form and its objects communication

[eva2002]

I wouldn't "disable" mouse events in the scene. I would just gave a flag set in the scene according to the state of the list box. Then if the flag is set (something is selected) I would do the main thing the event is supposed to do, otherwise I would just emit a signal with mouse click position so that you can connect to it and set up the labels.

I would also do it that way but I have no idea how to work it out in qt. My problem is I don't know how to communication between the 2 widgets. I am still new to qt.

below are codes I did but got stuck halfway.

Mainwindow.h

....
private:
    QLabel *posX;
    QLabel *posY;
    QListWidget *area;
    mapscene *scene;

....
private:
    QLabel *posX;
    QLabel *posY;
    QListWidget *area;
    mapscene *scene;

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Mainwindow.cpp

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    posX = new QLabel;
    posX->setMinimumWidth(50);
    posX->setFrameShape(QFrame::Box);
 
    posY = new QLabel;
    posY->setMinimumWidth(50);
    posY->setFrameShape(QFrame::Box);
 
    area = new QListWidget;
    area->setMaximumWidth(180);
    area->setMinimumHeight(300);
    //assume all items added
 
    scene = new mapscene;
    scene->setSceneRect(0, 0, 600, 600);
}

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    posX = new QLabel;
    posX->setMinimumWidth(50);
    posX->setFrameShape(QFrame::Box);

    posY = new QLabel;
    posY->setMinimumWidth(50);
    posY->setFrameShape(QFrame::Box);

    area = new QListWidget;
    area->setMaximumWidth(180);
    area->setMinimumHeight(300);
    //assume all items added

    scene = new mapscene;
    scene->setSceneRect(0, 0, 600, 600);
}

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mapscene.h

class mapscene : public QGraphicsScene
{
public:
    mapscene();
 
protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent);
    void mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent);
 
private:
    QGraphicsEllipseItem *item;
};

class mapscene : public QGraphicsScene
{
public:
    mapscene();

protected:
    void mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent);
    void mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent);

private:
    QGraphicsEllipseItem *item;
};

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mapscene.cpp

const int ellsize = 5;
 
mapscene::mapscene()
{
    item = new QGraphicsEllipseItem;
    item->setBrush(Qt::red);
    addItem(item);
}
 
void mapscene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
    //check status of listbox. How to check?
 
    removeItem(item);
 
    item->setRect(mouseEvent->scenePos().x(),mouseEvent->scenePos().y(),ellsize, ellsize);
    addItem(item);
 
    //update posX and posY (Qlabel of Mainwindow). How to update?
 
    QGraphicsScene::mousePressEvent(mouseEvent);
}
 
void mapscene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
    QGraphicsScene::mouseReleaseEvent(mouseEvent);
}

const int ellsize = 5;

mapscene::mapscene()
{
    item = new QGraphicsEllipseItem;
    item->setBrush(Qt::red);
    addItem(item);
}

void mapscene::mousePressEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
    //check status of listbox. How to check?

    removeItem(item);

    item->setRect(mouseEvent->scenePos().x(),mouseEvent->scenePos().y(),ellsize, ellsize);
    addItem(item);

    //update posX and posY (Qlabel of Mainwindow). How to update?

    QGraphicsScene::mousePressEvent(mouseEvent);
}

void mapscene::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouseEvent)
{
    QGraphicsScene::mouseReleaseEvent(mouseEvent);
}

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