无法连接 qml 信号和 c++ 插槽

Question

我正在尝试将 QML 信号连接到 C++ 插槽。但是当我继续使用 Qt guide 时，出现了两个错误：

file:///home/muhammad/Documents/qt_projects/build-Plaq-Desktop_Qt_5_8_0_GCC_64bit-Debug/qrc:/main.qml: No such file or directory

QObject::connect: Cannot connect (null)::qmlSignal(QString) to PlaqueFinder::cppSlot(QString)

这是我在 main.cpp 中的代码：

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <plaquefinder.h>
#include <QQuickView>
#include <QString>
#include <QObject>
int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);

    QQmlApplicationEngine engine;
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));
    QQuickView view(QUrl::fromLocalFile("qrc:/main.qml"));
    QObject* item = (QObject*)view.rootObject();
    PlaqueFinder plaq;
    QObject::connect(item, SIGNAL(qmlSignal(QString)),
                         &plaq, SLOT(cppSlot(QString)));

    return app.exec();
}

我该如何解决？

Answer 1

不幸的是这个例子不准确

试试这个：

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
    QGuiApplication app(argc, argv);
    QQmlApplicationEngine engine;
    engine.load(QUrl(QLatin1String("qrc:/main.qml")));
    QObject* item = (QObject*)engine.rootObjects()[0];
    PlaqueFinder plaq;
    QObject::connect(item, SIGNAL(qmlSignal(QString)), &plaq, SLOT(cppSlot(QString)));
    return app.exec();
}

通过这一行，您正在创建 QQuickView，无需通过加载相同的 qml 再次创建。

engine.load(QUrl(QLatin1String("qrc:/main.qml")));

如果你想连接一些嵌套对象信号，然后使用findChild 获得适当的 item

无法连接 qml 信号和 c++ 插槽

can't connect qml signal and c++ slot

c++

qt

qml

slot

qt-signals