Draggable QActions in Qt

[vajindarladdad]

Hi All Experts ,
I am developing an application in which i want a QMenu in which the actions are draggable.
Is there any standard Flag that can be set to the QMenu or QAction .

I have developed a Custom QMenu, in which i have implemented the drag and drop Events.
But the problem is that .. the action is getting added to the end , this happens only when the beforeAction is 0.

class CustomMenu : public QMenu
{
  Q_OBJECT
 
public:
    CustomMenu(QWidget *parent = 0);
     bool addActionBool;
     bool check;
    QAction *beforeAction;
    QAction *afterAction;
    QAction  *action;
    QPoint startPos;
    int i;
protected:
    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    void dragEnterEvent(QDragEnterEvent *event);
    void dragMoveEvent(QDragMoveEvent *event);
    void dropEvent(QDropEvent *event);
 
private:
    void performDrag();
};

class CustomMenu : public QMenu
{
  Q_OBJECT

public:
    CustomMenu(QWidget *parent = 0);
     bool addActionBool;
     bool check;
    QAction *beforeAction;
    QAction *afterAction;
    QAction  *action;
    QPoint startPos;
    int i;
protected:
    void mousePressEvent(QMouseEvent *event);
    void mouseMoveEvent(QMouseEvent *event);
    void dragEnterEvent(QDragEnterEvent *event);
    void dragMoveEvent(QDragMoveEvent *event);
    void dropEvent(QDropEvent *event);

private:
    void performDrag();
};

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CustomMenu::CustomMenu(QWidget *parent):QMenu(parent)
{
    setAcceptDrops(true);
    //action = new QAction(this);
}
 
void CustomMenu::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton)
    {
        startPos = event->pos();
        action = this->activeAction(); // getting the current active action
    }
    QMenu::mousePressEvent(event);
}
 
void CustomMenu::mouseMoveEvent(QMouseEvent *event)
{
    if (event->buttons() & Qt::LeftButton) {
        int distance = (event->pos() - startPos).manhattanLength();
        if (distance >= QApplication::startDragDistance())
        {
            performDrag();
        }
    }
    QMenu::mouseMoveEvent(event);
}
 
void CustomMenu::performDrag()
{
    check =  action->isChecked();
    if (action) {
        QMimeData *mimeData = new QMimeData;
        mimeData->setText(action->text());
 
        QDrag *drag = new QDrag(this);
        drag->setMimeData(mimeData);
        if (drag->exec(Qt::MoveAction) == Qt::MoveAction)
            /*delete action;*/removeAction(action);
    }
}
 
void CustomMenu::dragEnterEvent(QDragEnterEvent *event)
{
    event->setDropAction(Qt::MoveAction);
    event->accept();
}
 
void CustomMenu::dragMoveEvent(QDragMoveEvent *event)
{
    event->setDropAction(Qt::MoveAction);
    event->accept();
 }
 
void CustomMenu::dropEvent(QDropEvent *event)
{
    QAction *newAction = new QAction(event->mimeData()->text(),this);
    newAction->setCheckable(true);
    newAction->setChecked(check);
    beforeAction = actionAt(QCursor::pos());
    insertAction(beforeAction,newAction); //It appends action if before is 0 or before is not a valid action for this widget. beforeAction is 0 here.
    event->setDropAction(Qt::MoveAction);
    event->accept();
 }

CustomMenu::CustomMenu(QWidget *parent):QMenu(parent)
{
    setAcceptDrops(true);
    //action = new QAction(this);
}

void CustomMenu::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton)
    {
        startPos = event->pos();
        action = this->activeAction(); // getting the current active action
    }
    QMenu::mousePressEvent(event);
}

void CustomMenu::mouseMoveEvent(QMouseEvent *event)
{
    if (event->buttons() & Qt::LeftButton) {
        int distance = (event->pos() - startPos).manhattanLength();
        if (distance >= QApplication::startDragDistance())
        {
            performDrag();
        }
    }
    QMenu::mouseMoveEvent(event);
}

void CustomMenu::performDrag()
{
    check =  action->isChecked();
    if (action) {
        QMimeData *mimeData = new QMimeData;
        mimeData->setText(action->text());

        QDrag *drag = new QDrag(this);
        drag->setMimeData(mimeData);
        if (drag->exec(Qt::MoveAction) == Qt::MoveAction)
            /*delete action;*/removeAction(action);
    }
}

void CustomMenu::dragEnterEvent(QDragEnterEvent *event)
{
    event->setDropAction(Qt::MoveAction);
    event->accept();
}

void CustomMenu::dragMoveEvent(QDragMoveEvent *event)
{
    event->setDropAction(Qt::MoveAction);
    event->accept();
 }

void CustomMenu::dropEvent(QDropEvent *event)
{
    QAction *newAction = new QAction(event->mimeData()->text(),this);
    newAction->setCheckable(true);
    newAction->setChecked(check);
    beforeAction = actionAt(QCursor::pos());
    insertAction(beforeAction,newAction); //It appends action if before is 0 or before is not a valid action for this widget. beforeAction is 0 here.
    event->setDropAction(Qt::MoveAction);
    event->accept();
 }

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where i am going wrong ??

[wysota]

Why ar you creating a new action in the drop event instead of reusing the original one? Are you sure beforeAction points to a valid action (can you retrieve its name) after using actionAt? To me it would seem more appropriate to use the position from the drop event and not from QCursor::pos().

[vajindarladdad]

Hello Sir,
beforeAction always comes out to be 0.
Not able to access it.
How to get the action which has the mouse focus ? I have used actionAt , but its not working.
I am struck here & I will reuse the original action instead of newAction.

[wysota]

Hello Sir,
beforeAction always comes out to be 0.
Not able to access it.

Probably because of misuse of QCursor::pos()

How to get the action which has the mouse focus ? I have used actionAt , but its not working.

The way you did it was incorrect. Don't use QCursor::pos() which is unreliable and returns the position in screen coordinates, not widget coordinates.

[vajindarladdad]

Sir ,
Please give me a hint to access the QAction based on the mouse position.
is there any other function to access it.

[wysota]

Probably QDropEvent::pos() and QMenu::actionAt() but I think I have already said that...

[vajindarladdad]

Thanks a million ,