"Device screen scaling": I already read the post from Tobias, but I'm not too clever from this. What is the main issue he tries to describe except lack of interest in compatibility?
That post was more my tiredness of only limited support of new mapsforge features in various apps (not just Locus, but this was the app John came up with) which limit app-independent development as we do at OpenAndroMaps. In an older discussion I got the impression that LoMaps have a bigger priority than compatibility, but this new thread let's me hope for a change :-)
But as far as device screen scaling is concerned - as a cross-app-theme-developer this is the most important issue. It was introduced with mapsforge 0.4 in 2014, at first I was a bit sceptical but with very high ppi nowadays it's a must for good rendering, as far as I'm concerned.
Here's a description of the problem I posted in a different forum:
Mapsforge maps are meant to be scaled to screen density of the device, so that a map at 160ppi looks exactly the same as with 480ppi. To do that, not only symbols and line width are scaled, but also map tile size. So if you have a map tile size of 256px at 160ppi, you get 768px at 480ppi.
Locus uses a mod of a very old mapsforge version with no scaled tiles. So with modern devices with very high pixel density, you still get 256px like for devices years ago. The only thing that is scaled is line width and symbols. But as these grow larger (3x as large at 480ppi), the space on a 256px map tile gets more crowded, and less can be displayed. So when looking at the same zoom level, less and coarse information is shown.
Here are some comparison of a densely mapped are at zoom level 17:
At first, it looks as if Locus shows more - but this isn't the case, as the area is only larger as the tile sizes are smaller. The same area can achieved by OruxMaps by using the zoom button.
Now here you can see what details are available if tile size is adjusted:
In Locus, streets are rendered much too fat, so they overlap and swallow too much space. Only a few symbols are displayed, as most are eliminated because of too little space.
So the scaling policy of OruxMaps is true to how the maps are meant to be displayed and can be scaled to every pixel density without loss of details. The only disadvantage is that with larger tile size direct comparison to online maps with old 256px tile size is not possible (although there are more HD maps coming with larger tile size as it's necessary to keep the legible on high density devices).
On my to-do-list for the Locus version right now is the idea of moving all zoom-appears 1-2 levels as this is the only possibility right now to get it a bit better, but with other disadvantages.
Other issues:
- Folder structure for themes: only one theme xml per folder is allowed, and folder are also needed. Any other app with theme support allows xml files in base folder and graphics whereever the xml points to. So a special Locus format is always necessary. I get the one folder, one theme policy, but why not two or more xml files?
- Forced connection of V4 maps with V4 themes - it should be possible to use V3 maps with V4/V5 themes, or V3 maps and V3 standard mapsforge themes etc. Maybe use standard-mapsforge for all themes, whatever version, and locus-mapsforge-fork for those themes with locus-extended="1" in the rendertheme tag? That would solve the issues of the two posts above.
Best regards,
Tobias
