1
0
Fork 0
mirror of https://github.com/gwm17/glfw.git synced 2024-11-22 10:18:51 -05:00
glfw/docs/internal.dox
Camilla Löwy 56a4cb0a3a Add runtime platform selection
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 #1655
Closes #1958
2021-10-13 21:47:11 +02:00

124 lines
4.6 KiB
Plaintext

/*!
@page internals_guide Internal structure
@tableofcontents
There are several interfaces inside GLFW. Each interface has its own area of
responsibility and its own naming conventions.
@section internals_public Public interface
The most well-known is the public interface, described in the glfw3.h header
file. This is implemented in source files shared by all platforms and these
files contain no platform-specific code. This code usually ends up calling the
platform and internal interfaces to do the actual work.
The public interface uses the OpenGL naming conventions except with GLFW and
glfw instead of GL and gl. For struct members, where OpenGL sets no precedent,
it use headless camel case.
Examples: `glfwCreateWindow`, `GLFWwindow`, `GLFW_RED_BITS`
@section internals_native Native interface
The [native interface](@ref native) is a small set of publicly available
but platform-specific functions, described in the glfw3native.h header file and
used to gain access to the underlying window, context and (on some platforms)
display handles used by the platform interface.
The function names of the native interface are similar to those of the public
interface, but embeds the name of the interface that the returned handle is
from.
Examples: `glfwGetX11Window`, `glfwGetWGLContext`
@section internals_internal Internal interface
The internal interface consists of utility functions used by all other
interfaces. It is shared code implemented in the same shared source files as
the public and event interfaces. The internal interface is described in the
internal.h header file.
The internal interface is in charge of GLFW's global data, which it stores in
a `_GLFWlibrary` struct named `_glfw`.
The internal interface uses the same style as the public interface, except all
global names have a leading underscore.
Examples: `_glfwIsValidContextConfig`, `_GLFWwindow`, `_glfw.monitorCount`
@section internals_platform Platform interface
The platform interface implements all platform-specific operations as a service
to the public interface. This includes event processing. The platform
interface is never directly called by application code and never directly calls
application-provided callbacks. It is also prohibited from modifying the
platform-independent part of the internal structs. Instead, it calls the event
interface when events interesting to GLFW are received.
The platform interface mostly mirrors those parts of the public interface that needs to
perform platform-specific operations on some or all platforms.
The window system bits of the platform API is called through the `_GLFWplatform` struct of
function pointers, to allow runtime selection of platform. This includes the window and
context creation, input and event processing, monitor and Vulkan surface creation parts of
GLFW. This is located in the global `_glfw` struct.
Examples: `_glfw.platform.createWindow`
The timer, threading and module loading bits of the platform API are plain functions with
a `_glfwPlatform` prefix, as these things are independent of what window system is being
used.
Examples: `_glfwPlatformGetTimerValue`
The platform interface also defines structs that contain platform-specific
global and per-object state. Their names mirror those of the internal
interface, except that an interface-specific suffix is added.
Examples: `_GLFWwindowX11`, `_GLFWcontextWGL`
These structs are incorporated as members into the internal interface structs
using special macros that name them after the specific interface used. This
prevents shared code from accidentally using these members.
Examples: `window->win32.handle`, `_glfw.x11.display`
@section internals_event Event interface
The event interface is implemented in the same shared source files as the public
interface and is responsible for delivering the events it receives to the
application, either via callbacks, via window state changes or both.
The function names of the event interface use a `_glfwInput` prefix and the
ObjectEvent pattern.
Examples: `_glfwInputWindowFocus`, `_glfwInputCursorPos`
@section internals_static Static functions
Static functions may be used by any interface and have no prefixes or suffixes.
These use headless camel case.
Examples: `isValidElementForJoystick`
@section internals_config Configuration macros
GLFW uses a number of configuration macros to select at compile time which
interfaces and code paths to use. They are defined in the GLFW CMake target.
Configuration macros the same style as tokens in the public interface, except
with a leading underscore.
Examples: `_GLFW_WIN32`, `_GLFW_BUILD_DLL`
*/