image_subscriber.cpp
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00001 /*
00002  * Copyright (c) 2014, Willow Garage, Inc.
00003  * All rights reserved.
00004  *
00005  * Redistribution and use in source and binary forms, with or without
00006  * modification, are permitted provided that the following conditions are met:
00007  *
00008  *     * Redistributions of source code must retain the above copyright
00009  *       notice, this list of conditions and the following disclaimer.
00010  *     * Redistributions in binary form must reproduce the above copyright
00011  *       notice, this list of conditions and the following disclaimer in the
00012  *       documentation and/or other materials provided with the distribution.
00013  *     * Neither the name of the Willow Garage, Inc. nor the names of its
00014  *       contributors may be used to endorse or promote products derived from
00015  *       this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
00018  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
00019  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
00020  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
00021  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
00022  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
00023  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00024  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00025  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
00026  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
00027  * POSSIBILITY OF SUCH DAMAGE.
00028  *
00029  * image_subscriber.cpp
00030  *
00031  *  Created on: Oct 30, 2012
00032  *      Author: jkammerl
00033  */
00034 
00035 #include "image_subscriber.h"
00036 
00037 // Size of image queue -
00038 // a large queue might increase the latency on the video stream
00039 #define IMAGE_BUFFER_SIZE 1
00040 
00041 namespace ros_http_video_streamer
00042 {
00043 
00044 ImageSubscriber::ImageSubscriber(const std::string& topic, const std::string& transport) :
00045     topic_(topic),
00046     transport_(transport),
00047     nh(""),
00048     it(nh),
00049     sub(),
00050     frame_mutex_(),
00051     frame_queue_()
00052 {
00053   if (!topic.empty())
00054   {
00055     subscribe();
00056   }
00057 }
00058 
00059 ImageSubscriber::~ImageSubscriber()
00060 {
00061 //  boost::mutex::scoped_lock lock(frame_mutex_);
00062   sub.reset();
00063 }
00064 
00065 void ImageSubscriber::subscribe()
00066 {
00067   boost::mutex::scoped_lock lock(frame_mutex_);
00068 
00069   sub.reset(new image_transport::SubscriberFilter());
00070   sub->subscribe(it, topic_, 1, image_transport::TransportHints(transport_));
00071   sub->registerCallback(boost::bind(&ImageSubscriber::image_cb, this, _1));
00072 
00073   emptyQueue();
00074 }
00075 
00076 void ImageSubscriber::emptyQueue()
00077 {
00078   frame_queue_.clear();
00079 }
00080 
00081 void ImageSubscriber::image_cb(const sensor_msgs::ImageConstPtr& msg)
00082 {
00083   boost::mutex::scoped_lock lock(frame_mutex_);
00084 
00085   sensor_msgs::ImageConstPtr new_msg = sensor_msgs::ImageConstPtr(new const sensor_msgs::Image(*msg));
00086 
00087   frame_queue_.push_front(new_msg);
00088 
00089   while (frame_queue_.size() > IMAGE_BUFFER_SIZE)
00090     frame_queue_.pop_back();
00091 }
00092 
00093 void ImageSubscriber::getImageFromQueue(sensor_msgs::ImageConstPtr& frame)
00094 {
00095   frame.reset();
00096   {
00097     boost::mutex::scoped_lock lock(frame_mutex_);
00098 
00099     // if queue not empty..
00100     if (frame_queue_.size())
00101     {
00102       // pop frame from back of queue
00103       frame = frame_queue_.back();
00104       frame_queue_.pop_back();
00105     }
00106   }
00107 }
00108 
00109 } // ros_http_video_streamer


ros_web_video
Author(s): Julius Kammer
autogenerated on Fri Aug 28 2015 12:38:36