dialog.cpp Example File
layouts/dynamiclayouts/dialog.cpp

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 #include <QtGui>

 #include "dialog.h"

 Dialog::Dialog(QWidget *parent)
     : QDialog(parent)
 {
     createRotableGroupBox();
     createOptionsGroupBox();
     createButtonBox();

     mainLayout = new QGridLayout;
     mainLayout->addWidget(rotableGroupBox, 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(rotableWidgets.count() % 2 == 0);

     foreach (QWidget *widget, rotableWidgets)
         rotableLayout->removeWidget(widget);

     rotableWidgets.enqueue(rotableWidgets.dequeue());

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

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

 void Dialog::createRotableGroupBox()
 {
     rotableGroupBox = new QGroupBox(tr("Rotable Widgets"));

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

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

     rotableLayout = new QGridLayout;
     rotableGroupBox->setLayout(rotableLayout);

     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, SIGNAL(currentIndexChanged(int)),
             this, SLOT(buttonsOrientationChanged(int)));

     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, SIGNAL(clicked()), this, SLOT(rotateWidgets()));
     connect(closeButton, SIGNAL(clicked()), this, SLOT(close()));
     connect(helpButton, SIGNAL(clicked()), this, SLOT(help()));
 }