README - wayland-protocols-imx - Git at Google

 Wayland protocols
 -----------------

 wayland-protocols contains Wayland protocols that add functionality not
 available in the Wayland core protocol. Such protocols either add
 completely new functionality, or extend the functionality of some other
 protocol either in Wayland core, or some other protocol in
 wayland-protocols.

 A protocol in wayland-protocols consists of a directory containing a set
 of XML files containing the protocol specification, and a README file
 containing detailed state and a list of maintainers.

 Protocol directory tree structure
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Protocols may be 'stable', 'unstable' or 'deprecated', and the interface
 and protocol names as well as place in the directory tree will reflect
 this.

 A stable protocol is a protocol which has been declared stable by
 the maintainers. Changes to such protocols will always be backward
 compatible.

 An unstable protocol is a protocol currently under development and this
 will be reflected in the protocol and interface names. See <<Unstable
 naming convention>>.

 A deprecated protocol is a protocol that has either been replaced by some
 other protocol, or declared undesirable for some other reason. No more
 changes will be made to a deprecated protocol.

 Depending on which of the above states the protocol is in, the protocol
 is placed within the toplevel directory containing the protocols with the
 same state. Stable protocols are placed in the +stable/+ directory,
 unstable protocols are placed in the +unstable/+ directory, and
 deprecated protocols are placed in the +deprecated/+ directory.

 Protocol development procedure
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 To propose a new protocol, create a patch adding the relevant files and
 Makefile.am entry to the wayland-protocols git repository with the
 explanation and motivation in the commit message. Then send the patch to
 the wayland-devel@lists.freedesktop.org mailing list using
 'git send-email' with the subject prefix 'RFC wayland-protocols' or
 'PATCH wayland-protocols' depending on what state the protocol is in.

 To propose changes to existing protocols, create a patch with the
 changes and send it to the list mentioned above while also CC:ing the
 maintainers mentioned in the README file. Use the same rule for adding a
 subject prefix as above and method for sending the patch.

 If the changes are backward incompatible changes to an unstable protocol,
 see <<Unstable protocol changes>>.

 Interface naming convention
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 All protocols should avoid using generic namespaces or no namespaces in
 the protocol interface names in order to minimize risk that the generated
 C API collides with other C API. Interface names that may collide with
 interface names from other protocols should also be avoided.

 For generic protocols not limited to certain configurations (such as
 specific desktop environment or operating system) the +wp_+ prefix
 should be used on all interfaces in the protocol.

 For operating system specific protocols, the interfaces should be
 prefixed with both +wp_+ and the operating system, for example
 +wp_linux_+, or +wp_freebsd_+, etc.

 Unstable naming convention
 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 Unstable protocols have a special naming convention in order to make it
 possible to make discoverable backward incompatible changes.

 An unstable protocol has at least two versions: the major version, which
 represents backward incompatible changes, and the minor version, which
 represents backward compatible changes to the interfaces in the protocol.

 The major version is part of the XML file name, the protocol name in the
 XML, and interface names in the protocol.

 Minor versions are the version attributes of the interfaces in the XML.
 There may be more than one minor version per protocol, if there are more
 than one global.

 The XML file and protocol name also has the word 'unstable' in them, and
 all of the interfaces in the protocol are prefixed with +z+ and
 suffixed with the major version number.

 For example, an unstable protocol called foo-bar with major version 2
 containing the two interfaces wp_foo and wp_bar both minor version 1 will
 be placed in the directory +unstable/foo-bar/+ consisting of one file
 called +README+ and one called +foo-bar-unstable-v2.xml+. The XML file
 will consist of two interfaces called +zwp_foo_v2+ and +zwp_bar_v2+ with
 the +version+ attribute set to +1+.

 Unstable protocol changes
 ~~~~~~~~~~~~~~~~~~~~~~~~~
 During the development of a new protocol it is possible that backward
 incompatible changes are needed. Such a change needs to be represented
 in the major and minor versions of the protocol.

 Assuming a backward incompatible change is needed, the procedure for how to
 do so is the following:

   . Make a copy of the XML file with the major version increased by +1+.
   . Increase the major version number in the protocol XML by +1+.
   . Increase the major version number in all of the interfaces in the
     XML by +1+.
   . Reset the minor version number (interface version attribute) of all
     the interfaces to +1+.

 Backward compatible changes within a major unstable version can be done
 in the regular way as done in core Wayland or in stable protocols.

 Declaring a protocol stable
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 Once it is decided that a protocol should be declared stable, meaning no
 more backward incompatible changes will ever be allowed, one last
 breakage is needed.

 The procedure of doing this is the following:

   . Create a new directory in the +stable/+ toplevel directory with the
     same name as the protocol directory in the +unstable/+ directory.
   . Copy the final version of the XML that is the version that was
     decided to be declared stable into the new directory. The target name
     should be the same name as the protocol directory but with the +.xml+
     suffix.
   . Rename the name of the protocol in the XML by removing the
     'unstable' part and the major version number.
   . Remove the +z+ prefix and the major version number suffix from all
     of the interfaces in the protocol.
   . Reset all of the interface version attributes to +1+.
   . Update the +README+ file in the unstable directory and create a new
     +README+ file in the new directory.

 Releases
 ~~~~~~~~
 Each release of wayland-protocols finalizes the version of the protocols
 to their state they had at that time.
	Wayland protocols
	-----------------

	wayland-protocols contains Wayland protocols that add functionality not
	available in the Wayland core protocol. Such protocols either add
	completely new functionality, or extend the functionality of some other
	protocol either in Wayland core, or some other protocol in
	wayland-protocols.

	A protocol in wayland-protocols consists of a directory containing a set
	of XML files containing the protocol specification, and a README file
	containing detailed state and a list of maintainers.

	Protocol directory tree structure
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	Protocols may be 'stable', 'unstable' or 'deprecated', and the interface
	and protocol names as well as place in the directory tree will reflect
	this.

	A stable protocol is a protocol which has been declared stable by
	the maintainers. Changes to such protocols will always be backward
	compatible.

	An unstable protocol is a protocol currently under development and this
	will be reflected in the protocol and interface names. See <<Unstable
	naming convention>>.

	A deprecated protocol is a protocol that has either been replaced by some
	other protocol, or declared undesirable for some other reason. No more
	changes will be made to a deprecated protocol.

	Depending on which of the above states the protocol is in, the protocol
	is placed within the toplevel directory containing the protocols with the
	same state. Stable protocols are placed in the +stable/+ directory,
	unstable protocols are placed in the +unstable/+ directory, and
	deprecated protocols are placed in the +deprecated/+ directory.

	Protocol development procedure
	~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
	To propose a new protocol, create a patch adding the relevant files and
	Makefile.am entry to the wayland-protocols git repository with the
	explanation and motivation in the commit message. Then send the patch to
	the wayland-devel@lists.freedesktop.org mailing list using
	'git send-email' with the subject prefix 'RFC wayland-protocols' or
	'PATCH wayland-protocols' depending on what state the protocol is in.

	To propose changes to existing protocols, create a patch with the
	changes and send it to the list mentioned above while also CC:ing the
	maintainers mentioned in the README file. Use the same rule for adding a
	subject prefix as above and method for sending the patch.

	If the changes are backward incompatible changes to an unstable protocol,
	see <<Unstable protocol changes>>.

	Interface naming convention
	~~~~~~~~~~~~~~~~~~~~~~~~~~~
	All protocols should avoid using generic namespaces or no namespaces in
	the protocol interface names in order to minimize risk that the generated
	C API collides with other C API. Interface names that may collide with
	interface names from other protocols should also be avoided.

	For generic protocols not limited to certain configurations (such as
	specific desktop environment or operating system) the +wp_+ prefix
	should be used on all interfaces in the protocol.

	For operating system specific protocols, the interfaces should be
	prefixed with both +wp_+ and the operating system, for example
	+wp_linux_+, or +wp_freebsd_+, etc.

	Unstable naming convention
	~~~~~~~~~~~~~~~~~~~~~~~~~~
	Unstable protocols have a special naming convention in order to make it
	possible to make discoverable backward incompatible changes.

	An unstable protocol has at least two versions: the major version, which
	represents backward incompatible changes, and the minor version, which
	represents backward compatible changes to the interfaces in the protocol.

	The major version is part of the XML file name, the protocol name in the
	XML, and interface names in the protocol.

	Minor versions are the version attributes of the interfaces in the XML.
	There may be more than one minor version per protocol, if there are more
	than one global.

	The XML file and protocol name also has the word 'unstable' in them, and
	all of the interfaces in the protocol are prefixed with +z+ and
	suffixed with the major version number.

	For example, an unstable protocol called foo-bar with major version 2
	containing the two interfaces wp_foo and wp_bar both minor version 1 will
	be placed in the directory +unstable/foo-bar/+ consisting of one file
	called +README+ and one called +foo-bar-unstable-v2.xml+. The XML file
	will consist of two interfaces called +zwp_foo_v2+ and +zwp_bar_v2+ with
	the +version+ attribute set to +1+.

	Unstable protocol changes
	~~~~~~~~~~~~~~~~~~~~~~~~~
	During the development of a new protocol it is possible that backward
	incompatible changes are needed. Such a change needs to be represented
	in the major and minor versions of the protocol.

	Assuming a backward incompatible change is needed, the procedure for how to
	do so is the following:

	. Make a copy of the XML file with the major version increased by +1+.
	. Increase the major version number in the protocol XML by +1+.
	. Increase the major version number in all of the interfaces in the
	XML by +1+.
	. Reset the minor version number (interface version attribute) of all
	the interfaces to +1+.

	Backward compatible changes within a major unstable version can be done
	in the regular way as done in core Wayland or in stable protocols.

	Declaring a protocol stable
	~~~~~~~~~~~~~~~~~~~~~~~~~~~
	Once it is decided that a protocol should be declared stable, meaning no
	more backward incompatible changes will ever be allowed, one last
	breakage is needed.

	The procedure of doing this is the following:

	. Create a new directory in the +stable/+ toplevel directory with the
	same name as the protocol directory in the +unstable/+ directory.
	. Copy the final version of the XML that is the version that was
	decided to be declared stable into the new directory. The target name
	should be the same name as the protocol directory but with the +.xml+
	suffix.
	. Rename the name of the protocol in the XML by removing the
	'unstable' part and the major version number.
	. Remove the +z+ prefix and the major version number suffix from all
	of the interfaces in the protocol.
	. Reset all of the interface version attributes to +1+.
	. Update the +README+ file in the unstable directory and create a new
	+README+ file in the new directory.

	Releases
	~~~~~~~~
	Each release of wayland-protocols finalizes the version of the protocols
	to their state they had at that time.