Question

所以我可以通过C ++代码更改某个QML对象的属性，但是我无法在屏幕上看到结果。我有一个重复64次的项目，我希望某个图像只显示第32个项目（来自C ++）所以我使用invokeMethod通过C ++访问该对象然后我使用setProperty来改变可见性，如果我查看它qDebug属性“可见”确实发生了变化，但我注意到屏幕上没有区别我仍然无法看到图像，但如果我从qml更改可见性，我可以看到它。

这是C ++代码：

int main(int argc, char *argv[])
{
  QGuiApplication app(argc, argv);
  QQuickView view;
  view.setSource(QUrl("qrc:///main.qml"));
  view.show();
  QQuickItem* child;
  QQmlApplicationEngine engine;
  engine.load(QUrl(QStringLiteral("qrc:///Board.qml")));
  QObject *rootObject = engine.rootObjects().first();
  QQuickItem *qmlObject = rootObject->findChild<QQuickItem*>("grid")->findChild<QQuickItem*>("repeter");
  QMetaObject::invokeMethod(qmlObject,"itemAt",Qt::DirectConnection,   Q_RETURN_ARG (QQuickItem*,child), Q_ARG(int,32));
  child=child->findChild<QQuickItem*>("pleaseWork");
  qDebug() << child->property("visible");
  child->setProperty("visible","true");
  qDebug() << child->property("visible");
  return app.exec();
}

我使用qDebug验证属性已更改

这是QML代码：

Item 
{
    id: root
    width: 8*45
    height: 8*45
    Grid 
    {
        id: grid
        objectName: "grid"
        rows: 8
        Repeater 
        {
            objectName: "repeter"
            model: 64 
            Image
            {
                objectName: "test"
                width: 45; height: 45 
                source: "images/dark_square.png"
                Image
                {
                    id: isit
                    objectName: "pleaseWork"
                    visible: false
                    source: "images/avail_dark.png"
                }
            }
        }
    }  
}

Answer 1

QQuickView和QQmlApplicationEngine是加载和显示QML视图的替代方法。您加载到QQmlApplicationEngine的内容与QQuickView的可见输出无关。

为了让事情顺利进行，您需要将QML文件的顶部元素从Item更改为Window并在屏幕上显示：

QQmlApplicationEngine engine;
engine.load(QUrl(QStringLiteral("qrc:///Board.qml")));
// end of your code

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

// continue with your code
QQuickItem *qmlObject = rootObject->findChild<QQuickItem*>("grid")->findChild<QQuickItem*>("repeter");

QML对象属性已从c ++更改，但我看不到结果

1 个答案: