qt生成二维码

#include "qrcode/qrencode.h"
void MainWindow::GenerateQRcode(QString tempstr)
{
    QRcode *qrcode;
    qrcode=QRcode_encodeString(tempstr.toStdString().c_str(),2,QR_ECLEVEL_Q,QR_MODE_8,1);
    qint32 temp_width=ui->label->width();
    qint32 temp_height=ui->label->height();
    qDebug()<<"temp_width="<<temp_width<<";temp_height="<<temp_height;
    qint32 qrcode_width=qrcode->width>0?qrcode->width:1;
    double scale_x=(double)temp_width/(double)qrcode_width;
    double scale_y=(double)temp_height/(double)qrcode_width;
    QImage mainimg=QImage(temp_width,temp_height,QImage::Format_ARGB32);
    QPainter painter(&mainimg);
    QColor background(Qt::white);
    painter.setBrush(background);
    painter.setPen(Qt::NoPen);
    painter.drawRect(0,0,temp_width,temp_height);
    QColor foreground(Qt::black);
    painter.setBrush(foreground);
    for(qint32 y=0;y<qrcode_width;y++)
    {
        for(qint32 x=0;x<qrcode_width;x++)
        {
            unsigned char b=qrcode->data[y*qrcode_width+x];
            if(b &0x01)
            {
                QRectF r(x*scale_x,y*scale_y,scale_x,scale_y);
                painter.drawRects(&r,1);
            }
        }
    }

   QPixmap mainmap=QPixmap::fromImage(mainimg);

   QLabel *plabel = new QLabel();

   plabel->setPixmap(mainmap);
   plabel->setVisible(true);
}