我正在尝试学习如何在C 和QML之间交换数据。考虑以下代码,这是QT示例之一的稍微修改的版本。
// 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" }
]
Component.onCompleted:
{ console.log(invite("William Green").name)}
}
接口文件Person.h
是
//Person.h
#ifndef PERSON_H
#define PERSON_H
#include <QObject>
class Person : public QObject
{
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
接口文件birthday.h
是
#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;
// Called from the QML side
Q_INVOKABLE Person* invite(const QString &name);
private:
Person *m_host;
QList<Person *> m_guests;
};
#endif // BIRTHDAYPARTY_H
Person
和BirthdayParty
C 类都暴露于QML通过
qmlRegisterType<BirthdayParty>("People", 1,0, "BirthdayParty");
qmlRegisterType<Person>("People", 1,0, "Person");
在main.cpp
中(为了简洁而不是在此粘贴)。
当前,当BirthdayParty
组件完成后,代码将"邀请"另一个人" William Green"与聚会"邀请"。邀请方法返回指向此人的指针,该人可以从JavaScript端访问其名称,并通过console.log
但是,如果我想将人(例如所有当前客人的名字)返回 列表,该怎么办?在我看来,根据这个页面我必须以某种方式使用QVariantList
。它是否正确?不幸的是,该页面只是提及如何从C 调用JavaScript函数,而不是反之亦然,因此我不确定如何进行。
,简而言之,我的问题是一个返回复杂的数据类型从C 返回到QML/JavaScript。
在您的情况下,您要公开qobject列表,并且在您的代码中已经通过qqmllistproperty完成:
Q_PROPERTY(QQmlListProperty<Person> guests READ guests)
然后,要获得元素,您必须使用长度以JS的方式进行元素:
Component.onCompleted: {
invite("William Green")
for(var i=0; i < guests.length; i++){
var guest = guests[i]
console.log(guest.name)
}
}
输出:
qml: Leo Hodges
qml: Jack Smith
qml: Anne Brown
qml: William Green