Add H5grovePyramidTilesApi.getPendingTilesCount
This MR adds a getPendingTilesCount
to H5grovePyramidTilesApi
so the number of currently fetching tiles can be retrieved.
@valentin.valls let me know if this is what you want for daiquiri-tomo#64 (closed)
@sfisher you might also be interested.