#ifndef CHECKBOX_H
#define CHECKBOX_H
 
#include <QWidget>
 
class CheckBox : public QWidget
{
  Q_OBJECT
 
  public:
    CheckBox(QWidget *parent = 0);
 
  private slots:
    void showTitle(int);
 
};
 
#endif
 

#include "checkbox.h"
#include <QCheckBox>
 
 
CheckBox::CheckBox(QWidget *parent)
    : QWidget(parent)
{
 
  QCheckBox *cb = new QCheckBox("Show Title", this);
  cb->setCheckState(Qt::Checked);
  cb->move(50, 50);
 
  connect(cb, SIGNAL(stateChanged(int)), this, SLOT(showTitle(int)));
}
 
 
void CheckBox::showTitle(int state)
{
  if (state == Qt::Checked) {
    setWindowTitle("QCheckBox");
  } else {
    setWindowTitle("");
  }
}
 

 
#include "checkbox.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  CheckBox window;
 
  window.setWindowTitle("QCheckBox");
  window.show();
  center(window);
 
  return app.exec();
}
 

 
#ifndef LISTWIDGET_H
#define LISTWIDGET_H
 
#include <QWidget>
#include <QPushButton>
#include <QListWidget>
 
class ListWidget : public QWidget
{
  Q_OBJECT
 
  public:
    ListWidget(QWidget *parent = 0);
 
  private slots:
    void addItem();
    void renameItem();
    void removeItem();
    void clearItems();
 
  private:
    QListWidget *lw;
    QPushButton *add;
    QPushButton *rename;
    QPushButton *remove;
    QPushButton *removeAll;
 
};
 
#endif
 

 
listwidget.cpp
#include "listwidget.h"
#include <QVBoxLayout>
#include <QInputDialog>
 
 
ListWidget::ListWidget(QWidget *parent)
    : QWidget(parent)
{
 
  QVBoxLayout *vbox = new QVBoxLayout();
  vbox->setSpacing(10);
 
  // must add it to another layout.
  QHBoxLayout *hbox = new QHBoxLayout(this);
 
  lw = new QListWidget(this);
  lw->addItem("The Omen"); 
  lw->addItem("The Exorcist");
  lw->addItem("Notes on a scandal");
  lw->addItem("Fargo");
  lw->addItem("Capote");
 
  add = new QPushButton("Add", this);
  rename = new QPushButton("Rename", this);
  remove = new QPushButton("Remove", this);
  removeAll = new QPushButton("Remove All", this);
 
  vbox->setSpacing(3);
  vbox->addStretch(1);
  vbox->addWidget(add);
  vbox->addWidget(rename);
  vbox->addWidget(remove);
  vbox->addWidget(removeAll);
  vbox->addStretch(1);
 
  hbox->addWidget(lw);
  hbox->addSpacing(15);
  hbox->addLayout(vbox);
 
  connect(add, SIGNAL(clicked()), this, SLOT(addItem()));
  connect(rename, SIGNAL(clicked()), this, SLOT(renameItem()));
  connect(remove, SIGNAL(clicked()), this, SLOT(removeItem()));
  connect(removeAll, SIGNAL(clicked()), this, SLOT(clearItems()));
 
  setLayout(hbox);
}
 
void ListWidget::addItem()
{
  QString item = QInputDialog::getText(this, "Item",
         "Enter new item");
  item = item.simplified();
  if (!item.isEmpty()) {
    lw->addItem(item);
    int r = lw->count() - 1;
    lw->setCurrentRow(r);
  }
}
 
void ListWidget::renameItem()
{
  QListWidgetItem *curitem = lw->currentItem();
  int r = lw->row(curitem);
  QString text = curitem->text();
  QString item = QInputDialog::getText(this, "Item", 
             "Enter new item", QLineEdit::Normal, text);
  item = item.simplified();
  if (!item.isEmpty()) {
    lw->takeItem(r);
    delete curitem;
    lw->insertItem(r, item);
    lw->setCurrentRow(r);
  }
}
 
void ListWidget::removeItem()
{
  QListWidgetItem *item = lw->currentItem();
 
  if (item) {
    int r = lw->row(item);
    lw->takeItem(r);
    delete item;
  }
}
 
void ListWidget::clearItems()
{
  if (lw->count() != 0)
    lw->clear();
}
 

 
main.cpp
#include "listwidget.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);  
 
  ListWidget window;
 
  window.setWindowTitle("QListWidget");
  window.show();
  center(window);
 
  return app.exec();
}
 

 
#ifndef PIXMAP_H
#define PIXMAP_H
 
#include <QWidget>
 
class Pixmap : public QWidget
{
  public:
    Pixmap(QWidget *parent = 0);
 
};
 
#endif
 

 
#include "pixmap.h"
#include <QPixmap>
#include <QLabel>
#include <QHBoxLayout>
 
Pixmap::Pixmap(QWidget *parent)
    : QWidget(parent)
{
  QHBoxLayout *hbox = new QHBoxLayout(this);
 
  QPixmap pixmap("bojnice.jpg");
 
  QLabel *label = new QLabel(this);
  label->setPixmap(pixmap);
 
  hbox->addWidget(label);
  setLayout(hbox);
}
 

 
#include "pixmap.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  Pixmap window;
 
  window.setWindowTitle("QPixmap");
  window.show();
  center(window);
 
  return app.exec();
}
 

 
#ifndef SPLITTER_H
#define SPLITTER_H
 
#include <QWidget>
 
class Splitter : public QWidget
{
  public:
    Splitter(QWidget *parent = 0);
 
};
 
#endif
 

 
#include "splitter.h"
#include <QFrame>
#include <QSplitter>
#include <QHBoxLayout>
 
 
Splitter::Splitter(QWidget *parent)
    : QWidget(parent)
{
  QHBoxLayout *hbox = new QHBoxLayout(this);
 
  QFrame *topleft = new QFrame(this);
  topleft->setFrameShape(QFrame::StyledPanel);
 
  QFrame *topright = new QFrame(this);
  topright->setFrameShape(QFrame::StyledPanel);
 
  QSplitter *splitter1 = new QSplitter(Qt::Horizontal, this);
  splitter1->addWidget(topleft);
  splitter1->addWidget(topright);
 
  QFrame *bottom = new QFrame(this);
  bottom->setFrameShape(QFrame::StyledPanel);
 
  QSplitter *splitter2 = new QSplitter(Qt::Vertical, this);
  splitter2->addWidget(splitter1);
  splitter2->addWidget(bottom);
 
  hbox->addWidget(splitter2);
  setLayout(hbox);
 
}
 

 
#include "splitter.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
 
  int WIDTH = 350;
  int HEIGHT = 300;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - WIDTH) / 2;
  y = (screenHeight - HEIGHT) / 2;
 
  widget.setGeometry(x, y, WIDTH, HEIGHT);
}
 
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  Splitter window;
 
  window.setWindowTitle("QSplitter");
  window.show();
  center(window);
 
  return app.exec();
}
 

 
#ifndef TABLE_H
#define TABLE_H
 
#include <QWidget>
 
class Table : public QWidget
{
  public:
    Table(QWidget *parent = 0);
 
};
 
#endif
 

 
#include "table.h"
#include <QHBoxLayout>
#include <QTableWidget>
 
Table::Table(QWidget *parent)
    : QWidget(parent)
{
  QHBoxLayout *hbox = new QHBoxLayout(this);
 
  QTableWidget *table = new QTableWidget(25, 25, this);
 
  hbox->addWidget(table);
  setLayout(hbox);
}
 

 
#include "table.h"
#include <QDesktopWidget>
#include <QApplication>
 
void center(QWidget &widget)
{
  int x, y;
  int screenWidth;
  int screenHeight;
  int width, height;
  QSize windowSize;
 
  QDesktopWidget *desktop = QApplication::desktop();
 
  width = widget.frameGeometry().width();
  height = widget.frameGeometry().height();  
 
  screenWidth = desktop->width();
  screenHeight = desktop->height();
 
  x = (screenWidth - width) / 2;
  y = (screenHeight - height) / 2;
 
  widget.move( x, y );
}
 
int main(int argc, char *argv[])
{
  QApplication app(argc, argv);
 
  Table window;
 
  window.setWindowTitle("QTableWidget");
  window.show();
  center(window);
 
  return app.exec();
}