How can I set a QWidget to auto-shrink when some containing QWidgets are set invisible?

[cdwijs]

Hi All,

I have made a Settings dialog, containing a number of widgets, such as Labels, buttons and checkboxes. These are organized in layouts. When I set one of such layouts to invisible, the settingsdialog stays the same size, but all the widgets are spread out.

How can I make sure the settings dialog shrinks when I hide a layout?

here are the steps I've taken:
1)Compile and run the program. Now a window called "Settings" is visible . See 1-Settings-changes-enabled.png

2)Click on the checkbox "Enable changes". Now the majority of the settings are no longer visible, but the window stays the same size See 2-Settings-changes-disabled.png

3)Next I resize the settings window with my mouse, so it's the minimum size. See 3-Settings-minimal size.png

Here's the program that makes the settings dialog:
rs232.h

/** Copyright (c) 2020-2020 LUMC. This file is created by Cedric de Wijs 
 * This file is (at your option) licensed as GPL version 2 or any later version
 * or LGPL version 2 or any later version. See the file LICENSE-GPL.txt and 
 * LICENSE-LGPL.txt for details. This file is distributed in the hope that it 
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. In no event shall
 * the copyright owner or contributors be liable for any damages however caused */

#ifndef RS232_H
#define RS232_H

#include <QTimer>
#include <QtWidgets>
#include <QWidget>
#include <QSerialPort>
#include <QString>
#include "ledindicator.h"
#include <QObject>
#include <QQueue>

enum STATES
{
   stateDisabled,
   stateOpen,
   statePortOk,
   stateClose,
};

class RS232 : public QWidget
{
    Q_OBJECT
public:
    RS232(QWidget *parent=nullptr);
    QString stateToString(STATES state);
public slots:
    //settings
    void slotShowSettings(bool clicked);
void slotEnableChangesBoxChanged(void);
signals: 
private:
    struct Settings
    {
        QString name;
        QString terminators;
        qint32 baudRate;
        QString stringBaudRate;
    };
    QIntValidator *m_intValidator = nullptr;
    Settings m_currentSettings;
    int myIndex;
    void showPortInfo(int idx);


    void fillPortsParameters(void);
    void fillPortsInfo(void);
    void gui2Settings(void);
    void settings2Gui(void);
    void readSettings(void);
    void writeSettings(void);
    QTimer *myTimer;
    QTimer *myTxTimer;
    QTimer *myRxTimer;

    QHBoxLayout *myHlayout;


    QPushButton *mySettingsBtn;
    QSerialPort *mySerialPort;
    QQueue<char> *myRxQueue;
    int myRxWdCounter=0;
    STATES myState=stateDisabled;


    //settings dialog
    QWidget *settingsWidget = nullptr;
    QVBoxLayout *settingsVlayout = nullptr;
        QVBoxLayout *topVlayout = nullptr;
            QLabel *warningLabel = nullptr;
            QLabel *warning2Label = nullptr;
            QCheckBox *enableChangesBox = nullptr;
            QGridLayout *commstateGLayout = nullptr;
                QLabel *stateLabel = nullptr;
                QLabel *myCurrentPortLabel = nullptr;
                QLabel *myRxdLabel = nullptr;
                LedIndicator *myRxLED = nullptr;
                QLabel *myTxdLabel = nullptr;
                LedIndicator *myTxLED = nullptr;
        QWidget *portAndParametersWidget = nullptr;
        QGridLayout *portAndParametersGLayout = nullptr;
            QLabel *selectPortLabel = nullptr;
            QComboBox *selectPortComboBox = nullptr;
            QLabel *descriptionLabel = nullptr;
            QLabel *manufacturerLabel = nullptr;
            QLabel *serialNumberLabel = nullptr;
            QLabel *locationLabel = nullptr;
            QLabel *vendorIdLabel = nullptr;
            QLabel *productIdLabel = nullptr;

            QLabel *selectParametersLabel = nullptr;
            QLabel *baudrateLabel = nullptr;
            QComboBox *baudrateComboBox = nullptr;
            QLabel *endOfLineLabel = nullptr;
            QLineEdit *endOfLineEdit = nullptr;
            QCheckBox *carriageReturnBox = nullptr;
            QCheckBox *newlineBox = nullptr;
        QHBoxLayout *botLayout = nullptr;
            QCheckBox *myEnableChkbox;
            QPushButton *ApplyBtn = nullptr;
            QPushButton *CancelBtn = nullptr;
    //end settings dialog
    //end gui
};

#endif // RS232_H

rs232.c

/** Copyright (c) 2020-2020 LUMC. This file is created by Cedric de Wijs 
 * This file is (at your option) licensed as GPL version 2 or any later version
 * or LGPL version 2 or any later version. See the file LICENSE-GPL.txt and 
 * LICENSE-LGPL.txt for details. This file is distributed in the hope that it 
 * will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. In no event shall
 * the copyright owner or contributors be liable for any damages however caused */

#include "rs232.h"
#include "../rs232-config.h"

#include <QDebug>
#include <QSerialPortInfo>
#include <QIntValidator>
#include <QtGui>

const int LED_SIZE = 10;
#define TIME_LED 32 //ms
#define TIME_BETWEEN_CHECKS 100 //ms
#define TIME_RX_WD  20 //*TIME_BETWEEN_CHECKS

#define SETTINGS_GROUP "RS232"
#define KEY_ENABLE "enable"
#define KEY_COMMPORT "commport"
#define KEY_TERMINATORS "terminators"
#define KEY_BAUDRATE "baudrate"

const QString TXT_NOT_AVAIL = " (NOT AVAILABLE)";
static const char blankString[] = QT_TRANSLATE_NOOP("Rs232Settings", "N/A");

const unsigned char RS232_TERMINATION_CHAR=0x3B;
const unsigned char RS232_CR=0x0D;

static int objectCount=0;

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


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

    myEnableChkbox = new QCheckBox();
    myEnableChkbox->setToolTip("Enable");

    myHlayout = new QHBoxLayout();
    myHlayout->addWidget(mySettingsBtn);

//settings dialog
    settingsVlayout = new QVBoxLayout();
        topVlayout = new QVBoxLayout();
            QFont font( "Arial", 16, QFont::Bold);
            warningLabel = new QLabel("Do not change these settings without");
            warningLabel->setFont(font);
            warning2Label = new QLabel("consulting the system administrator");
            warning2Label->setFont(font);
            enableChangesBox = new QCheckBox("Enable Changes");
            commstateGLayout = new QGridLayout();
                stateLabel = new QLabel("");
                myCurrentPortLabel = new QLabel("");
                myRxdLabel =  new QLabel("Rxd");
                myRxLED = new LedIndicator();
                myRxLED->setLedSize(LED_SIZE);
                myRxLED->setOnColor(Qt::green);
                myRxLED->setToolTip("Rx");
                myTxdLabel =  new QLabel("Txd");
                myTxLED = new LedIndicator();
                myTxLED->setLedSize(LED_SIZE);
                myTxLED->setOnColor(Qt::green);
                myTxLED->setToolTip("Tx");
            commstateGLayout->addWidget(stateLabel,1,1,1,5,Qt::AlignLeft);
            commstateGLayout->addWidget(myCurrentPortLabel,2,1,Qt::AlignLeft);
            commstateGLayout->addWidget(myRxdLabel,2,2,Qt::AlignLeft);
            commstateGLayout->addWidget(myRxLED,2,3,Qt::AlignLeft);
            commstateGLayout->addWidget(myTxdLabel,2,4,Qt::AlignLeft);
            commstateGLayout->addWidget(myTxLED,2,5,Qt::AlignLeft);

            commstateGLayout->setColumnStretch(1,0);
            commstateGLayout->setColumnStretch(2,0);
            commstateGLayout->setColumnStretch(3,0);
            commstateGLayout->setColumnStretch(4,0);

        topVlayout->addWidget(warningLabel);
        topVlayout->addWidget(warning2Label);
        topVlayout->addWidget(enableChangesBox);
        topVlayout->addLayout(commstateGLayout);
        portAndParametersGLayout = new QGridLayout();
        portAndParametersWidget = new QWidget();
        portAndParametersWidget->setLayout(portAndParametersGLayout);
            selectPortLabel = new QLabel("Select Serial Port");
            selectPortComboBox = new QComboBox();
            descriptionLabel = new QLabel("Description: ");
            manufacturerLabel = new QLabel("Manufacturer: ");
            serialNumberLabel = new QLabel("Serial number: ");
            locationLabel = new QLabel("Location: ");
            vendorIdLabel = new QLabel("Vendor Identifier: ");
            productIdLabel = new QLabel("Product Identifier: ");
        portAndParametersGLayout->addWidget(selectPortLabel,0,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(selectPortComboBox,1,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(descriptionLabel,2,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(manufacturerLabel,3,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(serialNumberLabel,4,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(locationLabel,5,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(vendorIdLabel,6,0,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(productIdLabel,7,0,Qt::AlignLeft);
            selectParametersLabel = new QLabel("Select Parameters");
            baudrateLabel = new QLabel("BaudRate");
            baudrateComboBox = new QComboBox();
            endOfLineLabel = new QLabel("End-Of-Line");
            endOfLineEdit = new QLineEdit();
            carriageReturnBox = new QCheckBox("\r (carriage return)");
            newlineBox = new QCheckBox("\n (newline)");
        portAndParametersGLayout->addWidget(selectParametersLabel,0,2,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(baudrateLabel,1,2,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(baudrateComboBox,1,3,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(endOfLineLabel,2,2,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(endOfLineEdit,2,3,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(carriageReturnBox,3,2,1,2,Qt::AlignLeft);
        portAndParametersGLayout->addWidget(newlineBox,4,2,1,2,Qt::AlignLeft);

        botLayout = new QHBoxLayout();
            myEnableChkbox = new QCheckBox("Enable Communication");
            ApplyBtn = new QPushButton("Apply");
            CancelBtn = new QPushButton("Cancel");
        botLayout->addWidget(myEnableChkbox);
        botLayout->addStretch();
        botLayout->addWidget(ApplyBtn);
        botLayout->addWidget(CancelBtn);
   settingsVlayout->addLayout(topVlayout);
   settingsVlayout->addWidget(portAndParametersWidget);
   settingsVlayout->addLayout(botLayout);

   settingsWidget = new QWidget();
   settingsWidget->setParent(nullptr);
   settingsWidget->setLayout(settingsVlayout);
   settingsWidget->setWindowTitle("Settings");



//end settings dialog
    //settings

    connect(enableChangesBox,&QCheckBox::toggled,this,&RS232::slotEnableChangesBoxChanged);

    setLayout(myHlayout);

    slotShowSettings(false); //debug, auto-show settings
}

void RS232::slotShowSettings(bool clicked)
{
    Q_UNUSED(clicked);
    enableChangesBox->setChecked(true);    //this does not emit a signal
    slotEnableChangesBoxChanged();          //so do it manually
    settingsWidget->show();
}

void RS232::slotEnableChangesBoxChanged(void)
{
    if (enableChangesBox->isChecked())
    {
        //unlock here
        portAndParametersWidget->setVisible(true);
        myEnableChkbox->setDisabled(false);
        ApplyBtn->setDisabled(false);
    }
    else
    {
        portAndParametersWidget->setVisible(false);
        myEnableChkbox->setDisabled(true);
        ApplyBtn->setDisabled(true);
        //howto resise the window back to the smallest size?
    }
}

Cheers,
Cedric

[Bonnie]

In your constructor, add

settingsVlayout->setSizeConstraint(QLayout::SetFixedSize);

[cdwijs]

Thank you, that works.

Kind regards,
Cedric