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Development Team/Almanac/GStreamer (view source)

Revision as of 14:29, 2 February 2011

9,045 bytes added ,  14:29, 2 February 2011
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{{Sugar Almanac}}
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{{Almanac}}
    
=== Where can I get additional resources and sample code on using the camera? ===
 
=== Where can I get additional resources and sample code on using the camera? ===
 
* [[Programming_the_camera]]
 
* [[Programming_the_camera]]
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 +
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=== How can I embed video files in my activity? ===
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Sugar, by default, can play back audio (encoded in Vorbis) and video (encoded in Theora) files in ogg containers.
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The following file will be helpful for embedding video or audio files into your activity.  After the code posting is a code snippet showing how to use this.
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<pre>
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import gtk
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import pygtk
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pygtk.require('2.0')
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import sys
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import pygst
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pygst.require('0.10')
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import gst
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import gst.interfaces
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import gobject
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import time
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gobject.threads_init()
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class Gplay:
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def __init__(self):
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self.window = None
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self.playing = False
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self.player = gst.element_factory_make("playbin", "playbin")
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xis = gst.element_factory_make("xvimagesink", "xvimagesink")
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self.player.set_property("video-sink", xis)
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bus = self.player.get_bus()
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bus.enable_sync_message_emission()
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bus.add_signal_watch()
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self.SYNC_ID = bus.connect('sync-message::element', self._onSyncMessageCb)
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def _onSyncMessageCb(self, bus, message):
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if message.structure is None:
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return True
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if message.structure.get_name() == 'prepare-xwindow-id':
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self.window.set_sink(message.src)
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message.src.set_property('force-aspect-ratio', True)
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return True
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def setFile(self, path):
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uri = "file://" + str( path )
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if self.player.get_property('uri') == uri:
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self.seek(gst.SECOND*0)
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return
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self.player.set_state(gst.STATE_READY)
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self.player.set_property('uri', uri)
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ext = uri[len(uri)-3:]
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if ext == "jpg":
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self.pause()
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else:
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self.play()
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def queryPosition(self):
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#"Returns a (position, duration) tuple"
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try:
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position, format = self.player.query_position(gst.FORMAT_TIME)
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except:
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position = gst.CLOCK_TIME_NONE
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try:
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duration, format = self.player.query_duration(gst.FORMAT_TIME)
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except:
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duration = gst.CLOCK_TIME_NONE
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return (position, duration)
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def seek(self, time):
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event = gst.event_new_seek(1.0, gst.FORMAT_TIME, gst.SEEK_FLAG_FLUSH | gst.SEEK_FLAG_ACCURATE, gst.SEEK_TYPE_SET, time, gst.SEEK_TYPE_NONE, 0)
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res = self.player.send_event(event)
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if res:
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self.player.set_new_stream_time(0L)
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def pause(self):
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self.playing = False
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self.player.set_state(gst.STATE_PAUSED)
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def play(self):
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self.playing = True
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self.player.set_state(gst.STATE_PLAYING)
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def stop(self):
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self.playing = False
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self.player.set_state(gst.STATE_NULL)
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self.nextMovie()
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def get_state(self, timeout=1):
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return self.player.get_state(timeout=timeout)
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def is_playing(self):
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return self.playing
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class PlayVideoWindow(gtk.Window):
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def __init__(self):
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gtk.Window.__init__(self)
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self.imagesink = None
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self.unset_flags(gtk.DOUBLE_BUFFERED)
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self.set_flags(gtk.APP_PAINTABLE)
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def set_sink(self, sink):
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if self.imagesink != None:
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assert self.window.xid
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self.imagesink = None
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del self.imagesink
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self.imagesink = sink
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self.imagesink.set_xwindow_id(self.window.xid)
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</pre>
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And here is a code snippet showing how you would use this file to embed media playback in your activity:
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<pre>
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#this is our video playback window
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self.gplay = Gplay( )
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self.gplayWin = PlayVideoWindow( )
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self.gplay.window = self.gplayWin
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self.gplayWin.set_type_hint( gtk.gdk.WINDOW_TYPE_HINT_DIALOG )
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self.gplayWin.set_decorated( False )
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self.gplayWin.set_transient_for( self ) #activity subclass
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self.gplayWin.move( 100, 100 )
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self.gplayWin.resize( 300, 400 )
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self.gplayWin.show_all( )
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</pre>
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Alternatively, you could embed your video into a gtk.DrawingArea:
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<pre>
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class VideoWidget(gtk.DrawingArea):
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    def __init__(self):
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        gtk.DrawingArea.__init__(self)
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        self.set_events(gtk.gdk.POINTER_MOTION_MASK |
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        gtk.gdk.POINTER_MOTION_HINT_MASK |
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        gtk.gdk.EXPOSURE_MASK |
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        gtk.gdk.KEY_PRESS_MASK |
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        gtk.gdk.KEY_RELEASE_MASK)
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        self.imagesink = None
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        self.unset_flags(gtk.DOUBLE_BUFFERED)
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        self.set_flags(gtk.APP_PAINTABLE)
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    def do_expose_event(self, event):
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        if self.imagesink:
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            self.imagesink.expose()
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            return False
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        else:
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            return True
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    def set_sink(self, sink):
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        assert self.window.xid
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        self.imagesink = sink
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        self.imagesink.set_xwindow_id(self.window.xid)
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</pre>
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=== How can I add play/pause buttons and a scrubber to my audio or video? ===
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The widget below is pre-configured to work with the gplay class above.  This widget takes two gtk.Images in its constructor.
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<pre>
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import gtk
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import pygtk
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pygtk.require('2.0')
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import pygst
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pygst.require('0.10')
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import gst
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import gst.interfaces
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import gobject
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import sugar.graphics.style
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class GScrub(gtk.Window):
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def __init__(self, gplay, playImg, pauseImg):
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gtk.Window.__init__(self)
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self._gplay = gplay
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self._playImg = playImg
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self._pauseImg = pauseImg
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self.UPDATE_INTERVAL = 500
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self.UPDATE_SCALE_ID = 0
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self.CHANGED_ID = 0
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self.was_playing = False
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self.p_position = gst.CLOCK_TIME_NONE
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self.p_duration = gst.CLOCK_TIME_NONE
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self.hbox = gtk.HBox()
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self.hbox.modify_bg( gtk.STATE_NORMAL, sugar.graphics.style.COLOR_BLACK.get_gdk_color() )
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self.hbox.modify_bg( gtk.STATE_INSENSITIVE, sugar.graphics.style.COLOR_BLACK.get_gdk_color() )
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self.add( self.hbox )
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self.button = gtk.Button()
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buttBox = gtk.EventBox()
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buttBox.add(self.button)
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buttBox.modify_bg( gtk.STATE_NORMAL, sugar.graphics.style.COLOR_BLACK.get_gdk_color() )
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self.button.set_image( self._playImg )
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self.button.set_property('can-default', True)
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self.button.set_relief(gtk.RELIEF_NONE)
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self.button.set_size_request( 55, 55 )
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buttBox.set_size_request( 55, 55 )
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self.button.show()
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buttBox.modify_bg( gtk.STATE_NORMAL, sugar.graphics.style.COLOR_BLACK.get_gdk_color() )
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self.button.modify_bg( gtk.STATE_ACTIVE, sugar.graphics.style.COLOR_BLACK.get_gdk_color() )
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self.button.connect('clicked', self._buttonClickedCb)
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self.hbox.pack_start(buttBox, expand=False)
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self.adjustment = gtk.Adjustment(0.0, 0.00, 100.0, 0.1, 1.0, 1.0)
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self.hscale = gtk.HScale(self.adjustment)
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self.hscale.set_draw_value(False)
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self.hscale.set_update_policy(gtk.UPDATE_CONTINUOUS)
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hscaleBox = gtk.EventBox()
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hscaleBox.modify_bg( gtk.STATE_NORMAL, sugar.graphics.style.COLOR_BLACK.get_gdk_color() )
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hscaleBox.add( self.hscale )
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self.hscale.connect('button-press-event', self._scaleButtonPressCb)
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self.hscale.connect('button-release-event', self._scaleButtonReleaseCb)
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self.hbox.pack_start(hscaleBox, expand=True)
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def removeCallbacks( self ):
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if self.UPDATE_SCALE_ID != 0:
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gobject.source_remove(self.UPDATE_SCALE_ID)
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self.UPDATE_SCALE_ID = 0
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if self.CHANGED_ID != 0:
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gobject.source_remove(self.CHANGED_ID)
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self.CHANGED_ID = 0
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def reset(self):
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self.adjustment.set_value(0)
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def _buttonClickedCb(self, widget):
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self.play_toggled()
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def set_button_play(self):
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self.button.set_image(self._playImg)
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def set_button_pause(self):
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self.button.set_image(self._pauseImg)
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def play_toggled(self):
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self.p_position, self.p_duration = self._gplay.queryPosition()
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if self.p_position == self.p_duration:
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self._gplay.seek(0)
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self._gplay.pause()
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if self._gplay.is_playing():
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self._gplay.pause()
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self.set_button_play()
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else:
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#if self._gplay.error:
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# #todo: check if we have "error", and also to disable everything
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# self.button.set_disabled()
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#else:
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self.doPlay()
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def doPlay(self):
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self._gplay.play()
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if self.UPDATE_SCALE_ID == 0:
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self.UPDATE_SCALE_ID = gobject.timeout_add(self.UPDATE_INTERVAL, self._updateScaleCb)
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self.set_button_pause()
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def _scaleButtonPressCb(self, widget, event):
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#self.button.set_sensitive(False)
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self.was_playing = self._gplay.is_playing()
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if self.was_playing:
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self._gplay.pause()
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# don't timeout-update position during seek
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if self.UPDATE_SCALE_ID != 0:
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gobject.source_remove(self.UPDATE_SCALE_ID)
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self.UPDATE_SCALE_ID = 0
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# make sure we get changed notifies
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if self.CHANGED_ID == 0:
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self.CHANGED_ID = self.hscale.connect('value-changed', self._scaleValueChangedCb)
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def _scaleButtonReleaseCb(self, widget, event):
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# see seek.cstop_seek
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widget.disconnect(self.CHANGED_ID)
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self.CHANGED_ID = 0
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#self.button.set_sensitive(True)
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if self.was_playing:
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self._gplay.play()
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if self.UPDATE_SCALE_ID != 0:
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pass
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#print('Had a previous update timeout id')
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else:
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self.UPDATE_SCALE_ID = gobject.timeout_add(self.UPDATE_INTERVAL, self._updateScaleCb)
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def _scaleValueChangedCb(self, scale):
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real = long(scale.get_value() * self.p_duration / 100) # in ns
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self._gplay.seek(real)
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# allow for a preroll
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self._gplay.get_state(timeout=50*gst.MSECOND) # 50 ms
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def _updateScaleCb(self):
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self.p_position, self.p_duration = self._gplay.queryPosition()
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if self.p_position != gst.CLOCK_TIME_NONE:
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value = self.p_position * 100.0 / self.p_duration
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if value > 99:
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value = 99
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elif value < 0:
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value = 0
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self.adjustment.set_value(value)
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if self._gplay.is_playing() and self.p_position == self.p_duration:
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self._gplay.pause()
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self.set_button_play()
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return True
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</pre>
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