Question

我有一个我正在接触QML的课程如下：

#ifndef MYTYPE_H
#define MYTYPE_H

#include <QString>
#include <QObject>


class MyType : public QObject
{
    Q_OBJECT
    Q_ENUMS(TestEnum)
    Q_PROPERTY(TestEnum foo READ foo WRITE setFoo NOTIFY fooChanged)

public:

    enum class TestEnum
    {
        State1 = 1,
        State2 = 2
    };

    MyType(QObject *parent = nullptr) :
        QObject(parent),
        mFoo(TestEnum::State1)
    {
    }

    TestEnum foo() const
    {
        return mFoo;
    }

    void setFoo(TestEnum foo)
    {
        if (foo == mFoo)
            return;

        mFoo = foo;
        emit fooChanged(mFoo);
    }

signals:
    void fooChanged(MyType::TestEnum blah);

private:
    TestEnum mFoo;
};

Q_DECLARE_METATYPE(MyType::TestEnum)

#endif // MYTYPE_H

这里我有一个枚举类型，我想向QML公开。

我将主要函数调用的类型注册为：

qmlRegisterType<MyType>("App", 1, 0, "MyType");

现在我的qml文件中有一个信号，我接受了这个枚举参数：

signal submitTextField(MyType::TestEnum state) // Compiler complains here

信号连接为：

QObject *topLevel = engine.rootObjects().value(0);
//QQuickWindow *window = qobject_cast<QQuickWindow *>(topLevel);
// This is just a class that implements the slot
HandleTextField handleTextField;
// connect our QML signal to our C++ slot
QObject::connect(topLevel, SIGNAL(submitTextField(MyType::TestEnum)),
                     &handleTextField, SLOT(handleSubmitTextField(MyType::TestEnum)));

实现槽的类定义为：

class HandleTextField : public QObject
{
    Q_OBJECT
public:
    explicit HandleTextField(QObject *parent = 0);

public slots:
    void handleSubmitTextField(MyType::TestEnum in);
    void handleFooChanged(MyType::TestEnum in);
public:
    MyType myType;

};

语法MyType::TestEnum无效。我很想将所有内容转换为ints并取消枚举，但想知道是否有办法在QML信号中使用此枚举类型。我可以MyType.State1 and MyType.State2但无法引用枚举类型。

Answer 1

好吧，似乎这不能用枚举来完成，即你必须使用ints。我做了以下更改并且有效：

class MyType : public QObject
{
    Q_OBJECT
    Q_ENUMS(TestEnum)
    Q_PROPERTY(TestEnum foo READ foo WRITE setFoo NOTIFY fooChanged)

public:

    enum TestEnum
    {
        State1 = 1,
        State2 = 2
    };

    MyType(QObject *parent = nullptr) :
        QObject(parent),
        mFoo(TestEnum::State1)
    {
    }

    TestEnum & foo()
    {
        return mFoo;
    }

    void setFoo(TestEnum foo)
    {
        if (foo == mFoo)
            return;

        mFoo = foo;
        emit fooChanged(static_cast<int>(mFoo));
    }

signals:
    void fooChanged(int blah);

private:
    TestEnum mFoo;
};

Q_DECLARE_METATYPE(MyType::TestEnum)

还需要更改插槽：

class HandleTextField : public QObject
{
    Q_OBJECT
public:
    explicit HandleTextField(QObject *parent = 0);

public slots:
    void handleSubmitTextField(int in);
    void handleFooChanged(int in);
public:
    MyType myType;

};

我们需要更改int类型的连接：

QObject::connect(topLevel, SIGNAL(submitTextField(int)),
                         &handleTextField, SLOT(handleSubmitTextField(int)));

最后信号被声明为：

signal submitTextField(int text)

带有C ++枚举类型

1 个答案: