is it necessary to use connection for frequent gui updation ??

[vasu_gupta]

I am working on a code which is used for automated dimension check on the basis of camera image...
for each new image the gui qlable and table(containing dimension details and pass or fail result) gets updated at the rate of 400 images per minute now , i am doing these updates using setvalue and all functions ....recently i came across a forum:
https://forum.qt.io/topic/24358/solved-qwidget-repaint-recursive-repaint-detected

according to which not using connection is an isuue...so can some one tell me if using setvalue fuction can become a problem or not if so then please tell me how to update table content and variable values with signal and slot

void StackedWidget_new::run_camimage()
{
    ////////CODE FOR TRIGGERING TEST SAMPLES FOR ALL 4 CAMERAS
    int k= fr_run.size();
    FrameRec frame;
   // qDebug()<<"REACHED HERE RUN_CAM";

    for(int i =0;i<k;i++)
    {

            frame=fr_run.back();
            fr_run.pop_back();
            cv::Mat m_ConvertImage=cv::Mat(frame.Height,frame.Width,CV_8UC1);
            std::copy( frame.buff, frame.buff+frame.Height*frame.Width, m_ConvertImage.data );
           if(frame.CameraIndex==0)
           {
               Cam1_run=m_ConvertImage;
               cam1_run = Mat2QImage(m_ConvertImage);
               ui->IMAGE_CAM_5->setPixmap(QPixmap::fromImage(cam1_run));
               ui->IMAGE_CAM_9->setPixmap(QPixmap::fromImage(cam1_run));

           }
           else if(frame.CameraIndex==1)
           {
                Cam2_run=m_ConvertImage;
               cam2_run = Mat2QImage(m_ConvertImage);
               ui->IMAGE_CAM_6->setPixmap(QPixmap::fromImage(cam2_run));
               ui->IMAGE_CAM_10->setPixmap(QPixmap::fromImage(cam2_run));
           }
           else if(frame.CameraIndex==2)
           {
                Cam3_run=m_ConvertImage;
               cam3_run = Mat2QImage(m_ConvertImage);
               ui->IMAGE_CAM_7->setPixmap(QPixmap::fromImage(cam3_run));
               ui->IMAGE_CAM_11->setPixmap(QPixmap::fromImage(cam3_run));
           }
           else if(frame.CameraIndex==3)
           {
               Cam4_run=m_ConvertImage;
               cam4_run = Mat2QImage(m_ConvertImage);
               ui->IMAGE_CAM_8->setPixmap(QPixmap::fromImage(cam4_run));
               ui->IMAGE_CAM_12->setPixmap(QPixmap::fromImage(cam4_run));
           }
           if(fr.size()==0)
           {
               CalibClick[2]=0;
           }
    }
    for(int i=0;i<ftr.size();i++)
    {
        switch (ftr[i]->cam_id)
        {
        case 1:

            ui->tableWidget_2->item(ftr[i]->index,4)->setText(QString::number(ftr[i]->inpix));
            ui->tableWidget_2->item(ftr[i]->index,5)->setText(QString::number(ftr[i]->inmm));

           if(ftr[i]->decision==1)
                    ui->tableWidget_2->item(ftr[i]->index,6)->setText("PASS");
            else
                    ui->tableWidget_2->item(ftr[i]->index,6)->setText("FAIL");

            break;

        case 2:
            ui->tableWidget_6->item(ftr[i]->index,4)->setText(QString::number(ftr[i]->inpix));
            ui->tableWidget_6->item(ftr[i]->index,5)->setText(QString::number(ftr[i]->inmm));
                    if(ftr[i]->decision==1)
                            ui->tableWidget_6->item(ftr[i]->index,6)->setText("PASS");
                    else
                            ui->tableWidget_6->item(ftr[i]->index,6)->setText("FAIL");
            break;
        case 3:
            ui->tableWidget_7->item(ftr[i]->index,4)->setText(QString::number(ftr[i]->inpix));
            ui->tableWidget_7->item(ftr[i]->index,5)->setText(QString::number(ftr[i]->inmm));
                    if(ftr[i]->decision==1)
                            ui->tableWidget_7->item(ftr[i]->index,6)->setText("PASS");
                    else
                            ui->tableWidget_7->item(ftr[i]->index,6)->setText("FAIL");
            break;
        case 4:
            ui->tableWidget_8->item(ftr[i]->index,4)->setText(QString::number(ftr[i]->inpix));
            ui->tableWidget_8->item(ftr[i]->index,5)->setText(QString::number(ftr[i]->inmm));
                    if(ftr[i]->decision==1)
                            ui->tableWidget_8->item(ftr[i]->index,6)->setText("PASS");
                    else
                            ui->tableWidget_8->item(ftr[i]->index,6)->setText("FAIL");
            break;

        }
    }


}

this is how i am updating table and qlabel right now

[mrjj]

Hi
it will only be a problem if you make too long lasting loop.
Then it will stop redrawing.