Qt/C++ 跑马灯效果

直接上代码合适:

头文件

classMusicMarqueeWidget:publicQWidget

{

    Q_OBJECT

public:

    explicit MusicMarqueeWidget(QWidget *parent = 0);

    void setText(const QString &newText)

    QString text() const { return m_myText; }

    QSize sizeHint() const;

protected:

    virtual void paintEvent(QPaintEvent *event);

    virtual void showEvent(QShowEvent *event);

    virtual void hideEvent(QHideEvent *event);

    virtual void timerEvent(QTimerEvent *event);

private:

    QString m_myText;

    int m_offset;

    int m_myTimerId;

};

源文件：

MusicMarqueeWidget::MusicMarqueeWidget(QWidget *parent)
    : QWidget(parent)
{
    m_offset = 0;
    m_myTimerId = 0;
    setStyleSheet("color:white");
}
void MusicMarqueeWidget::setText(const QString &newText)
{
    int length = fontMetrics().width(newText) >= width() ? 45 : 25;
    m_myText = newText.leftJustified(length, ' ');
    update();
    updateGeometry();
}
QSize MusicMarqueeWidget::sizeHint() const
{
    return fontMetrics().size(0, text());
}
void MusicMarqueeWidget::paintEvent(QPaintEvent *event)
{
    QWidget::paintEvent(event);
    QPainter painter(this);
    QFont f(font());
    f.setBold(false);
    painter.setFont(f);
    int textWidth = fontMetrics().width(text());
    if(textWidth < 1)
    {
        return;
    }
    int x = -m_offset;
    while(x < width())
    {
        painter.drawText(x, 0, textWidth, height(),
                         Qt::AlignLeft | Qt::AlignVCenter, text());
        x += textWidth;
    }
    painter.end();
}
void MusicMarqueeWidget::showEvent(QShowEvent *event)
{
    QWidget::showEvent(event);
    m_myTimerId = startTimer(30);
}
void MusicMarqueeWidget::timerEvent(QTimerEvent *event)
{
    if(event->timerId() == m_myTimerId)
    {
        ++m_offset;
        if (m_offset >= fontMetrics().width(text()))
        {
            m_offset = 0;
        }
        scroll(-1, 0);
    }
    else
    {
        QWidget::timerEvent(event);
    }
}
void MusicMarqueeWidget::hideEvent(QHideEvent *event)
{
    QWidget::hideEvent(event);
    killTimer(m_myTimerId);
    m_myTimerId = 0;
}
应该没什么问题了

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