@Tobias: hmm so you want to say that new mapsForge may dynamically change rendered tile size based on defined parameter? So Locus should define as you wrote, till density 320dpi, use 256px, then 512px? I'll look what I may do here, thanks
I just thought that's the reason why lines are too thick in
Klaus' example. All render parameters like line thickness are scaled with the device scale factor in standard mapsforge (like with "dp" in Locus fork), even if the tile size is fixed. It looks normal if tile sizes are also scaled by this factor, but more cramped with high dpi if tile sizes stays at 256px.
There is the standard model with mapsforge viewer that tile sizes are scaled by device scale factor (and rounded to a multiple of 64, see
here), so it's 256px at 160dpi, 384px at 240dpi, 512px at 320dpi and so on.
But other apps are using because of compatibility reasons with their own map viewer fixed sizes at all dpi, e.g. OruxMaps 512px or BCN 256px. So the latter looks similar to Locus with ML maps, the former looks less cramped at the same zoom level.