Refactor out HeadlessFrontend and HeadlessBackend gl independent code to gfx.
Define gl::HeadlessBackend as subclass, instantiated by gfx::HeadlessBackend static factory method.
GL dependent tests are still using gl::HeadlessBackend directly (not through gfx).
- 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`.
This patch will make Mapbox GL Core never use OpenGL
directly. We should consider locking into OpenGL ES 2.0
to simplify the code path and remove #ifdefs.
Vendorize the submodules and a simple CMake build
system for all them. The dependencies will inherit
compilation options for core.
The goal is to make Mapbox GL Core completely self
contained with a simple offline build.
Most of the STL is header-only anyway, and statically linking it only has a small overhead. On the other hand, it allows us to build more portable executables.
Previously, `target_include_directories(mbgl-loop-uv PUBLIC ${NODEJS_INCLUDE_DIRS})` always applied. Compiles were working by accident because node is always installed in CI. Instead, split and inline loop-uv.cmake contents: linux uses `target_add_mason_package(mbgl-loop-uv PUBLIC libuv)`, node uses `target_include_directories(mbgl-loop-node PUBLIC ${NODEJS_INCLUDE_DIRS})`.
- Platform-specific LocalGlyphRasterizer is responsible for deciding which glyphs to rasterize locally and for implementing the rasterization.
- Default platform implementation doesn't locally generate any glyphs -> no behavior change
- Unit test uses StubLocalGlyphRasterizer, which returns a single fixed bitmap for all CJK glyphs
- Rename glyph_loader.test to glyph_manager.test
Enables -fvisibility=hidden for iOS and Linux, and adds a workaround for GCC 6.3-7.1
Adds a GCC 6 build
Enables diagnostics for C files
Fixes a shadow warning in parsedate.c
rationale: encodePNG is only used in tests + sample apps, but shouldn't actually be part of the core library. In #7828, we're removing the libpng dependency for Android, and using a libpng-free version of encodePNG allows us to run the core unit tests on Android without pulling in libpng just for the test suite. In a next step, we should remove encodePNG() from the image.hpp header, which is a public header.
