从Qt 5.3中的代码中的任何位置获取QML根对象

Question

1. 如何rootContext()->findChild()从C++代码中的任何位置检索根对象(下面的代码返回0,也返回0)(类是注册的QML类型,类组件定义是根的直接子类的类方法,请参阅objectName )并在运行时添加生成的QQuickItem？
2. 有myclass注册为QML类型.如何Button使用最底层的代码将QML添加到场景中？

在main.qml(片段)中

import QtQuick 2.3
import QtQuick.Window 2.2

Window {
    objectName: root

    visible: true
    width: 360
    height: 100

    // ...
}

myclass.cpp

void myclass::add_hip()
{
    setProperty("hip", 87);

    QQmlEngine *engine = QtQml::qmlEngine(this);

//    QObject *root = engine->rootContext()->findChild<QObject*>("womanObj");
    QQuickWindow *window = qobject_cast<QQuickWindow *>(root);
    QObject *wobj = window->findChild<QObject *>("womanObj");
    // 1. Define a QML component.
    QQmlComponent *readHipComp = new QQmlComponent(engine);
    readHipComp->setData("import QtQuick.Controls 1.2\n\
                         Button {\n\
                             anchors.top: addHipBtn.top\n\
                             anchors.left: addHipBtn.left\n\
                             anchors.margins: 3\n\
                             text: \"Hip value\"\n\
                             onClicked: {\n\
                                 msgDlg.text = myclass.hip\n\
                                 msgDlg.open()\n\
                             }\
                         }", QUrl());
    // 2. Create the component instance.
    QQuickItem *readHipBtn = qobject_cast<QQuickItem *>(readHipComp->create());
    // 3. Add the instance to the scene.
//    readHipBtn->setParentItem(qobject_cast<QQuickItem *>(engine->rootContext()->contextObject()));

//    QObject *root = QtQml::qmlContext(this)->findChild<QQuickItem *>("root");
//    readHipBtn->setParent(root);
}

UPDATE

extern QQuickWindow *window;
void myclass::add_hip()
{ 

   //...
 readHipBtn->setParentItem(window->contentItem());
//...
}

工作,但3.)它没有看到其他main.qml对象.

Answer 1

您不需要 objectName。

获取根元素并检查它是否是一个窗口：

QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
QObject *root = engine.rootObjects()[0];

QQuickWindow *window = qobject_cast<QQuickWindow *>(root);
if (!window) {
    qFatal("Error: Your root item has to be a window.");
    return -1;
}
window->show();