Simon's newWindowComponent example

gistfile1.cpp

#include <QtQml>

class NewWindowContext : public QQmlContext
{
    Q_OBJECT
public:
    NewWindowContext(QQmlContext *parentContext)
        : QQmlContext(parentContext)
        , handle(0)
    {}

    // Use QExplicitlySharedDataPointer<WebContentsAdapter> in real version :)
    void *handle;
};

class WebView : public QObject, public QQmlParserStatus
{
    Q_OBJECT
    Q_INTERFACES(QQmlParserStatus)
    Q_PROPERTY(QQmlComponent* newWindowComponent READ newWindowComponent WRITE setNewWindowComponent)
public:
    WebView();

    void setNewWindowComponent(QQmlComponent *comp) { m_newWindowComponent = comp; }
    QQmlComponent *newWindowComponent() const { return m_newWindowComponent; }

    Q_INVOKABLE void createNewWindow();

    virtual void classBegin() {}
    virtual void componentComplete();

private:
    QQmlComponent *m_newWindowComponent;
};

WebView::WebView()
    : m_newWindowComponent(0)
{
    qDebug() << "WebView::WebView()";
}

void WebView::createNewWindow()
{
    Q_ASSERT(m_newWindowComponent);

    QQmlContext *parentContext = m_newWindowComponent->creationContext();
    if (!parentContext)
        parentContext = qmlContext(this);
    // ### can this happen??
    if (!parentContext) {
        QQmlEngine *engine = qmlEngine(this);
        Q_ASSERT(engine);
        parentContext = engine->rootContext();
    }
    NewWindowContext *newContext = new NewWindowContext(parentContext);
    newContext->handle = this; // Or anything, really :)
    m_newWindowComponent->create(newContext);
}

void WebView::componentComplete()
{
    QQmlContext *context = qmlContext(this);

    void *handle = 0;
    while (context) {
        if (NewWindowContext *newWindowContext = qobject_cast<NewWindowContext*>(context)) {
            qSwap(newWindowContext->handle, handle);
            break;
        }
        context = context->parentContext();
    }
    if (handle)
        qDebug() << "WebView created from another WebView!" << handle;
    else
        qDebug() << "Standalone WebView complete";
}

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);

    QQmlEngine engine;

    qmlRegisterType<WebView>("TestWebEngine", 1, 0, "WebView");

    QQmlComponent doc(&engine);
    doc.setData(""
            "import QtQuick 2.0\n"
            "import TestWebEngine 1.0\n"

            "Item {\n"
            "    Component {\n"
            "        id: viewComponent\n"
            "        WebView { }\n"
            "    }\n"
            "    Component {\n"
            "        id: secondWindowComponent\n"
            "        Loader {\n"
// This doesn't work
            "            sourceComponent: viewComponent\n"
// But this does, weirdly.
//             "            WebView { }\n"
            "        }\n"
            "    }\n"
            "\n"
            "    property QtObject initialWebView: WebView {\n"
            "        newWindowComponent: secondWindowComponent\n"
            "    }\n"
            "}", QUrl());

    QScopedPointer<QObject> root(doc.create());
    if (!root) {
        qDebug() << doc.errors().first().toString();
        return 1;
    }

    QObject *initialView = qvariant_cast<QObject*>(root->property("initialWebView"));
    QMetaObject::invokeMethod(initialView, "createNewWindow");

    return 0;
}

#include "main.moc"