message_view.py

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from python_qt_binding.QtCore import QObject


class MessageView(QObject):
    """
    A message details renderer. When registered with rqt_bag, a MessageView is called
    whenever the timeline playhead moves.
    """
    name = 'Untitled'

    def __init__(self, timeline, topic):
        super(MessageView, self).__init__()
        self.timeline = timeline
        self.topic = topic

    def message_viewed(self, msg_details):
        """View the message.

        :param msg_details: the details of the message to be viewed
        :type msg_details: Message namedtuple (stamp, message). Stamp is the
            timestamp, message is the message received

        """
        pass

    def message_cleared(self):
        """
        Clear the currently viewed message (if any).
        """
        pass

    def timeline_changed(self):
        """
        Called when the messages in a timeline change, e.g. if a new message is recorded, or
        a bag file is added
        """
        pass

    def close(self):
        """
        Close the message view, releasing any resources.
        """
        pass

# NOTE: event function should not be changed in subclasses
    def event(self, event):
        """
        This function will be called to process events posted by post_event
        it will call message_cleared or message_viewed with the relevant data
        """
        msg_data = event.data
        if msg_data:
            self.message_viewed(msg_data)
        else:
            self.message_cleared()
        return True