This adds compile-time support for multiple platforms and runtime
detection of them. Window system related platform functions are now
called from shared code via the function pointer struct _GLFWplatform.
The timer, thread and module loading platform functions are still called
directly by name and the implementation chosen at link-time. These
functions are the same for any backend on a given OS, including the Null
backend.
The platforms are now enabled via CMake dependent options following the
GLFW_BUILD_<platform> pattern instead of a mix of automagic and ad-hoc
option names. There is no longer any option for the Null backend as it
is now always enabled.
Much of the struct stitching work in platform.h was based on an earlier
experimental branch for runtime platform selection by @ronchaine.
Every platform function related to windows, contexts, monitors, input,
event processing and Vulkan have been renamed so that multiple sets of
them can exist without colliding. Calls to these are now routed through
the _glfw.platform struct member. These changes makes up most of this
commit.
For Wayland and X11 the client library loading and display creation is
used to detect a running compositor/server. The XDG_SESSION_TYPE
environment variable is ignored for now, as X11 is still by far the more
complete implementation.
Closes#1655Closes#1958
The native access functions for context handles did not verify that the
context had been created with the same API the function was for.
This makes these functions emit GLFW_NO_WINDOW_CONTEXT on API mismatch.
This adds the glfwInitAllocator function for specifying a custom memory
allocator to use instead of the C runtime library.
The allocator is a struct of type GLFWallocator with fields
corresponding to malloc, realloc and free, while the internal API
corresponds to calloc, realloc and free.
Heap allocation calls are filtered before reaching the user-provided
functions, so deallocation of NULL and allocations of zero bytes are not
passed on, reallocating NULL is transformed into an allocation and
reallocating to size zero is transformed into deallocation.
The clearing of a new block to zero is performed by the internal
calloc-like function.
Closes#544.
Fixes#1628.
Closes#1947.
PFN_FunctionName is more readable than SCREAMSOUP_T.
Context creation API function typedefs are kept as-is where the original
header provided them, for compatibility and familiarity reasons.
Fixes formatting, semantics and documentation. Adds
glfwGetOSMesaContext. Adds support for OSMesa context attributes.
Updates changelog and credits. Adds license and copyright headers.
Removes superfluous code (the shared code provides many conveniences).
Removes loading of unused OSMesa functions. Removes empty platform
structs. Fixes version string format. Removes build dependency on
the OSMesa header and library (only the library is needed and only at
runtime).
Closes#850.
