QT: c++ 中通过objectName访问qml中的对象

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// c++
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#include <QApplication>

#include <QDeclarativeView>

#include <QDeclarativeContext>

#include <QObject>

#include <QGraphicsObject>

#include <QDeclarativeItem>


int main(int argc, char *argv[])
{
    QApplication app(argc, argv);



    QDeclarativeView view;
     view.setSource(QUrl::fromLocalFile("main.qml"));
     view.show();

     QDeclarativeItem *item = view.rootObject()->findChild<QDeclarativeItem*>("myRect");
     if (item) {
         item->setProperty("color", QColor(Qt::yellow));
     }
     return app.exec();
 }

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// qml 界面显示   main.qml
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import Qt 4.7

 Item {
     width: 200; height: 200

     Rectangle {
         anchors.fill: parent
         color: "red"
         objectName: "myRect"
     }
 }