Dynamic Layouts Example | Qt Widgets 5.13.0

Qt 5.13 | Qt Widgets | Dynamic Layouts Example

Qt 5.13.0 Reference Documentation

# Dynamic Layouts Example

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      #include <QtWidgets>

      #include "dialog.h"

      Dialog::Dialog(QWidget *parent)
          : QDialog(parent)
      {
          createRotatableGroupBox();
          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"));
      }

      void Dialog::buttonsOrientationChanged(int index)
      {
          mainLayout->setSizeConstraint(QLayout::SetNoConstraint);
          setMinimumSize(0, 0);

          Qt::Orientation orientation = Qt::Orientation(
                  buttonsOrientationComboBox->itemData(index).toInt());

          if (orientation == buttonBox->orientation())
              return;

          mainLayout->removeWidget(buttonBox);

          int spacing = mainLayout->spacing();

          QSize oldSizeHint = buttonBox->sizeHint() + QSize(spacing, spacing);
          buttonBox->setOrientation(orientation);
          QSize newSizeHint = buttonBox->sizeHint() + QSize(spacing, spacing);

          if (orientation == Qt::Horizontal) {
              mainLayout->addWidget(buttonBox, 2, 0);
              resize(size() + QSize(-oldSizeHint.width(), newSizeHint.height()));
          } else {
              mainLayout->addWidget(buttonBox, 0, 3, 2, 1);
              resize(size() + QSize(newSizeHint.width(), -oldSizeHint.height()));
          }

          mainLayout->setSizeConstraint(QLayout::SetDefaultConstraint);
      }

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

          for (QWidget *widget : qAsConst(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);
          }
      }

      void Dialog::help()
      {
          QMessageBox::information(this, tr("Dynamic Layouts Help"),
                                     tr("This example shows how to change layouts "
                                        "dynamically."));
      }

      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();
      }

      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);
      }

      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);
      }