Update Live Image from Camera

[benz6699]

I get one live image from camera each time I call the function "vc3d_GetImage(0,iTotalImage,true,&iRemainImg, pB)". After that I will call the function "loadImage(unsigned char *pB)" to display the image. However the image is not updated all the while. Only the last image is showed at the end. For example I call the function "vc3d_GetImage(0,iTotalImage,true,&iRemainImg, pB)" 5 times. The display is not updated 5 times. The display is only updated once (the fifth image) at the end. What has I done wrong?

void MainWindow::on_pBCapture_clicked()
{
    ui->lImageCount->setText("0");
    int iTotalImage = ui->sBTotalImage->value();
 
    int iImgWidth, iImgHeight;
    int count = 0;
    unsigned char *pBuffer=NULL;
    unsigned char *pBuffer2=NULL;
 
    /* to get the width and height of image */
    int iStatus = vc3d_GetImageSizeVr(0, &iImgWidth, &iImgHeight);
 
    if (iStatus>0)
    {
        int iRemainImg = iTotalImage;
        pBuffer = new unsigned char[iImgWidth*iImgHeight];
        pBuffer2 = new unsigned char[iImgWidth*iImgHeight];
        // Get one image (or more when in a loop)
        do
        {
           unsigned char *pB;
            if (iRemainImg%2)
            {
                pB=pBuffer;
            }
            else
            {
                pB=pBuffer2;
            }
            /* Get the one image when this function is called */
            iStatus = vc3d_GetImage(0,iTotalImage,true,&iRemainImg, pB);
            if (iStatus == 1)
            {
                count++;
                ui->lImageCount->setText(QString::number(count));
                loadImage(pB);
            }
           //delete [] pBuffer;
        }while (iRemainImg>0 && iStatus>0);
    }
}
 
void MainWindow::loadImage(unsigned char *pB)
{
    QGraphicsScene* scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);
    QImage image = QImage(pB, 1280, 1024, QImage::Format_Indexed8);
    scene->clear();
    QGraphicsPixmapItem* pi = scene->addPixmap(QPixmap::fromImage(image));
    ui->graphicsView->fitInView(scene->sceneRect(), Qt::KeepAspectRatio);
    ui->graphicsView->update();
    ui->graphicsView->viewport()->update();
    ui->graphicsView->show();
}

void MainWindow::on_pBCapture_clicked()
{
    ui->lImageCount->setText("0");
    int iTotalImage = ui->sBTotalImage->value();
    
    int iImgWidth, iImgHeight;
    int count = 0;
    unsigned char *pBuffer=NULL;
    unsigned char *pBuffer2=NULL;

    /* to get the width and height of image */
    int iStatus = vc3d_GetImageSizeVr(0, &iImgWidth, &iImgHeight);

    if (iStatus>0)
    {
        int iRemainImg = iTotalImage;
        pBuffer = new unsigned char[iImgWidth*iImgHeight];
        pBuffer2 = new unsigned char[iImgWidth*iImgHeight];
        // Get one image (or more when in a loop)
        do
        {
           unsigned char *pB;
            if (iRemainImg%2)
            {
                pB=pBuffer;
            }
            else
            {
                pB=pBuffer2;
            }
            /* Get the one image when this function is called */
            iStatus = vc3d_GetImage(0,iTotalImage,true,&iRemainImg, pB);
            if (iStatus == 1)
            {
                count++;
                ui->lImageCount->setText(QString::number(count));
                loadImage(pB);
            }
           //delete [] pBuffer;
        }while (iRemainImg>0 && iStatus>0);
    }
}

void MainWindow::loadImage(unsigned char *pB)
{
    QGraphicsScene* scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);
    QImage image = QImage(pB, 1280, 1024, QImage::Format_Indexed8);
    scene->clear();
    QGraphicsPixmapItem* pi = scene->addPixmap(QPixmap::fromImage(image));
    ui->graphicsView->fitInView(scene->sceneRect(), Qt::KeepAspectRatio);
    ui->graphicsView->update();
    ui->graphicsView->viewport()->update();
    ui->graphicsView->show();
}

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[stampede]

Updating a display widget in a loop like that won't give it enough time to redraw. Create a slot to capture and update single image and then use a timer with reasonable timeout to capture the image.
Btw. creating new graphics scene just to display new image is not necessary, you can add first image with scene->addPixmap and then reuse the QGraphicsPixmapItem object by updating displayed pixmap with QGraphicsPixmapItem::setPixmap() method.