Question

我已将ObjectName设置为main中的一个类，并希望从另一个类访问此对象：

的main.cpp

int main(int argc, char *argv[])
{
   QApplication app(argc, argv);
   QQmlApplicationEngine engine;
   ImageProvider *imageProvider = new ImageProvider(&engine,QQmlImageProviderBase::Image,0);
   PageBuffer p;
   p.setObjectName("Object"); 
   engine.rootContext()->setContextProperty("p",&p);
   engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
   engine.addImageProvider("images", imageProvider);

return app.exec();
}

我尝试从以下位置访问PageBuffer p的课程：

QImage ImageProvider ::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
 {
    QQuickWindow *window = qobject_cast<QQuickWindow*>(m_engine->rootObjects()[0]);
    PageBuffer *p = window->findChild<PageBuffer *>("Object");
    cout<<p->current_box; //error at runtime
    QImage e;
    e.load("Pic4.jpg");
    return e; 
 }

但我似乎无法访问对象PageBuffer的任何成员，也许是因为指针，我怎样才能从对象p访问函数？

Answer 1

您可以将pageBuffer成员介绍给ImageProvider：

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QQmlApplicationEngine engine;
    ImageProvider *imageProvider = new ImageProvider(&engine,QQmlImageProviderBase::Image,0);
    PageBuffer p;
    imageProvider->setPageBuffer(p);
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    engine.addImageProvider("images", imageProvider);

    return app.exec();
}

然后您不需要搜索对象孩子，您可以直接访问pageBuffer：

QImage ImageProvider::requestImage(const QString &id, QSize *size, const QSize &requestedSize)
{
    QQuickWindow *window = qobject_cast<QQuickWindow*>(m_engine->rootObjects()[0]);
    PageBuffer *p = pageBuffer();
    cout << p->current_box;
    QImage e;
    e.load("Pic4.jpg");
    return e; 
}

使用QQuickWindow访问成员函数

1 个答案: