27.QT-QProgressBar动态实现多彩进度条(详解)

#ifndef PROGRESSBAR_H
#define PROGRESSBAR_H
#include <QtGui>

class ProgressBar : public QWidget
{
    Q_OBJECT

    QProgressBar m_bar;
    QLabel       m_value;
    QSlider      m_slider;
    QImage       m_image;

protected slots:
    void  onvalueChanged(int value);
public:
    explicit ProgressBar(const QString&  fileName,QWidget *parent = 0);  
};

#endif // PROGRESSBAR_H

#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);

     /*设置布局*/
     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()));
}