Method paintEvent

src/qprogressindicator.cpp:91–122

* @brief QProgressIndicator::paintEvent draw the spinner. */

 * @brief QProgressIndicator::paintEvent draw the spinner.
 */
void QProgressIndicator::paintEvent(QPaintEvent * /*event*/) {
  if (!m_displayedWhenStopped && !isAnimated()) {
    return;
  }

  int width = qMin(this->width(), this->height());

  QPainter p(this);
  p.setRenderHint(QPainter::Antialiasing);

  auto outerRadius = int((width - 1) * 0.5);
  auto innerRadius = int((width - 1) * 0.5 * 0.38);

  int capsuleHeight = outerRadius - innerRadius;
  int capsuleWidth =
      (width > 32) ? int(capsuleHeight * 0.23) : int(capsuleHeight * 0.35);
  int capsuleRadius = capsuleWidth / 2;

  for (int i = 0; i < 12; ++i) {
    QColor color = m_color.isValid() ? m_color : palette().windowText().color();
    color.setAlphaF(1.0f - (i / 12.0f));
    p.setPen(Qt::NoPen);
    p.setBrush(color);
    p.save();
    p.translate(rect().center());
    p.rotate(int(m_angle - i * 30.0f));
    p.drawRoundedRect(int(-capsuleWidth * 0.5), -(innerRadius + capsuleHeight),
                      capsuleWidth, capsuleHeight, capsuleRadius,
                      capsuleRadius);
    p.restore();
  }
}