faderwidget.cpp

/****************************************************************************
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** Copyright (C) 2006 Trolltech AS. All rights reserved.
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** This file is part of the documentation of Qt. It was originally
** published as part of Qt Quarterly.
**
** This file may be used under the terms of the GNU General Public License
** version 2.0 as published by the Free Software Foundation or under the
** terms of the Qt Commercial License Agreement. The respective license
** texts for these are provided with the open source and commercial
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#include <QtGui>

#include "faderwidget.h"

FaderWidget::FaderWidget(QWidget *parent,QColor _startColor)
    : QWidget(parent)
{
    //if (parent)
    //    startColor = parent->palette().window().color();
    //else
        startColor = _startColor;//Qt::white;

    currentAlpha = 0;
    duration = 200;

    timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(update()));

    setAttribute(Qt::WA_DeleteOnClose);
    resize(parent->size());
}

void FaderWidget::start()
{
    currentAlpha = 255;
    timer->start(20);
    show();
}

void FaderWidget::paintEvent(QPaintEvent * /* event */)
{
    QPainter painter(this);
    QColor semiTransparentColor = startColor;
    semiTransparentColor.setAlpha(currentAlpha);
    painter.fillRect(rect(), semiTransparentColor);

    currentAlpha -= 255 * timer->interval() / duration;
    if (currentAlpha <= 0) {
        timer->stop();
        close();
    }
}