#include "ProgressBar.h"
ProgressBar:: ProgressBar(const QString&  fileName,QWidget *parent ) :
    QWidget(parent),
    m_bar(this),
    m_value(this),
    m_slider(this),
    m_image(fileName)
{
    m_bar.setMaximum(100);
    m_bar.setMinimum(0);
    m_bar.setValue(0);
    m_bar.setTextVisible(false);
    m_bar.setFixedHeight(20);
    m_slider.setMaximum(100);
    m_slider.setMinimum(0);
    m_slider.setValue(0);
    m_slider.setOrientation(Qt::Horizontal);
    m_value.setText(QString("%1%").arg(m_bar.value()));
    m_value.setAlignment(Qt::AlignRight|Qt::AlignVCenter);
    m_value.setMinimumWidth(40);
     
     QHBoxLayout* hlayout=new QHBoxLayout();
     hlayout->addWidget(&m_slider);
     hlayout->addWidget(&m_value,0,Qt::AlignRight);
     QVBoxLayout* vlayout=new QVBoxLayout();
     vlayout->addWidget(&m_bar);
     vlayout->addLayout(hlayout);
     setLayout(vlayout);
     connect(&m_slider,SIGNAL(valueChanged ( int)),&m_bar,SLOT(setValue (int)));
     connect(&m_bar,SIGNAL(valueChanged ( int)),this,SLOT(onvalueChanged (int)));
     onvalueChanged(m_bar.value());
}
void ProgressBar::onvalueChanged(int value)
{
    QString qss="QProgressBar{"
               "border: 1px solid rgb(16, 135, 209);"
               "background: rgba(248,248,255,180);"
               "border-radius: 6px; }"
               "QProgressBar::chunk:enabled {"
               "border-radius: 4px; "
               "background: qlineargradient(x1:0, y1:0, x2:1, y2:0" ;
    double v= m_bar.maximum();
    double EndColor=static_cast<double>(value)/v ;    //获取比例
    for(int i=0;i<100;i++)
    {
     double Current=EndColor*i/100;
     QRgb rgb =m_image.pixel((m_image.width()-1)*Current,m_image.height()/2);
     QColor c(rgb);
     qss.append(QString(",stop:%1  rgb(%2,%3,%4)").arg(i/100.0).arg(c.red()).arg(c.green()).arg(c.blue()));
    }
    qss.append(");}");
    m_bar.setStyleSheet(qss);
    m_value.setText(QString("%1%").arg(m_bar.value()));
}
文章来源:https://www.cnblogs.com/lifexy/p/9193109.html
27.QT-QProgressBar动态实现多彩进度条(详解)
原文:https://www.cnblogs.com/xiongjim/p/9674175.html