Add an option to extend zooms if still dropping, but with a limit (#131)

* Add an option to extend zooms if still dropping, but with a limit

* At least when to overzoom, even if not actually doing it yet

* Refactor to give tile-join access to overzoom()

* Didn't work, but *might* have worked

* OK, it did something now

* Ah, there's the bug!

* Hook up pmtiles and dirtiles as overzooming sources

* Add command line option to enable or disable overzooming

* Add (currently broken) test of overzooming in tile-join

* Slightly more abstraction for the tile-join readers

* Factor out duplicated code

* Move construction into a constructor

* More changing accessors to methods

* Reduce magic

* Start tracking a list of the tiles at maxzoom

* I think it worked?

* Add missing #include

* Fix sequence of overzoomed tiles (Y sorts backwards for TMS)

* Don't spend memory on overzooming when we aren't going to use it

* Diff rather than cmp, in the hope of figuring out this broken test

* Keep full coordinate precision if we might extend zooms

* Try a slightly different byte limit

* Make drop-densest more consistent across tile boundaries

* Also affects this test

* Does it behave any differently if it can extend forever?

* I think the discrepancy is a thread-safety problem here

* Revert "Does it behave any differently if it can extend forever?"

This reverts commit 0dff0a0acc.

* Lost this change to the test

* This time for sure!

* Revert "Also affects this test"

This reverts commit cd1f7c2e78.

* Revert "Make drop-densest more consistent across tile boundaries"

This reverts commit 563f7d2bc2.

* Revert "Try a slightly different byte limit"

This reverts commit 2e271213d6.

* Add some more explanatory comments

* Amend the join-test to detect my current bug

* Allow overzooming to complete the zoom if it ever starts

* Forgot to correct the test

* Update changelog and version

* Cleanups from code review

* Remove version number from fixture to fix test

Makefile

@@ -67,7 +67,7 @@ tippecanoe-enumerate: enumerate.o
 tippecanoe-decode: decode.o projection.o mvt.o write_json.o text.o jsonpull/jsonpull.o dirtiles.o pmtiles_file.o
 	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3
 
-tile-join: tile-join.o projection.o mbtiles.o mvt.o memfile.o dirtiles.o jsonpull/jsonpull.o text.o evaluator.o csv.o write_json.o pmtiles_file.o
+tile-join: tile-join.o projection.o mbtiles.o mvt.o memfile.o dirtiles.o jsonpull/jsonpull.o text.o evaluator.o csv.o write_json.o pmtiles_file.o clip.o
 	$(CXX) $(PG) $(LIBS) $(FINAL_FLAGS) $(CXXFLAGS) -o $@ $^ $(LDFLAGS) -lm -lz -lsqlite3 -lpthread
 
 tippecanoe-json-tool: jsontool.o jsonpull/jsonpull.o csv.o text.o geojson-loop.o
@@ -404,8 +404,16 @@ join-test: tile-join
 	./tippecanoe-decode -x generator -x generator_options -x name -x description tests/join-population/empty.dirtiles > tests/join-population/empty.out.json.check
 	cmp tests/join-population/empty.out.json.check tests/join-population/empty.out.json
 	rm -rf tests/join-population/empty.dirtiles tests/join-population/empty.out.dirtiles tests/join-population/empty.out.json.check
-
-
+	#
+	# Test overzooming of tilesets with different maxzooms
+	#
+	mkdir -p tests/ne_110m_ocean/join
+	./tippecanoe -q -z2 -f -o tests/ne_110m_ocean/join/ocean.mbtiles tests/ne_110m_ocean/in.json
+	./tippecanoe -q -z4 -d8 -y name -f -o tests/ne_110m_ocean/join/countries.mbtiles tests/ne_110m_admin_0_countries/in.json.gz
+	./tile-join --overzoom -f -o tests/ne_110m_ocean/join/joined.mbtiles tests/ne_110m_ocean/join/ocean.mbtiles tests/ne_110m_ocean/join/countries.mbtiles
+	./tippecanoe-decode -x generator tests/ne_110m_ocean/join/joined.mbtiles > tests/ne_110m_ocean/join/joined.mbtiles.json.check
+	cmp tests/ne_110m_ocean/join/joined.mbtiles.json.check tests/ne_110m_ocean/join/joined.mbtiles.json
+	rm -f tests/ne_110m_ocean/join/ocean.mbtiles tests/ne_110m_ocean/join/countries.mbtiles tests/ne_110m_ocean/join/joined.mbtiles tests/ne_110m_ocean/join/joined.mbtiles.json.check
 
 join-filter-test:
 	# Comes out different from the direct tippecanoe run because null attributes are lost