Is it possible to have a "wrap" behaviour in QMenu? - qt

Question

I have to store many items in a QMenu. If there is too many items QMenu wraps them ans begins a new column, but it happens only if these items can not fit into screen height.
I'd like to have QMenu which wraps items when the menu height reaches, for example, parent widget's height or any other custom value.
I wasn't able to find any properties in QMenu for achieving this. Setting maximumHeight gave no result. After digging into QMenu sources I found that the "wrapping logic" works based on popupGeometry method result. But popupGeometry uses screen size, and it is private so I don't know a way to change it.

Answer 1

As I didn't find the answer, I had to implement this control by myself.
It is a popup widget, using QToolButton as an owner. It can arrange items in a grid depending on item's height and required menu height.
class myLabel:public QLabel
{
Q_OBJECT
// QObject interface
public:
myLabel(QWidget* parent=0):QLabel(parent){}
bool event(QEvent *e)
{
if(e->type()==QEvent::MouseButtonPress)
emit clicked();
return QLabel::event(e);
}
void setAction(QAction *a)
{
setText(a->text());
_action=a;
}
QAction* action()
{
return _action;
}
signals:
void clicked();
private:
QAction* _action;
};
class myMenu: public QWidget
{
Q_OBJECT
public:
myMenu(QWidget* owner,QWidget* parent=0):QWidget(parent){
this->setWindowFlags(Qt::Popup);
l = new QGridLayout(this);
l->setContentsMargins(QMargins(3,3,3,3));
_owner=owner;
QString style="QLabel:hover{background-color: white;} ";
setStyleSheet(style);
}
void addAction(QAction*a){_actions.append(a);}
QVector<QAction*> actions(){return _actions;}
void setItemHeight(int val){_itemHeight=val;}
void setHeight(int val){_height=val;}
private:
QVector<QAction*> _actions;
QGridLayout *l ;
QWidget*_owner;
int _itemHeight=30;
int _height=200;
private slots:
void popup()
{
clear();
//move popup under toolbutton
QPoint p = _owner->geometry().bottomLeft();
p.setY(p.y()+1);
this->move(_owner->parentWidget()->mapToGlobal(p));
//calculate rows count
int rows = _height/_itemHeight;
//calculate cols count
int cols = _actions.size()/rows;
int d = _actions.size()%rows;
if(d>0)
cols++;
for(int i=0;i<rows;i++)
for(int j=0;j<cols;j++)
{
int index = i+j*rows;
if(index<_actions.size())
{
myLabel *lb = new myLabel(this);
connect(lb,SIGNAL(clicked()),this,SLOT(onClick()));
lb->setFixedHeight(_itemHeight);
lb->setAction(_actions[index]);
l->addWidget(lb,i,j);
}
}
this->repaint();
this->show();
}
void clear()
{
while(l->itemAt(0)!=NULL)
{
QLayoutItem* i = l->takeAt(0);
if(i->widget())
delete i->widget();
if(i->layout())
delete i->layout();
delete i;
}
}
void onClick()
{
myLabel *g = qobject_cast<myLabel*>(sender());
g->action()->trigger();
close();
}
// QWidget interface
protected:
void closeEvent(QCloseEvent *)
{
qobject_cast<QToolButton*>(_owner)->setDown(false);
}
signals:
void closed();
};
There's also an example showing how to create and fill myMenu and how to receive a selected action.
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
//set-up myMenu, btMyMenu is a QToolButton
myMenu *mMenu = new myMenu(ui->btMyMenu,this);
connect(ui->btMyMenu,SIGNAL(pressed()),mMenu,SLOT(popup()));
for(int i=0;i<20;i++)
{
QAction *a = new QAction("Action "+QString::number(i),this);
connect(a,SIGNAL(triggered(bool)),this,SLOT(onActSelected()));
mMenu->addAction(a);
}
//mMenu can be customized
mMenu->setHeight(100);
mMenu->setItemHeight(50);
}
void MainWindow::onActSelected()
{
QAction *a = qobject_cast<QAction*>(sender());
ui->btMyMenu->setText(a->text());
}
Any comments about how to improve this solution are appreciated!