How to resolve the QObject errors

subram_QT

I wrote the following code to assign image source runtime .

class Main : public QQuickView
{
Q_OBJECT

public:
static Main *instance();

void mousePressEvent(QMouseEvent* m);
//void keyReleaseEvent(QKeyEvent* e);
void setup();
static QObject *rootObject;
static QObject *image;

 int lock_value;
static QStringList lockimage;

private:
explicit Main();

};

//main.cpp
main instance ()
{
QDeclarativeView* view = NULL;
view->setSource(QUrl::fromLocalFile("main.qml"));
rootObject = dynamic_cast<QObject *>(view->rootObject());
//rootObject = (QObject *)view->rootObject();
// find element by name
image = rootObject->findChild<QObject *>(QString("status_locked_img"));
}

display instance ()
{

image->setProperty("source", QString("images/image1.png"));

}

//main.qml

Rectangle {
id:status_locked
color: "black"
width: 10; height:10
x:8;y:6
property int type : lock_status
Image {
objectName: status_locked_img
visible: true
}

I am getting error while building

" error: C2681: 'QGraphicsObject *' : invalid expression type for dynamic_cast"

please help me in resolving this error

SGaist

Hi,

Please enclose your code with coding tags, that will make it readable.

When casting QObject derivative, you should use "qobject_cast":http://qt-project.org/doc/qt-5.0/qtcore/qobject.html#qobject_cast

koahnig

In addition to SGaist comments "here is the description for placing code tags.":http://qt-project.org/wiki/ForumHelp#e3f82045ad0f480d3fb9e0ac2d58fb01

subram_QT

after adding qobject_cast

" rootObject = qobject_cast<QObject *>(view->rootObject());"

I am getting following error

19: error: C2665: 'qobject_cast' : none of the 2 overloads could convert all the argument types
C:\Qt\Qt5.0.2\5.0.2\msvc2012_64\include\QtCore/qobject.h(456): could be 'T qobject_cast<QObject*>(QObject )'
with
[
T=QObject *
]
C:\Qt\Qt5.0.2\5.0.2\msvc2012_64\include\QtCore/qobject.h(465): or 'T qobject_cast<QObject>(const QObject *)'
with
[
T=QObject *
]
while trying to match the argument list '(QGraphicsObject *)'

SGaist

Are you missing:

@#include <QGraphicsObject>@

?