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network_camera_receiver/CMakeLists.txt

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+# ============================================================================
+# network_camera_receiver —— 静态库
+# 仅负责从网络视频流抓取最新帧，不包含任何人脸检测逻辑、不依赖 libfacedetection。
+# ============================================================================
+
+add_library(network_camera_receiver STATIC
+    src/network_camera_receiver.cpp
+)
+
+target_include_directories(network_camera_receiver PUBLIC
+    ${CMAKE_CURRENT_SOURCE_DIR}/include
+)
+
+# OpenCV 用于视频采集；Threads 用于后台抓帧线程。
+# 设为 PUBLIC，链接本库的目标可传递获得这些依赖。
+target_link_libraries(network_camera_receiver PUBLIC
+    ${OpenCV_LIBS}
+    Threads::Threads
+)
+
+if(CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
+    target_compile_options(network_camera_receiver PRIVATE -O3)
+elseif(MSVC)
+    target_compile_options(network_camera_receiver PRIVATE /O2)
+endif()

network_camera_receiver/include/network_camera_receiver.h

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+/*
+ * @Author: Liu zhenyu
+ * @Description: 网络摄像头接收器（重构版）
+ *               仅负责从视频流抓取最新帧，不做任何检测/显示。
+ *               主程序通过 getLatestFrame() 拉取最新帧后自行处理。
+ */
+
+#ifndef NETWORK_CAMERA_RECEIVER_H
+#define NETWORK_CAMERA_RECEIVER_H
+
+#include <opencv2/opencv.hpp>
+#include <string>
+#include <thread>
+#include <mutex>
+#include <atomic>
+
+class NetworkCameraReceiver {
+public:
+    NetworkCameraReceiver(const std::string& host_ip, int port = 5000);
+    ~NetworkCameraReceiver();
+
+    // 打开视频流
+    bool connect();
+    // 启动后台抓帧线程（不阻塞）
+    void start();
+    // 停止抓帧线程并 join
+    void stop();
+    // 取最新帧（深拷贝到 out）；自上次取帧后若无新帧则返回 false
+    bool getLatestFrame(cv::Mat& out);
+    // 视频流是否已打开
+    bool isOpened() const;
+
+private:
+    // 后台抓帧循环
+    void captureLoop();
+
+    std::string stream_url;
+    cv::VideoCapture cap;
+
+    std::thread capture_thread;
+    std::mutex mtx;                 // 保护 latest_frame
+    cv::Mat latest_frame;           // 最新一帧
+    std::atomic<bool> has_new_frame{false};
+    std::atomic<bool> running{false};
+};
+
+#endif // NETWORK_CAMERA_RECEIVER_H

network_camera_receiver/src/network_camera_receiver.cpp

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+/*
+ * @Author: Liu zhenyu
+ * @Description: 网络摄像头接收器（重构版）实现
+ *               后台线程持续抓帧并更新最新帧缓冲；主线程按需拉取。
+ */
+
+#include "network_camera_receiver.h"
+#include <iostream>
+#include <chrono>
+
+NetworkCameraReceiver::NetworkCameraReceiver(const std::string& host_ip, int port) {
+    stream_url = "http://" + host_ip + ":" + std::to_string(port) + "/video";
+}
+
+NetworkCameraReceiver::~NetworkCameraReceiver() {
+    stop();
+    if (cap.isOpened()) cap.release();
+}
+
+bool NetworkCameraReceiver::connect() {
+    std::cout << "尝试连接到视频流: " << stream_url << std::endl;
+    cap.open(stream_url);
+    if (!cap.isOpened()) {
+        std::cerr << "无法打开视频流: " << stream_url << std::endl;
+        return false;
+    }
+    std::cout << "视频流连接成功。" << std::endl;
+    return true;
+}
+
+bool NetworkCameraReceiver::isOpened() const {
+    return cap.isOpened();
+}
+
+void NetworkCameraReceiver::start() {
+    // 已在运行则直接返回
+    if (running.exchange(true)) return;
+    capture_thread = std::thread(&NetworkCameraReceiver::captureLoop, this);
+}
+
+void NetworkCameraReceiver::stop() {
+    // 未运行则直接返回
+    if (!running.exchange(false)) return;
+    if (capture_thread.joinable()) capture_thread.join();
+}
+
+void NetworkCameraReceiver::captureLoop() {
+    cv::Mat frame;
+    while (running.load()) {
+        cap >> frame;
+        if (frame.empty()) {
+            // 流暂未就绪或读取失败，稍作等待避免空转占满 CPU
+            std::this_thread::sleep_for(std::chrono::milliseconds(10));
+            continue;
+        }
+        {
+            std::lock_guard<std::mutex> lock(mtx);
+            // 仅保留最新一帧，旧帧直接丢弃
+            frame.copyTo(latest_frame);
+        }
+        has_new_frame.store(true);
+    }
+}
+
+bool NetworkCameraReceiver::getLatestFrame(cv::Mat& out) {
+    if (!has_new_frame.load()) return false;
+    // 先清标记：若在此期间后台又写入新帧，标记会被再次置 true，下一轮可取到
+    has_new_frame.store(false);
+    std::lock_guard<std::mutex> lock(mtx);
+    if (latest_frame.empty()) return false;
+    latest_frame.copyTo(out);
+    return true;
+}