little tips of painter.drawRect in Qt

一个QImage或QPixmap新建变量时，第一次填充图片时设置的宽高正常（fill），其后的绘制操作（draw）则会在绘制的矩形底边和右边加上painter.pen().width()

在下面代码17行设置端点查看内存可以直观看到只在右边和底边++

 // 1.  生成掩码图
     const int width = ;
     const int height = ;
     QImage maskImg(width, height, QImage::Format_Mono);
     QPainter maskPainter(&maskImg);
     //
     maskPainter.setPen(QPen(Qt::white, ));
     maskPainter.setBrush(Qt::white);
     maskPainter.drawRect(, , width, height);
     maskPainter.setPen(QPen(Qt::black, ));
     maskPainter.setBrush(Qt::black);
     maskPainter.drawRect(, -, width, height);
     maskPainter.setPen(QPen(Qt::black, ));
     maskPainter.setBrush(Qt::black);
     maskPainter.drawRect(, , , );

     maskImg.save("/home/lt47/Desktop/ORIGIN.jpg");
     qDebug() << maskImg.byteCount();
     qDebug() << maskImg.bytesPerLine();
     QRgb b = maskImg.pixel(,);
     qDebug() << qRed(b) << qGreen(b) << qBlue(b);
     QRgb ww = maskImg.pixel(,);
     qDebug() << qRed(ww) << qGreen(ww) << qBlue(ww);