LCM库——c++封装（二）

说明

C++支持代码主要集中在lcm-cpp.hpp和lcm-cpp-impl.hpp两个文件中

简单用例

读消息

#include <stdio.h>
#include <lcm/lcm-cpp.hpp>
#include "exlcm/example_t.hpp"

class Handler {
  public:
    ~Handler() {}
    void handleMessage(const lcm::ReceiveBuffer *rbuf, const std::string &chan,
                       const exlcm::example_t *msg)
    {
        int i;
        printf("Received message on channel \"%s\":\n", chan.c_str());
        printf("  timestamp   = %lld\n", (long long) msg->timestamp);
        printf("  position    = (%f, %f, %f)\n", msg->position[0], msg->position[1],
               msg->position[2]);
        printf("  orientation = (%f, %f, %f, %f)\n", msg->orientation[0], msg->orientation[1],
               msg->orientation[2], msg->orientation[3]);
        printf("  ranges:");
        for (i = 0; i < msg->num_ranges; i++)
            printf(" %d", msg->ranges[i]);
        printf("\n");
        printf("  name        = '%s'\n", msg->name.c_str());
        printf("  enabled     = %d\n", msg->enabled);
    }
};

int main(int argc, char **argv)
{
    lcm::LCM lcm;

    if (!lcm.good())
        return 1;

    Handler handlerObject;
    lcm.subscribe("EXAMPLE", &Handler::handleMessage, &handlerObject);

    while (0 == lcm.handle()) {
        // Do nothing
    }
    return 0;
}

发消息

#include <lcm/lcm-cpp.hpp>
#include "exlcm/example_t.hpp"

int main(int argc, char **argv)
{
    lcm::LCM lcm;
    if (!lcm.good())
        return 1;

    exlcm::example_t my_data;
    my_data.timestamp = 0;

    my_data.position[0] = 1;
    my_data.position[1] = 2;
    my_data.position[2] = 3;

    my_data.orientation[0] = 1;
    my_data.orientation[1] = 0;
    my_data.orientation[2] = 0;
    my_data.orientation[3] = 0;

    my_data.num_ranges = 15;
    my_data.ranges.resize(my_data.num_ranges);
    for (int i = 0; i < my_data.num_ranges; i++)
        my_data.ranges[i] = i;

    my_data.name = "example string";
    my_data.enabled = true;

    lcm.publish("EXAMPLE", &my_data);
    return 0;
}

读Log

#include <stdio.h>
#include <lcm/lcm-cpp.hpp>
#include "exlcm/example_t.hpp"

int main(int argc, char **argv)
{
    if (argc < 2) {
        fprintf(stderr, "usage: read_log <logfile>\n");
        return 1;
    }

    // Open the log file.
    lcm::LogFile log(argv[1], "r");
    if (!log.good()) {
        perror("LogFile");
        fprintf(stderr, "couldn't open log file %s\n", argv[1]);
        return 1;
    }

    while (1) {
        // Read a log event.
        const lcm::LogEvent *event = log.readNextEvent();
        if (!event)
            break;

        // Only process messages on the EXAMPLE channel.
        if (event->channel != "EXAMPLE")
            continue;

        // Try to decode the message.
        exlcm::example_t msg;
        if (msg.decode(event->data, 0, event->datalen) != event->datalen)
            continue;

        // Decode success!  Print out the message contents.
        printf("Message:\n");
        printf("  timestamp   = %lld\n", (long long) msg.timestamp);
        printf("  position    = (%f, %f, %f)\n", msg.position[0], msg.position[1], msg.position[2]);
        printf("  orientation = (%f, %f, %f, %f)\n", msg.orientation[0], msg.orientation[1],
               msg.orientation[2], msg.orientation[3]);
        printf("  ranges:");
        for (int i = 0; i < msg.num_ranges; i++)
            printf(" %d", msg.ranges[i]);
        printf("\n");
        printf("  name        = '%s'\n", msg.name.c_str());
        printf("  enabled     = %d\n", msg.enabled);
    }

    // Log file is closed automatically when the log variable goes out of
    // scope.
    printf("done\n");
    return 0;
}