how to dynamically adding rows to QVBoxLayout

[stdave]

I am interested in dynamically adding layout rows to a QVBoxLayout - I have seen examples of this when there is a existing ui form, but I am add odds as to how to do this dynamically. Existing code follows, with a photo of output. I would like to be able to push my "Add" button, or maybe issue a control key to add rows ;

#include <QApplication>
#include <QPushButton>
#include <QHBoxLayout>
#include <QVBoxLayout>

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

// Vertical layout with 3 buttons
QVBoxLayout *vLayout = new QVBoxLayout;
QPushButton *b4 = new QPushButton("Add");
vLayout->addWidget(b4);

// Horizontal layout with 3 buttons
QHBoxLayout *hLayout = new QHBoxLayout;
QPushButton *b1 = new QPushButton("A");
QPushButton *b2 = new QPushButton("B");
QPushButton *b3 = new QPushButton("C");
hLayout->addWidget(b1);
hLayout->addWidget(b2);
hLayout->addWidget(b3);

// Outer Layer
QVBoxLayout *mainLayout = new QVBoxLayout;

// Add the previous two inner layouts
mainLayout->addLayout(vLayout);
mainLayout->addLayout(hLayout);

// Create a widget
QWidget *w = new QWidget();

// Set the outer layout as a main layout
// of the widget
w->setLayout(mainLayout);

// Window title
w->setWindowTitle("layouts");

// Display
w->show();

// Event loop
return app.exec();

}

Form looks like this;
https://ibb.co/nMnbfCK

[JonB]

@stdave
To add layouts to a layout use QBoxLayout::addLayout(). For example

QVBoxLayout *vLayout = new QVBoxLayout;
for (int i = 0; i < 3; i++)
    vlayout->addLayout(new QHBoxLayout);

[stdave]

OK - please forgive my newbie-isms, but here is what I have done - while putting the whole thing in a class, I have implemented your suggestion thus, without any different effect. Pressing the "Add" button puts me to a method which executes suggestion;

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QHBoxLayout>
#include <QVBoxLayout>
#include <QPushButton>
#include <QMessageBox>

void on_button4_clicked()
{
    QVBoxLayout *vLayout = new QVBoxLayout;
    for (int i = 0; i < 3; i++)
        vLayout->addLayout(new QHBoxLayout);

    QMessageBox msgBox;
    msgBox.setText("The document has been modified.");
    msgBox.exec();
 }

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

QWidget *widget = new QWidget;

QPushButton *button1 = new QPushButton("A");
QPushButton *button2 = new QPushButton("B");

QHBoxLayout *hLayout = new QHBoxLayout;
hLayout->addWidget(button1);
hLayout->addWidget(button2);

QPushButton *button4 = new QPushButton("Add",this);
QVBoxLayout *vLayout = new QVBoxLayout;
vLayout->addWidget(button4);

QVBoxLayout *vMainLayout = new QVBoxLayout;

vMainLayout->addLayout(vLayout);
vMainLayout->addLayout(hLayout);

widget->setLayout(vMainLayout);
widget->show();
connect(button4, &QPushButton::released, this, on_button4_clicked);

setCentralWidget(widget);

}

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

[SGaist]

Hi,

You are just adding layouts to a newly created layout that has nothing to do with your widget.