Qt 自定义动态进度条，双层进度动态显示

我在一个项目中，要从文件将数据导入到数据库中，由于导入数据量大，在导入的过程中，有时候进度条会停留在0％大概半分钟之久，如果没有动态提示的话，用户很可能误认为该软件已经死了。所以我在进度条上显示“数据正在加载中，请稍后。。。”的动态显示。这样用户就不会认为程序死了。

#include "myprocessbar.h"
#include <QStyleOptionProgressBar>
#include <QPainter>
#include <QTimer>

MyProcessBar::MyProcessBar(QWidget *parent) : QProgressBar (parent)
{

    m_timer =new QTimer(this);
    this->setAlignment(Qt::AlignTrailing);
    this->setTextVisible(false);
    this->setStyleSheet("QProgressBar{height:20px;border-radius:10px;}\
               QProgressBar::chunk{border-radius:10px;background-color:#05B8CC;} ");

    connect(m_timer,&QTimer::timeout,[this](){
        int _value =this->value();
        if(_value!=0)
        {
            if(m_currvalue >= _value)
                m_currvalue=0;
            m_currvalue++;
            this->repaint();
        }
        else {
                    this->repaint();
             }

    });
    m_timer->start(50);
}

void MyProcessBar::setRange(int minimum, int maximum)
{
    m_maxvalue=maximum;
    QProgressBar::setRange(minimum,maximum);
}

void MyProcessBar::paintEvent(QPaintEvent *e)
{
    QProgressBar::paintEvent(e);
    QStyleOptionProgressBar opt;
    initStyleOption(&opt);

    if (m_currvalue != 0)
    {
        QPainter painter(this);
        QRect rect1 = style()->subElementRect(QStyle::SE_ProgressBarContents, &opt, this);
        //QRectF rect1=this->rect();
        double _width=static_cast<double>(m_currvalue)/static_cast<double>(m_maxvalue)*rect1.width();
        QLinearGradient gradient(0,0,_width,rect1.height());
        gradient.setColorAt(0,Qt::red);
        gradient.setColorAt(1,Qt::blue);
        painter.setBrush(gradient);
        QRectF rect2=QRectF(rect1.topLeft(),QSize(static_cast<int>(_width),static_cast<int>(rect1.height())));
        rect2.adjust(0,0.8,0,-2);
        painter.drawRoundedRect(rect2, 10, 10);
        //painter.drawRect(rect);


        painter.drawText(QPointF(rect1.width()/2.0,rect1.height()/1.5),QString("%1%").arg(this->value()));
    }
    else
    {
        QPainter painter(this);

        QRect rect1 = style()->subElementRect(QStyle::SE_ProgressBarContents, &opt, this);
        static int num = 0;
        double _width = this->width();

        switch ((num++)%3) {
            case 0:
                painter.drawText(QPointF(_width/3.0,rect1.height()/1.5),"正在努力加载中，请稍后。");
                break;
            case 1:
                painter.drawText(QPointF(_width/3.0,rect1.height()/1.5),"正在努力加载中，请稍后。。");
                break;
            case 2:
                painter.drawText(QPointF(_width/3.0,rect1.height()/1.5),"正在努力加载中，请稍后。。。");
                break;
        }
    }

}