Get active window title in X

Question

I'm trying to get the title of the active window. The application is a background task so if the user has Eclipse open the function returns "Eclipse - blabla", so it's not getting the window title of my own window. I'm developing this in Python 2.6 using PyQt4.

My current solution, borrowed and slightly modified from an old answer here at SO, looks like this:

def get_active_window_title():
    title = ''
    root_check = ''

    root = Popen(['xprop', '-root'],  stdout=PIPE)

    if root.stdout != root_check:
        root_check = root.stdout

        for i in root.stdout:
            if '_NET_ACTIVE_WINDOW(WINDOW):' in i:
                id_ = i.split()[4]
                id_w = Popen(['xprop', '-id', id_], stdout=PIPE)

        for j in id_w.stdout:
            if 'WM_ICON_NAME(STRING)' in j:
                if title != j.split()[2]:
                    return j.split("= ")[1].strip(' \n\"')

It works for most windows, but not all. For example it can't find my kopete chat windows, or the name of the application i'm currently developing.

My next try looks like this:

def get_active_window_title(self):
    screen = wnck.screen_get_default()
    if screen == None:
        return "Could not get screen"
    window = screen.get_active_window()
    if window == None:
        return "Could not get window"
    title = window.get_name()
    return title;

But for some reason window is always None.

Does somebody have a better way of getting the current window title, or how to modify one of my ways, that works for all windows?

Edit:

In case anybody is wondering this is the way I found that seems to work for all windows.

def get_active_window_title(self):
    root_check = ''
    root = Popen(['xprop', '-root'],  stdout=PIPE)

    if root.stdout != root_check:
        root_check = root.stdout

        for i in root.stdout:
            if '_NET_ACTIVE_WINDOW(WINDOW):' in i:
                id_ = i.split()[4]
                id_w = Popen(['xprop', '-id', id_], stdout=PIPE)
        id_w.wait()
        buff = []
        for j in id_w.stdout:
            buff.append(j)

        for line in buff:
            match = re.match("WM_NAME\((?P<type>.+)\) = (?P<name>.+)", line)
            if match != None:
                type = match.group("type")
                if type == "STRING" or type == "COMPOUND_TEXT":
                    return match.group("name")
        return "Active window not found"

Answer 1

I modified your solution slightly so it should run more efficiently (it passes parameters to xprop so only the data it needs is returned). Also, I'm not sure it's necessary to buffer the output of xprop so I took that out. It should also correct return "Active window not found" if for some reason it can't find the active window.

def get_active_window_title(self):
    root = Popen(['xprop', '-root', '_NET_ACTIVE_WINDOW'], stdout=PIPE)

    for line in root.stdout:
        m = re.search('^_NET_ACTIVE_WINDOW.* ([\w]+)$', line)
        if m != None:
            id_ = m.group(1)
            id_w = Popen(['xprop', '-id', id_, 'WM_NAME'], stdout=PIPE)
            break

    if id_w != None:
        for line in id_w.stdout:
            match = re.match("WM_NAME\(\w+\) = (?P<name>.+)$", line)
            if match != None:
                return match.group("name")

    return "Active window not found"