image_recv.cpp

#include <iostream>
#include <vector>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>

#define  oops(msg)  {perror(msg); exit(1);}

int main(int argc, char *argv[])
{
    struct sockaddr_in saddr; 
    struct hostent *hp;
    int sock; 

    if (argc < 3) {
        fprintf(stderr, "ERROR, no port provided");
        exit(1);
    }
    hp = gethostbyname(argv[1]);
    if (hp == NULL) {
        oops("no such computer");
    }
    sock = socket(AF_INET, SOCK_STREAM, 0);
    if (sock == -1) {
        oops("socket");
    }
    bzero(&saddr, sizeof(saddr));
    bcopy(hp->h_addr, (struct sockaddr *)&saddr.sin_addr, hp->h_length);
    saddr.sin_family = AF_INET;
    saddr.sin_port = htons(atoi(argv[2]));
    if (connect(sock, (struct sockaddr *)&saddr, sizeof(saddr)) != 0) {
        oops("connect");
    }

    cv::namedWindow("Display image", cv::CV_WINDOW_AUTOSIZE);
    
    char data_size_str[20] = {0};
    for (;;) {
        recv(sock, data_size_str, 15, 0);    // 读取数据的大小
        int framelen = atoi(data_size_str);  // 文本转化成int
        // 接收压缩后的图像数据
        std::vector<uchar> buff(framelen);
        int bytes = 0;
        for (int i = 0; i < framelen ; i += bytes) {
            if ((bytes = recv(sock, &buff[0]+i, framelen-i, 0)) == -1) {
                oops("Receive");
            }
        }
        // 解压图像
        cv::Mat frame = cv::imdecode(cv::Mat(buff), cv::CV_LOAD_IMAGE_COLOR);
        cv::imshow("Display image", frame);
        cv::waitKey(20);
    }
    close(sock);    
}