qt rolling label

The final renderings

The code is simple, direct Source
Code

#include "salabel.h"

#include <QPainter>
SALabel::SALabel(QWidget *parent)
    :QLabel(parent)
{
    QFont serifFont("Times", 20, QFont::Bold); 
    setFont(serifFont);
    m_curIndex = 0;//当前角码
    m_showText = "This is a textTicker Text!";//显示的文字
    m_charWidth = fontMetrics().width("a");//每个字符的宽度
    m_charLength = fontMetrics().width(m_showText); //总的文字长度
    startTimer(50);//定时器计算文字、刷新
}
SALabel::~SALabel()
{
   killTimer(1);
}

void SALabel::paintEvent(QPaintEvent *event)
{
    QLabel::paintEvent(event);
    QPainter painter(this);
    QPen pen(QBrush(linearGrad),2);
    painter.setPen(pen);//设置渐变
    //根据Label的宽度和显示字符串的长度，计算每次drawText的位置和次数
    for(int Index = 0;-m_charWidth * m_curIndex + m_charLength * Index< width();Index++)
    {
        painter.drawText(-m_charWidth * m_curIndex + m_charLength * Index, 30, m_showText);
    }
}
void SALabel::timerEvent(QTimerEvent *event)
{
    if(event->timerId() == 1)
    {
        m_curIndex++; //每次移动的字符串
        update();
        if (m_curIndex > m_showText.length())
        {
             m_curIndex = 0;
        }
    }
}
void SALabel::resizeEvent(QResizeEvent *event)
{
    linearGrad.setStart(0,0);
    linearGrad.setFinalStop(event->size().width(),0);
    linearGrad.setColorAt(0, Qt::black);
    linearGrad.setColorAt(1, Qt::red);
}