Not able to access parentWidget()

Question

I am working on a camera project. In this i have created a Window type QT Widget application. I have also added 2 separate dialog window classes which are supposed to access the functions in the MainWindow class. One of the dialog class is able to access the functions from the main class using connect function and putting parentWidget() calue for QObject *context parameter. The dialog class is called on camera button using non modal method :

void MainWindow::on_addCamera_Button_clicked()
{
    flag1 = 1;
    if(imageFilename != ""){
        c++;
        camera = new CameraDialog(this);
        camera->show();
        img2.copyTo(im);
        img2.copyTo(img);
        img2.copyTo(img1);
        imshow("Map",img1);
        setMouseCallback("Map", onMouseClick, &p);
        connect(timer_ossm, SIGNAL(timeout()), this, SLOT(gui_update_Original_Video()));
        connect(timer_ossm, SIGNAL(timeout()), this, SLOT(gui_update_Image_Coordinate()));
        }
    else {
        QMessageBox::warning(this,"..",(QString)"Enter Image!");
    }
}

And the connect statements that work fine in CameraDialog class are :

CameraDialog::CameraDialog(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::CameraDialog)
{
    ui->setupUi(this);
    ui->pushButton_Done->setCheckable(true);
    cout<<parentWidget()<<endl;
    connect(ui->pushButton_Done,SIGNAL(clicked()),parentWidget(),SLOT(clearVal()));
    connect(ui->pushButton_Done,SIGNAL(clicked()),parentWidget(),SLOT(updateFlag()));
    connect(ui->pushButton_Done, SIGNAL(released()),this,SLOT(close()));
    connect(ui->pushButton_Apply,SIGNAL(clicked()),parentWidget(),SLOT(updateImage());
    connect(ui->pushButton_Cancel,SIGNAL(clicked()),parentWidget(),SLOT(clearVal()));
}

But when I try the same thing for another class for a different dialog window (which accessed using the same non modal approach)it show that there is no value for parentWidget(), i.e, it shows value 0 when trying to print value of parentWidget(). Because of this the same connect functions in the 1st dialog class(CameraDialog) are not working. How do I solve this issue so that the second class can also access the functions in the MainWindow class?

Thanks!

@MohammadrezaPanahi, yes I get this message on my application output when I try to open my second dialog box `QObject::connect: Cannot connect QPushButton::clicked() to (null)::clearVal()` `QObject::connect: Cannot connect QPushButton::clicked() to (null)::updateFlag()` — Aditya, Jul 06 '18 at 11:24
No. My program stops unexpectedly. I believe the error is because the second dialog class is not able to use the MainWindow class as parentWidget(). I also tried setparent() method for the second dialog class's object, but it didn't work. — Aditya, Jul 06 '18 at 11:28
do you using ` camera->setWindowFlags( Qt::Window); camera->setWindowModality( Qt::ApplicationModal );` before show dialog? — BattleTested_закалённый в бою, Jul 06 '18 at 11:30
No.Is this supposed to allow the second dialog class to access the MainWindow functions using connect function? — Aditya, Jul 06 '18 at 11:37
send your main windows code and dialog code where got error... — BattleTested_закалённый в бою, Jul 06 '18 at 11:38
if its long, can you email that? just that part of the code that makes error — BattleTested_закалённый в бою, Jul 06 '18 at 11:39
@MohammadrezaPanahi, I tried your statements `camera->setWindowFlags( Qt::Window); camera->setWindowModality( Qt::ApplicationModal );` For the first dialog class and now my first dialog window is also not working. How do I undo this. Also, I can only send screen shots of the program as my teammates are not allowing to send code. — Aditya, Jul 06 '18 at 12:01
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/174499/discussion-between-mohammadreza-panahi-and-aditya). — BattleTested_закалённый в бою, Jul 06 '18 at 12:52

Not able to access parentWidget()

0 Answers0