python-kivy 1.7.2-1 / usr / share / pyshared / kivy / support.py

'''
Support
=======

Activate other framework/toolkit inside our event loop
'''

__all__ = ('install_gobject_iteration', 'install_twisted_reactor',
    'install_android')


def install_gobject_iteration():
    '''Import and install gobject context iteration inside our event loop.
    This is used as soon as gobject is used (like gstreamer)
    '''

    from kivy.clock import Clock
    import gobject
    if hasattr(gobject, '_gobject_already_installed'):
        # already installed, don't do it twice.
        return

    gobject._gobject_already_installed = True

    # get gobject mainloop / context
    loop = gobject.MainLoop()
    gobject.threads_init()
    context = loop.get_context()

    # schedule the iteration each frame
    def _gobject_iteration(*largs):
        # XXX we need to loop over context here, otherwise, we might have a lag.
        loop = 0
        while context.pending() and loop < 10:
            context.iteration(False)
            loop += 1
    Clock.schedule_interval(_gobject_iteration, 0)

# -----------------------------------------------------------------------------
# Android support
# -----------------------------------------------------------------------------

g_android_redraw_count = 0


def _android_ask_redraw(*largs):
    # after wakeup, we need to redraw more than once, otherwise we get a
    # black screen
    global g_android_redraw_count
    from kivy.core.window import Window
    Window.canvas.ask_update()
    g_android_redraw_count -= 1
    if g_android_redraw_count < 0:
        return False


def install_android():
    '''Install hooks for android platform.

    * Automaticly sleep when the device is paused
    * Auto kill the application is the return key is hitted
    '''
    try:
        import android
    except ImportError:
        print 'Android lib is missing, cannot install android hooks'
        return

    from kivy.clock import Clock
    from kivy.logger import Logger
    import pygame

    Logger.info('Support: Android install hooks')

    # Init the library
    android.init()
    android.map_key(android.KEYCODE_MENU, pygame.K_MENU)
    android.map_key(android.KEYCODE_BACK, pygame.K_ESCAPE)

    # Check if android must be paused or not
    # If pause is asked, just leave the app.
    def android_check_pause(*largs):
        # do nothing until android ask for it.
        if not android.check_pause():
            return

        from kivy.app import App
        from kivy.base import stopTouchApp
        from kivy.logger import Logger
        from kivy.core.window import Window
        global g_android_redraw_count

        # try to get the current running application
        Logger.info('Android: Must to in sleep mode, check the app')
        app = App.get_running_app()

        # no running application, stop our loop.
        if app is None:
            Logger.info('Android: No app running, stop everything.')
            stopTouchApp()
            return

        # try to go to pause mode
        if app.dispatch('on_pause'):
            Logger.info('Android: App paused, now wait for resume.')

            # app goes in pause mode, wait.
            android.wait_for_resume()

            # is it a stop or resume ?
            if android.check_stop():
                # app must stop
                Logger.info('Android: Android want to close our app.')
                stopTouchApp()
            else:
                # app resuming now !
                Logger.info('Android: Android resumed, resume the app')
                app.dispatch('on_resume')
                Window.canvas.ask_update()
                g_android_redraw_count = 25  # 5 frames/seconds during 5 seconds
                Clock.unschedule(_android_ask_redraw)
                Clock.schedule_interval(_android_ask_redraw, 1 / 5)
                Logger.info('Android: App resume completed.')

        # app don't support pause mode, just stop it.
        else:
            Logger.info('Android: App doesn\'t support pause mode, stop.')
            stopTouchApp()

    Clock.schedule_interval(android_check_pause, 0)


def install_twisted_reactor(**kwargs):
    '''Installs a threaded twisted reactor, which will schedule one
    reactor iteration before the next frame only when twisted needs
    to do some work.

    any arguments or keyword arguments passed to this function will be
    passed on the the threadedselect reactors interleave function, these
    are the arguments one would usually pass to twisted's reactor.startRunning

    Unlike the default twisted reactor, the installed reactor will not handle
    any signals unnless you set the 'installSignalHandlers' keyword argument
    to 1 explicitly.  This is done to allow kivy to handle teh signals as
    usual, unless you specifically want the twisted reactor to handle the
    signals (e.g. SIGINT).'''
    import twisted

    # prevent installing more than once
    if hasattr(twisted, '_kivy_twisted_reactor_installed'):
        return
    twisted._kivy_twisted_reactor_installed = True

    # dont let twisted handle signals, unless specifically requested
    kwargs.setdefault('installSignalHandlers', 0)

    # install threaded-select reactor, to use with own event loop
    from twisted.internet import _threadedselect
    _threadedselect.install()

    # now we can import twisted reactor as usual
    from twisted.internet import reactor
    from collections import deque
    from kivy.base import EventLoop
    from kivy.logger import Logger
    from kivy.clock import Clock

    # will hold callbacks to twisted callbacks
    q = deque()

    # twisted will call the wake function when it needsto do work
    def reactor_wake(twisted_loop_next):
        Logger.trace("Support: twisted wakeup call to schedule task")
        q.append(twisted_loop_next)

    # called every frame, to process the reactors work in main thread
    def reactor_work(*args):
        Logger.trace("Support: processing twisted task queue")
        while len(q):
            q.popleft()()

    # start the reactor, by telling twisted how to wake, and process
    def reactor_start(*args):
        Logger.info("Support: Starting twisted reactor")
        reactor.interleave(reactor_wake, **kwargs)
        Clock.schedule_interval(reactor_work, 0)

    # make sure twisted reactor is shutdown if eventloop exists
    def reactor_stop(*args):
        '''will shutdown the twisted reactor main loop
        '''
        if reactor.threadpool:
            Logger.info("Support: Stooping twisted threads")
            reactor.threadpool.stop()
        Logger.info("Support: Shutting down twisted reactor")
        reactor._mainLoopShutdown()

    # start and stop teh reactor along with kivy EventLoop
    EventLoop.bind(on_start=reactor_start)
    EventLoop.bind(on_stop=reactor_stop)