[Patch] Use visitor pattern for painting tiles

[michael2402]

Migrate towards a visitor pattern.

Only the default zoom level is painted this way, the missed tiles are still painted using the old function.

Using streams and by adding a simple parallelStream() I was able to execute the image processors in parallel. This speeds up drawing a lot.

[Don-vip]

AbstractTileSourceLayer grows bigger than 2000 lines, it causes a checkstyle violation, is there a way to refactor it?

[michael2402]

I know. I also added some sonar warnings ;-)

I am currently attempting to separate the TileSet (coordinate conversion, range, ...) stuff and separate it from the tile loading so that that class can be refactored to a static class and then extracted. I want to move the painter to a new class as well. After that, AbstractTileSourceLayer won't contain any paint code and thus be small again ;-).

[wiktorn]

I like this change. I'm thinking about taking this a bit further, and create a structure that would map:
screen area -> tile(x,y,z), tile area to paint

This would allow us to parallelize whole paintTiles/missedTiles algorithm and then - just paint all the tiles in computed places.

[michael2402]

Yes, this is the next step I am planing.

I don't like the current structure of the missed tiles algorithm. It makes parallelization and extension (like limiting the number of tiles to paint) difficult.

I am currently planing to do a new collection algorithm that computes all tiles that need painting and then remove the old paint class. I am currently making the screen area more universal and respect the bounds of the projection - this will finally fix the problem that JOSM paints the wrong side of the world close to 180° ;-)

[michael2402]

This should be able to be applied as soon as 16.7 is out.

[michael2402]

I updated this one to the current version, too.

Can you give priority to this one, since I want to work on the tile source more. You don't need to fix Somar warnings (e.g. p -> getTile(p)). After this patch I will work on a patch that moves lots of code around and will then allow to use the same layer for multiple MapViews.

[Don-vip]

In 10820/josm:

fix #13222 - Use visitor pattern for painting tiles (patch by michael2402) - gsoc-core