imageview.cpp

void ImageView::paintEvent(QPaintEvent*)
{
  if (this->imageBuffer.empty()){ return; }

  double widgetWidth = this->width();
  double widgetHeight = this->height();
  QRectF target(0, 0, widgetWidth, widgetHeight);

  QImage tempQImage = *this->imageBuffer.at(this->imageBuffer.count()-1);
  tempQImage = tempQImage.scaled(rect().size(), Qt::KeepAspectRatio, Qt::SmoothTransformation);

  double imageSizeWidth = static_cast<double>(tempQImage.width());
  double imageSizeHeight = static_cast<double>(tempQImage.height());
  QRectF source(0.0, 0.0, imageSizeWidth, imageSizeHeight);

  int deltaX = 0;
  int deltaY = 0;
  if(source.width() < target.width())
      deltaX = target.width() - source.width();
  else
      deltaX = source.width() - target.width();

  if(source.height() < target.height())
      deltaY = target.height() - source.height();
  else
      deltaY = source.height() - target.height();

  QPainter painter(this);
  painter.translate(deltaX / 2, deltaY / 2);

  painter.drawImage(source, tempQImage);
}