GB28181/preview_worker.cpp at main · AndroidCoderPeng/GB28181 · GitHub

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//
// Created by peng on 2026/1/6.
//

#include "preview_worker.hpp"

#include <QDebug>
#include <QPixmap>
#include <opencv2/imgproc.hpp>

PreviewWorker::PreviewWorker(const uint16_t width, const uint16_t height, const size_t bufferSize, QObject* parent)
    : QObject{parent} {
    _width = width;
    _height = height;
    _ringBuffer.capacity = bufferSize;
    _ringBuffer.frames.reserve(bufferSize);
}

PreviewWorker::~PreviewWorker() = default;

void PreviewWorker::frameReceived(const cv::Mat& frame) {
    if (frame.empty() || !frame.data)
        return;

    QMutexLocker lock(&_mutex);

    // 环形缓冲区写入逻辑
    if (_ringBuffer.frames.size() < _ringBuffer.capacity) {
        // 初始化阶段：直接添加
        _ringBuffer.frames.push_back(frame.clone());
    } else {
        // 正常运行：覆盖最旧帧
        _ringBuffer.frames[_ringBuffer.writeIndex] = frame.clone();
    }

    _ringBuffer.writeIndex = (_ringBuffer.writeIndex + 1) % _ringBuffer.capacity;
    if (_ringBuffer.count < _ringBuffer.capacity) {
        ++_ringBuffer.count;
    }

    // 触发处理（如果未在处理中）
    if (!_isProcessing && _ringBuffer.count > 0) {
        _isProcessing = true;
        lock.unlock(); // 先解锁再emit，避免死锁
        handleFrame();
    }
}

void PreviewWorker::handleFrame() {
    cv::Mat frame;
    {
        QMutexLocker lock(&_mutex);
        if (_ringBuffer.count == 0) {
            _isProcessing = false;
            return;
        }

        frame = _ringBuffer.frames[_ringBuffer.readIndex];
        _ringBuffer.readIndex = (_ringBuffer.readIndex + 1) % _ringBuffer.capacity;
        --_ringBuffer.count;
    }

    {
        cv::Mat resizedFrame;
        try {
            cv::resize(frame, resizedFrame, cv::Size(640, 360), 0, 0,
                       cv::INTER_LINEAR);
        } catch (...) {
            qWarning() << "Error during resize in PreviewWorker";
            return; // 发生错误则退出
        }

        if (resizedFrame.empty()) {
            qWarning() << "Resized frame is empty!";
            return;
        }

        QImage qimg;
        if (resizedFrame.channels() == 3) {
            // OpenCV 是 BGR, Qt 是 RGB
            cv::cvtColor(resizedFrame, resizedFrame, cv::COLOR_BGR2RGB);
            qimg = QImage(resizedFrame.data, resizedFrame.cols, resizedFrame.rows,
                          resizedFrame.step, QImage::Format_RGB888);
        } else if (resizedFrame.channels() == 1) {
            qimg = QImage(resizedFrame.data, resizedFrame.cols, resizedFrame.rows,
                          resizedFrame.step,
                          QImage::Format_Grayscale8);
        } else {
            qWarning() << "Unsupported Mat format for preview.";
            return;
        }

        if (qimg.isNull()) {
            qWarning() << "QImage conversion failed!";
            return;
        }
        // 发射信号，传递给主线程显示，复制 QImage 数据，确保线程安全
        emit onPreviewReady(qimg.copy());
    }

    // 继续处理下一帧
    handleFrame();
}