Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?

[sierdzio]

@cdwijs said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

rs232Rx = new RS232(myHlayout);
rs232Tx = new RS232(myHlayout);

Why do you specify the parent here? Calling just addWidget() is enough.

[cdwijs]

@sierdzio said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

@cdwijs said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

rs232Rx = new RS232(myHlayout);
rs232Tx = new RS232(myHlayout);

Why do you specify the parent here? Calling just addWidget() is enough.

Thanks Sierdzio, I have just tried it, but this line causes the widget to float in it's own window:
rs232Rx = new RS232();

This line causes the widget to correctly place itself in the QSplitter.
rs232Rx = new RS232(myHlayout);

Maybe this is only true on my PC:
Windows 7 enterprise SP1
QT 5.10.1
mingw53_32

Cheers,
Cedric

[sierdzio]

@cdwijs said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

Thanks Sierdzio, I have just tried it, but this line causes the widget to float in it's own window:

That's because your splitter needs a parent.

myHlayout = new QSplitter();

[cdwijs]

@sierdzio said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

@cdwijs said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

Thanks Sierdzio, I have just tried it, but this line causes the widget to float in it's own window:

That's because your splitter needs a parent.

myHlayout = new QSplitter();

I'm not convinced :-) This yields 3 floating windows:

    myVlayout = new QSplitter(parent);
    myVlayout->setOrientation(Qt::Vertical);
    myRxLabel = new QLabel("Rx");
    myTxLabel = new QLabel("Tx");
    myClearBtn = new QPushButton("Clear");
    myLog = new QPlainTextEdit();
    myHlayout = new QSplitter(myVlayout);
    myHlayout->setOrientation(Qt::Horizontal);
    myHlayout->addWidget(myRxLabel);
    rs232Rx = new RS232();
    myHlayout->addWidget(rs232Rx);
    myHlayout->addWidget(myTxLabel);
    rs232Tx = new RS232();
    myHlayout->addWidget(rs232Tx);
    myHlayout->addWidget(myClearBtn);
    myVlayout->addWidget(myLog);
    myVlayout->addWidget(myHlayout);
    myVlayout->show();

This yields the desired effect:

 myRxLabel = new QLabel("Rx");
    myTxLabel = new QLabel("Tx");
    myClearBtn = new QPushButton("Clear");
    myLog = new QPlainTextEdit();
    myHlayout = new QSplitter();
    myHlayout->setOrientation(Qt::Horizontal);
    myHlayout->addWidget(myRxLabel);
    rs232Rx = new RS232(myHlayout);
    myHlayout->addWidget(rs232Rx);
    myHlayout->addWidget(myTxLabel);
    rs232Tx = new RS232(myHlayout);
    myHlayout->addWidget(rs232Tx);
    myVlayout = new QSplitter();
    myVlayout->setOrientation(Qt::Vertical);
    myHlayout->addWidget(myClearBtn);
    myVlayout->addWidget(myLog);
    myVlayout->addWidget(myHlayout);
    myVlayout->show();

I noticed this yields the 2 RS232 widgets to be displayed before the Rx and Tx labels, and finally the clear button:

myRxLabel = new QLabel("Rx");
    myTxLabel = new QLabel("Tx");
    myClearBtn = new QPushButton("Clear");
    myLog = new QPlainTextEdit();
    myHlayout = new QSplitter();
    myHlayout->setOrientation(Qt::Horizontal);
    rs232Rx = new RS232(myHlayout);
    rs232Tx = new RS232(myHlayout);
    myHlayout->addWidget(myRxLabel);
    myHlayout->addWidget(rs232Rx);
    myHlayout->addWidget(myTxLabel);
    myHlayout->addWidget(rs232Tx);
    myVlayout = new QSplitter();
    myVlayout->setOrientation(Qt::Vertical);
    myHlayout->addWidget(myClearBtn);
    myVlayout->addWidget(myLog);
    myVlayout->addWidget(myHlayout);
    myVlayout->show();

Cheers,
Cedric

[SGaist]

Hi,

Can you show the RS232 constructor content ?

[cdwijs]

@SGaist
Sure:

RS232::RS232(QWidget *parent)
{
    qDebug()<<Q_FUNC_INFO;
#ifdef FAKE_MESSAGES
    myTimer = new QTimer();
    connect(myTimer,&QTimer::timeout,this,&RS232::slotTimer);
    myTimer->setInterval(500);
    myTimer->start();
#endif
    mySettingsDia = new SettingsDialog;
    myRxQueue = new QQueue<unsigned char>;
    myRxQueue->clear();

    mySerialPort = new QSerialPort ;
    myTxTimer = new QTimer();
    myTxTimer->setSingleShot(true);
    myRxTimer = new QTimer();
    myRxTimer->setSingleShot(true);

    myLabel = new QLabel("COM-");

    mySettingsBtn = new QPushButton;
    mySettingsBtn->setIcon(QIcon(":/images/wrench.png"));
    mySettingsBtn->setToolTip("Settings");

    myConnectBtn = new QPushButton;
    myConnectBtn->setIcon(QIcon(":/images/disconnected.png"));
    myConnectBtn->setToolTip("Connect");

    const int LED_SIZE = 10;
    myRxLED = new LedIndicator();
    myRxLED->setLedSize(LED_SIZE);
    myRxLED->setOnColor(Qt::green);
    myRxLED->setToolTip("Rx");

    myTxLED = new LedIndicator();
    myTxLED->setLedSize(LED_SIZE);
    myTxLED->setOnColor(Qt::green);
    myTxLED->setToolTip("Tx");

    myHlayout = new QSplitter();
    myHlayout->setOrientation(Qt::Horizontal);
    myHlayout->addWidget(myLabel);
    myHlayout->addWidget(myTxLED);
    myHlayout->addWidget(myRxLED);
    myHlayout->addWidget(mySettingsBtn);
    myHlayout->addWidget(myConnectBtn);

    connect(mySettingsBtn,&QPushButton::clicked,this,&RS232::slotSettings);
    connect(myConnectBtn,&QPushButton::clicked,this,&RS232::slotConnect);
    connect(mySerialPort,&QSerialPort::readyRead,this,&RS232::slotRx);
    connect(myRxTimer,&QTimer::timeout,this,slotRxTimer);
    connect(myTxTimer,&QTimer::timeout,this,slotTxTimer);
    myHlayout->setParent(parent);
    myHlayout->show();
}

And the class:

class RS232 : public QWidget
{
    Q_OBJECT
public:
    RS232(QWidget *parent=0);
public slots:
    slotSettings(bool clicked);
    slotConnect(bool clicked);
    slotDisconnect(bool clicked);
    slotMessage(QString string);
    slotRx();
    slotRxTimer();
    slotTxTimer();
#ifdef FAKE_MESSAGES
    slotTimer();
#endif
signals:
    void sigOpenChanged(bool open);
    void sigReceived(QString msg);
private:
#ifdef FAKE_MESSAGES
    QTimer *myTimer;
#endif
    QTimer *myTxTimer;
    QTimer *myRxTimer;
    LedIndicator *myRxLED;
    LedIndicator *myTxLED;
    SettingsDialog *mySettingsDia;
    QSplitter *myHlayout;
    QLabel *myLabel;
    QPushButton *mySettingsBtn;
    QPushButton *myConnectBtn;
    SettingsDialog::Settings *mySerSettings;
    QSerialPort *mySerialPort;
    QQueue<unsigned char> *myRxQueue;
};

[sierdzio]

@cdwijs said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

RS232::RS232(QWidget *parent)

You are not initializing the parent class! Should be:

RS232::RS232(QWidget *parent) : QWidget(parent)

That should fix your problems. @SGaist well done :-)

[SGaist]

Also, you are using QSplitter like a layout manager which it is not. It's currently "floating" in RS232. Either put the splitter in a QVBox/HBoxLayout in RS232 (and other widgets you are using) or, depending on what you want to do, use layouts in place of QSplitter.

[cdwijs]

@SGaist said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

Also, you are using QSplitter like a layout manager which it is not. It's currently "floating" in RS232. Either put the splitter in a QVBox/HBoxLayout in RS232 (and other widgets you are using) or, depending on what you want to do, use layouts in place of QSplitter.

I have made a new program that uses 3 layers (toplevel,midlevel,fourbuttons) of widgets:
https://github.com/cdwijs/qt-experiments/tree/master/untitled2
This works as expected, I see one window with groups of groups of buttons.

Is this the correct way of doing things?

Cheers,
Cedric

[SGaist]

It depends, why do you need. Do you really have any use for all these QSplitter ?

[cdwijs]

@SGaist said in Parenting: why is a custom widget placed in a QSplitter not automatically a child of that splitter?:

It depends, why do you need. Do you really have any use for all these QSplitter ?

The splitters make sure I never have to alter the program if the end user wants to change some cosmetic aspect. I agree however that this program overuses Qsplitters.