The setup I am using is Qt 5.1 + Qt Quick 2 + Qt Quick Controls.
I have a Main QML window. I handle the processing part of the Main window in a C++ class called AppController.
Now, Main has a button “Authorize”, clicking which should spawn another Authorizer QML window. The way I have handled this is to invoke AppController::launchOAuth2Browser() slot by connecting it to Main.Authorize.clicked() signal. The slot creates an instance of Authorizer QML using the new QQmlApplicationEngine. Thus, the C++ class of Main handles the creation of the other QML window (which I don’t know is the best way to do it).
Now, Authorizer window has a child object WebView. I need to connect the WebView.urlChanged() signal to an OAuth2::onBrowserUrlChanged() slot.
Here is the code that handles the window creation part, and the connection part.
void AppController::launchOauth2Browser(QUrl& url)
{
QQmlApplicationEngine *engine = new QQmlApplicationEngine("OAuth2Browser.qml");
QQmlContext *context = engine->rootContext();
context->setContextProperty("oauth2", m_oauth2);
QObject *topLevel = engine->rootObjects().value(0);
QQuickWindow *window = qobject_cast<QQuickWindow *>(topLevel);
window->show();
QWebView *browser = topLevel->findChild<QWebView *>("Browser");
qDebug() << "connecting urlChanged to onBrowserUrlChanged";
QObject::connect(browser, &QWebView::urlChanged, m_oauth2, &OAuth2::onBrowserUrlChanged);
browser->setUrl(url);
qDebug() << "connecting closeBrowser to close";
QObject::connect(m_oauth2, &OAuth2::closeBrowser, window, &QQuickWindow::close);
}
However, when this code runs, it gives error at the following line:
QObject::connect(browser, &QWebView::urlChanged, m_oauth2, &OAuth2::onBrowserUrlChanged);
The error says:
QObject::connect: invalid null parameter
Here is the Authorizer window code:
Window {
id: window
width: 500
height: 500
ColumnLayout {
anchors.fill: parent
WebView {
objectName: "Browser"
id: browser
Layout.fillHeight: true
Layout.fillWidth: true
}
Label {
id: loadingStatus
Layout.fillWidth: true
text: browser.loadProgress + "% loaded."
}
}
}
I know that m_oauth2 is not null – it has already been referenced earlier. So, browser has to be null, the reason of which I don’t know. I have already created the QML window. Shouldn’t the child objects be created with it as well?
Aside from that, where do you think I should have handled the new window creation? from the Main QML window itself, using dynamic window management, or the current C++ implementation which has the AppController have to deal with UI code?
P.S.: Look at the first reply (posted by me) that explains the now changed error.
↧
