將C ++自定義類型暴露給QML

Question

我有以下C ++自定義對象，希望在QML中將其用作enum類型：

#include <QtQml>
#include <QApplication>
#include <QQmlApplicationEngine>

#include "database/uepeoplemodel.h"
#include "core/uestatus.h"
#include "core/uedatabaseconnectionstatus.h"

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QQmlApplicationEngine engine;

    UeStatus* ueApplicationStatus=new UeStatus(qApp);
    UePeopleModel* uePeopleModel=new UePeopleModel(qApp);

    QObject::connect(uePeopleModel,
                     SIGNAL(ueSignalDatabaseConnectionChanged(UeDatabaseConnectionStatus::UeTypeDatabaseConnectionStatus)),
                     ueApplicationStatus,
                     SLOT(ueSignalDatabaseConnectionChanged(UeDatabaseConnectionStatus::UeTypeDatabaseConnectionStatus)));

    uePeopleModel->ueConnectToDatabase();

    engine.rootContext()->setContextProperty("uePeopleModel",
                                             uePeopleModel);
    engine.rootContext()->setContextProperty("ueApplicationStatus",
                                             ueApplicationStatus);
    engine.addImageProvider(QLatin1String("uePeopleModel"),
                            uePeopleModel);

    qmlRegisterUncreatableType<UeDatabaseConnectionStatus::UeTypeDatabaseConnectionStatus>("si.mikroelektronika",
                                                                                           1,
                                                                                           0,
                                                                                           "UeTypeDatabaseConnectionStatus",
                                                                                           "Database Connection Status");

    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));

    return app.exec();
}

我收到以下編譯錯誤（在Linux work002 3.19.0-28-generic #30-Ubuntu SMP Mon Aug 31 15:52:51 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux上使用gcc version 4.9.2在Linux work002 3.19.0-28-generic #30-Ubuntu SMP Mon Aug 31 15:52:51 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux ：

在/opt/QtOpenSource55/5.5/gcc_64/include/QtCore/qobject.h:40:0中包含的文件中，從/opt/QtOpenSource55/5.5/gcc_64/include/QtCore/qabstractanimation.h:37，從/ opt / QtOpenSource55中包含/5.5/gcc_64/include/QtCore/QtCore:4，來自/opt/QtOpenSource55/5.5/gcc_64/include/QtQml/QtQmlDepends:3，來自/opt/QtOpenSource55/5.5/gcc_64/include/QtQml/QtQml:3，來自../ueBlagajnaClient/main.cpp:1：/opt/QtOpenSource55/5.5/gcc_64/include/QtCore/qobjectdefs.h:88:5：錯誤：可能未將類定義聲明為好友Q_DECL_CONSTEXPR const QMetaObject * qt_getEnumMetaObject（ENUM ）Q_DECL_NOEXCEPT {return＆staticMetaObject; } \\ ^ ../ueBlagajnaClient/database/../core/uedatabaseconnectionstatus.h:17:5：注意：擴展宏'Q_ENUM'Q_ENUM（UeTypeDatabaseConnectionStatus）^ /opt/QtOpenSource55/5.5/gcc_64/include/QtCore/ qobjectdefs.h：88：35：錯誤：“ QMetaObject”既不是函數也不是成員函數； 無法聲明為朋友Q_DECL_CONSTEXPR const QMetaObject * qt_getEnumMetaObject（ENUM）Q_DECL_NOEXCEPT {return＆staticMetaObject; } \\ ^ ../ueBlagajnaClient/database/../core/uedatabaseconnectionstatus.h:17:5：注意：擴展宏'Q_ENUM'Q_ENUM（UeTypeDatabaseConnectionStatus）^ /opt/QtOpenSource55/5.5/gcc_64/include/QtCore/ qobjectdefs.h：88：35：錯誤：預期為';' 在成員聲明朋友Q_DECL_CONSTEXPR常量QMetaObject * qt_getEnumMetaObject（ENUM）Q_DECL_NOEXCEPT結束時{return＆staticMetaObject; } \\ ^ ../ueBlagajnaClient/database/../core/uedatabaseconnectionstatus.h:17:5：注意：擴展宏'Q_ENUM'Q_ENUM（UeTypeDatabaseConnectionStatus）^ /opt/QtOpenSource55/5.5/gcc_64/include/QtCore/ qobjectdefs.h：88：73：錯誤：ISO C ++禁止聲明沒有類型的“ qt_getEnumMetaObject” [-fpermissive]朋友Q_DECL_CONSTEXPR const QMetaObject qt_getEnumMetaObject（ENUM）Q_DECL_NOEXCEPT {return＆staticMetaObject; } \\ ^ ../ueBlagajnaClient/database/../core/uedatabaseconnectionstatus.h:17:5：注意：在宏“ Q_ENUM”的擴展中Q_ENUM（UeTypeDatabaseConnectionStatus）^ ../ueBlagajnaClient/database/../core/uedatabaseconnectionstatus .h：在成員函數'int UeDatabaseConnectionStatus :: qt_getEnumMetaObject（UeDatabaseConnectionStatus :: UeTypeDatabaseConnectionStatus）'中：/opt/QtOpenSource55/5.5/gcc_64/include/QtCore/qobjectdefs.h:88:101：錯誤：無法轉換'const QMetaObject *'返回朋友Q_DECL_CONSTEXPR const QMetaObject中的'int *'。 Qt_getEnumMetaObject（ENUM）Q_DECL_NOEXCEPT {return＆staticMetaObject; } \\ ^ ../ueBlagajnaClient/database/../core/uedatabaseconnectionstatus.h:17:5：注意：擴展宏'Q_ENUM'Q_ENUM（UeTypeDatabaseConnectionStatus）^在/opt/QtOpenSource55/5.5/gcc_64/ include / QtQml / QtQml：9：0，來自../ueBlagajnaClient/main.cpp:1：/opt/QtOpenSource55/5.5/gcc_64/include/QtQml/qqml.h：實例化為'int qmlRegisterUncreatableType（const char ，int ，int，const char *，const QString＆）[with T = UeDatabaseConnectionStatus :: UeTypeDatabaseConnectionStatus]'：../ueBlagajnaClient/main.cpp:35:120：此處需要/opt/QtOpenSource55/5.5/gcc_64/include/QtQml/ qqml.h：83：59：錯誤：“ staticMetaObject”不是“ UeDatabaseConnectionStatus :: UeTypeDatabaseConnectionStatus”的成員。const char * className = T :: staticMetaObject.className（）; \\ ^ /opt/QtOpenSource55/5.5/gcc_64/include/QtQml/qqml.h:134:5：注意：在擴展宏“ QML_GETTYPENAMES” QML_GETTYPENAMES時^從/opt/QtOpenSource55/5.5/gcc_64/include/QtQml包含的文件中/ QtQml：9：0，來自../ueBlagajnaClient/main.cpp:1：/opt/QtOpenSource55/5.5/gcc_64/include/QtQml/qqml.h:144:51：錯誤：“ staticMetaObject”不是該成員'UeDatabaseConnectionStatus :: UeTypeDatabaseConnectionStatus'uri，versionMajor，versionMinor，qmlName，＆T :: staticMetaObject，^ Makefile：1319：目標“ main.o”的配方失敗：*** [main.o]錯誤1 08:04:15 ：進程“ / usr / bin / make”以代碼2退出。生成/部署項目ueBlagajnaClient時出錯（套件：Desktop Qt 5.5.0 GCC 64bit）執行步驟“ Make”時

為什么以及如何擺脫此錯誤？ 我如何濫用qmlRegisterUncreatableType方法？

Answer 1

如果要使用qmlRegisterType ，則使用的類必須是繼承QObject並具有Q_OBJECT宏的類：

class UeTypeDatabaseConnectionStatus: public QObject
{
    Q_OBJECT

public:
    enum StatusEnum
    {
        NOT_CONNECTED=false,
        CONNECTED=true
    }
    Q_ENUM(StatusEnum)
    ...
}

在QML中，可以像創建其他任何QML類一樣創建它的實例。

編輯：但是，由於您要做的只是使用枚舉值，請改用qmlRegisterUncreatableType 。 這樣就可以注冊類型，但是您不能創建它的實例。

要訪問枚舉值，請導入類型並像其他枚舉一樣使用它：

connectionProperty: UeTypeDatabaseConnectionStatus.CONNECTED;