Hierarchy Example (ActiveQt) | Active Qt 5.15.19 (original) (raw)

The Hierarchy example is shows how to write an in-process ActiveX control. The control is a QWidget subclass with child widgets that are accessible as sub-types.

class QParentWidget : public QWidget { Q_OBJECT Q_CLASSINFO("ClassID", "{d574a747-8016-46db-a07c-b2b4854ee75c}"); Q_CLASSINFO("InterfaceID", "{4a30719d-d9c2-4659-9d16-67378209f822}"); Q_CLASSINFO("EventsID", "{4a30719d-d9c2-4659-9d16-67378209f823}"); public: explicit QParentWidget(QWidget *parent = nullptr);

[QSize](qsize.html) sizeHint() const override;

public slots: void createSubWidget(const QString &name);

QSubWidget *subWidget(const [QString](qstring.html) &name);

private: QVBoxLayout *m_vbox; };

The QParentWidget class provides slots to create a widget with a name, and to return a pointer to a named widget. The class declaration uses Q_CLASSINFO() to provide the COM identifiers for this class.

The constructor of QParentWidget creates a vertical box layout. New child widgets are automatically added to the layout.

void QParentWidget::createSubWidget(const QString &name) { QSubWidget *sw = new QSubWidget(this, name); m_vbox->addWidget(sw); sw->setLabel(name); sw->show(); }

The createSubWidget slot creates a new QSubWidget with the name provided in the parameter, and sets the label to that name. The widget is also shown explicitly.

QSubWidget *QParentWidget::subWidget(const QString &name) { return findChild<QSubWidget *>(name); }

The subWidget slot uses the QObject::findChild() function and returns the first child of type QSubWidget that has the requested name.

class QSubWidget : public QWidget { Q_OBJECT Q_PROPERTY(QString label READ label WRITE setLabel)

Q_CLASSINFO("ClassID", "{850652f4-8f71-4f69-b745-bce241ccdc30}");
Q_CLASSINFO("InterfaceID", "{2d76cc2f-3488-417a-83d6-debff88b3c3f}");
Q_CLASSINFO("ToSuperClass", "QSubWidget");

public: QSubWidget(QWidget *parent = nullptr, const QString &name = QString());

void setLabel(const [QString](qstring.html) &text);
[QString](qstring.html) label() const;

[QSize](qsize.html) sizeHint() const override;

protected: void paintEvent(QPaintEvent *e) override;

private: QString m_label; };

The QSubWidget class has a single string-property label, and implements the paintEvent to draw the label. The class uses again Q_CLASSINFO to provide the COM identifiers, and also sets the ToSuperClass attribute to QSubWidget, to ensure that only no slots of any superclasses (i.e. QWidget) are exposed.

QSubWidget::QSubWidget(QWidget *parent, const QString &name) : QWidget(parent) { setObjectName(name); }

void QSubWidget::setLabel(const QString &text) { m_label = text; setObjectName(text); update(); }

QString QSubWidget::label() const { return m_label; }

QSize QSubWidget::sizeHint() const { QFontMetrics fm(font()); return QSize(fm.horizontalAdvance(m_label), fm.height()); }

void QSubWidget::paintEvent(QPaintEvent *) { QPainter painter(this); painter.setPen(palette().text().color()); painter.drawText(rect(), Qt::AlignCenter, m_label); }

The implementation of the QSubWidget class is self-explanatory.

#include "objects.h" #include

QAXFACTORY_BEGIN("{9e626211-be62-4d18-9483-9419358fbb03}", "{75c276de-1df5-451f-a004-e4fa1a587df1}") QAXCLASS(QParentWidget) QAXTYPE(QSubWidget) QAXFACTORY_END()

The classes are then exported using a QAxFactory. QParentWidget is exported as a full class (which can be created ), while QSubWidget is only exported as a type, which can only be created indirectly through APIs of QParentWidget.

To build the example you must first build the QAxServer library. Then run qmake and your make tool in activeqt/hierarchy.

The demonstration requires your WebBrowser to support ActiveX controls, and scripting to be enabled.

This widget can have many children!

Example project @ code.qt.io