How to pass promoted form's QSpinBoxes values to MainWindow

Question

In my project I promoted Qt Designer form class to mainwindow.ui. promoted ui I named as doublerect.ui and which containing two QspinBoxes one is sb_rect_height and other one is sb_rect_width . Now I need to pass those spinboex values to mainwindow.there for I created getters and setters. But when I access getter from mainwindow those values print as this 0 This main weight , 1072693248 This main height . So please tell me and give me a solution how can I access those spinboxes values from mainwindow.This my complete code

doublerect.cpp

#include "doublerect.h"
#include "ui_doublerect.h"
#include "mainwindow.h"
#include "qdebug.h"

DoubleRect::DoubleRect(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::DoubleRect)
{
    ui->setupUi(this);
    connect(ui->sb_rect_height, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
            this, &DoubleRect::setHeight);
    connect(ui->sb_rect_width, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged),
            this, &DoubleRect::setWidth);
}

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

int DoubleRect::getWidth() const
{
    return width;
}

void DoubleRect::setWidth(int value)
{
    width = value;
}

int DoubleRect::getHeight() const
{
    return height;
}

void DoubleRect::setHeight(int value)
{
    height = value;
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <qdebug.h>
#include <QColorDialog>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);
    ui->widgethide->setVisible(true);
}

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

void MainWindow::addRect()
{

    DoubleRect *obj = new DoubleRect();
    int height = obj->getHeight();
    int width = obj->getWidth();
    qDebug()<< height <<"This main height";
    qDebug()<< width <<"This main width";

}

void MainWindow::on_btnRect_clicked()
{
    addRect();
}

Answer 1

Methods setHeight and setWidth of DoubleRect class should be in section - private slots.

public:
  explicit DoubleRect(QWidget *parent = 0);
  ~DoubleRect();

  int getWidth() const;
  int getHeight() const;
public slots:

private slots:
  void setHeight(int value);
  void setWidth(int value);

EDIT

When addRect method is called, in constructor of DoubleRect you assign signal valueChanged() of SpinBox with your slots - setHeight and setWidth, then you want to print width and height using qDebug(), but first you need to change value of spinbox in order to slots can be invoked - and width with height can be set.

You cannot create obj every time you call addRect() method. This object should be create only one time. Then signal-slots connection is made, and when values of spinbox are changed, your slots will be called setting height and width correctly.

EDIT 2 You can define DoubleRect object as member of MainWindow:

class MainWindow : public QMainWindow
{
  Q_OBJECT
private:
  Ui::MainWindow *ui;
  QGraphicsScene * scene;
  QGraphicsView * view;
  DoubleRect* obj;
};

create this object in ctor of MainWindow

MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  //...
  obj = new DoubleRect();
}

now, when you change value of SpinBox, slots setWidth/setHeight will be called, and invoking 'addRect' method you should get correct values.

EDIT 3

I have downloaded your project, I use QT 4.8.4, after some modifications it works, so

[1] changes in doublerect.cpp

 DoubleRect::DoubleRect(QWidget *parent) :
 QWidget(parent),
 ui(new Ui::DoubleRect)
 {
    ui->setupUi(this);
    // NEW LINES !!! 
    connect (ui->sb_rect_height, SIGNAL(valueChanged(int)), this, SLOT(setHeight(int)));
    connect (ui->sb_rect_width, SIGNAL(valueChanged(int)), this, SLOT(setWidth(int)));
 }

use connect function to make connection between SIGNAL - SLOT

[2] changes in doublerect.h

class DoubleRect : public QWidget
{
   Q_OBJECT
public:
  explicit DoubleRect(QWidget *parent = 0);
  ~DoubleRect();

  int getWidth() const;
  int getHeight() const;
 public slots:
 private slots:      // NEW LINES, these methods must be slots
   void setHeight(int value);
   void setWidth(int value);
 private:
    Ui::DoubleRect *ui;
    int width;
    int height;
 };

and the most important things, changes in mainwindow.cpp

void MainWindow::addRect()
{
  //DoubleRect *obj = new DoubleRect();  // don't create new object
  int height = ui->widgethide->getHeight();
  int width = ui->widgethide->getWidth();
  qDebug()<< height <<"This main height";
  qDebug()<< width <<"This main width";
}

you don't need to create DoubleRect object, this object exists already, pointer to instance of this object is ui->widgethide.