Compilation error when trying to use a Custom Widget

[PontiacGTX]

Adding up a Custom defined Widget within QT Creator throws a compilation error when I am trying a new widget, so I am coming back to C++ after a while and I had forgotten part of the qt framework but I have tried to start with something simple as defining my own QSlider

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    QWidget* tempWidgetCustomSlider = new QWidget();
    CustomSlider* cSlider =new CustomSlider(tempWidgetCustomSlider);
    QObject* objGrid =ui->centralwidget->layout()->findChild<QObject*>("gridLayout1");
    if(objGrid!=nullptr){
        QWidget* qwidgetCast = qobject_cast<QWidget *>(objGrid);
        //QGridLayout* grid = new QGridLayout(qwidgetCast);
        //grid->addWidget(cSlider,0,0);
        qwidgetCast->layout()->addWidget(cSlider);
    }
  

}

declaration for custom widget

#ifndef CUSTOMSLIDER_H
#define CUSTOMSLIDER_H

#include <QSlider>



class CustomSlider : public QSlider
{
public:
    CustomSlider(QWidget * parent=nullptr);
};

#endif // CUSTOMSLIDER_H

definition for custom widget

#include "CustomSlider.h"
#include <QWidget>
CustomSlider::CustomSlider(QWidget* parent):QSlider(parent)
{
    if(parent){
        parent->setContentsMargins(0,0,0,0);
        parent->setFixedSize(20,20);
        parent->setStyleSheet("QSlider {"
                              "background-color: #f0f0f0;"
                              "border: none;"
                              "border-radius: " + QString::number(10) + "px;"
                                                      "}"
                                                      "QSlider:hover {"
                                                      "background-color: #e0e0e0;"
                                                      "}"
                                                      "QSlider::handle:horizontal {"
                                                      "background-color: #ffffff;"
                                                      "border: 1px solid #999999;"
                                                      "height: 20px;"
                                                      "width: 20px;"
                                                      "margin: -5px -10px;"
                                                      "border-radius: 10px;"
                                                      "}");
    }
}

but I am getting the following error

:-1: error: CMakeFiles/QTWidgetTest.dir/mainwindow.cpp.obj: in function `MainWindow::MainWindow(QWidget*)':

\source\repos qt\QTWidgetTest\mainwindow.cpp:14: error: undefined reference to `CustomSlider::CustomSlider(QWidget*)'

[mpergand]

@PontiacGTX
Hi,

Seems you forget to include CustomSlider.h

Your code is over complicated, if you want to add the slider to gridLayout1, there is more simple:

CustomSlider* cSlider =new CustomSlider(nullptr);
ui->gridLayout1->addWidget(cSlider);   // or addWidget(cSlider,0,0)

QWidget* tempWidgetCustomSlider = new QWidget();

What this line is supposed to do ?

[ChrisW67]

@PontiacGTX Have you added CustomSlider.cpp to the add_executable(...) in your CMakeLists.txt file?

[JoeCFD]

@ChrisW67
Q_OBJECT is missing as well

class CustomSlider : public QSlider
{    
   Q_OBJECT

public:
    explicit CustomSlider(QWidget * parent=nullptr);
};