv[1],"pid")==0){
    int pid = atoi(argv[2]);
    XWindowFinder finder(pid);
    finder.print();
    return 0;
  }
  return 0;
}

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标签： gui

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