tools/scan-view/startfile.py

"""Utility for opening a file using the default application in a cross-platform
manner. Modified from http://code.activestate.com/recipes/511443/.
"""

__version__ = '1.1x'
__all__ = ['open']

import os
import sys
import webbrowser
import subprocess

_controllers = {}
_open = None


class BaseController(object):
    '''Base class for open program controllers.'''

    def __init__(self, name):
        self.name = name

    def open(self, filename):
        raise NotImplementedError


class Controller(BaseController):
    '''Controller for a generic open program.'''

    def __init__(self, *args):
        super(Controller, self).__init__(os.path.basename(args[0]))
        self.args = list(args)

    def _invoke(self, cmdline):
        if sys.platform[:3] == 'win':
            closefds = False
            startupinfo = subprocess.STARTUPINFO()
            startupinfo.dwFlags |= subprocess.STARTF_USESHOWWINDOW
        else:
            closefds = True
            startupinfo = None

        if (os.environ.get('DISPLAY') or sys.platform[:3] == 'win' or
                                                    sys.platform == 'darwin'):
            inout = file(os.devnull, 'r+')
        else:
            # for TTY programs, we need stdin/out
            inout = None

        # if possible, put the child precess in separate process group,
        # so keyboard interrupts don't affect child precess as well as
        # Python
        setsid = getattr(os, 'setsid', None)
        if not setsid:
            setsid = getattr(os, 'setpgrp', None)

        pipe = subprocess.Popen(cmdline, stdin=inout, stdout=inout,
                                stderr=inout, close_fds=closefds,
                                preexec_fn=setsid, startupinfo=startupinfo)

        # It is assumed that this kind of tools (gnome-open, kfmclient,
        # exo-open, xdg-open and open for OSX) immediately exit after lauching
        # the specific application
        returncode = pipe.wait()
        if hasattr(self, 'fixreturncode'):
            returncode = self.fixreturncode(returncode)
        return not returncode

    def open(self, filename):
        if isinstance(filename, basestring):
            cmdline = self.args + [filename]
        else:
            # assume it is a sequence
            cmdline = self.args + filename
        try:
            return self._invoke(cmdline)
        except OSError:
            return False


# Platform support for Windows
if sys.platform[:3] == 'win':

    class Start(BaseController):
        '''Controller for the win32 start progam through os.startfile.'''

        def open(self, filename):
            try:
                os.startfile(filename)
            except WindowsError:
                # [Error 22] No application is associated with the specified
                # file for this operation: '<URL>'
                return False
            else:
                return True

    _controllers['windows-default'] = Start('start')
    _open = _controllers['windows-default'].open


# Platform support for MacOS
elif sys.platform == 'darwin':
    _controllers['open']= Controller('open')
    _open = _controllers['open'].open


# Platform support for Unix
else:

    import commands

    # @WARNING: use the private API of the webbrowser module
    from webbrowser import _iscommand

    class KfmClient(Controller):
        '''Controller for the KDE kfmclient program.'''

        def __init__(self, kfmclient='kfmclient'):
            super(KfmClient, self).__init__(kfmclient, 'exec')
            self.kde_version = self.detect_kde_version()

        def detect_kde_version(self):
            kde_version = None
            try:
                info = commands.getoutput('kde-config --version')

                for line in info.splitlines():
                    if line.startswith('KDE'):
                        kde_version = line.split(':')[-1].strip()
                        break
            except (OSError, RuntimeError):
                pass

            return kde_version

        def fixreturncode(self, returncode):
            if returncode is not None and self.kde_version > '3.5.4':
                return returncode
            else:
                return os.EX_OK

    def detect_desktop_environment():
        '''Checks for known desktop environments

        Return the desktop environments name, lowercase (kde, gnome, xfce)
        or "generic"

        '''

        desktop_environment = 'generic'

        if os.environ.get('KDE_FULL_SESSION') == 'true':
            desktop_environment = 'kde'
        elif os.environ.get('GNOME_DESKTOP_SESSION_ID'):
            desktop_environment = 'gnome'
        else:
            try:
                info = commands.getoutput('xprop -root _DT_SAVE_MODE')
                if ' = "xfce4"' in info:
                    desktop_environment = 'xfce'
            except (OSError, RuntimeError):
                pass

        return desktop_environment


    def register_X_controllers():
        if _iscommand('kfmclient'):
            _controllers['kde-open'] = KfmClient()

        for command in ('gnome-open', 'exo-open', 'xdg-open'):
            if _iscommand(command):
                _controllers[command] = Controller(command)

    def get():
        controllers_map = {
            'gnome': 'gnome-open',
            'kde': 'kde-open',
            'xfce': 'exo-open',
        }

        desktop_environment = detect_desktop_environment()

        try:
            controller_name = controllers_map[desktop_environment]
            return _controllers[controller_name].open

        except KeyError:
            if _controllers.has_key('xdg-open'):
                return _controllers['xdg-open'].open
            else:
                return webbrowser.open


    if os.environ.get("DISPLAY"):
        register_X_controllers()
    _open = get()


def open(filename):
    '''Open a file or an URL in the registered default application.'''

    return _open(filename)