本系列所有文章可以在这里查看[http://blog.csdn.net/cloud_castle/article/category/2123873](http://blog.csdn.net/cloud_castle/article/category/2123873) 接上文[Qt5官方demo解析集24——Extending QML - Default Property Example](http://blog.csdn.net/cloud_castle/article/details/37384881) 这个例子主要向我们介绍了在QML类型中定义函数的方法。 person.h: ~~~ #ifndef PERSON_H #define PERSON_H #include <QObject> class Person : public QObject // 基本的person类没有改变,删掉了这个demo用不上的Boy和Girl { Q_OBJECT Q_PROPERTY(QString name READ name WRITE setName) Q_PROPERTY(int shoeSize READ shoeSize WRITE setShoeSize) public: Person(QObject *parent = 0); QString name() const; void setName(const QString &); int shoeSize() const; void setShoeSize(int); private: QString m_name; int m_shoeSize; }; #endif // PERSON_H ~~~ person.cpp: ~~~ #include "person.h" Person::Person(QObject *parent) : QObject(parent), m_shoeSize(0) { } QString Person::name() const { return m_name; } void Person::setName(const QString &n) { m_name = n; } int Person::shoeSize() const { return m_shoeSize; } void Person::setShoeSize(int s) { m_shoeSize = s; } ~~~ birthdayparty.h: ~~~ #ifndef BIRTHDAYPARTY_H #define BIRTHDAYPARTY_H #include <QObject> #include <QQmlListProperty> #include "person.h" class BirthdayParty : public QObject { Q_OBJECT Q_PROPERTY(Person *host READ host WRITE setHost) Q_PROPERTY(QQmlListProperty<Person> guests READ guests) public: BirthdayParty(QObject *parent = 0); Person *host() const; void setHost(Person *); QQmlListProperty<Person> guests(); int guestCount() const; Person *guest(int) const; // ![0] // 这里定义了一个函数 Q_INVOKABLE void invite(const QString &name); // 为了在QML中能够调用该函数,我们需要使用宏Q_INVOKABLE // ![0] // 该宏使得这个函数可以被通过元对象系统调用 // 否则在QML中对其调用时编译器将抱怨invite未定义 private: Person *m_host; QList<Person *> m_guests; }; #endif // BIRTHDAYPARTY_H ~~~ birthdayparty.cpp: ~~~ #include "birthdayparty.h" BirthdayParty::BirthdayParty(QObject *parent) : QObject(parent), m_host(0) { } // ![0] Person *BirthdayParty::host() const { return m_host; } void BirthdayParty::setHost(Person *c) { m_host = c; } QQmlListProperty<Person> BirthdayParty::guests() { return QQmlListProperty<Person>(this, m_guests); } int BirthdayParty::guestCount() const { return m_guests.count(); } Person *BirthdayParty::guest(int index) const { return m_guests.at(index); } void BirthdayParty::invite(const QString &name) // 函数实现 { Person *person = new Person(this); person->setName(name); m_guests.append(person); } // ![0] ~~~ example.qml: ~~~ import QtQuick 2.0 import People 1.0 BirthdayParty { host: Person { name: "Bob Jones" shoeSize: 12 } guests: [ Person { name: "Leo Hodges" }, Person { name: "Jack Smith" }, Person { name: "Anne Brown" } ] // ![0] Component.onCompleted: invite("William Green") // 我们需要在一个handler中调用这个函数 // ![0] // 这里是在组件完成时调用 } ~~~ main.cpp: ~~~ #include <QCoreApplication> #include <QQmlEngine> #include <QQmlComponent> #include <QDebug> #include "birthdayparty.h" #include "person.h" int main(int argc, char ** argv) { QCoreApplication app(argc, argv); qmlRegisterType<BirthdayParty>("People", 1,0, "BirthdayParty"); qmlRegisterType<Person>("People", 1,0, "Person"); QQmlEngine engine; QQmlComponent component(&engine, QUrl("qrc:example.qml")); BirthdayParty *party = qobject_cast<BirthdayParty *>(component.create()); if (party && party->host()) { qWarning() << party->host()->name() << "is having a birthday!"; qWarning() << "They are inviting:"; for (int ii = 0; ii < party->guestCount(); ++ii) qWarning() << " " << party->guest(ii)->name(); } else { qWarning() << component.errors(); } return 0; } ~~~ 运行结果: ![](https://box.kancloud.cn/2016-01-18_569cbd086574c.jpg) 可以看到前三位客人是作为guests属性值初始化就存在的,而William Green则是在组件加载完成后才"被邀请"的。