The QMenu will not show immediately, why?

[koilin]

When I pressed the right mouse button, I will let the QMenu.exec(). I could not see the menu immediately. After I moved the mouse, then the menu will show. Why? Could anyone give me an idea? How to find the problem. It's very difficulty to debug at this time. Thank you!

[Jonny174]

Show your code where you exec menu

[axiula]

I have met the same problem, let me show my code.

QCursor cur = this->cursor();
PopMenu *menu = new PopMenu(this);
QAction* activeAction = menu->exec(cur.pos());

class MyIconStyle : public QPlastiqueStyle
{
Q_OBJECT
public:
virtual int pixelMetric(PixelMetric metric, const QStyleOption * option, const QWidget * widget) const;
};

class MyMenu : public QMenu
{
Q_OBJECT
public:
explicit MyMenu(QWidget *parent);

protected:
MyIconStyle *m_pMyStyle;
};

class PopMenu : public MyMenu
{
Q_OBJECT
public:
explicit PopMenu(QWidget *parent);
protected:
QAction *action1;
QAction *action2;

//sub_menus

QAction *sub_action_16[2];
QAction *sub_action_24[2];

QLabel *label_title;

bool eventFilter(QObject *obj, QEvent *event);

public slots:
void triggeredDeal(QAction *action);
};

[amleto]

1) use code tags.
2) just writing

QCursor cur = this->cursor();
PopMenu *menu = new PopMenu(this);
QAction* activeAction = menu->exec(cur.pos());

provides no context at all as to where and how your code is called.

With that said, I don't know why you would be experiencing a delay before the menu is shown.

[axiula]

the PopMenu is a class derived the QMenu. In the contextMenuEvent of the DisplayWindow, the code is called . The menu is not immediately shown. After moved the mouse, then the menu will show. It's seem like a problem of render because the cpu is used for decoding the multi-channel
realtime stream & the gpu is used for rendering the YUV on the DisplayWindow at the same time. I find that if I reduce the channels from 8 to 6,the popmenu is immediately shown.

void DisplayWindow::contextMenuEvent (QContextMenuEvent *event)
{
    QCursor cur = this->cursor();
    PopMenu *menu = new PopMenu(this);
    QAction* activeAction = menu->exec(cur.pos());
}

void DisplayWindow::contextMenuEvent (QContextMenuEvent *event)
{
    QCursor cur = this->cursor();
    PopMenu *menu = new PopMenu(this);
    QAction* activeAction = menu->exec(cur.pos());
}

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.h file

class MyIconStyle : public QPlastiqueStyle
{
Q_OBJECT
public:
virtual int pixelMetric(PixelMetric metric, const QStyleOption * option, const QWidget * widget) const;
};
 
class MyMenu : public QMenu
{
Q_OBJECT
public:
explicit MyMenu(QWidget *parent);
 
protected:
MyIconStyle *m_pMyStyle;
};
 
class PopMenu : public MyMenu
{
Q_OBJECT
public:
explicit PopMenu(QWidget *parent);
protected:
QAction *action1;
QAction *action2;
 
//sub_menus
 
QAction *sub_action_16[2];
QAction *sub_action_24[2];
 
QLabel *label_title;
 
bool eventFilter(QObject *obj, QEvent *event);
 
public slots:
void triggeredDeal(QAction *action);
};

class MyIconStyle : public QPlastiqueStyle
{
Q_OBJECT
public:
virtual int pixelMetric(PixelMetric metric, const QStyleOption * option, const QWidget * widget) const;
};

class MyMenu : public QMenu
{
Q_OBJECT
public:
explicit MyMenu(QWidget *parent);

protected:
MyIconStyle *m_pMyStyle;
};

class PopMenu : public MyMenu
{
Q_OBJECT
public:
explicit PopMenu(QWidget *parent);
protected:
QAction *action1;
QAction *action2;

//sub_menus

QAction *sub_action_16[2];
QAction *sub_action_24[2];

QLabel *label_title;

bool eventFilter(QObject *obj, QEvent *event);

public slots:
void triggeredDeal(QAction *action);
};

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