docs/compat.dox - third_party/glfw - Git at Google

 /*!

 @page compat Standards conformance

 @tableofcontents

 This guide describes the various API extensions used by this version of GLFW.
 It lists what are essentially implementation details, but which are nonetheless
 vital knowledge for developers intending to deploy their applications on a wide
 range of machines.

 The information in this guide is not a part of GLFW API, but merely
 preconditions for some parts of the library to function on a given machine.  Any
 part of this information may change in future versions of GLFW and that will not
 be considered a breaking API change.


 @section compat_x11 X11 extensions, protocols and IPC standards

 As GLFW uses Xlib directly, without any intervening toolkit
 library, it has sole responsibility for interacting well with the many and
 varied window managers in use on Unix-like systems.  In order for applications
 and window managers to work well together, a number of standards and
 conventions have been developed that regulate behavior outside the scope of the
 X11 API; most importantly the
 [Inter-Client Communication Conventions Manual](http://www.tronche.com/gui/x/icccm/)
 (ICCCM) and
 [Extended Window Manager Hints](http://standards.freedesktop.org/wm-spec/wm-spec-latest.html)
 (EWMH) standards.

 GLFW uses the `_MOTIF_WM_HINTS` window property to support borderless windows.
 If the running window manager does not support this property, the
 `GLFW_DECORATED` hint will have no effect.

 GLFW uses the ICCCM `WM_DELETE_WINDOW` protocol to intercept the user
 attempting to close the GLFW window.  If the running window manager does not
 support this protocol, the close callback will never be called.

 GLFW uses the EWMH `_NET_WM_PING` protocol, allowing the window manager notify
 the user when the application has stopped responding, i.e. when it has ceased to
 process events.  If the running window manager does not support this protocol,
 the user will not be notified if the application locks up.

 GLFW uses the EWMH `_NET_WM_STATE_FULLSCREEN` window state to tell the window
 manager to make the GLFW window full screen.  If the running window manager does
 not support this state, full screen windows may not work properly.  GLFW has
 a fallback code path in case this state is unavailable, but every window manager
 behaves slightly differently in this regard.

 GLFW uses the EWMH `_NET_WM_BYPASS_COMPOSITOR` window property to tell a
 compositing window manager to un-redirect full screen GLFW windows.  If the
 running window manager uses compositing but does not support this property then
 additional copying may be performed for each buffer swap of full screen windows.

 GLFW uses the
 [clipboard manager protocol](http://www.freedesktop.org/wiki/ClipboardManager/)
 to push a clipboard string (i.e. selection) owned by a GLFW window about to be
 destroyed to the clipboard manager.  If there is no running clipboard manager,
 the clipboard string will be unavailable once the window has been destroyed.

 GLFW uses the
 [X drag-and-drop protocol](http://www.freedesktop.org/wiki/Specifications/XDND/)
 to provide file drop events.  If the application originating the drag does not
 support this protocol, drag and drop will not work.

 GLFW uses the XInput 2 extension to provide sub-pixel cursor motion events.  If
 the running X server does not support this version of this extension, cursor
 motion will be snapped to the pixel grid.

 GLFW uses the XRandR 1.3 extension to provide multi-monitor support.  If the
 running X server does not support this version of this extension, multi-monitor
 support will not function and only a single, desktop-spanning monitor will be
 reported.

 GLFW uses the XRandR 1.3 and Xf86vidmode extensions to provide gamma ramp
 support.  If the running X server does not support either or both of these
 extensions, gamma ramp support will not function.

 GLFW uses the Xkb extension and detectable auto-repeat to provide keyboard
 input.  If the running X server does not support this extension, a non-Xkb
 fallback path is used.


 @section compat_glx GLX extensions

 The GLX API is the default API used to create OpenGL contexts on Unix-like
 systems using the X Window System.

 GLFW uses the GLX 1.3 `GLXFBConfig` functions to enumerate and select framebuffer pixel
 formats.  If GLX 1.3 is not supported, @ref glfwInit will fail.

 GLFW uses the `GLX_MESA_swap_control,` `GLX_EXT_swap_control` and
 `GLX_SGI_swap_control` extensions to provide vertical retrace synchronization
 (or _vsync_), in that order of preference.  Where none of these extension are
 available, calling @ref glfwSwapInterval will have no effect.

 GLFW uses the `GLX_ARB_multisample` extension to create contexts with
 multisampling anti-aliasing.  Where this extension is unavailable, the
 `GLFW_SAMPLES` hint will have no effect.

 GLFW uses the `GLX_ARB_create_context` extension when available, even when
 creating OpenGL contexts of version 2.1 and below.  Where this extension is
 unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
 hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
 will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
 `GLFW_OPENGL_FORWARD_COMPAT` hints to `GL_TRUE` will cause @ref
 glfwCreateWindow to fail.

 GLFW uses the `GLX_ARB_create_context_profile` extension to provide support for
 context profiles.  Where this extension is unavailable, setting the
 `GLFW_OPENGL_PROFILE` hint to anything but `GLFW_OPENGL_ANY_PROFILE`, or setting
 `GLFW_CLIENT_API` to anything but `GLFW_OPENGL_API` will cause @ref
 glfwCreateWindow to fail.

 GLFW uses the `GLX_ARB_context_flush_control` extension to provide control over
 whether a context is flushed when it is released (made non-current).  Where this
 extension is unavailable, the `GLFW_CONTEXT_RELEASE_BEHAVIOR` hint will have no
 effect and the context will always be flushed when released.

 @section compat_wgl WGL extensions

 The WGL API is used to create OpenGL contexts on Microsoft Windows and other
 implementations of the Win32 API, such as Wine.

 GLFW uses either the `WGL_EXT_extension_string` or the
 `WGL_ARB_extension_string` extension to check for the presence of all other WGL
 extensions listed below.  If both are available, the EXT one is preferred.  If
 neither is available, no other extensions are used and many GLFW features
 related to context creation will have no effect or cause errors when used.

 GLFW uses the `WGL_EXT_swap_control` extension to provide vertical retrace
 synchronization (or _vsync_).  Where this extension is unavailable, calling @ref
 glfwSwapInterval will have no effect.

 GLFW uses the `WGL_ARB_pixel_format` and `WGL_ARB_multisample` extensions to
 create contexts with multisampling anti-aliasing.  Where these extensions are
 unavailable, the `GLFW_SAMPLES` hint will have no effect.

 GLFW uses the `WGL_ARB_create_context` extension when available, even when
 creating OpenGL contexts of version 2.1 and below.  Where this extension is
 unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
 hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
 will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
 `GLFW_OPENGL_FORWARD_COMPAT` hints to `GL_TRUE` will cause @ref
 glfwCreateWindow to fail.

 GLFW uses the `WGL_ARB_create_context_profile` extension to provide support for
 context profiles.  Where this extension is unavailable, setting the
 `GLFW_OPENGL_PROFILE` hint to anything but `GLFW_OPENGL_ANY_PROFILE` will cause
 @ref glfwCreateWindow to fail.

 GLFW uses the `WGL_ARB_context_flush_control` extension to provide control over
 whether a context is flushed when it is released (made non-current).  Where this
 extension is unavailable, the `GLFW_CONTEXT_RELEASE_BEHAVIOR` hint will have no
 effect and the context will always be flushed when released.

 @section compat_osx OpenGL 3.2 and later on OS X

 Support for OpenGL 3.2 and above was introduced with OS X 10.7 and even then
 only forward-compatible, core profile contexts are supported.  Support for
 OpenGL 4.1 was introduced with OS X 10.9, also limited to forward-compatible,
 core profile contexts.  There is also still no mechanism for requesting debug
 contexts.  Versions of Mac OS X earlier than 10.7 support at most OpenGL
 version 2.1.

 Because of this, on OS X 10.7 and later, the `GLFW_CONTEXT_VERSION_MAJOR` and
 `GLFW_CONTEXT_VERSION_MINOR` hints will cause @ref glfwCreateWindow to fail if
 given version 3.0 or 3.1, the `GLFW_OPENGL_FORWARD_COMPAT` hint must be set to
 `GL_TRUE` and the `GLFW_OPENGL_PROFILE` hint must be set to
 `GLFW_OPENGL_CORE_PROFILE` when creating OpenGL 3.2 and later contexts and the
 `GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored.

 Also, on Mac OS X 10.6 and below, the `GLFW_CONTEXT_VERSION_MAJOR` and
 `GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 2.1,
 setting the `GLFW_OPENGL_PROFILE` or `GLFW_OPENGL_FORWARD_COMPAT` hints to
 a non-default value will cause @ref glfwCreateWindow to fail and the
 `GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored.

 */
	/*!

	@page compat Standards conformance

	@tableofcontents

	This guide describes the various API extensions used by this version of GLFW.
	It lists what are essentially implementation details, but which are nonetheless
	vital knowledge for developers intending to deploy their applications on a wide
	range of machines.

	The information in this guide is not a part of GLFW API, but merely
	preconditions for some parts of the library to function on a given machine. Any
	part of this information may change in future versions of GLFW and that will not
	be considered a breaking API change.


	@section compat_x11 X11 extensions, protocols and IPC standards

	As GLFW uses Xlib directly, without any intervening toolkit
	library, it has sole responsibility for interacting well with the many and
	varied window managers in use on Unix-like systems. In order for applications
	and window managers to work well together, a number of standards and
	conventions have been developed that regulate behavior outside the scope of the
	X11 API; most importantly the
	[Inter-Client Communication Conventions Manual](http://www.tronche.com/gui/x/icccm/)
	(ICCCM) and
	[Extended Window Manager Hints](http://standards.freedesktop.org/wm-spec/wm-spec-latest.html)
	(EWMH) standards.

	GLFW uses the `_MOTIF_WM_HINTS` window property to support borderless windows.
	If the running window manager does not support this property, the
	`GLFW_DECORATED` hint will have no effect.

	GLFW uses the ICCCM `WM_DELETE_WINDOW` protocol to intercept the user
	attempting to close the GLFW window. If the running window manager does not
	support this protocol, the close callback will never be called.

	GLFW uses the EWMH `_NET_WM_PING` protocol, allowing the window manager notify
	the user when the application has stopped responding, i.e. when it has ceased to
	process events. If the running window manager does not support this protocol,
	the user will not be notified if the application locks up.

	GLFW uses the EWMH `_NET_WM_STATE_FULLSCREEN` window state to tell the window
	manager to make the GLFW window full screen. If the running window manager does
	not support this state, full screen windows may not work properly. GLFW has
	a fallback code path in case this state is unavailable, but every window manager
	behaves slightly differently in this regard.

	GLFW uses the EWMH `_NET_WM_BYPASS_COMPOSITOR` window property to tell a
	compositing window manager to un-redirect full screen GLFW windows. If the
	running window manager uses compositing but does not support this property then
	additional copying may be performed for each buffer swap of full screen windows.

	GLFW uses the
	[clipboard manager protocol](http://www.freedesktop.org/wiki/ClipboardManager/)
	to push a clipboard string (i.e. selection) owned by a GLFW window about to be
	destroyed to the clipboard manager. If there is no running clipboard manager,
	the clipboard string will be unavailable once the window has been destroyed.

	GLFW uses the
	[X drag-and-drop protocol](http://www.freedesktop.org/wiki/Specifications/XDND/)
	to provide file drop events. If the application originating the drag does not
	support this protocol, drag and drop will not work.

	GLFW uses the XInput 2 extension to provide sub-pixel cursor motion events. If
	the running X server does not support this version of this extension, cursor
	motion will be snapped to the pixel grid.

	GLFW uses the XRandR 1.3 extension to provide multi-monitor support. If the
	running X server does not support this version of this extension, multi-monitor
	support will not function and only a single, desktop-spanning monitor will be
	reported.

	GLFW uses the XRandR 1.3 and Xf86vidmode extensions to provide gamma ramp
	support. If the running X server does not support either or both of these
	extensions, gamma ramp support will not function.

	GLFW uses the Xkb extension and detectable auto-repeat to provide keyboard
	input. If the running X server does not support this extension, a non-Xkb
	fallback path is used.


	@section compat_glx GLX extensions

	The GLX API is the default API used to create OpenGL contexts on Unix-like
	systems using the X Window System.

	GLFW uses the GLX 1.3 `GLXFBConfig` functions to enumerate and select framebuffer pixel
	formats. If GLX 1.3 is not supported, @ref glfwInit will fail.

	GLFW uses the `GLX_MESA_swap_control,` `GLX_EXT_swap_control` and
	`GLX_SGI_swap_control` extensions to provide vertical retrace synchronization
	(or _vsync_), in that order of preference. Where none of these extension are
	available, calling @ref glfwSwapInterval will have no effect.

	GLFW uses the `GLX_ARB_multisample` extension to create contexts with
	multisampling anti-aliasing. Where this extension is unavailable, the
	`GLFW_SAMPLES` hint will have no effect.

	GLFW uses the `GLX_ARB_create_context` extension when available, even when
	creating OpenGL contexts of version 2.1 and below. Where this extension is
	unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
	hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
	will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
	`GLFW_OPENGL_FORWARD_COMPAT` hints to `GL_TRUE` will cause @ref
	glfwCreateWindow to fail.

	GLFW uses the `GLX_ARB_create_context_profile` extension to provide support for
	context profiles. Where this extension is unavailable, setting the
	`GLFW_OPENGL_PROFILE` hint to anything but `GLFW_OPENGL_ANY_PROFILE`, or setting
	`GLFW_CLIENT_API` to anything but `GLFW_OPENGL_API` will cause @ref
	glfwCreateWindow to fail.

	GLFW uses the `GLX_ARB_context_flush_control` extension to provide control over
	whether a context is flushed when it is released (made non-current). Where this
	extension is unavailable, the `GLFW_CONTEXT_RELEASE_BEHAVIOR` hint will have no
	effect and the context will always be flushed when released.

	@section compat_wgl WGL extensions

	The WGL API is used to create OpenGL contexts on Microsoft Windows and other
	implementations of the Win32 API, such as Wine.

	GLFW uses either the `WGL_EXT_extension_string` or the
	`WGL_ARB_extension_string` extension to check for the presence of all other WGL
	extensions listed below. If both are available, the EXT one is preferred. If
	neither is available, no other extensions are used and many GLFW features
	related to context creation will have no effect or cause errors when used.

	GLFW uses the `WGL_EXT_swap_control` extension to provide vertical retrace
	synchronization (or _vsync_). Where this extension is unavailable, calling @ref
	glfwSwapInterval will have no effect.

	GLFW uses the `WGL_ARB_pixel_format` and `WGL_ARB_multisample` extensions to
	create contexts with multisampling anti-aliasing. Where these extensions are
	unavailable, the `GLFW_SAMPLES` hint will have no effect.

	GLFW uses the `WGL_ARB_create_context` extension when available, even when
	creating OpenGL contexts of version 2.1 and below. Where this extension is
	unavailable, the `GLFW_CONTEXT_VERSION_MAJOR` and `GLFW_CONTEXT_VERSION_MINOR`
	hints will only be partially supported, the `GLFW_OPENGL_DEBUG_CONTEXT` hint
	will have no effect, and setting the `GLFW_OPENGL_PROFILE` or
	`GLFW_OPENGL_FORWARD_COMPAT` hints to `GL_TRUE` will cause @ref
	glfwCreateWindow to fail.

	GLFW uses the `WGL_ARB_create_context_profile` extension to provide support for
	context profiles. Where this extension is unavailable, setting the
	`GLFW_OPENGL_PROFILE` hint to anything but `GLFW_OPENGL_ANY_PROFILE` will cause
	@ref glfwCreateWindow to fail.

	GLFW uses the `WGL_ARB_context_flush_control` extension to provide control over
	whether a context is flushed when it is released (made non-current). Where this
	extension is unavailable, the `GLFW_CONTEXT_RELEASE_BEHAVIOR` hint will have no
	effect and the context will always be flushed when released.

	@section compat_osx OpenGL 3.2 and later on OS X

	Support for OpenGL 3.2 and above was introduced with OS X 10.7 and even then
	only forward-compatible, core profile contexts are supported. Support for
	OpenGL 4.1 was introduced with OS X 10.9, also limited to forward-compatible,
	core profile contexts. There is also still no mechanism for requesting debug
	contexts. Versions of Mac OS X earlier than 10.7 support at most OpenGL
	version 2.1.

	Because of this, on OS X 10.7 and later, the `GLFW_CONTEXT_VERSION_MAJOR` and
	`GLFW_CONTEXT_VERSION_MINOR` hints will cause @ref glfwCreateWindow to fail if
	given version 3.0 or 3.1, the `GLFW_OPENGL_FORWARD_COMPAT` hint must be set to
	`GL_TRUE` and the `GLFW_OPENGL_PROFILE` hint must be set to
	`GLFW_OPENGL_CORE_PROFILE` when creating OpenGL 3.2 and later contexts and the
	`GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored.

	Also, on Mac OS X 10.6 and below, the `GLFW_CONTEXT_VERSION_MAJOR` and
	`GLFW_CONTEXT_VERSION_MINOR` hints will fail if given a version above 2.1,
	setting the `GLFW_OPENGL_PROFILE` or `GLFW_OPENGL_FORWARD_COMPAT` hints to
	a non-default value will cause @ref glfwCreateWindow to fail and the
	`GLFW_OPENGL_DEBUG_CONTEXT` hint is ignored.

	*/