QGraphicsObject: ContextMenu does not show up

[SGaist]

Hi,

Make it a member variable and delete it in your class destructor.

[JonB]

@sandro4912
For dynamically created QMenu, then as @SGaist says.

But are you sure you need QMenu:popUp() and not just QMenu::exec() for your use case? It depends how you want it to work. If the simple exec() suffices you should be able to just use a stack (local) variable QMenu menu. You don't need the menu after it has returned the action the user clicked.

For your coordinates/click area, I don't think we're going to know. Is your image indeed 100x100 size, or is that maybe some default? Why don't you play with a bigger/smaller image and see what the pattern is?

[sandro4912]

there is nothing wrong with the image but to sort it out i did this:

void Room::paint(
        QPainter *painter,
        const QStyleOptionGraphicsItem *option,
        QWidget *widget)
{
    QRectF rect{boundingRect()};
    painter->setPen(Qt::black);
    painter->drawRect(rect);
}

QRectF Room::boundingRect() const
{
    return QRectF{ 0, 0, 200, 200};
}

Still the Menu is not popped up on the whole rect. It only appeas like on 1/3 of the size of QRectF{ 0, 0, 200, 200}; so is not always half. Does contextMenuEvent maybe check the size from somewhere else but not from the boundingRect ? Or is this simply a bug in QT?

I also compiled the code an a second OS to sort out that its not annother bug with KDE/Neon. But on Windows 10 same behaviour.

Also I stayed with the local Menu:

void Room::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
    qDebug() << boundingRect();
    qDebug() << roomImage().size();

    QMenu menu;
    menu.addAction(mGuessWumpusAction);
    menu.addAction(mGuessBatAction);
    menu.addAction(mGuessPitAction);
    menu.exec(event->screenPos());
}

Any more ideas??

[sandro4912]

let me know if you need more information to find a solution for this issue. Maybe is even a qt bug.

[Christian Ehrlicher]

@sandro4912 said in QGraphicsObject: ContextMenu does not show up:

Still the Menu is not popped up on the whole rect. It only appeas like on 1/3 of the size of QRectF{ 0, 0, 200, 200}; so is not always half. Does contextMenuEvent maybe check the size from somewhere else but not from the boundingRect ?

I don't understand what you say here - does the popup / context menu event only works on 1/3 of your widget? Is the popup not as big as you expect?

[sandro4912]

the popup itself looks perfect.

The problem is it does not get triggered in the whole 200x200 area of the widget. It only looks like it gets shown in a smaller rectangle from the top left point.

so in 200x200 maybe only in 80x80 from top left point it gets created.

I would expect in the whole rectangle the context menu gets triggere.

maybe i should make a minimal running example so it can be verifyed.

[Christian Ehrlicher]

Ok, now it's clear to me. There are two examples (diagramscene, boxes) which work fine for me. Maybe you can try them out.

[sandro4912]

I made a minimal program and it works:

#ifndef RECTANGLE_H
#define RECTANGLE_H

#include <QGraphicsObject>

class Rectangle : public QGraphicsObject
{
    Q_OBJECT
public:
    explicit Rectangle(QGraphicsObject *parent = nullptr);

    QRectF boundingRect() const override;

    void paint(QPainter *painter,
               const QStyleOptionGraphicsItem *option,
               QWidget *widget) override;

protected:
    void contextMenuEvent(QGraphicsSceneContextMenuEvent *event) override;
};

#endif // RECTANGLE_H

#include "rectangle.h"

#include <QGraphicsSceneContextMenuEvent>
#include <QPainter>
#include <QMenu>

Rectangle::Rectangle(QGraphicsObject *parent)
    : QGraphicsObject(parent)
{
}

QRectF Rectangle::boundingRect() const
{
    return QRectF{ 0, 0, 100, 100};
}

void Rectangle::paint(
        QPainter *painter,
        const QStyleOptionGraphicsItem *option,
        QWidget *widget)
{
    Q_UNUSED(option)
    Q_UNUSED(widget)

    QRectF rect{boundingRect()};
    painter->setPen(Qt::black);
    painter->drawRect(rect);
}

void Rectangle::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
    QMenu menu;
    menu.addAction("Action 1");
    menu.addAction("Action 2");
    menu.exec(event->screenPos());
}

#include "rectangle.h"

#include <QApplication>
#include <QGraphicsScene>
#include <QGraphicsView>

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

    QGraphicsScene scene;

    Rectangle rectangle;
    scene.addItem(&rectangle);

    QGraphicsView view;
    view.setScene(&scene);

    view.show();
    return QApplication::exec();
}

Everything fine here the popup shows up in all the widget. The reason it does not work in my programm is. At some point i changed the class from QGraphicsObject to QGraphicsWidget. If we modify the minimal programm to have QGraphicsWidget as a base for Rectangle we get the Issue again:

#ifndef RECTANGLE_H
#define RECTANGLE_H

#include <QGraphicsWidget>

class Rectangle : public QGraphicsWidget
{
    Q_OBJECT
public:
    explicit Rectangle(QGraphicsWidget *parent = nullptr);

    QRectF boundingRect() const override;

    void paint(QPainter *painter,
               const QStyleOptionGraphicsItem *option,
               QWidget *widget) override;

protected:
    void contextMenuEvent(QGraphicsSceneContextMenuEvent *event) override;
};

#endif // RECTANGLE_H

#include "rectangle.h"

#include <QGraphicsSceneContextMenuEvent>
#include <QPainter>
#include <QMenu>

Rectangle::Rectangle(QGraphicsWidget *parent)
    : QGraphicsWidget(parent)
{
}

QRectF Rectangle::boundingRect() const
{
    return QRectF{ 0, 0, 100, 100};
}

void Rectangle::paint(
        QPainter *painter,
        const QStyleOptionGraphicsItem *option,
        QWidget *widget)
{
    Q_UNUSED(option)
    Q_UNUSED(widget)

    QRectF rect{boundingRect()};
    painter->setPen(Qt::black);
    painter->drawRect(rect);
}

void Rectangle::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
{
    QMenu menu;
    menu.addAction("Action 1");
    menu.addAction("Action 2");
    menu.exec(event->screenPos());
}

#include "rectangle.h"

#include <QApplication>
#include <QGraphicsScene>
#include <QGraphicsView>

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

    QGraphicsScene scene;

    Rectangle rectangle;
    scene.addItem(&rectangle);

    QGraphicsView view;
    view.setScene(&scene);

    view.show();
    return QApplication::exec();
}

So why is the behaviour different with QGraphicWidget? How can it get fixed there?

[Christian Ehrlicher]

You forgot to set a proper size of the QGraphicsWidget: https://doc.qt.io/qt-5/qgraphicswidget.html#size-prop - since it's a widget you have to treat it like a widget which also means you have to set a proper size since there is no layout from where the size could be calculated from.

[sandro4912]

I solved the issue by resize in the constructor:

    resize(boundingRect().size());

That should be it or any other things to concern?

[Christian Ehrlicher]

@sandro4912 said in QGraphicsObject: ContextMenu does not show up:

That should be it or any other things to concern?

That's fine.