ZmqPubExtractor.cpp

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#include <ZmqPubExtractor.h>

#include <iostream>

#include <stringtricks.h>

using namespace std;

ZmqPubExtractor::ZmqPubExtractor(zmq::context_t & _ctx,
                                 const PubSubEndpoint & _source,
                                 const PubSubEndpoint & _destination,
                                 const Roi<unsigned int> & _roi):
        Extractor(_ctx, _source), destination(_destination), roi(_roi) {
}

ZmqPubExtractor::~ZmqPubExtractor() {

}

std::string ZmqPubExtractor::type() {
    return "zmqPub";
}

std::string ZmqPubExtractor::identifier() {
    return destination.topic;
}

std::list<std::string> ZmqPubExtractor::parameters() {
    return {SSTR(roi.x), SSTR(roi.y), SSTR(roi.width), SSTR(roi.height)};
}

void ZmqPubExtractor::extractSetup() {
    destinationSocket = new zmq::socket_t(ctx, ZMQ_PUB);
    destinationSocket->connect(destination.endpoint.c_str());
}

void ZmqPubExtractor::extractImpl(unsigned int width,
                                  unsigned int height,
                                  unsigned int bytesPerPixel,
                                  uint64_t highResTime,
                                  uint64_t wallTime,
                                  zmq::message_t * sourceImage) {
    (void) highResTime;
    (void) wallTime;

    zmq::message_t header(destination.topic.length());
    memcpy(header.data(), destination.topic.c_str(), destination.topic.length());
    destinationSocket->send(header, ZMQ_SNDMORE);

    /* TODO: maybe stop preview transmission if too many packets are on the way.
             This might be helpful:

        zmq::message_t data(((char*)sourceImage->data()) + (((roi.y * width) + roi.x) * bytesPerPixel),
                            roi.width * roi.height * bytesPerPixel,
                            cbWrapper,
                            new std::function<void()>([=]{delete sourceImage;}));
        destinationSocket->send(data);
    */

    zmq::message_t dimensions(5 * 4); /* width, height, bytesPerPixel, extract_width, extract_height [uint32] */
    insertNetworkUInt32(((char*)dimensions.data()) + 0, width);
    insertNetworkUInt32(((char*)dimensions.data()) + 4, height);
    insertNetworkUInt32(((char*)dimensions.data()) + 8, bytesPerPixel);
    insertNetworkUInt32(((char*)dimensions.data()) + 12, roi.width);
    insertNetworkUInt32(((char*)dimensions.data()) + 16, roi.height);
    destinationSocket->send(dimensions, ZMQ_SNDMORE);
    
    if(roi.width > width) {
        roi.width = width;
    }
    if(roi.height > height) {
        roi.height = height;
    }

    /* we want to free the image buffer as fast as possible, so we copy our roi
       even in cases where the data is in the right shape already */
    zmq::message_t destinationImage(roi.width * roi.height * bytesPerPixel);
    for(unsigned int i = 0; i < roi.height; ++i) {
        memcpy(((char*)destinationImage.data()) + i * roi.width * bytesPerPixel,
               ((char*)sourceImage->data()) + ((((roi.y + i) * width) + roi.x) * bytesPerPixel),
               roi.width * bytesPerPixel);
    }
    delete sourceImage;
    destinationSocket->send(destinationImage);
}

void ZmqPubExtractor::extractTeardown() {
    delete destinationSocket;
}