Qt Documentation

Contents

Dynamic Layouts Example

Shows how to re-orient widgets in running applications.

Dynamic Layouts implements dynamically placed widgets within running applications. The widget placement depends on whether Horizontal or Vertical is chosen.

For more information, visit the Layout Management page.

Dialog Constructor

To begin with, the application creates the UI components by calling the following methods:

  • createRotatableGroupBox()
  • createOptionsGroupBox()
  • createButtonBox()

It then adds the UI components to a GridLayout (mainLayout).

Finally, Dialog::rotateWidgets() is called.

    createOptionsGroupBox();
    createButtonBox();

    mainLayout = new QGridLayout;
    mainLayout->addWidget(rotatableGroupBox, 0, 0);
    mainLayout->addWidget(optionsGroupBox, 1, 0);
    mainLayout->addWidget(buttonBox, 2, 0);
    setLayout(mainLayout);

    mainLayout->setSizeConstraint(QLayout::SetMinimumSize);

    setWindowTitle(tr("Dynamic Layouts"));

Creating the Main Widgets

The createRotatableGroupBox() method creates a rotatable group box, then adds a series of widgets:

It goes on to add signals and slots to each widget, and assigns a QGridLayout called rotatableLayout.

void Dialog::createRotatableGroupBox()
{
    rotatableGroupBox = new QGroupBox(tr("Rotatable Widgets"));

    rotatableWidgets.enqueue(new QSpinBox);
    rotatableWidgets.enqueue(new QSlider);
    rotatableWidgets.enqueue(new QDial);
    rotatableWidgets.enqueue(new QProgressBar);

    int n = rotatableWidgets.count();
    for (int i = 0; i < n; ++i) {
        connect(rotatableWidgets[i], SIGNAL(valueChanged(int)),
                rotatableWidgets[(i + 1) % n], SLOT(setValue(int)));
    }

    rotatableLayout = new QGridLayout;
    rotatableGroupBox->setLayout(rotatableLayout);

    rotateWidgets();
}

Adding Options

createOptionsGroupBox() creates the following widgets:

  • optionsGroupBox
  • buttonsOrientationLabel
  • buttonsOrientationComboBox. The orientation of the ComboBox is either horizontal (default value) or vertical. These two values are added during the startup of the application. It is not possible to leave the option empty.
void Dialog::createOptionsGroupBox()
{
    optionsGroupBox = new QGroupBox(tr("Options"));

    buttonsOrientationLabel = new QLabel(tr("Orientation of buttons:"));

    buttonsOrientationComboBox = new QComboBox;
    buttonsOrientationComboBox->addItem(tr("Horizontal"), Qt::Horizontal);
    buttonsOrientationComboBox->addItem(tr("Vertical"), Qt::Vertical);

    connect(buttonsOrientationComboBox,
            QOverload<int>::of(&QComboBox::currentIndexChanged),
            this,
            &Dialog::buttonsOrientationChanged);

    optionsLayout = new QGridLayout;
    optionsLayout->addWidget(buttonsOrientationLabel, 0, 0);
    optionsLayout->addWidget(buttonsOrientationComboBox, 0, 1);
    optionsLayout->setColumnStretch(2, 1);
    optionsGroupBox->setLayout(optionsLayout);
}

Adding Buttons

createButtonBox() constructs a QDialogButtonBox called buttonBox to which are added a closeButton, a helpButton and a rotateWidgetsButton. It then assigns a signal and a slot to each button in buttonBox.

void Dialog::createButtonBox()
{
    buttonBox = new QDialogButtonBox;

    closeButton = buttonBox->addButton(QDialogButtonBox::Close);
    helpButton = buttonBox->addButton(QDialogButtonBox::Help);
    rotateWidgetsButton = buttonBox->addButton(tr("Rotate &Widgets"),
                                               QDialogButtonBox::ActionRole);

    connect(rotateWidgetsButton, &QPushButton::clicked, this, &Dialog::rotateWidgets);
    connect(closeButton, &QPushButton::clicked, this, &Dialog::close);
    connect(helpButton, &QPushButton::clicked, this, &Dialog::help);
}

Rotating the Widgets

Removes the current widgets and activates the next widget.

void Dialog::rotateWidgets()
{
    Q_ASSERT(rotatableWidgets.count() % 2 == 0);

    foreach (QWidget *widget, rotatableWidgets)
        rotatableLayout->removeWidget(widget);

    rotatableWidgets.enqueue(rotatableWidgets.dequeue());

    const int n = rotatableWidgets.count();
    for (int i = 0; i < n / 2; ++i) {
        rotatableLayout->addWidget(rotatableWidgets[n - i - 1], 0, i);
        rotatableLayout->addWidget(rotatableWidgets[i], 1, i);
    }
}

Running the Example

To run the example from Qt Creator, open the Welcome mode and select the example from Examples. For more information, visit Building and Running an Example.

Files:

© 2019 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners. The documentation provided herein is licensed under the terms of the GNU Free Documentation License version 1.3 as published by the Free Software Foundation. Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners.