int32_t WsiToDcm::getOpenslideLevelForDownsample()

in src/wsiToDcm.cpp [260:287]

• 13 lines of code
• 4 McCabe index (conditional complexity)

int32_t WsiToDcm::getOpenslideLevelForDownsample(int64_t downsample) {
  /*
      Openslide API  identifies image closest to the downsampled image in size
      with the API call: openslide_get_best_level_for_downsample(osr,
      downsample); optimal level selection selects the level with
      magnification above required level. Downsample acquistions can result in
      image dimensions which are non-interger multiples of the highest
      magnification which can result in the openslide_get_level_downsample
      reporting level downsampling of a non-fixed multiple:

      Example: Aperio svs imaging,  E.g. (40x -> 10x reports the 10x image has
      having a downsampling factor of 4.00018818010427.)

      The code below, computes the desired frame dimensions and then selects
      the frame which is the best match.
  */
    const int64_t tw = largestSlideLevelWidth_ / downsample;
    const int64_t th = largestSlideLevelHeight_ / downsample;
    int32_t levelToGet;
    for (levelToGet = 1; levelToGet < svsLevelCount_; ++levelToGet) {
      int64_t lw, lh;
      openslide_get_level_dimensions(getOpenSlidePtr(), levelToGet, &lw, &lh);
      if (lw < tw || lh < th) {
        break;
      }
    }
    return (levelToGet - 1);
}