QToolbar resizing

[Pl45m4]

@Alexey-Serebryakov

Apparently it's called extension button

When a toolbar is resized in such a way that it is too small to

show all the items it contains, an extension button will appear as

the last item in the toolbar. Pressing the extension button will

pop up a menu containing the items that do not currently fit in

the toolbar.

Check line 409 from: https://code.woboq.org/qt5/qtbase/src/widgets/widgets/qtoolbar.cpp.html#409

If you read further:

When a QToolBar is not a child of a QMainWindow, it loses the ability

to populate the extension pop up with widgets added to the toolbar using

addWidget(). Please use widget actions created by inheriting QWidgetAction

and implementing QWidgetAction::createWidget() instead.

So this is the case here :) Because as you've said, you don't have a QMainWindow based "main" window. But you could try what they suggest (QWidgetActions + createWidget())

[Alexey Serebryakov]

@Pl45m4 hi, thanks a lot, in general all be works!

So, consider following code skeleton

class MeWidget : public QWidget {
// some widget implementation
public:
    ...
signals:
    ...
public slots:
    ...
}

class MyWidgetAction : public QWidgetAction {
public:
    MyWidgetAction(QObject *parent) : QWidgetAction(parent) {}

protected:
    QWidget *createWidget(QWidget *parent) {
        auto *widget = new MyWidget();
        // some widget tuning
        // but how widget can communicate with application toolbars, menus??
        return widget;
    }
};

[Pl45m4]

@Alexey-Serebryakov said in QToolbar resizing:

// but how widget can communicate with application toolbars, menus??

Haven't done something like this before and I don't know if you can use the default, empty popUp and simply put in your widgets to connect your QWidgetActions with your slots or if you have to create your own "extension widget" with createWidget.

QWidgetActions work like normal QActions, which will additionally create a widget (button) to make them work in a ToolBar, for example.

Maybe it helps to look further into the code.

PopUpMenu setup:

• https://code.woboq.org/qt5/qtbase/src/widgets/widgets/qtoolbarlayout.cpp.html#_ZN14QToolBarLayout15setUsePopupMenuEb

PopUpMenu is filled here:

• https://code.woboq.org/qt5/qtbase/src/widgets/widgets/qtoolbarlayout.cpp.html#548

Found also these two:

• https://stackoverflow.com/questions/32350658/qtoolbar-how-does-the-extension-button-get-called
• https://stackoverflow.com/questions/40597210/issue-with-qt-toolbar-extension-button

Edit:

Or maybe you just have to fill your ToolBar using your QWidgetActions:createWidget and the rest is handled automatically... but I dont know :) I usually use QMainWindow.

[Alexey Serebryakov]

@Pl45m4 thank you for more detailed information. But isn't clear for me. :-(

Unfortunately, QToolBarLayout and QToolExtension button are in Qt private classes.

I can't understand what the purpose of QWidgetAction. So what I do in case when my widget already created outside QWidgetAction::createWidget() ?

Consider,

class MyWidget: public QWidget {
// may be some complex widget, with signal/slots...
};
...
MyWidget *widget = new MyWidget();
// some tunning of my widget

QWidgetAction *action = new QWidgetAction(toolbar);
action->setDefaultWidget(widget);

toolbar->insertWidget(action);

So by this way widget does not showing in popup menu by clicking extension button (>>). Because QWidgetAction::createWidget() return null pointer by default implementation.

2. Ok, make some changes

MyWidget *widget = new MyWidget();
// some tunning of my widget
...
class QMyWidgetAction : public QWidgetAction {
public:
    explicit QMyWidgetAction(QWidget *widget, QObject *parent) : QWidgetAction(parent), widget_(widget)
    QWidget *createWidget(QWidget *parent) { return widget_; }
private:
  MyWidget *widget_;
}

This doesn't work too.

3. HOW CAN I SHOW MY WIDGET IN POPUP MENU BY CLICKING EXTENSION BUTTON WITHOUT SUBCLASSING QWidgetAction???? I need create my widget outside QToolBar and QWidgetAction! :-((((((((

Thanks a lot, but I'm already go to mad.
Why they do that implementation???????? :-(((((

[Pl45m4]

@Alexey-Serebryakov said in QToolbar resizing:

class QMyWidgetAction : public QWidgetAction {
public:
explicit QMyWidgetAction(QWidget *widget, QObject *parent) : QWidgetAction(parent), widget_(widget)
QWidget *createWidget(QWidget *parent) { return widget_; }
private:
MyWidget *widget_;
}

Forgot Q_OBJECTmacro?! (But I dont know if this will change anything).

I will try it myself and give feedback later.

[Alexey Serebryakov]

@Pl45m4 ok thanks.

So about Q_OBJECT never mind.

[Pl45m4]

@Alexey-Serebryakov

According to the docs, it says that you need a QMainWindow mainWindow with your ToolBar so that the so called "extension button [>>]" works.

So I made a Testproject:
(New Qt App -> QWidget as base class instead of QMainWindow).

Main.cpp (nothing special)
My main widget (still a QWidget and no MainWindow) is called MainWidget).

#include "mainwidget.h"

#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWidget w;
    w.show();
    return a.exec();
}

Widget code:

#include "mainwidget.h"
#include "ui_mainwidget.h"
#include <QToolBar>
#include  <QAction>
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QDebug>
#include <QPushButton>

MainWidget::MainWidget(QWidget *parent)
    : QWidget(parent)
    , ui(new Ui::MainWidget)
{
    ui->setupUi(this);

    QToolBar *tb = new QToolBar();
    QAction *a1 = new QAction("A");
    QAction *a2 = new QAction("B");
    QAction *a3 = new QAction("C");
    QAction *a4 = new QAction("D");
    QAction *a5 = new QAction("E");

    connect(a1, &QAction::triggered, [=](){

        qDebug() << "A";

    });
    QPushButton *pb = new QPushButton("ANOTHER TEST");
    MyWidgetAction *wa = new MyWidgetAction(pb, tb);

    tb->addAction(a1);
    tb->addAction(a2);
    tb->addAction(a3);

    tb->addAction(wa);

    tb->addAction(a4);
    tb->addAction(a5);




    QVBoxLayout *vBox = new QVBoxLayout();
    vBox->addWidget(tb);
    setLayout(vBox);


}

MainWidget::~MainWidget()
{
    delete ui;
}

Custom Widget Action:

#ifndef MYWIDGETACTION_H
#define MYWIDGETACTION_H

#include <QObject>
#include <QWidget>
#include <QWidgetAction>

class MyWidgetAction: public QWidgetAction
{
    Q_OBJECT
public:
    MyWidgetAction(QWidget *w, QWidget* parent);

    QWidget* createWidget(QWidget* parent);

private:

    QWidget *m_widget; // Does NOT work
};

#endif // MYWIDGETACTION_H

#include "mywidgetaction.h"
#include <QPushButton>
#include <QLineEdit>
#include <QDebug>

MyWidgetAction::MyWidgetAction(QWidget *w, QWidget *parent)
    : QWidgetAction(parent),
      m_widget(w) // Does NOT work
{
}

QWidget *MyWidgetAction::createWidget(QWidget *parent)
{
    QPushButton *widget = new QPushButton("Test", parent);
//    QLineEdit *widget = new QLineEdit(parent);
    return widget;


// // ####  Does not work ####
//    m_widget->setParent(parent);
//    return m_widget;

}

When you have custom widgets in your ToolBar and no QMainWindow, you'll need the custom QWidgetActons.

What you've tried doesn't seem to work. Apparently the createWidget function has to create your widget. You can't pass a widget to your widgetAction class and use it there. Even when you re-parent it, it does not work.
I think, it's because it tries to re-build your widget every time the extension menu is shown, so it fills the menu one by one with the hidden widgets and creates its actions.

In my case, the PushButton widget saying "ANOTHER TEST" does not work with the extension menu, but the PushButton ("Test") created by createWidgetinside MyWidgetAction class works.
Even other widgets like QLineEdits or every other custom widget, that you can put in a QToolBar will work, when you do it like this :)

That you can not pass widgets to WidgetAction to stay more flexible, is very unfortunate and I also don't like it, but maybe the other way won't work because of some reason.
... but that is something you should ask the Qt Devs :)

Edit:

(BTW: Ubuntu + Qt 5.15)

[Alexey Serebryakov]

@Pl45m4 thank you, my first implementation do the same as your code.

So, this another but doesn't work correctly,

class ToolBarWidgetAction : public QWidgetAction {
    Q_OBJECT
public:
    explicit ToolBarWidgetAction(QWidget *widget, QObject *parent) : QWidgetAction(parent), widget_(widget) {}
    ~ToolBarWidgetAction() Q_DECL_OVERRIDE { widget_->setParent(Q_NULLPTR); }

    QWidget *createWidget(QWidget *parent) Q_DECL_OVERRIDE {
            // Create container, put my widget and return container widget
            QFrame *widget = new QFrame(parent); // just container for my widget
            widget->setMinimumHeight(32);
             //widget_->setParent(widget); // ???
        
            auto layout = new QHBoxLayout();
            layout->setContentsMargins(0, 0, 0, 0);
            layout->setSpacing(0);
            layout->addWidget(widget_.data());
            widget->setSizePolicy(QSizePolicy::MinimumExpanding, QSizePolicy::Minimum);
            widget->setLayout(layout);
            widget->show();
            widget_->show();
            widget->update();

            return widget;
    }
    void deleteWidget(QWidget *widget) Q_DECL_OVERRIDE {
        // Reparent my widget and delete container
        widget_->hide();
        widget->layout()->removeWidget(widget_.data());
        widget_->setParent(Q_NULLPTR);

        QWidgetAction::deleteWidget(widget);
    }

private:
    const QScopedPointer<QWidget, QScopedPointerDeleteLater> widget_; // store pointer to my widget
};

// Then use it

auto *myWidget = new MyWidget(toolBar); // my original widget
toolBar->addAction(new ToolBarWidgetAction(myWidget, toolBar));

My widget does not showing on toolbar but correctly showing in popup menu by click extension button.

What's wrong?

[Pl45m4]

@Alexey-Serebryakov said in QToolbar resizing:

widget->show();
widget_->show();
widget->update();

I think calling show() is wrong and not needed. What kind of widget is your widget_? Maybe try it without the QFrame

[Alexey Serebryakov]

@Pl45m4 There are may be some kind of complex widgets like derived from QWidget or QFrame buttons with comboboxes that might be a different states.