Send cv::Mat with FIFO

code/C++/.clang-format

@@ -2,4 +2,8 @@ Language: Cpp
 BasedOnStyle: LLVM
 IndentWidth: 2
 ColumnLimit: 132
-SortIncludes: CaseSensitive
+SortIncludes: true
+AlignAfterOpenBracket: DontAlign
+AllowShortIfStatementsOnASingleLine: AllIfsAndElse
+AllowShortLoopsOnASingleLine: true
+# AllowShortNamespacesOnASingleLine: true

code/C++/FIFO_w_OpenCV/.gitignore

@@ -0,0 +1,3 @@
+# xmake
+.xmake/
+build/

code/C++/FIFO_w_OpenCV/README.md

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+Пример отправки и получения `cv::Mat` через FIFO в неблокируемом потоке
+
+⚠️ Параметры изображения, такие как **размеры** и **каналы** не передаются.

code/C++/FIFO_w_OpenCV/reader.cpp

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+#include <fcntl.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/select.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <opencv2/opencv.hpp>
+
+#define FIFO_NAME "cvMat"
+#define MAX_BUF 150 * 150 * 4
+
+using namespace cv;
+
+int main() {
+  unsigned int timeout_seconds = 2;
+
+  while (true) {
+    int fd = open(FIFO_NAME, O_RDONLY | O_NONBLOCK);
+    if (fd < 0) {
+      perror("open");
+      return EXIT_FAILURE;
+    }
+
+    struct pollfd waiter = {.fd = fd, .events = POLLIN};
+
+    while (true) {
+      bool stop = false;
+
+      int poll_result = poll(&waiter, 1, timeout_seconds * 1000);
+      switch (poll_result) {
+      case 0:
+        puts("No data from fifo");
+        break;
+
+      case 1:
+        if (waiter.revents & POLLIN) {
+          std::vector<uchar> buff;
+          char tempBuff[256];
+          ssize_t bytesRead;
+
+          while ((bytesRead = read(fd, tempBuff, sizeof(tempBuff))) > 0) buff.insert(buff.end(), tempBuff, tempBuff + bytesRead);
+          printf("Received: %d\n", buff.size());
+
+          Mat img(cv::Size(810, 1080), CV_8UC3, buff.data());
+          cv::imwrite("received.jpg", img);
+        } else if (waiter.revents & POLLERR) {
+          puts("Got a POLLERR");
+          return EXIT_FAILURE;
+        } else if (waiter.revents & POLLHUP) {
+          stop = true; // Writer closed its end
+          break;
+        }
+        break;
+
+      default:
+        perror("poll error");
+        return EXIT_FAILURE;
+      }
+
+      if (stop) break;
+    }
+
+    if (close(fd) < 0) {
+      perror("close");
+      return EXIT_FAILURE;
+    }
+  }
+
+  return EXIT_SUCCESS;
+}

code/C++/FIFO_w_OpenCV/writer.cpp

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+#include <random>
+#include <vector>
+
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <opencv2/opencv.hpp>
+
+#define FIFO_NAME "cvMat"
+
+// const std::vector<std::string> imageFiles = {"bus.jpg", "cat_dog.jpg", "girl_faces.png"};
+const std::vector<std::string> imageFiles = {"bus.jpg"};
+
+cv::Mat getFrame(const std::string source);
+std::string getRandomImage(std::vector<std::string> images);
+
+int main(int argc, char const *argv[]) {
+  if (!mkfifo(FIFO_NAME, 0666)) {
+    std::perror("open");
+    return EXIT_FAILURE;
+  }
+
+  cv::Mat frame = getFrame(getRandomImage(imageFiles));
+  cv::Mat flat = frame.reshape(1, frame.total() * frame.channels());
+  std::vector<uchar> buffer = frame.isContinuous() ? flat : flat.clone();
+
+  int fd = open(FIFO_NAME, O_WRONLY);
+  write(fd, buffer.data(), buffer.size());
+  printf("Sended: %d\n", buffer.size());
+  close(fd);
+
+  cv::Mat my_mat = cv::Mat(frame.rows, frame.cols, frame.type(), buffer.data());
+  cv::imwrite("sended.png", my_mat);
+
+  return EXIT_SUCCESS;
+}
+
+cv::Mat getFrame(const std::string source) {
+  cv::Mat image = cv::imread(source, cv::IMREAD_COLOR);
+
+  if (image.empty()) {
+    std::perror("failed to load image");
+    const cv::Mat emptyFrame(480, 640, CV_8UC3, cv::Scalar(44, 44, 44));
+    return emptyFrame;
+  } else {
+    return image;
+  }
+}
+
+std::string getRandomImage(std::vector<std::string> images) {
+  std::random_device rd;
+  std::mt19937 gen(rd());
+  std::uniform_int_distribution<> dis(0, images.size() - 1);
+  int randomIndex = dis(gen);
+  std::string randomString = images[randomIndex];
+
+  return randomString;
+}

code/C++/FIFO_w_OpenCV/xmake.lua

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+set_project("fifo_woth_opencv")
+set_languages("c99", "cxx17")
+add_rules("mode.debug", "mode.release")
+
+if is_mode("debug") then
+    set_symbols("debug")
+    set_optimize("none")
+end
+
+add_includedirs(
+    "/usr/include/opencv4/"
+)
+add_linkdirs(
+)
+
+target("reader")
+    set_kind("binary")
+    add_syslinks("opencv_highgui", "opencv_imgcodecs", "opencv_core")
+    add_files("reader.cpp")
+
+target("writer")
+    set_kind("binary")
+    add_syslinks("opencv_imgcodecs", "opencv_core")
+    add_files("writer.cpp")