Switching between two ui forms / QMainWindow screens

[nitks.abhinav]

Hi,
I very well know that QMainWindow is top level/parent window. That's what initially I did, when classes "RaptorLrsGUI" and "RaptorCoreGUI" are derived from QWidget and QStackedWidget is used , I don't see anything on screen, it goes blank. The below code is exactly as per suggested and it does not work.
Also I have changed the code to remove showMaximized on widget and use single shot timer.

Thanks for your patience..:-)

Base::Base(QWidget *parent) : QMainWindow(parent, Qt::FramelessWindowHint)
{
       qDebug() << "Base CTOR called\n";
 
       QPalette pal = palette();  // retrieves the default palette for the widget, as defined by the app's style
       pal.setColor( QPalette::Window, Qt::white );
       setPalette( pal );
 
       setAutoFillBackground( true );
 
       //Show the first screen, loading raptor status       
       lrsGUI = new RaptorLrsGUI;                                                   //RaptorLrsGUI derived from QWidget
       lrsGUI->setlabel(QString("Loading Raptor Status..."));
       coreGUI = new RaptorCoreGUI;                                             //RaptorCoreGUI derived from QWidget
 
       stackedWidget = new QStackedWidget();       
       stackedWidget->addWidget(lrsGUI);
       stackedWidget->addWidget(coreGUI);
 
       stackedWidget->setCurrentIndex(0);       
}
 
Base::~Base()
{
    qDebug() << "Main Thread: destroying base objects \n";
    delete lrsGUI;
    delete coreGUI;
    delete stackedWidget;
}
 
 
void Base::rcvInitData()
{
    qDebug()<< "Main Thread (CALLBACK): Display second screen\n";
    stackedWidget->setCurrentIndex(1);
}

Base::Base(QWidget *parent) : QMainWindow(parent, Qt::FramelessWindowHint)
{
       qDebug() << "Base CTOR called\n";

       QPalette pal = palette();  // retrieves the default palette for the widget, as defined by the app's style
       pal.setColor( QPalette::Window, Qt::white );
       setPalette( pal );

       setAutoFillBackground( true );

       //Show the first screen, loading raptor status       
       lrsGUI = new RaptorLrsGUI;                                                   //RaptorLrsGUI derived from QWidget
       lrsGUI->setlabel(QString("Loading Raptor Status..."));
       coreGUI = new RaptorCoreGUI;                                             //RaptorCoreGUI derived from QWidget

       stackedWidget = new QStackedWidget();       
       stackedWidget->addWidget(lrsGUI);
       stackedWidget->addWidget(coreGUI);

       stackedWidget->setCurrentIndex(0);       
}

Base::~Base()
{
    qDebug() << "Main Thread: destroying base objects \n";
    delete lrsGUI;
    delete coreGUI;
    delete stackedWidget;
}


void Base::rcvInitData()
{
    qDebug()<< "Main Thread (CALLBACK): Display second screen\n";
    stackedWidget->setCurrentIndex(1);
}

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Rest of the code remain same as earlier.

[d_stranz]

You create the QStackedWidget, but you do not give it any parent. You do not tell your QMainWidget to use the QStackedWidget as its "centralWidget". Thus the QStackedWidget is never shown, so it is always invisible.

Line 16 should be:

stackedWidget = new QStackedWidget( this );

stackedWidget = new QStackedWidget( this );

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and add a line at the end of the constructor:

setCentralWidget( stackedWidget );

setCentralWidget( stackedWidget );

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If you want the background of the Raptor* widgets to be white, this code needs to be moved to their constructors. It does nothing if you have it in the Base constructor:

QPalette pal = palette();  // retrieves the default palette for the widget, as defined by the app's style
       pal.setColor( QPalette::Window, Qt::white );
       setPalette( pal );

QPalette pal = palette();  // retrieves the default palette for the widget, as defined by the app's style
       pal.setColor( QPalette::Window, Qt::white );
       setPalette( pal );

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Edit: Actually, maybe this is incorrect. If you set the palette before creating the stacked and Raptor* widgets, it is possible that they will inherit the QPalette:: Window setting from the Base class.

[nitks.abhinav]

I made the changes the but still I can see white screen with title bar (screenshot attached) , below is the complete code.

Thanks you for all the help,

/Second UI */
namespace Ui {
class RaptorCoreGUI;
}
 
class RaptorCoreGUI : public QWidget
{
    Q_OBJECT
 
public:
    explicit RaptorCoreGUI(QWidget *parent = 0);
    ~RaptorCoreGUI();
    void configInitData(bool);
    void setlabel(QString);
 
private:
    Ui::RaptorCoreGUI *ui;
};
 
/*First UI*/
amespace Ui {
class RaptorLrsGUI;
}
 
class RaptorLrsGUI : public QWidget
{
    Q_OBJECT
 
public:
    explicit RaptorLrsGUI(QWidget *parent = 0);
    ~RaptorLrsGUI();
    void setlabel(QString);
 
private:
    Ui::RaptorLrsGUI *ui;
};
 
/*Base class  derived from  QMainWindow*/
class Base : public QMainWindow
{
    Q_OBJECT
public:
   RaptorLrsGUI *lrsGUI;
   RaptorCoreGUI *coreGUI;
   QStackedWidget *stackedWidget;
   QVBoxLayout *layout;
  ~Base();
   explicit Base (QWidget *parent = 0);
 
 
private slots:
    void rcvInitData();
};
 
/*Second UI CPP*/
RaptorCoreGUI::RaptorCoreGUI(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::RaptorCoreGUI)
{
    ui->setupUi(this);
    this->setAutoFillBackground(true);
    this->setStyleSheet("background-color:white;");
}
 
RaptorCoreGUI::~RaptorCoreGUI()
{
    delete ui;
}
 
 
void RaptorCoreGUI::setlabel(QString label)
{
    qDebug() << "Main Thread(COREGUI): Setting Label\n";    
    ui->label->setText(label);
}
 
/*First UI cpp*/
RaptorLrsGUI::RaptorLrsGUI(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::RaptorLrsGUI)
{    
    ui->setupUi(this);
    this->setAutoFillBackground(true);
    this->setStyleSheet("background-color:white;");
}
 
RaptorLrsGUI::~RaptorLrsGUI()
{
    qDebug() << "Main Thread: destroying the ui object \n";
    delete ui;
}
 
void RaptorLrsGUI::setlabel(QString label)
{
    qDebug() << "Main Thread(LSRGUI): Setting Label\n";    
    ui->label->setText(label);
}
 
 
/*main.cpp*/
Base::Base(QWidget *parent) :
      QMainWindow(parent, Qt::FramelessWindowHint)
{
       qDebug() << "Base CTOR called\n";
 
       QPalette pal = palette();  // retrieves the default palette for the widget, as defined by the app's style
       pal.setColor( QPalette::Window, Qt::white );
       setPalette( pal );
 
       setAutoFillBackground( true );
 
 
       //Show the first screen, loading raptor status       
       lrsGUI = new RaptorLrsGUI;
       lrsGUI->setlabel(QString("Loading Raptor Status..."));
       coreGUI = new RaptorCoreGUI;
 
       stackedWidget = new QStackedWidget(this);
       stackedWidget->addWidget(lrsGUI);
       stackedWidget->addWidget(coreGUI);
 
       stackedWidget->setCurrentIndex(0);
       setCentralWidget(stackedWidget);
}
 
Base::~Base()
{
    qDebug() << "Main Thread: destroying base objects \n";
    delete lrsGUI;
    delete coreGUI;
    delete stackedWidget;
}
 
void Base::rcvInitData()
{
    qDebug()<< "Main Thread (CALLBACK): Display second screen\n";
    stackedWidget->setCurrentIndex(1);
}
 
//! [1]
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
 
    //Instantiate base class    
    Base baseObj;
 
 
    //instantiate Client thread object
    ClientThread clientThread;
    qDebug() << "Connecting sendmsg and handle_callback1()\n";
    QObject::connect(&clientThread, SIGNAL(sendInitData()), &baseObj, SLOT(rcvInitData()), Qt::QueuedConnection);
 
    qDebug() << "Main Thread: starting clockThread\n";
    clientThread.start();
 
    app.exec();
    qDebug() << "Mian Thread: Quiting clockThread\n";
    clientThread.quit();
    qDebug() << "Main Thread: Waiting on clockThread \n";
    clientThread.wait();
    return 0;
}

/Second UI */
namespace Ui {
class RaptorCoreGUI;
}

class RaptorCoreGUI : public QWidget
{
    Q_OBJECT

public:
    explicit RaptorCoreGUI(QWidget *parent = 0);
    ~RaptorCoreGUI();
    void configInitData(bool);
    void setlabel(QString);

private:
    Ui::RaptorCoreGUI *ui;
};

/*First UI*/
amespace Ui {
class RaptorLrsGUI;
}

class RaptorLrsGUI : public QWidget
{
    Q_OBJECT

public:
    explicit RaptorLrsGUI(QWidget *parent = 0);
    ~RaptorLrsGUI();
    void setlabel(QString);

private:
    Ui::RaptorLrsGUI *ui;
};

/*Base class  derived from  QMainWindow*/
class Base : public QMainWindow
{
    Q_OBJECT
public:
   RaptorLrsGUI *lrsGUI;
   RaptorCoreGUI *coreGUI;
   QStackedWidget *stackedWidget;
   QVBoxLayout *layout;
  ~Base();
   explicit Base (QWidget *parent = 0);


private slots:
    void rcvInitData();
};

/*Second UI CPP*/
RaptorCoreGUI::RaptorCoreGUI(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::RaptorCoreGUI)
{
    ui->setupUi(this);
    this->setAutoFillBackground(true);
    this->setStyleSheet("background-color:white;");
}

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


void RaptorCoreGUI::setlabel(QString label)
{
    qDebug() << "Main Thread(COREGUI): Setting Label\n";    
    ui->label->setText(label);
}

/*First UI cpp*/
RaptorLrsGUI::RaptorLrsGUI(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::RaptorLrsGUI)
{    
    ui->setupUi(this);
    this->setAutoFillBackground(true);
    this->setStyleSheet("background-color:white;");
}

RaptorLrsGUI::~RaptorLrsGUI()
{
    qDebug() << "Main Thread: destroying the ui object \n";
    delete ui;
}

void RaptorLrsGUI::setlabel(QString label)
{
    qDebug() << "Main Thread(LSRGUI): Setting Label\n";    
    ui->label->setText(label);
}


/*main.cpp*/
Base::Base(QWidget *parent) :
      QMainWindow(parent, Qt::FramelessWindowHint)
{
       qDebug() << "Base CTOR called\n";

       QPalette pal = palette();  // retrieves the default palette for the widget, as defined by the app's style
       pal.setColor( QPalette::Window, Qt::white );
       setPalette( pal );

       setAutoFillBackground( true );


       //Show the first screen, loading raptor status       
       lrsGUI = new RaptorLrsGUI;
       lrsGUI->setlabel(QString("Loading Raptor Status..."));
       coreGUI = new RaptorCoreGUI;

       stackedWidget = new QStackedWidget(this);
       stackedWidget->addWidget(lrsGUI);
       stackedWidget->addWidget(coreGUI);

       stackedWidget->setCurrentIndex(0);
       setCentralWidget(stackedWidget);
}

Base::~Base()
{
    qDebug() << "Main Thread: destroying base objects \n";
    delete lrsGUI;
    delete coreGUI;
    delete stackedWidget;
}

void Base::rcvInitData()
{
    qDebug()<< "Main Thread (CALLBACK): Display second screen\n";
    stackedWidget->setCurrentIndex(1);
}

//! [1]
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);

    //Instantiate base class    
    Base baseObj;


    //instantiate Client thread object
    ClientThread clientThread;
    qDebug() << "Connecting sendmsg and handle_callback1()\n";
    QObject::connect(&clientThread, SIGNAL(sendInitData()), &baseObj, SLOT(rcvInitData()), Qt::QueuedConnection);

    qDebug() << "Main Thread: starting clockThread\n";
    clientThread.start();

    app.exec();
    qDebug() << "Mian Thread: Quiting clockThread\n";
    clientThread.quit();
    qDebug() << "Main Thread: Waiting on clockThread \n";
    clientThread.wait();
    return 0;
}

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[d_stranz]

I think we need to start from zero, because something is clearly wrong with what you are doing now.

Please write and run these two programs. You can simply comment out the lines in your current main.cpp and replace them with these lines:

#include <QtWidgets/QApplication>
#include "RaptorCoreGUI.h"
 
int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
 
	RaptorCoreGUI w;
	w.show();
	return a.exec();
}

#include <QtWidgets/QApplication>
#include "RaptorCoreGUI.h"

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);

	RaptorCoreGUI w;
	w.show();
	return a.exec();
}

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#include <QtWidgets/QApplication>
#include "RaptorLrsGUI.h"
 
int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
 
	RaptorLrsGUI w;
	w.show();
	return a.exec();
}

#include <QtWidgets/QApplication>
#include "RaptorLrsGUI.h"

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);

	RaptorLrsGUI w;
	w.show();
	return a.exec();
}

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In each case, do you see the windows you expect to see?

[nitks.abhinav]

Yes I can see the windows (attached)

IMG-4835 --> coreGUI
ING-4836 --> lrsGUI

[d_stranz]

OK, good. The problem is not with your Raptor* widgets.

Next step. Do you see the RaptorLrsGUI window when you run this code?

#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtWidgets/QStackedWidget>
#include "RaptorLrsGUI.h"
 
int main(int argc, char *argv[])
{
	QApplication a(argc, argv);
 
	QMainWindow w;
        QStackedWidget * pStack = new QStackedWidget( &w );
        RaptorLrsGUI * pLrs = new RaptorLrsGUI;
        pStack->addWidget( pLrs );
        w.setCentralWidget( pStack );
	w.show();
	return a.exec();
}

#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QtWidgets/QStackedWidget>
#include "RaptorLrsGUI.h"

int main(int argc, char *argv[])
{
	QApplication a(argc, argv);

	QMainWindow w;
        QStackedWidget * pStack = new QStackedWidget( &w );
        RaptorLrsGUI * pLrs = new RaptorLrsGUI;
        pStack->addWidget( pLrs );
        w.setCentralWidget( pStack );
	w.show();
	return a.exec();
}

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If it does, substitute "w.showMaximized()" for "w.show()". Does it still work?