buffer.py

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# Copyright (c) 2008, Willow Garage, Inc.
# All rights reserved.
# 
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
# 
#     * Redistributions of source code must retain the above copyright
#       notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above copyright
#       notice, this list of conditions and the following disclaimer in the
#       documentation and/or other materials provided with the distribution.
#     * Neither the name of the Willow Garage, Inc. nor the names of its
#       contributors may be used to endorse or promote products derived from
#       this software without specific prior written permission.
# 
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# POSSIBILITY OF SUCH DAMAGE.

# author: Wim Meeussen

import roslib; roslib.load_manifest('tf2_ros')
import rospy
import tf2
import tf2_ros
from tf2_msgs.srv import FrameGraph, FrameGraphResponse
import rosgraph.masterapi

class Buffer(tf2.BufferCore, tf2_ros.BufferInterface):
    def __init__(self, cache_time = None, debug = True):
        if cache_time != None:
            tf2.BufferCore.__init__(self, cache_time)
        else:
            tf2.BufferCore.__init__(self)
        tf2_ros.BufferInterface.__init__(self)

        if debug:
            #Check to see if the service has already been advertised in this node
            try:
                m = rosgraph.masterapi.Master(rospy.get_name())
                m.lookupService('~tf2_frames')
            except (rosgraph.masterapi.Error, rosgraph.masterapi.Failure):   
                self.frame_server = rospy.Service('~tf2_frames', FrameGraph, self.__get_frames)

    def __get_frames(self, req):
       return FrameGraphResponse(self.all_frames_as_yaml()) 
        
    # lookup, simple api 
    def lookup_transform(self, target_frame, source_frame, time, timeout=rospy.Duration(0.0)):
        self.can_transform(target_frame, source_frame, time, timeout)
        return self.lookup_transform_core(target_frame, source_frame, time)

    # lookup, advanced api 
    def lookup_transform_full(self, target_frame, target_time, source_frame, source_time, fixed_frame, timeout=rospy.Duration(0.0)):
        self.can_transform_full(target_frame, target_time, source_frame, source_time, fixed_frame, timeout)
        return self.lookup_transform_full_core(target_frame, target_time, source_frame, source_time, fixed_frame)


    # can, simple api
    def can_transform(self, target_frame, source_frame, time, timeout=rospy.Duration(0.0)):
        if timeout != rospy.Duration(0.0):
            start_time = rospy.Time.now()
            while (rospy.Time.now() < start_time + timeout and 
                   not self.can_transform_core(target_frame, source_frame, time)):
                rospy.Duration(0.05).sleep()
        return self.can_transform_core(target_frame, source_frame, time)
    
    # can, advanced api
    def can_transform_full(self, target_frame, target_time, source_frame, source_time, fixed_frame, timeout=rospy.Duration(0.0)):
        if timeout != rospy.Duration(0.0):
            start_time = rospy.Time.now()
            while (rospy.Time.now() < start_time + timeout and 
                   not self.can_transform_full_core(target_frame, target_time, source_frame, source_time, fixed_frame)):
                rospy.Duration(0.05).sleep()
        return self.can_transform_full_core(target_frame, target_time, source_frame, source_time, fixed_frame)