Qt报警涟漪扩散

DrawRippleWidget::DrawRippleWidget(QWidget *parent) : QWidget(parent)

  , m_timeId(0)

{

}

DrawRippleWidget::~DrawRippleWidget()

{

}

void DrawRippleWidget::timerEvent(QTimerEvent *e)

{

    if (e->timerId() == m_timeId)

    {

        ++m_frameNo;

        update(m_updateRect);

    }

}

void DrawRippleWidget::paintEvent(QPaintEvent *e)

{

    Q_UNUSED(e);

    QPainter painter(this);

    drawRipple(&painter, this->width()/2, this->height()/2);

}

void DrawRippleWidget::drawRipple(QPainter *painter, int x, int y)

{

    int h = 32;

    m_updateRect = QRect(x - h / 2, y - h / 2, h, h);

    m_timeId = startTimer(30);

    for (int diameter = 0; diameter < h; diameter += 4) {

        int delta = abs((m_frameNo % 64) - diameter );

        int alpha = 200 - (delta * delta) / 2 - diameter;

        if (alpha > 0) {

            painter->setPen(QPen(QColor(255, 0, 0, alpha), 1));

            painter->drawEllipse(QRect(x - diameter / 2, y - diameter / 2,

                                       diameter, diameter));

        }

    }

}

实现效果

代码下载：http://download.csdn.net/download/u010304326/10258631