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 sizeHint() const override; public slots: void createSubWidget(const QString &name); QSubWidget *subWidget(const QString &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.
QParentWidget::QParentWidget(QWidget *parent) : QWidget(parent), m_vbox(new QVBoxLayout(this)) { }
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
槽创建新的
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
槽使用
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 &text); QString label() const; QSize 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); }
实现为
QSubWidget
class is self-explanatory.
#include "objects.h" #include <QAxFactory> 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
.
要构建范例必须先构建
QAxServer
库。然后运行 qmake 和 make 工具在
activeqt/hierarchy
.
The demonstration 要求 WebBrowser 支持 ActiveX 控件,并启用脚本。
<script language="javascript"> function createSubWidget( form ) { ParentWidget.createSubWidget( form.nameEdit.value ); } function renameSubWidget( form ) { var SubWidget = ParentWidget.subWidget( form.nameEdit.value ); if ( !SubWidget ) { alert( "No such widget " + form.nameEdit.value + "!" ); return; } SubWidget.label = form.labelEdit.value; form.nameEdit.value = SubWidget.label; } function setFont( form ) { ParentWidget.font = form.fontEdit.value; } </script> <p> This widget can have many children! </p> <object ID="ParentWidget" CLASSID="CLSID:d574a747-8016-46db-a07c-b2b4854ee75c" CODEBASE="http://www.qt-project.org/demos/hierarchy.cab"> [Object not available! Did you forget to build and register the server?] </object><br /> <form> <input type="edit" ID="nameEdit" value="<enter object name>" /> <input type="button" value="Create" onClick="createSubWidget(this.form)" /> <input type="edit" ID="labelEdit" /> <input type="button" value="Rename" onClick="renameSubWidget(this.form)" /> <br /> <input type="edit" ID="fontEdit" value="MS Sans Serif" /> <input type="button" value = "Set Font" onClick="setFont(this.form)" /> </form>