Qt-点击QML按钮时如何运行C++函数?使用QQmlApplicationEngine

Question

myclass.h

#ifndef MYCLASS_H
#define MYCLASS_H
#include <QDebug>
#include <QObject>
class MyClass : public QObject
{
public:
    MyClass();
public slots:
    void buttonClicked();
    void buttonClicked(QString &in);
};
#endif // MYCLASS_H

---

myclass.cpp

#include "myclass.h"
MyClass::MyClass()
{
}
void MyClass::buttonClicked()
{
    // Do Something
}
void MyClass::buttonClicked(QString &in)
{
    qDebug() << in;
}

---

main.cpp

#include <QApplication>
#include <QQmlApplicationEngine>
#include <myclass.h>
#include <QQmlContext>
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QQmlApplicationEngine engine;
    engine.load(QUrl(QStringLiteral("qrc:///main.qml")));
    MyClass myClass;  // A class containing my functions
    // Trying to "SetContextProperty" as I saw people do it to achieve C++/QML connection
    QQmlContext * context = new QQmlContext(engine.rootContext());
    context->setContextProperty("_myClass", &myClass);
    return app.exec();
}

我想在myClass类中使用一个函数，当单击QML按钮时，该函数会获取一个QString参数。。

当我编译&跑一切进展顺利。但是当我点击按钮时。。它在调试器中显示此错误：

qrc:///main.qml:80:ReferenceError:_myClass未定义

>>"QML文件中的第80行"：

74:    MouseArea {
75:        id: mouseArea1
76:        anchors.fill: parent
77:        hoverEnabled: true;
78:        onEntered: { rectangle1.border.width = 2 }
79:        onExited: { rectangle1.border.width = 1 }
80:        onClicked: _myClass.buttonClicked("Worked?")
81:    }

---

编辑：(至于编译错误引起的错误(

正如@Jairo所建议的，所有类都必须从QObject继承。

仍在寻找解决我主要问题的方法。

Answer 1

哦。这里有几处不对。(代码甚至可以编译吗？(

第一件事。当将某些内容传递给QML引擎的根属性时，您不能创建新的上下文——您必须直接使用根上下文，如下所示：

engine.rootContext()->setContextProperty("_myClass", &myClass);

接下来，类定义有一些问题。请参阅下面代码中的我的评论：

class MyClass : public QObject
{
    // This macro is required for QObject support.  You should get a compiler
    // error if you don't include this.
    Q_OBJECT
public:
    // QObjects are expected to support a parent/child hierarchy.  I've modified
    // the constructor to match the standard.
    explicit MyClass(QObject *parent = 0);
public slots:
    // This method needs to take either a QString or a const reference to one.
    // (QML doesn't support returning values via the parameter list.)
    void buttonClicked(const QString& in);
};

构造函数的实现应该将父类传递给基类：

MyClass::MyClass(QObject *parent) :
    QObject(parent)
{
}