[QT Creator] how to paint on widgets?

[Tomasz]

Hello!

I've started to learn QT4, and I've got a problem. I've created simple application with QTCreator - one window with two tabs on it (QTabWidget with tab and tab_2), Now I've got 3 files:

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
 
namespace Ui {
    class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
 
private:
    Ui::MainWindow *ui;
};
 
#endif // MAINWINDOW_H

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

namespace Ui {
    class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

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

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

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mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}

#include "mainwindow.h"
#include "ui_mainwindow.h"

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

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

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i main.cpp

#include <QtGui/QApplication>
#include "mainwindow.h"
 
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
 
    return a.exec();
}

#include <QtGui/QApplication>
#include "mainwindow.h"

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

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Now I want to draw something with QPainter on tab_2. I've read a lot of tutorails but I didn't found it. What should I write and where? I can only paint on MainWindow with MainWindow::PaintEvent. If it's not a problem can someone write me simple code which will work?

thanks in advance
best regards
Tomasz

[wysota]

There are two ways of doing what you want. A shorter (yet not as powerful) one is to install a so called "event filter" on the tab and intercept its paint event elsewhere (i.e. in your main window). The other solution is to make your tab_2 a custom widget and reimplement its paint Event. Try to use the second version, it's much more appropriate in OOP in general.