测试QQuickView（QWindow）是否在Qt 5.0.x中全屏显示

Question

For a QWidget we can test if it is displayed in full-screen with flags() & Qt::WindowFullScreen . The same doesn't seem to work with QQuickView (which is a QQuickWindow which is a QWindow ), as QWindow::flags() always returns Qt::WindowMinimized , whatever the reason might be. I display the window using this code:

QQuickView w;
w.setSource(...);
w.show(); /* or */ w.showFullScreen();

In Qt 5.1, QWindow::visibility() was introduced. It returns a new enum type which contains QWindow::FullScreen and behaves properly.

How can I test if a QWindow is shown in full-screen in Qt 5.0.x ? I want to implement a "toggle full-screen" function. Keeping track of the current state seems to be the wrong way (yet it would be a possible work-around). I don't understand why QWindow::flags() returns Qt::WindowMinimized ...

Code to reproduce issue (press RETURN to see the output of QWindow::flags() ):

test.qml

import QtQuick 2.0
Rectangle {
    signal test();
    width: 100; height: 100
    focus: true
    Keys.onReturnPressed: test()
}

main.cpp

#include <QGuiApplication>
#include <QQuickView>
#include <QQuickItem>
#include <QDebug>

class Test : public QObject {
    Q_OBJECT
public slots:
    void test() {
        QQuickItem *item = qobject_cast<QQuickItem*>(sender());
        QQuickWindow *window = item->window();
        qDebug() << window->flags(); // Will print 0x1 == Qt::WindowMinimized
    }
};
int main(int argc, char *argv[])
{
    QGuiApplication a(argc, argv);

    QQuickView w;
    w.setSource(QUrl("...(relative path to the qml file from above)..."));
    w.show(); // Please also test w.showFullScreen();

    QObject::connect(w.rootObject(), SIGNAL(test()),
                     new Test, SLOT(test()));

    return a.exec();
}

#include "main.moc"

test.pro

QT += quick
TEMPLATE = app
SOURCES += main.cpp

Answer 1

Use method QWindow::windowState() . It returns key Qt::WindowFullScreen that you seek.

bool isFullScreen = w.windowState().testFlag(Qt::WindowFullScreen);