ScreenSaver Qt Old School Way

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Article Metadata

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Tested with

Devices(s): Emulator / desktop / device

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Compatibility

Platform(s): All Qt Supported

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Article

Keywords: QWidget

Created: skumar_rao (29 Nov 2010)

Last edited: hamishwillee (11 Oct 2012)

Note: The recommend way of working with screen-saver is QSplashScreen

Basically we will override QWidget::repaint() to call QApplication::flush(), which gets all the events in the application's event queue processed immediately. This is where the real magic of the splash screen happens, and why we can paint on the screen without having any sort of event loop.

qoldschoolsplashscreen.h

class QOldSchoolSplashScreen : public QWidget
{
public:
    QOldSchoolSplashScreen( const QPixmap &pixmap );
 
    void setStatus( const QString &message, int alignment = Qt::AlignLeft, const QColor &color = Qt::black );
    void finish( QWidget *mainWin );
    void repaint();
 
protected:
    void mousePressEvent( QMouseEvent * );
 
private:
    QPixmap pix;
};

qoldschoolsplashscreen.cpp

QOldSchoolSplashScreen::QOldSchoolSplashScreen(const QPixmap &pixmap)
    : QWidget(0),
    pix( pixmap ) {
 
    //setErasePixmap( pix );
    resize( pix.size() );
    QRect scr = QApplication::desktop()->screenGeometry();
    move( scr.center() - rect().center() );
    show();
    repaint();
}
 
void QOldSchoolSplashScreen::setStatus(
        const QString &message
      , int alignment
      , const QColor &color ) {
 
    QPixmap textPix = pix;
    QPainter painter( &textPix);
    painter.setPen( color );
    QRect r = rect();
    r.setRect( r.x() + 10, r.y() + 10, r.width() - 20, r.height() - 20 );
    painter.drawText( r, alignment, message );
 
    repaint();
}
 
 
void QOldSchoolSplashScreen::repaint() {
    QWidget::repaint();
    QApplication::flush();
}
 
void QOldSchoolSplashScreen::finish( QWidget *) {
    close();
}
 
void QOldSchoolSplashScreen::mousePressEvent( QMouseEvent * ) {
    hide();
}

Then we will use as

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
 
    QPixmap pixmap;
     pixmap.load("c:/data/myscreen.png");
 
    QOldSchoolSplashScreen *splash = new QOldSchoolSplashScreen( pixmap );
    splash->setFont( QFont("Times", 10, QFont::Bold) );
    splash->setStatus( "Initializing..." );
    a.processEvents();
 
    Widget w;
#if defined(Q_WS_S60)
    w.showMaximized();
#else
    w.show();
#endif
 
    splash->finish( &w );
    delete splash;
 
    return a.exec();
}

if we want the widget (screensaver ) to go away as soon as user clicks on it

    void QOldSchoolSplashScreen::mousePressEvent( QMouseEvent * ) {
        hide();
    }

--skumar_rao 18:16, 29 November 2010 (UTC)