Qt+Opencv+QThread，Qt多线程同时显示多路USB摄像头信息至ui界面

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前言

Win10环境下，通过Qt+Opencv+QThread，实现多路USB摄像头数据显示至ui界面。主要思想是通过Opencv的VideoCapture类，及Qthread类中的moveToThread方法实现，此外由于VideoCapture类的open方法的参数为摄像头的索引号，当外接多个USB摄像头的时候有可能造成索引号顺序不固定的问题，通过判断摄像头的硬件ID，即每个摄像头的vid、pid码，以实现在ui界面固定的位置（QLabel）显示固定的摄像头画面。

本案例中USB摄像头与PC机之间的连接方式要特别注意，每个摄像头应该单独连接至PC机的各个USB接口，不能使用多个摄像头连接至单个USB hub，再将USB hub连接至PC机的方式，本人使用的笔记本自带一个摄像头，然后外接的两个摄像头分别连接在笔记本的两个USB接口上。

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效果

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代码资源链接

本篇博客工程文件夹内所有代码内容，请至此处下载。

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核心代码

pro文件

本次方案中的Opnecv直接通过官网的windows环境下的.exe安装模式安装，将inclue文件夹及Lib文件夹放至工程文件夹内，并通过"$$PWD"指引到当前文件夹。

QT       += core gui multimedia
greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
CONFIG += c++11
# You can make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    camera.cpp \
    main.cpp \
    mainwindow.cpp
HEADERS += \
    camera.h \
    mainwindow.h
FORMS += \
    mainwindow.ui
INCLUDEPATH += "$$PWD"/opencv/include\
               "$$PWD"/opencv/include/opencv \
               "$$PWD"/opencv/include/opencv2 \
Debug:
{
    LIBS += "$$PWD"/opencv/lib/opencv_world3416d.lib \
            "$$PWD"/VIDPID.lib
}
Release:
{
    LIBS += "$$PWD"/opencv/lib/opencv_world3416.lib \
            "$$PWD"/VIDPID.lib
}
DEFINES -= UNICODE
DEFINES += UMBCS
QMAKE_CXXFLAGS -= -Zc:strictStrings
# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

camera.h

#ifndef CAMERA_H
#define CAMERA_H

#include 
#include 
#include 
#include 
#include 
#include 
#include 

using namespace std;
using namespace cv;

class Camera:public QObject
{
    Q_OBJECT
public:
    Camera();
    ~Camera();

signals:
    void sendPicture(const QImage &img);

public slots:
    void camNumber(const int &n);
    void openCamera();
    void mainwindowDisplay();

private:
    VideoCapture capture;
    Mat src_image;
    int camera_num = 0;
};

#endif // CAMERA_H

camera.cpp

#include "camera.h"
#include 

Camera::Camera()
{

}
Camera::~Camera()
{

}

void Camera::camNumber(const int &n)
{
    camera_num = n;
}

void Camera::openCamera()
{
    capture.set(CV_CAP_PROP_FRAME_HEIGHT, 960);
    capture.set(CV_CAP_PROP_FRAME_HEIGHT, 1280);

//        capture.open(camera_num,cv::CAP_DSHOW);
    capture.open(camera_num);
    if(!capture.isOpened())
    {
        qDebug() << "camer_num:"<<camera_num<<"not open";
        return;
    }
}

void Camera::mainwindowDisplay()
{
    qDebug() << camera_num;
    capture >> src_image;
    QImage img1 = QImage((const unsigned char*)src_image.data,
                         src_image.cols, src_image.rows,
                         QImage::Format_RGB888).rgbSwapped();
    emit sendPicture(img1);
 }

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include 
#include 
#include 
#include 
#include 
#include "camera.h"

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();

private slots:
    void on_pushButton_opencamera_clicked();
    void recivePicture(QImage);
    void recivePicture_1(QImage);
    void recivePicture_2(QImage);

private:
    Ui::MainWindow *ui;
    QThread *firstThread;
    Camera *MyCamThread;

    QThread *secondThread;
    Camera *MyCamThread_2;

    QThread *thirdThread;
    Camera *MyCamThread_3;

    QTimer fps_timer;
    QTimer fps_timer_1;
    QTimer fps_timer_2;

//    int camer_indx;
    int A,B,C;

    QList<QCameraInfo> camera_list;
};
#endif // MAINWINDOW_H

mainwindow.cpp

获取USB摄像头硬件ID的方法见此篇博客，将编译生成的lib文件放入工作文件夹。

#include "mainwindow.h"
#include "ui_mainwindow.h"
extern "C" __declspec(dllexport) int getCamIDFromPidVid(const char* pidvid);

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    camera_list = QCameraInfo::availableCameras();

    for(auto i =0;i<camera_list.size();i++)
    {
        qDebug()<<camera_list.at(i).description();
    }

    const char* pidvid_0 = "vid_2894&pid_0004";
    A = getCamIDFromPidVid(pidvid_0);
    std::cout << A << std::endl;

    const char* pidvid_1 = "vid_1e4e&pid_0109";
    B = getCamIDFromPidVid(pidvid_1);
    std::cout << B << std::endl;

    const char* pidvid_2 = "vid_30c9&pid_0041";
    C = getCamIDFromPidVid(pidvid_2);
    std::cout << C << std::endl;

    firstThread = new QThread;
    MyCamThread = new Camera;

    secondThread = new QThread;
    MyCamThread_2 = new Camera;

    thirdThread = new QThread;
    MyCamThread_3 = new Camera;

    MyCamThread->moveToThread(firstThread);
    MyCamThread_2->moveToThread(secondThread);
    MyCamThread_3->moveToThread(thirdThread);

    fps_timer.setInterval(30);

    connect(&fps_timer, SIGNAL(timeout()), MyCamThread, SLOT(mainwindowDisplay()));
    connect(MyCamThread, SIGNAL(sendPicture(QImage)),this,SLOT(recivePicture(QImage)));

    connect(&fps_timer, SIGNAL(timeout()), MyCamThread_2, SLOT(mainwindowDisplay()));
    connect(MyCamThread_2, SIGNAL(sendPicture(QImage)),this,SLOT(recivePicture_1(QImage)));

    connect(&fps_timer, SIGNAL(timeout()), MyCamThread_3, SLOT(mainwindowDisplay()));
    connect(MyCamThread_3, SIGNAL(sendPicture(QImage)),this,SLOT(recivePicture_2(QImage)));

}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::recivePicture(QImage img)
{
    QImage newImg = img.scaled(ui->label->width(), ui->label->height());
    ui->label->setPixmap(QPixmap::fromImage(newImg));
}

void MainWindow::recivePicture_1(QImage img)
{
    QImage newImg = img.scaled(ui->label_2->width(), ui->label_2->height());
    ui->label_2->setPixmap(QPixmap::fromImage(newImg));
}

void MainWindow::recivePicture_2(QImage img)
{
    QImage newImg = img.scaled(ui->label_3->width(), ui->label_3->height());
    ui->label_3->setPixmap(QPixmap::fromImage(newImg));
}

void MainWindow::on_pushButton_opencamera_clicked()
{
    MyCamThread->camNumber(C);
    MyCamThread_2->camNumber(B);
    MyCamThread_3->camNumber(A);

    MyCamThread->openCamera();
    MyCamThread_2->openCamera();
    MyCamThread_3->openCamera();

    fps_timer.start();

    firstThread->start();
    secondThread->start();
    thirdThread->start();

}

mainwindow.ui

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代码资源链接

本篇博客工程文件夹内所有代码内容，请至此处下载。

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