A meta window manager to set the default window manager for Ubuntu MATE. Runs standalone but not when the session is starting up.

mate-meta-wm

#!/usr/bin/env python3

# Copyright (C) 2018 Martin Wimpress <code@ubuntu-mate.org>
#
# 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 2 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, write to the
# Free Software Foundation, Inc.,
# 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

import gi
import os
import platform
import psutil
import setproctitle
import signal
import subprocess
import sys

from subprocess import DEVNULL, PIPE

from gi.repository import GLib
from gi.repository import Gio
from gi.repository import GObject

# Workaround introspection bug, gnome bug 622084
signal.signal(signal.SIGINT, signal.SIG_DFL)

def schema_has_key(schema, key):
    settings=Gio.Settings.new(schema)
    schema = settings.get_property('settings-schema')
    return schema.has_key(key)

def set_string(schema, path, key, value):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    try:
        settings.set_string(key, value)
    except:
        print('Unable set ' + key + ' with ' + value + ' in ' + schema)
        pass

def get_string(schema, path, key):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    return settings.get_string(key)

def get_int(schema, path, key):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    return settings.get_int(key)

def set_int(schema, path, key, value):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    settings.set_int(key, value)

def get_enum(schema, path, key):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    return settings.get_enum(key)

def set_enum(schema, path, key, value):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    settings.set_enum(key, value)

def get_bool(schema, path, key):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    return settings.get_boolean(key)

def set_bool(schema, path, key, value):
    if path:
        settings = Gio.Settings.new_with_path(schema, path)
    else:
        settings = Gio.Settings.new(schema)
    settings.set_boolean(key, value)

def reset_dconf_path(path):
    subprocess.call(['dconf', 'reset', '-f', path], stdout=DEVNULL, stderr=DEVNULL)

def set_dconf_value(path, value):
    subprocess.call(['dconf', 'write', path, value], stdout=DEVNULL, stderr=DEVNULL)

def get_dconf_value(path):
    dconf = subprocess.Popen(['dconf', 'read', path], stdin=PIPE, stdout=PIPE, stderr=PIPE)
    dconf_output, dconf_error = dconf.communicate()
    return dconf_output.decode().strip()

def process_running(name):
    uid = os.getuid()
    for process in psutil.process_iter():
        try:
            proc = process.as_dict(attrs=['name', 'uids'])
        except psutil.NoSuchProcess:
            pass
        else:
            if name == proc['name'] and uid == proc['uids'].real:
                return True
    return False

def kill_process(name):
    uid = os.getuid()
    for process in psutil.process_iter():
        try:
            proc = process.as_dict(attrs=['name', 'pid', 'uids'])
        except psutil.NoSuchProcess:
            pass
        else:
            if name == proc['name'] and uid == proc['uids'].real:
                try:
                    target = psutil.Process(proc['pid'])
                    target.kill()
                except psutil.NoSuchProcess:
                    pass

def find_on_path(command):
    """Is command on the executable search path?"""
    if 'PATH' not in os.environ:
        return False
    path = os.environ['PATH']
    for element in path.split(os.pathsep):
        if not element:
            continue
        filename = os.path.join(element, command)
        if os.path.isfile(filename) and os.access(filename, os.X_OK):
            return True
    return False

def replace_windowmanager(new_wm):
    print('Enabling ' + new_wm)
    #if new_wm == 'marco':
    #    wm_params = '--composite'
    #elif new_wm == 'compiz':
    #    wm_params = '--keep-desktop-hints'

    # Make sure Compiz use the same theme as Marco to
    # prevent theme/xcursor changes when switching themes.
    if (new_wm == 'compiz'):
        mate_theme = get_string('org.mate.interface', None, 'gtk-theme')
        mate_cursor_theme = get_string('org.mate.peripherals-mouse', None, 'cursor-theme')
        mate_cursor_size = get_int('org.mate.peripherals-mouse', None, 'cursor-size')

        schemasource = Gio.SettingsSchemaSource.get_default()
        gnome_desktop_schema = schemasource.lookup('org.gnome.desktop', False)
        if gnome_desktop_schema:
            set_string('org.gnome.desktop.wm.preferences', None, 'theme', mate_theme)
            set_string('org.gnome.desktop.interface', None, 'cursor-theme', mate_cursor_theme)
            set_int('org.gnome.desktop.interface', None, 'cursor-size', mate_cursor_size)

        # metacity >= 3.20 - this schema may not be installed
        metacity_schema = schemasource.lookup('org.gnome.metacity.theme', False)
        if metacity_schema:
            set_string('org.gnome.metacity.theme', None, 'name', mate_theme)
            # FIXME! Don't assume 'metacity' is 1
            set_enum('org.gnome.metacity.theme', None, 'type', 1)

    if process_running(new_wm):
        kill_process(new_wm)

    set_string('org.mate.session.required-components', None, 'windowmanager', new_wm)
    pid = subprocess.Popen([new_wm, '--replace'], stdout=DEVNULL, stderr=DEVNULL).pid
    return pid

def check_glx_features():
    if find_on_path('glxinfo'):
        process = subprocess.Popen(['glxinfo'], stdout=PIPE)
        out = process.communicate()[0].decode("UTF-8")
        if out.count("Software Rasterizer") == 0:
            software_rasterizer = False
        else:
            software_rasterizer = True

        if out.count("texture_from_pixmap") > 2:
            texture_from_pixmap = True
        else:
            texture_from_pixmap = False
    else:
        software_rasterizer = False
        texture_from_pixmap = False
    return software_rasterizer, texture_from_pixmap

if __name__ == "__main__":
    setproctitle.setproctitle('mate-meta-wm')
    # The most basic check, can we actually change the default window manager?
    if schema_has_key('org.mate.session.required-components', 'windowmanager'):
        # Only change things if mate-meta-wm is the configured window manager.
        current_wm = get_string('org.mate.session.required-components', None, 'windowmanager')
        if current_wm == 'mate-meta-wm':
            software_rasterizer, texture_from_pixmap = check_glx_features()
            compiz_capable = False
            marco_capable = False
            marco_no_composite_capable = False

            if find_on_path('compiz'):
                if not software_rasterizer and texture_from_pixmap:
                     compiz_capable = True

            if find_on_path('marco'):
                marco_capable = True

            if compiz_capable:
                pid = replace_windowmanager('compiz')
                print('Compiz is PID: ' + str(pid))
            else:
                pid = replace_windowmanager('marco')
                print('Marco is PID: ' + str(pid))
        else:
            print(current_wm + ' is already configured. Doing nothing.')
    else:
        print('Could not find the MATE schema. I have no power here.')