* Add simple unit tests for SymbolSizeBinder
* Fix bug in symbol size uniform value calculation
For camera functions we were setting the zoom levels in "covering ranges" to
`[(zoom stop <= tile zoom), (zoom stop >= 1 + tile zoom)]`, but then evaluating
the function at `[tile_zoom, tile_zoom + 1]`.
* Check for it != end() before accessing it->first
Introduce a second level of immutability, over each of the collections held by a style: sources, images, and layers. Tracking immutability at this level allows us to short-circuit significant portions of the RenderStyle update logic via a simple equality check, greatly improving performance.
* Eliminate updateBatch in favor of diffing layers and detecting changes to properties upon which layout depends.
* Replace RenderSource::{update,remove,invalidate,reload}Tiles with a single update method
* Replace TilePyramid::{update,remove,invalidate,reload}Tiles with a single update method
* Remove Style& dependency TODO from GeometryTile and TileParameters
Otherwise, an ActorRef that's in the process of sending a message could attempt to access an invalid Scheduler reference:
Thread 1 Thread 2
--------------------------------------------------
Scheduler::Scheduler
Actor::Actor
weakMailbox.lock()
Actor::~Actor
Scheduler::~Scheduler
mailbox->push()
scheduler.schedule() 💣
* Eliminates the need for EnableImmutableFromThis
* Eliminates the dependency of {Source,Layer}::Impl on corresponding Render class (circular dependency)
Avoid dangling references in the following sequence:
auto& id = layer->getID();
layer->setMaxZoom(2);
std::cout << id;
The reference would be dangling because mutating the layer allocates a new Immutable impl, and there may be no references to the prior impl, which held the id.
This adds a `convertJSON` template, to be used like:
Error error
optional<Foo> foo = convertJSON<Foo>(string, error);
Internally, it parses the string with RapidJSON and then calls `convert<Foo>(parsed, error)`.
While here, rationalize GeoJSON converters and fix error handling for Tileset conversion in OfflineDownload.
