How to get promoted widget to show?

Sailanarmo

I am trying to do a simple demo for myself however I cannot get my slider or my qspinbox to show up.

I created a simple getter and setter within a custom Slider and SpinBox class:

#include <QObject>
#include <QWidget>
#include <QSlider>

class Slider : public QSlider
{
    Q_OBJECT
public:
    Slider(QWidget *parent = nullptr);

    void updateValue(int value) { this->setValue(value); }
    int get() const { return this->value(); }
};

I then add a QSlider onto the QtDesigner and promote the QSlider to my Slider class.

In my MainWindow.h, I simply create a Slider as a private member like such Slider newSlider; In MainWindow.cpp:

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

However, when I run the program, the QSlider does not show up. What am I doing wrong?

KillerSmath

@Sailanarmo
You can promote your class directly on Qt Designer.

mrjj

Hi
First of all.
You dont need to make a variable for it. ( the newSlider(parent) )
as the widget you promoted is now the slider and can be accessed via
ui->slidername ( same name as the promo widget)

Also, if you see nothing, i would guess on that for
Slider(QWidget *parent = nullptr); in cpp, you do not call base class to set it up?

Slider::Slider(QWidget *parent) : QSlider(parent) {
...
}

Sailanarmo

@KillerSmath This is exactly what I did. However it still isn't showing up when I run the program.

mrjj

Hi
Do you call base class in your constructor ?

Sailanarmo

@mrjj This was it! Thank you, this was driving me absolutely nuts haha.

mrjj

Heh yep, also due no error is shown, its simply not there.
Did you noice that its in UI and no need to add extra variable for it ?

Sailanarmo

@mrjj I did notice that and I have changed it as well!