qml stackview在堆栈，导致connect无法连接

我有多个QML文件可以通过StackView进行推送。如何将它们连接到C+？

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我的项目包含6个qml文件：main.qml打开一个新的ApplicationWindow并声明工具栏。它还使用initalItem homescreen.qml初始化StackView。在主屏幕上，我有不同的按钮，通过stack.push（“URL”）打开不同的qml文件。除了main.qml之外，所有文件都以Item {}开头。我已经能够连接main.qml和home.qml中的信号。但是我无法访问堆栈中更深层的对象。我不知道是否需要更改我的.cpp代码来访问其他对象，或者我是否应该更改StackView的初始化，以便在开始时加载和访问所有文件。这是代码，分解为非常基础：

• main.qml ApplicationWindow { Rectangle{ id: homeButton objectName: "homeButton" signal qmlSignal(string msg) MouseArea { onClicked: {stack.push({item:"qrc:/home.qml}); homeButton.qmlSignal("Hello")} } } StackView{ initalItem: "qrc:/home.qml" } }
• secondframe.qml //主屏幕后面的randomw qml文件 Item { Rectangle{ id: test objectName: "test" signal qmlSignal(string msg) MouseArea { onClicked: {stack.push({item:"qrc:/thirdframe.qml}); test.qmlSignal("Hello")} } } }
• main.cpp中 QApplication app (argc, argv); QQmlEngine enigne; QQmlComponent component(&engine, QUrl(QStringLiteral("qrl:/main.qml"))); QObject *object = componet.create(); QQmlComponent newcomponent(&engine, QUrl(QStringLiteral("qrl:/secondframe.qml"))); QObject *newobject = newcomponet.create(); MyClass myClass QObject *home = object->findChild<QObject*>("homeButton"); // I'm able to connect to every Object in the main.qml or home.qml QObject::connect(home,SIGNAL(qmlSignal(Qstring)), &myClass, SLOT(cppSlot(QString))); QObject *test = newobject->findChild<QObject*>("test"); // Can't connect to the Objects in secondframe.qml QObject::connect(test,SIGNAL(qmlSignal(Qstring)), &myClass, SLOT(cppSlot(QString)));
• 回答1：

一种比进入QML树并提取可能存在或可能不存在的对象更好的方法是为QML提供基于C ++的API。

1. 创建一个基于QObject的类，它具有QML需要能够作为插槽或调用的方法 Q_INVOKABLE class MyAPI : public QObject { Q_OBJECT public slots: void cppSlot(const QString &text); };
2. 创建一个实例并将其公开给QML MyAPI myApi; QQmlEngine engine; engine.rootContext()->setContextProperty("_cppApi", &myApi);
3. 在QML中使用，就像“_cppApi”是对象id一样 MouseArea { onClicked: {stack.push({item:"qrc:/thirdframe.qml}); _cppApi.cppSlot("Hello")} }:

回答2：

在堆栈上按qml之后，对象将是可访问的。因此，当你发出一些信号时，当对象将在堆栈上时，解决方案可以如下所示：

MyClass myClass
QObject *home = object->findChild<QObject*>("homeButton");    // I'm able to connect to every Object in the main.qml or home.qml
QObject::connect(home,SIGNAL(qmlSignal(Qstring)), &myClass, SLOT(cppSlot(QString)));

connect( myClass, MyClass::emitWhenQMLIsAlreadyOnTheStack, this, [this](){
    QObject *test = newobject->findChild<QObject*>("test");       // Now you should be able to connect
    QObject::connect(test,SIGNAL(qmlSignal(Qstring)), &myClass, SLOT(cppSlot(QString));
});