Create Widget in QMainWindow and load to ScrollArea - c++

Question

I tried to create a Mainwindow with an slot, which creates a Widget and loads it to the ScrollArea in the Mainwindow. This doesn't work, so I tired to create the Widget in the constructor of the mainwindow and I always get errors and don't know why.. so what's the right declaration of the Widget?
#include <QtGui>
class Mainwindow : public QMainWindow
{
Q_OBJECT
public:
Mainwindow(QMainWindow *parent = 0);
public slots:
private:
QScrollArea *List,*Sublist,*Overall,*Settings;
QLabel *label_title;
QPushButton *bn_exit,*bn_list,*bn_overall,*bn_settings;
};
//! ------------------------------------- Mainlist -------------------------------------
class Sublist : public QWidget{
Q_OBJECT
private:
QLabel *title;
public:
Sublist(QWidget *parent = 0);
};
and .cpp
Mainwindow::Mainwindow(QMainWindow *parent) : QMainWindow(parent) {
this->resize(1024,576);
//this->setWindowFlags(Qt::Popup);
QPalette palette;
palette.setColor(QPalette::Background, QColor(16,16,16));
this->setPalette(palette);
Sublist SecondList;
//! [Set ScrollAreas]
List = new QScrollArea(this);
List->setGeometry(0,60,200,456);
List->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
Sublist = new QScrollArea(this);
Sublist->setGeometry(200,60,824,456);
Sublist->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
//Sublist->setWidget(SecondList)
}
//! ---------------------------------------- MainList------------------------------------------------------
Sublist::Sublist(QWidget *parent){
resize(1200,1200);
title = new QLabel("Title",this);
title->setGeometry(1120,1120,40,90);
}

Answer 1

I have played around with your code a bit, noticed a few things:
In class Mainwindow you define your QScrollArea variables:
QScrollArea *List,*Sublist,*Overall,*Settings;
You define a variable named Sublist of type QScrollArea, but you also have a class of the same name:
class Sublist : public QWidget
Probably would be a good idea to change the variable names for your scroll areas:
QScrollArea *list, *subList, *overall, *settings;
Next, in the constructor for class Sublist you pass a pointer to the parent class but never assign it to your base class. You also have a QLabel widget that never is placed anywhere. What seems to be needed is a layout for your custom widget.
The Sublist class could be something like this:
//.h
class Sublist : public QWidget
{
Q_OBJECT
public:
Sublist(QWidget *parent = 0);
private:
QLabel *title;
QVBoxLayout *layout;
};
//.cpp
Sublist::Sublist(QWidget *parent) : QWidget(parent) {
resize(1200,1200);
title = new QLabel("Title");
title->setGeometry(1120,1120,40,90);
QVBoxLayout *layout = new QVBoxLayout;
layout->addWidget(title);
setLayout(layout);
}
The Mainwindow class something like this:
//.h
class Mainwindow : public QMainWindow
{
Q_OBJECT
public:
Mainwindow(QMainWindow *parent = 0);
private:
Sublist *secondList;
QScrollArea *list, *subList, *overall, *settings;
QLabel *label_title;
QPushButton *bn_exit,*bn_list,*bn_overall,*bn_settings;
};
//.cpp
Mainwindow::Mainwindow(QMainWindow *parent) : QMainWindow(parent)
{
this->resize(1024,576);
QPalette palette;
palette.setColor(QPalette::Background, QColor(16,16,16));
palette.setColor(QPalette::Foreground, QColor(255,255,255));//set text to white
this->setPalette(palette);
secondList = new Sublist(this);
//! [Set ScrollAreas]
list = new QScrollArea(this);
list->setGeometry(0,60,200,456);
list->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
subList = new QScrollArea(this);
subList->setGeometry(200,60,824,456);
subList->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
subList->setWidget(secondList);
}
Im still not 100% sure this is what you where trying to achieve with this code, but I hope that I have helped you to resolve some of the issues in your current implementation.