This change enables attaching images to the style with batches and
avoids massive re-allocations. Thus, it improves UI performance
especially at start-up time.
- Do not carry it over everywhere as parameter, it is a shared
instance anyway and the lifecycle is pretty much the app lifecycle
from the moment we instantiate a map.
- Rename to BackgroundScheduler because it is a Scheduler that will
do tasks in the background, we don't make assumptions if it is a
thread pool or a single thread.
- Most importantly, remove the dependency from `core` on `platform`.
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.
* Always return image metrics exclusive of padding
* Work with integer coordinates whenever possible
* Eliminate redundant SpriteAtlasElement members
* Fix asymmetric re-padding in getIconQuad when pixelRatio != 1
* Add explanatory comments
- Expose glyph and icon information to workers via message interface.
- Glyph/SpriteAtlas track which tiles have outstanding requests
and send messages to them when glyphs/icons become available.
- Remove obsolete "updateSymbolDependentTiles" pathway
- Symbol preparation for a tile now depends on all glyphs becoming
available before it can start.
- Start tracking individual icons needed for a tile, although we don't
do anything with the information yet.
- Introduce typedef for GlyphID
- check that sprite metrics are within the bounds of the sprite. fix#714
- make sprite metrics problems Errors instead of Warnings
- check for negative image width, height
Now it works more like StubStyleObserver: you can assign std::functions to specific slots based on resource type.
Rewrite resource loading tests in that style, making them less like integration tests of Style and more like unit tests of Source, GlyphStore, and SpriteStore.
* Standardize on std::exception_ptr as the error representation
(fixes#2854).
* Don't format textual strings at the error source; pass on the
constituent data via observer method parameters instead.
* Use the null object pattern to simplify observer notification code.
* Further refactoring for ResourceLoading tests.
