qt滚动字幕 从右到左和从下到上滚动

qt滚动字幕的控件还是很常用的，但是大部分教程都是从右到左的滚动，所以我就封装了一个控件支持从下到上的滚动。原理都是一样的，利用QTIME去控制文字的位置。先上效果图：

话不多上，上代码。

#ifndef SOCROLL_H
#define SOCROLL_H

#include <QLabel>
#include <QPainter>
#include <QPaintEvent>
#include <QObject>
#include <QWidget>
#include <QTimer>
#include <QPainter>
#include <QFontMetrics>
#include <QResizeEvent>
#include <QDebug>
namespace  custom{

/*移动方向*/
enum HEAD{
    RTOL, //从右到左
    DTOT  //从下到上
};

class swscroll : public QLabel
{
     Q_OBJECT

public:
    swscroll(QWidget *parent = nullptr);
    ~swscroll();
    /*设置滚动的文本
    *inparam    scrollText  滚动的文本
    *inparam    eHead   滚动的方向
    */
    int setScrollText(QString scrollText, HEAD eHead);

    /*设置滚动的速度
    *inparam    nMs          每次滚动的毫秒数
    *inparam    nPixelSize   每次滚动距离
    * inparam   nDistance    两个滚动文本间距
    */
    int setDelay(int nMs, int nPixelSize, int nDistance);

    /*计算和保存字符串的换行
    *inparam    strSrcText  滚动文本
    *inparam    nWidth      滚动宽度
    * inparam   font        字体信息
    */
    inline QString LineFeed(const QString strSrcText, int nWidth, QFont font);

protected:
    void resizeEvent(QResizeEvent *event);
    void paintEvent(QPaintEvent *event);
    void timeOut();

private:

    QString m_strScrollText;//滚动的文本
    int m_nMs; //定时器的秒数
    int m_nPixelSize; //移动的像素点
    int m_nMoveOffset;//移动的距离
    int m_nMoveSize; //移动的总大小
    int m_nDistance=0; // 循环滚动的间隔
    QTimer* timer;     //时间定时器

    QVector<QString> m_strArray; //保存换行字符串
    int m_nFontSize; //字体大小
    HEAD m_eHead;   //滚动方向

};
}
#endif // SOCROLL_H

#include "custom/swscroll.h"
using namespace custom;

swscroll::swscroll(QWidget *parent)
    : QLabel(parent)
{
    m_nMs = 0;
    m_nPixelSize = 0;
    m_nMoveSize = 0;
    m_nMoveOffset = 0;
    m_nDistance=0;
    timer = new QTimer(this);
    connect(timer, &QTimer::timeout, this, &swscroll::timeOut);
}

swscroll::~swscroll()
{

}
void swscroll::resizeEvent(QResizeEvent *event)
{
    /*窗体大小改变要重新保存换行字符串*/
    m_strArray.clear();
    LineFeed(m_strScrollText, width(), font());
    QLabel::resizeEvent(event);
}

QString swscroll::LineFeed(const QString strSrcText, int nWidth, QFont font)
{
    QString strText = strSrcText;
    QFontMetrics fm(font);
    if (!strText.isEmpty())
    {
        int j=0,i;
        for ( i = 1; i < strText.size() + 1; i++)
        {
            /*width()-fontMetrics().width("a")*3/2  防止一行最后一个没有显示完全*/
            if (fm.width(strText.mid(j,i-j)) > width()-fontMetrics().width("a")*3/2)
            {
                m_strArray.append(strText.mid(j,i-j));
                j=i;
            }
        }
        if(i != j)
            m_strArray.append(strText.mid(j,i-j));
    }
    return strText;
}

void swscroll::paintEvent(QPaintEvent *event)
{
    QPainter painter(this);
    QFontMetrics fm(font());

    if (m_strScrollText.isEmpty())
    {
        return;
    }

    if(m_eHead == RTOL)
    {
        int nW = fontMetrics().width( m_strScrollText);
        int nH = fm.height();
        if( width() < nW )
        {
            int nX1 = width() - m_nMoveOffset;
            int nX2 = width()+nW+m_nDistance - m_nMoveOffset;
            painter.drawText(nX1, nH, m_strScrollText);
            painter.drawText(nX2,nH, m_strScrollText);
        }
        else
        {
            painter.drawText( 0, nH, m_strScrollText);
        }
    }
    if(m_eHead == DTOT)
    {
        int nI=0,
            nIndex=1,
            nNextIndex=0,
            nFontHeight =fm.height();

        QString strText = m_strScrollText;
        /*字体大小变化时，重新计算换行字符串*/
        if(QFontInfo(font()).pixelSize() != m_nFontSize)
        {
            m_nFontSize = QFontInfo(font()).pixelSize();
            m_strArray.clear();
            LineFeed(strText, width(), font());
        }

        if( m_strArray.count()*nFontHeight > height())
        {
            nNextIndex=m_strArray.count()+1;
            for (nI = 0; nI < m_strArray.count(); nI++)
            {
                int nX1 = fm.width("a")/2 ,
                        nY1 = height() - m_nMoveOffset + nIndex*fm.height(),
                        nX2 = fm.width("a")/2 ,
                        nY2 = height()+m_nDistance - m_nMoveOffset + nNextIndex*fm.height();

                if( nY1 > 0 && nY1 < height()+fm.height())
                    painter.drawText(nX1,nY1 , m_strArray.at(nI));
                if( nY2 > 0 && nY2 < height()+fm.height())
                    painter.drawText(fm.width("a")/2, nY2, m_strArray.at(nI));
                nIndex++;
                nNextIndex++;

            }
        }
        else
        {
            for (nI = 0; nI < m_strArray.count(); nI++)
            {
                int nX1 = fm.width("a")/2 ,
                        nY1 = nIndex*fm.height();
                painter.drawText(nX1,nY1 , m_strArray.at(nI));
                nIndex++;
            }
        }

    }

}
void swscroll::timeOut()
{
    /*从左到右*/
    if(m_eHead == RTOL)
    {
        m_nMoveSize = fontMetrics().width(m_strScrollText);
        m_nMoveOffset = m_nMoveOffset + m_nPixelSize;
        if(m_nMoveOffset > m_nMoveSize + width()+m_nDistance)
        {
            m_nMoveOffset =width() ;
        }
    }
    /*从下到上*/
    else if(m_eHead == DTOT )
    {
        m_nMoveSize = height()+fontMetrics().height()* (m_strArray.count())+m_nDistance;
        m_nMoveOffset = m_nMoveOffset + m_nPixelSize;
        if(m_nMoveOffset >= m_nMoveSize )
        {
            if( m_nDistance >= 0 )
            {
                m_nMoveOffset =height();
            }
            else
            {
                m_nMoveOffset = 0;
            }
        }
    }
    update();
}

int swscroll::setDelay(int nMs, int nPixelSize, int nDistance)
{
    if(nMs <= 0)
    {
        return -1;
    }
    if(nPixelSize <= 0)
    {
        return -1;
    }
    if(nDistance < 0)
    {
        return -1;
    }
    m_nMs = nMs;
    m_nPixelSize = nPixelSize;
    m_nDistance = nDistance;
    timer->start( nMs );

    return 0;
}
int swscroll::setScrollText(QString scrollText, HEAD eHead  )
{
    if (scrollText.isEmpty())
    {
        return -1;
    }
    m_nMoveOffset =0;
    m_strScrollText = scrollText;
    m_eHead = eHead;
    return 0;
}
#endif // SOCROLL_H

测试：

	custom::swscroll roll;
    QFont ft;
    ft.setPointSize(50);
    roll.setFont(ft);
    roll.setScrollText("abcdefghijklmnopqrstuvwxyz",custom::RTOL);
    //roll.setScrollText("abcdefghijklmnopqrstuvwxyz",custom::DTOT);
    roll.setGeometry(100,100,100,300);
    roll.setDelay(10,1,200);
	roll.show();