c++ - 使用嵌套类创建到 cpp 类对象的 qml 连接

Question

我正在尝试创建一个到我的自定义 cpp 类“EState”的连接。EState 包含三个类，其中两个子类有一些自己的类。

到目前为止，我能够在 QML 中通过以下方式访问变量:

// ...
Estate.B.bSub.targetSpeed = 0
// ...

EState构造函数初始化子类，子类初始化它的子类。

// main.cpp

QGuiApplication app(argc, argv);
QQmlApplicationEngine engine;

EState *state = new EState();


engine.rootContext()->setContextProperty("EState", state);

//主体结束

//顶级类

class EState : public QObject
{
    Q_OBJECT
    Q_PROPERTY(EAState *A MEMBER mA NOTIFY aChanged)
    Q_PROPERTY(EBState *B MEMBER mB NOTIFY bChanged)
    Q_PROPERTY(QList<ECState*> Cs MEMBER mCs NOTIFY csChanged)

public:
    EState();
    ~EState(){}

    EAState * mA;
    EBState * mB;
    QList<ECState *> mCs;
    ECState *COne;
    ECState *CTwo;

signals:
    void aChanged();
    void bChanged();
    void csChanged();
};

EState::EState()
{
    mA = new EAState();
    mB = new EBState();
    COne = new ECState();
    CTwo = new ECState();

     mCs = {COne, CTwo};
}

//顶级类(class)结束

//中间类

class EBState : public QObject
{
    Q_OBJECT    
    Q_PROPERTY(BSub * bSub MEMBER mBSub NOTIFY bSubChanged)

public:
    EBState();
    ~EBState(){}

    BSub *  mBSub;              

signals:
    void bSubChanged();
};

EBState::EBState()
{  
    mBSub = new BSub();
}

//结束中间类

//最内层

class BSub : public QObject {
    Q_OBJECT
    Q_PROPERTY(float targetSpeed MEMBER mTargetSpeed NOTIFY targetSpeedChanged)

public:
    BSub ()
    ~BSub (){}
    float mTargetSpeed = 0;

signals:
    void targetSpeedChanged(); 
};

MSub::MSub()
{
     mTargetSpeed = 0;
}

//最里面的类结束

在 QML 中，我想通过以下方式(或类似方式)接收内部类的信号:

 Connections
 {
      target: EStates

      B.bSub.onTargetSpeedChanged: 
      {
           console.log(targetSpeed);          
      }     
 }

当前的错误信息是:qrc:/QML/main. qml: 204 不存在的附加对象

Answer 1

您有 2 个错误:

• QML 中对象 EState 名称中的拼写错误，因为您将其注册为 EState:setContextProperty("EState", state); 但您将其用作 目标:庄园。

• Connections 目标是指具有信号的对象，即 EState.B.bSub 而不是 EState。

综合以上，解决方案是:

Connections
{
    target: EState.B.bSub

    onTargetSpeedChanged: 
    {
        console.log(EState.B.bSub.targetSpeed);
        // or
        // console.log(target.targetSpeed);    
    }     
}