Qt实现字幕无间隙滚动效果

#ifndef TEXTSCROLL_H
#define TEXTSCROLL_H
 
#include <QObject>
#include <QWidget>
#include <QTimer>
#include <QPainter>
#include <QFontMetrics>
#include <QResizeEvent>
class textScroll : public QWidget
{
    Q_OBJECT
 
private:
 
    QTimer* timer;          //时间定时器
    QRgb   textColor;
    QString m_text;
    QString m_showText;
    QFont font;
    int m_ms;
    int m_pixelSize;
    int m_moveOffset;
    int m_moveSize;
    int blankSuffix;
    float speed;        //滑动速度,值越大越快
 
    void paintEvent(QPaintEvent *event);
    void resizeEvent(QResizeEvent *event);
 
public:
 
    explicit textScroll(QWidget *parent = 0);    //qRgb(int r, int g, int b)
 
    void setDelay(int ms,int pixelSize);    //设置滚动延迟,多少ms滚动多少像素点
 
    void setText(QString text,QRgb textColor,float speed=0.70,int blankSuffix=20); //设置字体,调用该函数后,将会自动启动定时器来滚动字幕
                                                  
 
 
    void restart();
 
 
signals:
 
public slots:
    void timeOut();
 
 
};
 
#endif // TEXTSCROLL_H

#include "textscroll.h"
#include <QDebug>
textScroll::textScroll( QWidget *parent) : QWidget(parent)
{
 
    timer = new QTimer(this);
    connect(timer, SIGNAL(timeout()), this, SLOT(timeOut()));
}
 
void textScroll::timeOut()
{
    qDebug()<<m_moveOffset<<m_moveSize;
    m_moveOffset+=m_pixelSize;
 
    if(m_moveOffset>m_moveSize)
    {
        m_moveOffset= 0;
    }
 
    update();
}
 
void textScroll::resizeEvent(QResizeEvent *event)
{
 
    font.setPixelSize(event->size().height()*0.75);
 
    m_showText = m_text;
    QFontMetrics metrics(font);
    int char_w = metrics.width(" ");
    setDelay(30,char_w*speed);
 
    int blankLine =width()/char_w+1;
 
    for(int i=0;i<blankLine;i++)
    {
        m_showText.insert(0," ");
    }
    m_moveSize=metrics.width(m_showText)+blankSuffix;
    m_moveOffset=0;
 
    update();
}
 
void textScroll::paintEvent(QPaintEvent *event)
{
 
      QPainter painter(this);
      painter.setFont(font);
 
      painter.setPen(QColor(120,120,120));
      painter.drawRect(QRect(0,0,width()-1,height()-1));   
 
      painter.setPen(QColor(textColor));
 
      painter.drawText(QRect(-m_moveOffset,0,width()-1+m_moveOffset,height()-1),
                       Qt::AlignVCenter|Qt::AlignLeft,m_showText);
 
 
 
}
 
 
void textScroll::setDelay(int ms,int pixelSize)    //设置滚动延迟,多少ms滚动多少像素点
{
 
    this->m_ms=ms;
    this->m_pixelSize=pixelSize;
}
 
 
void textScroll::setText(QString text, QRgb textColor, float speed, int blankSuffix) //设置字体
{
    this->blankSuffix = blankSuffix;
    this->speed = speed;
 
    font.setFamily("Microsoft Yahei");
    font.setPixelSize(height()*0.75);
 
    this->textColor = textColor;
 
    m_text = text;
    m_showText = m_text;
 
    QFontMetrics metrics(font);
    int char_w = metrics.width(" ");
    setDelay(50,char_w*speed);
 
    int blankLine =width()/char_w+2;
 
    for(int i=0;i<blankLine;i++)
    {
        m_showText.insert(0," ");
    }
 
 
    m_moveSize=metrics.width(m_showText)+blankSuffix;
 
    m_moveOffset=0;
    if(!timer->isActive())
    {
        if(m_ms)
        {
            timer->start(m_ms);
        }
    }
 
}
 
void textScroll::restart()
{
    m_moveOffset=0;
 
    update();
 
}