Function applyBoxBlur

app/src/UI/Widgets/PainterContext.cpp:1776–1785

* @brief Three-pass separable box-blur applied in place to the given image. */

 * @brief Three-pass separable box-blur applied in place to the given image.
 */
static void applyBoxBlur(QImage& image, int radius)
{
  for (int pass = 0; pass < 3; ++pass) {
    QImage blurred(image.size(), QImage::Format_ARGB32_Premultiplied);
    blurred.fill(Qt::transparent);
    boxBlurHorizontal(image, blurred, radius);
    image.fill(Qt::transparent);
    boxBlurVertical(blurred, image, radius);
  }
}

/**
 * @brief Renders the given draw callback as a coloured drop shadow.