动态布局范例

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.

更多信息，拜访布局管理页面。

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 ).

最后， Dialog::rotateWidgets() 被调用。

    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,
            &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 ， helpButton 和 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);
    for (QWidget *widget : std::as_const(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);
    }
}

运行范例

要运行范例从 Qt Creator ，打开 Welcome 模式，然后选择范例从 Examples 。更多信息，拜访构建和运行范例 .

范例工程 @ code.qt.io