#ifndef APPWINDOW_H
#define APPWINDOW_H

#include <QWidget>

namespace Ui
{
    class appwindow;
}

class appwindow : public QWidget
{
    Q_OBJECT

public:
    appwindow(QWidget *parent = 0);
    ~appwindow();

public slots:
    void startPaint();

protected:
    void changeEvent(QEvent *e);
    void paintEvent(QEvent* e);

private:
    Ui::appwindow *ui;
};

#endif // APPWINDOW_H

#include "appwindow.h"
#include "ui_appwindow.h"
#include <QPainter>

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

    connect(ui->pushButton, SIGNAL(clicked()), this, SLOT(startPaint()));
}

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

void appwindow::changeEvent(QEvent *e)
{
    QWidget::changeEvent(e);
    switch (e->type()) {
    case QEvent::LanguageChange:
        ui->retranslateUi(this);
        break;
    default:
        break;
    }
}

void appwindow::startPaint()
{
    update();
}


void appwindow::paintEvent(QEvent* e)
{
    QPainter painter(this);
    QBrush brush(Qt::red, Qt::SolidPattern);
    painter.setBrush(brush);
    painter.drawLine(10,10,-100,100);
}