path: root/randrproto.txt

	       The X Resize, Rotate and Reflect Extension
			      Version 1.2
			       2006-4-13
      
			      Jim Gettys
			   Jim.Gettys@hp.com
		     Cambridge Research Laboratory
				HP Labs
			Hewlett Packard Company
      
			     Keith Packard
			keith.packard@intel.com
		     Open Source Technology Center
			   Intel Corporation

1. Introduction

The X Resize, Rotate and Reflect Extension, called RandR for short,
brings the ability to resize, rotate and reflect the root window of a
screen. It is based on the X Resize and Rotate Extension as specified
in the Proceedings of the 2001 Usenix Technical Conference [RANDR].

RandR as implemented and integrated into the X server differs in
one substantial fashion from the design discussed in that paper: that
is, RandR 1.0 does not implement the depth switching described in that
document, and the support described for that in the protocol in that
document and in the implementation has been removed from the
protocol described here, as it has been overtaken by events.

These events include:
      ► Modern toolkits (in this case, GTK+ 2.x) have progressed to the point
        of implementing migration between screens of arbitrary depths
      ► The continued advance of Moore's law has made limited amounts of VRAM
        less of an issue, reducing the pressure to implement depth switching
	on laptops or desktop systems
      ► The continued decline of legacy toolkits whose design would have
        required depth switching to support migration
      ► The lack of depth switching implementation experience in the 
        intervening time, due to events beyond our control

Additionally, the requirement to support depth switching might
complicate other re-engineering of the device independent part of the
X server that is currently being contemplated.
	
Rather than further delaying RandR's widespread deployment for a feature
long wanted by the community (resizing of screens, particularly on laptops),
or the deployment of a protocol design that might be flawed due to lack of
implementation experience, we decided to remove depth switching from the
protocol. It may be implemented at a later time if resources and
interests permit as a revision to the protocol described here, which will
remain a stable base for applications. The protocol described here has been
implemented in the main X.org server, and more fully in the hw/kdrive
implementation in the distribution, which fully implements resizing,
rotation and reflection.

1.2 Introduction to version 1.2 of the extension

One of the significant limitations found in version 1.1 of the RandR
protocol was the inability to deal with the Xinerama model where multiple
monitors display portions of a common underlying screen. In this environment,
zero or more video outputs are associated with each CRT controller which
defines both a set of video timings and a 'viewport' within the larger
screen. This viewport is independent of the overall size of the screen, and
may be located anywhere within the screen. 

The effect is to decouple the reported size of the screen from the size
presented by each video output, and to permit multiple outputs to present
information for a single screen.

To extend RandR for this model, we separate out the output, CRTC and screen
configuration information and permit them to be configured separately. For
compatibility with the 1.1 version of the protocol, we make the 1.1 requests
simultaneously affect both the screen and the (presumably sole) CRTC and
output. The set of available outputs are presented with UTF-8 encoded names
and may be connected to CRTCs as permitted by the underlying hardware. CRTC
configuration is now done with full mode information instead of just size
and refresh rate, and these modes have names. These names also use UTF-8
encoding. New modes may also be added by the user.

Additional requests and events are provided for this new functionality.

       ┌────────────────────────────────┬──────────┐
    ┏━━━━━━━┳───────────────┐       ╔════════╗ ╔════════╗
    ┃   1   ┃               │       ║   A    ║ ║   B    ║
    ┃   ┏━━━╋━━━━━━━━━━━━━━━┫       ║        ║ ║        ║
    ┣━━━╋━━━┛               ┃       ╚════════╝ ╚════════╝
    │   ┃         2         ┃─────────────────┐
    │   ┃                   ┃        ╔═══════════════════╗ 
    │   ┃                   ┃        ║                   ║
    │   ┗━━━━━━━━━━━━━━━━━━━┫        ║        C          ║
    └───────────────────────┘        ║                   ║
    ┌──────┐  ┏━━━━┓  ╔══════╗       ║                   ║
    │screen│  ┃CRTC┃  ║output║       ╚═══════════════════╝
    └──────┘  ┗━━━━┛  ╚══════╝

In this picture, the screen is covered (incompletely) by two CRTCs. CRTC1
is connected to two outputs, A and B. CRTC2 is connected to output C.
Outputs A and B will present exactly the same region of the screen using
the same mode line. Output C will present a different (larger) region of
the screen using a different mode line.

RandR provides information about each available CRTC and output; the
connection between CRTC and output is under application control, although
the hardware will probably impose restrictions on the possible
configurations. The protocol doesn't try to describe these restrictions,
instead it provides a mechanism to find out what combinations are supported.

For instance, dual-link DVI gangs two CRTC outputs together to provide higher
bandwidth for large resolution screens. This is exposed in RandR by
requiring that nothing be connected to the second CRTC when driving a high
resolution screen on the first.

1.1 Acknowledgements

Our thanks to the contributors to the design found on the xpert mailing
list, in particular:

Alan Hourihane for work on the early implementation
Andrew C. Aitchison for help with the XFree86 DDX implementation
Andy Ritger for early questions about how mergefb/Xinerama work with RandR
Carl Worth for editing the specification and Usenix paper
David Dawes for XFree86 DDX integration work
Thomas Winischhofer for the hardware-accelerated SiS rotation implementation
Matthew Tippet and Kevin Martin for splitting outputs and CRTCs to more
fully expose what video hardware can do

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2. Screen change model

Screens may change dynamically, either under control of this extension, or
due to external events. Examples include: monitors being swapped, pressing a
button to switch from internal display to an external monitor on a laptop,
or, eventually, the hotplug of a display card entirely on busses such as
Cardbus or Express Card which permit hot-swap (which will require other work
in addition to this extension).

Since the screen configuration is dynamic and asynchronous to the client and
may change at any time RandR provides mechanisms to ensure that your clients
view is up to date with the configuration possibilities of the moment and
enforces applications that wish to control the configuration to prove that
their information is up to date before honoring requests to change the
screen configuration (by requiring a timestamp on the request).

Interested applications are notified whenever the screen configuration
changes, providing the current size of the screen and subpixel order (see
the Render extension [RENDER]), to enable proper rendering of subpixel
decimated client text to continue, along with a time stamp of the
configuration change. A client must refresh its knowledge of the screen
configuration before attempting to change the configuration after a
notification, or the request will fail.

To avoid multiplicative explosion between orientation, reflection and sizes,
the sizes are only those sizes in the normal (0) rotation.

Rotation and reflection and how they interact can be confusing. In Randr,
the coordinate system is rotated in a counter-clockwise direction relative
to the normal orientation. Reflection is along the window system coordinate
system, not the physical screen X and Y axis, so that rotation and
reflection do not interact. The other way to consider reflection is to is
specified in the "normal" orientation, before rotation, if you find the
other way confusing.

We expect that most clients and toolkits will be oblivious to changes to the
screen structure, as they generally use the values in the connections Display
structure directly. By toolkits updating the values on the fly, we believe
pop-up menus and other pop up windows will position themselves correctly in
the face of screen configuration changes (the issue is ensuring that pop-ups
are visible on the reconfigured screen).

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3. Data Types

The subpixel order is shared with the Render extension, and is documented
there. The only datatype defined is the screen size, defined in the normal
(0 degree) orientation.

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4. Errors

Errors are sent using core X error reports.

Output
	A value for an OUTPUT argument does not name a defined OUTPUT.
CRTC
	A value for a CRTC argument does not name a defined CRTC.
Mode
	A value for a MODE argument does not name a defined MODE.

                              ❧❧❧❧❧❧❧❧❧❧❧

5. Protocol Types

RRCONFIGSTATUS { Success
		 InvalidConfigTime
		 InvalidTime
		 Failed }

	A value of type RRCONFIGSTATUS returned when manipulating the output
	configuration or querying information from the server that has some
	time-dependency.
	
	InvalidConfigTime indicates that the supplied configuration
	timestamp does not match the current X server configuration
	timestamp. Usually this means that the output configuration has
	changed since the timestamp was received by the application.

	InvalidTime indicates that the supplied output reconfiguration time
	is earlier than the most recent output reconfiguration request.
	Generally this indicates that another application has reconfigured
	the output using a later timestamp.

	Failed is returned whenever the operation is unsuccessful for some
	other reason. This generally indicates that the requested output
	configuration is unsupported by the hardware. The goal is to make
	these limitations expressed by the protocol, but when that isn't
	possible it is correct to return this error value. If, as a
	implentor, you find this error code required, please submit the
	hardware constraints that exist so that a future version of the
	extension can correctly capture the configuration constraints in
	your system.

ROTATION { Rotate_0
	   Rotate_90
	   Rotate_180
	   Rotate_270
	   Reflect_X
	   Reflect_Y }

	These values are used both to indicate a set of allowed rotations
	and reflections as well as to indicate a specific rotation and
	reflection combination.

RRSELECTMASK { RRScreenChangeNotifyMask
	       RRCrtcChangeNotifyMask (New in version 1.2)
	       RROutputChangeNotifyMask (New in version 1.2) 
	       RROutputPropertyNotifyMask (New in version 1.2) }

SIZEID { CARD16 }

MODE { XID or None }

RRMODEORIGIN { RRModeOriginPreferred,
	       RRModeOriginDetailed,
	       RRModeOriginVESA,
	       RRModeOriginConfig,
	       RRModeOriginUser,
	       RRModeOriginOther }

	These values are used to indicate to the application the origin
	of each mode.

	Preferred modes come from the monitor as the preferred mode for
	this monitor; generally these are used for fixed-pixel flat panels
	to indicate the native resolution of the panel.

	Detailed modes also come from the monitor as additional modes that
	may not follow the VESA specification.

	VESA modes are either standard modes from the VESA spec or modes
	generated from the GTF using the monitor specifications.

	Config modes are those provided as a part of the X server
	configuration.

	User modes are those defined through the RandR protocol during X
	server operation.

	Other modes covers modes that come from any other source; space
	aliens, tarot cards, whatever.

CRTC { XID }

OUTPUT { XID }

CONNECTION { Connected, Disconnected, UnknownConnection }

	This value provides an indication of whether an output is actually
	connected to a monitor or other presentation device.

SUBPIXELORDER { SubPixelUnknown		The subpixel order uses the Render
	        SubPixelHorizontalRGB	extensions definitions; they are here
	        SubPixelHorizontalBGR	only for convenience.
	        SubPixelVerticalRGB
	        SubPixelVerticalBGR
	        SubPixelNone }

SCREENSIZE { widthInPixels, heightInPixels: CARD16
	     widthInMillimeters, heightInMillimeters: CARD16 }

MODEFLAG { HSyncPositive
	   HSyncNegative
	   VSyncPositive
	   VSyncNegative
	   Interlace
	   DoubleScan
	   CSync
	   CSyncPositive
	   CSyncNegative
	   HSkewPresent
	   BCast
	   PixelMultiplex
	   DoubleClock
	   ClockDivideBy2 }

OUTPUTOPTION { RROutputOptionScaleNone,
	       RROutputOptionScaleMaxAspect,
	       RROutputOptionScaleMax }

	These options select paramaters of the output which are independent
	of the output mode.
	
	The scale options are used for fixed panels and select between
	different scaling options for non-native resolutions.
	
MODEINFO { id: MODE
	   name: STRING
           widthInPixels, heightInPixels: CARD16
           widthInMillimeters, heightInMillimeters: CARD32
           dotClock: CARD32
           hSyncStart, hSyncEnd, hTotal, hSkew: CARD16
           vSyncStart, vSyncEnd, vTotal: CARD16
           modeFlags: SETofMODEFLAG
	   modeOrigin: MODEORIGIN }

OUTPUTCONFIG { output: OUTPUT
	       options: SETofOUTPUTOPTION }

REFRESH { rates: LISTofCARD16 }

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6. Extension Initialization

The name of this extension is "RANDR".

┌───
    RRQueryVersion
	client-major-version:	CARD32
	client-minor-version:	CARD32
      ▶
	major-version:		CARD32
	minor-version:		CARD32
└───

	The client sends the highest supported version to the server
	and the server sends the highest version it supports, but no
	higher than the requested version. Major versions changes can
	introduce incompatibilities in existing functionality, minor
	version changes introduce only backward compatible changes.
	It is the clients responsibility to ensure that the server
	supports a version which is compatible with its expectations.

                              ❧❧❧❧❧❧❧❧❧❧❧

7. Extension Requests

┌───
    RRSelectInput
	window: WINDOW
	enable: SETofRRSELECTMASK
└───
	Errors: Window, Value

	If 'enable' is RRScreenChangeNotifyMask, RRScreenChangeNotify events
	will be sent when the screen configuration changes, either from
	this protocol extension, or due to detected external screen
	configuration changes. RRScreenChangeNotify may also be sent when
	this request executes if the screen configuration has changed since
	the client connected, to avoid race conditions.

	New for version 1.2:
	
	If 'enable' contains RRCrtcChangeMask, RRCrtcChangeNotify events
	will be sent when a the configuration for a CRTC associated with the
	screen changes, either through this protocol extension or due to
	detected external changes. RRCrtcChangeNotify may also be sent when
	this request executes if the CRTC configuration has changed since
	the client connected, to avoid race conditions. 
	
	If 'enable' contains RROutputChangeMask, RROutputChangeNotify events
	will be sent when a the configuration for an output associated with
	the screen changes, either through this protocol extension or due to
	detected external changes. RROutputChangeNotify may also be sent
	when this request executes if the output configuration has changed
	since the client connected, to avoid race conditions. 

	If 'enable' contains RROutputPropertyNotifyMask,
	RROutputPropertyNotify events will be sent when properties change on
	this output.
	
┌───
    RRSetScreenConfig
	window: WINDOW
	timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	size-id: SIZEID
	rotation: ROTATION
	rate: CARD16
      ▶
	status: RRCONFIGSTATUS
	new-timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	root: WINDOW
	subpixelOrder: SUBPIXELORDER
└───
	Errors: Value, Match

	If 'timestamp' is less than the time when the configuration was last
	successfully set, the request is ignored and InvalidTime returned in
	status.
	
	If 'config-timestamp' is not equal to when the server's screen
	configurations last changed, the request is ignored and
	InvalidConfigTime returned in status. This could occur if the
	screen changed since you last made a RRGetScreenInfo request,
	perhaps by a different piece of display hardware being installed.
	Rather than allowing an incorrect call to be executed based on stale
	data, the server will ignore the request.

	'rate' contains the desired refresh rate. If it is zero, the server
	selects an appropriate rate.

	This request may fail for other indeterminate reasons, in which case
	'status' will be set to Failed and no configuration change will be
	made.
	
	This request sets the screen to the specified size, rate, rotation
	and reflection.

	When this request succeeds, 'status' contains Success and the
	requested changes to configuration will have been made.
	
	'new-time-stamp' contains the time at which this request was
	executed.
	
	'config-timestamp' contains the time when the possible screen
	configurations were last changed.
	
	'root' contains the root window for the screen indicated by the
	window.

	'subpixelOrder' contains the resulting subpixel order of the screen
	to allow correct subpixel rendering.

	Value errors are generated when 'rotation', 'rate' or 'size-id'
	are invalid.

┌───
    RRGetScreenInfo
	window: WINDOW
      ▶	
	rotations: SETofROTATION
	root: WINDOW
	timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	size-id: SIZEID
	rotation: ROTATION
	rate: CARD16
	sizes: LISTofSCREENSIZE
	refresh: LISTofREFRESH
└───

	Errors: Window

	RRGetScreenInfo returns information about the current and available
	configurations for the screen associated with 'window'.

	'rotations' contains the set of rotations and reflections supported
	by the screen.

	'root' is the root window of the screen.
	
	'config-timestamp' indicates when the screen configuration
	information last changed: requests to set the screen will fail
	unless the timestamp indicates that the information the client
	is using is up to date, to ensure clients can be well behaved
	in the face of race conditions. 
	
	'timestamp' indicates when the configuration was last set.
	
	'size-id' indicates which size is active.

	'rate' is the current refresh rate. This is zero when the refresh
	rate is unknown or on devices for which refresh is not relevant.

	'sizes' is the list of possible frame buffer sizes (at the normal
	orientation. Each size indicates both the linear physical size of
	the screen and the pixel size.

	'refresh' is the list of refresh rates for each size. Each element
	of 'sizes' has a corresponding element in 'refresh'. An empty list
	indicates no known rates, or a device for which refresh is not
	relevant.

	The default size of the screen (the size that would become the
	current size when the server resets) is the first size in the
	list.

7.1. Extension Requests added in version 1.2 of the extension

As introduced above, version 1.2 of the extension splits the screen size
from the crtc and output configuration, permitting the subset of the screen
presented by multiple outputs to be configured. As a separate notion, the
size of the screen itself may be arbitrarily configured within a defined
range. As crtcs and outputs are added and removed from the system, the set
returned by the extension will change so that applications can detect
dynamic changes in the display environment.

┌───
    RRGetScreenSizeRange
	window: WINDOW
      ▶
	CARD16	minWidth, minHeight
	CARD16	maxWidth, maxHeight
└───
	Errors: Window

	Returns the range of possible screen sizes. The screen may be set to
	any size within this range.

┌───
    RRSetScreenSize
	window: WINDOW
	width: CARD16
	height: CARD16
	width-in-millimeters: CARD32
	height-in-millimeters: CARD32
└───
	Errors: Window, Match, Value

	Sets the screen to the specified size. 'width' and 'height' must be
	within the range allowed by GetScreenSizeRanges, otherwise a Value
	error results. All active monitors must be configured to display a
	subset of the specified size, else a Match error results.

	'width-in-millimeters' and 'height-in-millimeters' can be set to
	reflect the physical size of the screen reported both through this
	extension and the core protocol. They must be non-zero, or Value
	error results.

┌───
    RRGetScreenResources
	window: WINDOW
      ▶
	timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	crtcs: LISTofCRTC
	outputs: LISTofOUTPUT
	modes: LISTofMODEINFO
└───
	Errors: Window

	RRGetScreenResources returns the list of outputs and crtcs connected
	to the screen associated with 'window'.

	'timestamp' indicates when the configuration was last set.
	
	'config-timestamp' indicates when the configuration information last
	changed. Requests to configure the output will fail unless the
	timestamp indicates that the information the client is using is up
	to date, to ensure clients can be well behaved in the face of race
	conditions.

	'crtcs' contains the list of CRTCs associated with the screen.

	'outputs' contains the list of outputs associated with the screen.

	'modes' contains the list of modes associated with the screen
	
	This request explicitly asks the server to ensure that the
	configuration data is up-to-date wrt the hardware. If that requires
	polling, this is when such polling would take place. Requests for
	further information should not poll, but rather return the data
	collected at this point.
	
┌───
    RRGetOutputInfo
	output: OUTPUT
	config-timestamp: TIMESTAMP
      ▶
	status: RRCONFIGSTATUS
	timestamp: TIMESTAMP
	crtc: CRTC
	options: SETofOUTPUTOPTION
	
	name: STRING
	connection: CONNECTION
	subpixel-order: SUBPIXELORDER
	possible-options: SETofOUTPUTOPTION
	crtcs: LISTofCRTC
	clones: LISTofOUTPUT
	modes: LISTofMODE
└───
	Errors: Output

	RRGetOutputInfo returns information about the current and available
	configurations 'output'. 
	
	If 'config-timestamp' does not match the current configuration
	timestamp (as returned by RRGetScreenResources), 'status' is set to
	InvalidConfigTime and the remaining reply data is empty. Otherwise,
	'status' is set to Success.

	'timestamp' indicates when the configuration was last set.
	
	'crtc' is the current source CRTC for video data, or Disabled if the
	output is not connected to any CRTC.

	'options' is the currently enabled set of options.
	
	'name' is a UTF-8 encoded string designed to be presented to the
	user to indicate which output this is. E.g. "S-Video" or "DVI".

	'connection' indicates whether the hardware was able to detect a
	device connected to this output. If the hardware cannot determine
	whether something is connected, it will set this to
	UnknownConnection.
	
	'subpixel-order' contains the resulting subpixel order of the
	connected device to allow correct subpixel rendering.

	'possible-options' indicate which options are supported by this
	output device.
	
	'crtcs' is the list of CRTCs that this output may be connected to.
	Attempting to connect this output to a different CRTC results in a
	Match error.

	'clones' is the list of outputs which may be simultaneously
	connected to the same CRTC along with this output. Attempting to
	connect this output with an output not in the 'clones' list
	results in a Match error.

	'modes' is the list of modes supported by this output. Attempting to
	connect this output to a CRTC not using one of these modes results
	in a Match error.

┌───
    RRListOutputProperties
    	output:OUTPUT
      ▶
      	atoms: LISTof ATOM
└───
	Errors: Output

	This request returns the atoms of properties currently defined on
	the output.

┌───
    RRChangeOutputProperty
    	output: OUTPUT
	property, type: ATOM
	format: {8, 16, 32}
	mode: { Replace, Prepend, Append }
	data: LISTofINT8 or LISTofINT16 or LISTofINT32
└───
	Errors: Alloc, Atom, Match, Value, Output
	
	This request alters the property for the specified output.  The type
	is uninterpreted by the server.  The format specifies whether the
	data should be viewed as a list of 8-bit, 16-bit, or 32-bit
	quantities so that the server can correctly byte-swap as necessary.

	If the mode is Replace, the previous property value is discarded.
	If the mode is Prepend or Append, then the type and format must
	match the existing property value (or a Match error results).  If
	the property is undefined, it is treated as defined with the correct
	type and format with zero-length data.
	
	For Prepend, the data is tacked on to the beginning of the existing
	data, and for Append, it is tacked on to the end of the existing data.

	This request generates a OutputPropertyNotify

	The lifetime of a property is not tied to the storing client.
	Properties remain until explicitly deleted, until the output is
	destroyed, or until server reset (see section 10).

	The maximum size of a property is server-dependent and may vary
	dynamically.  

┌───
    RRDeleteOutputProperty
    	output: OUTPUT
	property: ATOM
└───
	Errors: Atom, Output
	
	This request deletes the property from the specified window if the
	property exists and generates a OutputPropertyNotify event unless
	the property does not exist.

┌───
    RRGetOutputProperty
    	output: OUTPUT
	property: ATOM
	type: ATOM or AnyPropertyType
	long-offset, long-length: CARD32
	delete: BOOL
      ▶
	type: ATOM or None
	format: {0, 8, 16, 32}
	bytes-after: CARD32
	value: LISTofINT8 or LISTofINT16 or LISTofINT32
└───
	Errors: Atom, Value, Output

	If the specified property does not exist for the specified output,
	then the return type is None, the format and bytes-after are zero,
	and the value is empty.  The delete argument is ignored in this
	case.  
	
	If the specified property exists but its type does not match the
	specified type, then the return type is the actual type of the
	property, the format is the actual format of the property (never
	zero), the bytes-after is the length of the property in bytes (even
	if the format is 16 or 32), and the value is empty.  The delete
	argument is ignored in this case.  
	
	If the specified property exists and either AnyPropertyType is
	specified or the specified type matches the actual type of the
	property, then the return type is the actual type of the property,
	the format is the actual format of the property (never zero), and
	the bytes-after and value are as follows, given:

		N = actual length of the stored property in bytes 
				  (even if the format is 16 or 32)
		I = 4 × offset
		T = N - I
		L = MINIMUM(T, 4 × long-length)
		A = N - (I + L)
	
	The returned value starts at byte index I in the property (indexing
	from 0), and its length in bytes is L.  However, it is a Value error
	if long-offset is given such that L is negative.  The value of
	bytes-after is A, giving the number of trailing unread bytes in the
	stored property.  If delete is True and the bytes-after is zero, the
	property is also deleted from the output, and a
	RROutputPropertyNotify event is generated.

┌───
    RRCreateMode
    	window: WINDOW
	modeinfo: MODEINFO
      ▶
      	mode: MODE
└───
	Errors: Window, Name, Value
	
	'modeinfo' provides a new mode for outputs on the screen
	associated with 'window'. If the name of 'modeinfo' names an
	existing mode, a Name error is returned.  If some parameter of the
	mode is not valid in some other way, a Value error is returned.

	The returned 'mode' provides the id for the mode.
	
┌───
    RRDestroyMode
      	mode: MODE
└───
	Errors: Mode, Access

	The user-defined 'mode' is destroyed. 'mode' must name a mode
	defined with RRCreateMode, else an Match error is returned.  If
	'mode' is in use by some CRTC or Output, then an Access error is
	returned.
	
┌───
    RRAddOutputMode
	output: OUTPUT
	mode: MODE
└───
	Errors: Output, Mode, Match

	'output' indicates which output is to be configured.

	'mode' specifies which mode to add. If 'mode' is not valid for
	'output', then a Match error is generated. 

	This request generates OutputChangeNotify events.
	
┌───
    RRDeleteOutputMode
	output: OUTPUT
	mode: MODE
└───
	Errors: Output, Mode

	'output' indicates which output is to be configured.

	'mode' specifies which mode to delete. 'mode' must have been added
	with RRAddOutputMode, else an Access error is returned. 'mode' must
	not be active, else a Match error is returned.

	This request generates OutputChangeNotify events.

┌───
    RRGetCrtcInfo
	crtc: CRTC
	config-timestamp: TIMESTAMP
      ▶
	status: RRCONFIGSTATUS
	timestamp: TIMESTAMP
	x, y: INT16
	width, height: CARD16
	mode: MODE
	rotation: ROTATION
	outputs: LISTofOUTPUT
	
	rotations: SETofROTATION
	possible-outputs: LISTofOUTPUT
└───

	Errors: Window

	RRGetCrtcModes returns information about the current and available
	configurations for the specified crtc connected to the screen
	associated with 'window'.

	If 'config-timestamp' does not match the current configuration
	timestamp (as returned by RRGetScreenResources), 'status' is set to
	InvalidConfigTime and the remaining reply data is empty. Otherwise,
	'status' is set to Success.
	
	'timestamp' indicates when the configuration was last set.
	
	'x' and 'y' indicate the position of this CRTC within the screen
	region. They will be set to 0 when the CRTC is disabled.

	'width' and 'height' indicate the size of the area presented by this
	CRTC.
	
	'mode' indicates which mode is active, or None indicating that the
	CRTC has been disabled and is not displaying the screen contents.

	'rotation' indicates the active rotation. It is set to Rotate_0
	when the CRTC is disabled.
	
	'outputs' is the list of outputs currently connected to this CRTC
	and is empty when the CRTC is disabled.

	'rotations' contains the set of rotations and reflections supported
	by the CRTC.

	'possible-outputs' lists all of the outputs which may be connected
	to this CRTC.

┌───
    RRSetCrtcConfig
	crtc: CRTC
	timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	x, y: INT16
	mode: MODE
	rotation: ROTATION
	outputs: LISTofOUTPUT
      ▶
	status: RRCONFIGSTATUS
	new-timestamp: TIMESTAMP
└───
	Errors: Value, Match

	If 'timestamp' is less than the time when the configuration was last
	successfully set, the request is ignored and InvalidTime returned in
	status.
	
	If 'config-timestamp' is not equal to when the monitor's
	configuration last changed, the request is ignored and
	InvalidConfigTime returned in status. This could occur if the
	monitor changed since you last made a RRGetScreenInfo request,
	perhaps by a different monitor being connected to the machine.
	Rather than allowing an incorrect call to be executed based on stale
	data, the server will ignore the request.

	'x' and 'y' contain the desired location within the screen for this
	monitor's content. 'x' and 'y' must be within the screen size, else
	a Value error results.

	'mode' is either the desired mode or None indicating the CRTC should
	be disabled. If 'mode' is not one of these values, a Value
	error results. 'mode' must be valid for all of the configured outputs,
	else a Match error.

	'rotation' contains the desired rotation along with which
	reflections should be enabled. The rotation and reflection values
	must be among those allowed for this monitor, else a Value error
	results.

	'outputs' contains the set of outputs that this CRTC should be
	connected to. The set must be among the list of acceptable output
	sets for this CRTC or a Match error results. 
	
	If 'mode' is None, then 'outputs' must be empty, else a Match error
	results. Conversely, if 'mode' is not None, then 'outputs' must not be
	empty, else a Match error results.
	
	This request may fail for other indeterminate reasons, in which case
	'status' will be set to Failed and no configuration change will be
	made.
	
	This request sets the CRTC to the specified position, mode, rotation
	and reflection. The entire area of the CRTC must fit within the
	screen size, else a Match error results. As an example, rotating the
	screen so that a single CRTC fills the entire screen before and
	after may necessitate disabling the CRTC, resizing the screen,
	then re-enabling the CRTC at the new configuration to avoid an
	invalid intermediate configuration.

	When this request succeeds, 'status' contains Success and the
	requested changes to configuration will have been made.
	
	'new-time-stamp' contains the time at which this request was
	executed.
	
┌───
    RRGetCrtcGammaSize
	crtc: CRTC
      ▶
	size: CARD16
└───
	Errors: Crtc

	This request returns the size of the gamma ramps used by 'crtc'.

┌───
    RRGetCrtcGamma
	crtc: CRTC
      ▶
      	red: LISTofCARD16
	green: LISTofCARD16
	blue: LISTofCARD16
└─── 
	Errors: Crtc
	
	This request returns the currently set gamma ramps for 'crtc'.  All
	three lists will be the size returned by the RRGetCrtcGammaSize
	request.
	
┌───
    RRSetCrtcGamma
	crtc: CRTC
	red: LISTofCARD16
	green: LISTofCARD16
	blue: LISTofCARD16
└───
	Errors: Crtc, Match
	
	This request sets the gamma ramps for 'crtc'. All three lists
	must be the size returned by RRGetCrtcGammaSize else a Value error
	results.

                              ❧❧❧❧❧❧❧❧❧❧❧

8. Extension Events

Clients MAY select for ConfigureNotify on the root window to be
informed of screen changes. This may be advantageous if all your
clients need to know is the size of the root window, as it avoids
round trips to set up the extension.

RRScreenChangeNotify is sent if RRSelectInput has requested it
whenever properties of the screen change, which may be due to external
factors, such as re-cabling a monitor, etc.

┌───
    RRScreenChangeNotify

	rotation: ROTATION;		new rotation
	sequenceNumber: CARD16		low 16 bits of request seq. number
	timestamp: TIMESTAMP		time screen was changed
	configTimestamp: TIMESTAMP	time config data was changed
	root: WINDOW			root window of screen
	window: WINDOW			window requesting notification
	size-id: SIZEID			index of new size
	subpixelOrder: SUBPIXELORDER	order of subpixels
	widthInPixels: CARD16
	heightInPixels: CARD16
	widthInMillimeters: CARD16
	heightInMillimeters: CARD16
└───
	This event is generated whenever the screen configuration is changed
	and sent to requesting clients. 'timestamp' indicates when the
	screen configuration was changed. 'configTimestamp' says when the
	last time the configuration was changed. 'root' is the root of the
	screen the change occurred on, 'window' is window selecting for this
	event. 'size-id' contains the index of the current size.

	This event is sent whenever the screen's configuration changes
	or if a new screen configuration becomes available that was
	not available in the past. In this case (config-timestamp in
	the event not being equal to the config-timestamp returned in
	the last call to RRGetScreenInfo), the client MUST call
	RRGetScreenInfo to update its view of possible screen
	configurations to have a correct view of possible screen
	organizations.

	Clients which select screen change notification events may be
	sent an event immediately if the screen configuration was
	changed between when they connected to the X server and
	selected for notification. This is to prevent a common race
	that might occur on log-in, where many applications start up
	just at the time when a display manager or log in script might
	be changing the screen size or configuration.

8.1 Events added in version 1.2 of the RandR extension

┌───
    RROutputChangeNotify:
	timestamp: TIMESTAMP		time screen was reconfigured
	config-timestamp: TIMESTAMP	time available config data was changed
	window: WINDOW			window requesting notification
	output: OUTPUT			output affected by change
	crtc: CRTC			connected CRTC or None
	mode: MODE			mode in use on CRTC or None
	connection: CONNECTION		connection status
└───

	This event is generated whenever the available output configurations
	have changed and is sent to requesting clients. 'timestamp'
	indicates when the crtc configuration was changed by a client.
	'config-timestamp' says when the last time the available
	configurations changed. 'root' is the root of the screen the change
	occurred on, 'window' is window selecting for this event. The
	precise change can be detected by examining the new state of the
	system.

┌───
    RROutputPropertyNotify:
	window: WINDOW			window requesting notification
	output: OUTPUT			output affected by change
	atom: ATOM			affected property
	time: TIMESTAMP			time property was changed
	subpixel-order: SUBPIXELORDER	order of subpixels
	state: { NewValue, Deleted }	new property state
└───

	This event is reported to clients selecting RROutputPropertyChange
	on the window and is generated with state NewValue when a property
	of the window is changed using RRChangeOutputProperty even when
	adding zero-length data and when replacing all or part of a property
	with identical data.  It is generated with state Deleted when a
	property of the window is deleted using either
	RRDeleteOutputProperty or RRGetOutputProperty.  The timestamp
	indicates the server time when the property was changed.

┌───
    RRCrtcChangeNotify
	timestamp: TIMESTAMP		time monitor was changed
	config-timestamp: TIMESTAMP	time config data was changed
	root: WINDOW			root window of screen
	window: WINDOW			window requesting notification
	crtc: CRTC			CRTC which changed
	mode: MODE			new mode
	rotation: ROTATION;		new rotation
	x: INT16			x position of CRTC within screen
	y: INT16			y position of CRTC within screen
└───
	This event is generated whenever the CRTC configuration is changed
	and sent to requesting clients. 'timestamp' indicates when the
	CRTC configuration was changed. 'config-timestamp' says when the
	last time the configuration was changed. 'root' is the root of the
	screen the change occurred on, 'window' is window selecting for this
	event.

	This event is sent whenever the monitor's configuration changes
	or if a new monitor configuration becomes available that was
	not available in the past. In this case (config-timestamp in
	the event not being equal to the config-timestamp returned in
	the last call to RRGetCrtcModes), the client MUST call
	RRGetCrtcModes to update its view of possible monitor
	configurations to have a correct view of possible monitor
	organizations.

	Clients which select monitor change notification events may be
	sent an event immediately if the monitor configuration was
	changed between when they connected to the X server and
	selected for notification. This is to prevent a common race
	that might occur on log-in, where many applications start up
	just at the time when a display manager or log in script might
	be changing the monitor size or configuration.

                              ❧❧❧❧❧❧❧❧❧❧❧

9. Extension Versioning

The RandR extension was developed in parallel with the implementation
to ensure the feasibility of various portions of the design. As
portions of the extension are implemented, the version number of the
extension has changed to reflect the portions of the standard provided.
This document describes the version 1.2 of the specification, the
partial implementations have version numbers less than that. Here's a
list of what each version provided:

	0.0: This prototype implemented resize and rotation in the
	     TinyX server Used approximately the protocol described in
	     the Usenix paper. Appeared in the TinyX server in
	     XFree86 4.2, but not in the XFree86 main server.

	0.1: Added subpixel order, added an event for subpixel order.
	     This version was never checked in to XFree86 CVS.

	1.0: Implements resize, rotation, and reflection. Implemented
	     both in the XFree86 main server (size change only at this
	     date), and fully (size change, rotation, and reflection)
	     in XFree86's TinyX server.

	1.1: Added refresh rates

	1.2: Separate screens from CRTCs and outputs, switch to full VESA
	     modes

Compatibility between 0.0 and 1.0 was *NOT* preserved, and 0.0 clients
will fail against 1.0 servers. The wire encoding op-codes were
changed for GetScreenInfo to ensure this failure in a relatively
graceful way. Version 1.1 servers and clients are cross compatible with
1.0. Version 1.1 is considered to be stable and we intend upward
compatibility from this point. Version 1.2 offers an extended model of the
system with multiple output support. It offers backward compatibility with
version 1.1.

                              ❧❧❧❧❧❧❧❧❧❧❧

10. Relationship with other extensions

Two other extensions have a direct relationship with this extension. This
section attempts to explain how these three are supposed to work together.

10.1 XFree86-VidModeExtension

XFree86-VidModeExtension changes the configuration of a single monitor
attached to the screen without changing the configuration of the screen
itself. It provides the ability to specify new mode lines for the server to
use along with selecting among existing mode lines. As it uses screen
numbers instead of window identifiers, it can be used to affect multiple
monitors in a single-screen Xinerama configuration. However, the association
between screen numbers and root windows in a multi-Screen environment is not
defined by the extension. Version 2.0 of this extension added the ability to
adjust the DAC values in a TrueColor server to modify the brightness curves
of the display.

All of the utility of this extension is subsumed by RandR version 1.2, RandR
should be used in preference to XFree86-VidModeExtension where both are
present.

10.2 Xinerama

Xinerama provides a mechanism for describing the relationship between the
overall screen display and monitors placed within that area. As such, it
provides the query functionality of RandR 1.2 without any of the
configuration functionality. Applications using Xinerama to discover
monitor geometry can continue to do so, with the caveat that they will not be
informed of changes when they occur. However, Xinerama configuration data
will be updated, so applications selecting for RandR notification and
re-querying the configuration with the Xinerama extension will get updated
information. It is probably better to view RandR as a superset of Xinerama
at this point and use it in preference to Xinerama where both are present.

                              ❧❧❧❧❧❧❧❧❧❧❧

Appendix A. Protocol Encoding

Syntactic Conventions

This document uses the same syntactic conventions as the core X
protocol encoding document.

A.1 Common Types

┌───
    ROTATION
	0x0001	Rotate_0
	0x0002	Rotate_90
	0x0004	Rotate_180
	0x0008	Rotate_270
	0x0010	Reflect_X
	0x0020	Reflect_Y
└───
	Used to encode both sets of possible rotations and individual
	selected rotations.

┌───
    RRSELECTMASK
	0x0001	ScreenChangeNotifyMask
	0x0002	CrtcChangeNotifyMask		Added in version 1.2
	0x0004	OutputChangeNotifyMask		Added in version 1.2
	0x0008	OutputPropertyNotifyMask	Added in version 1.2
└───
      Event select mask for RRSelectInput
      
┌───
    RRCONFIGSTATUS
	0x0 Success
	0x1 InvalidConfigTime
	0x2 InvalidTime
	0x3 Failed
└───
	Return status for requests which depend on time.
	
┌───
    RRMODEORIGIN
	0	RRModeOriginPreferred
	1	RRModeOriginDetailed
	2	RRModeOriginVESA
	3	RRModeOriginConfig
	4	RRModeOriginUser
	5	RRModeOriginOther
└───
	Origin of mode information.

┌───
    MODEINFO (44)				Added in version 1.2
	4	CARD32		id
	2	CARD16		width in pixels
	2	CARD16		height in pixels
	4	CARD32		width in millimeters
	4	CARD32		height in millimeters
	4	CARD32		dot clock
	2	CARD16		h sync start
	2	CARD16		h sync end
	2	CARD16		h total
	2	CARD16		h skew
	2	CARD16		v sync start
	2	CARD16		v sync end
	2	CARD16		v total
	2	CARD16		name length
	4	SETofMODEFLAG	mode flags
	1	MODEORIGIN	mode origin
	3			unused
└───
	
	An output mode specifies the complete CRTC timings for
	a specific mode. The vertical and horizontal synchronization rates
	can be computed given the dot clock and the h total/v total
	values. If the dot clock is zero, then all of the timing
	parameters and flags are not used, and must be zero as this
	indicates that the timings are unknown or otherwise unused.
	The name itself will be encoded separately in each usage.
	
┌───
    MODEFLAG
	0x00000001	HSyncPositive
	0x00000002	HSyncNegative
	0x00000004	VSyncPositive
	0x00000008	VSyncNegative
	0x00000010	Interlace
	0x00000020	DoubleScan
	0x00000040	CSync
	0x00000080	CSyncPositive
	0x00000100	CSyncNegative
	0x00000200	HSkewPresent
	0x00000400	BCast
	0x00000800	PixelMultiplex
	0x00001000	DoubleClock
	0x00002000	ClockDivideBy2
└───
┌───
    CONNECTION
	0		Connected
	1		Disconnected
	2		UnknownConnection
└───
┌───
    OUTPUTOPTION
	1		RROutputOptionScaleNone
	2		RROutputOptionScaleMaxAspect
	4		RROutputOptionScaleMax
└───
┌───
    OUTPUTCONFIG
    	4	CARD32		output
	4	CARD32		set of output options
└───


A.2 Protocol Requests

Opcodes 1 and 3 were used in the 0.0 protocols, and will return
errors if used in version 1.0.

┌───
    RRQueryVersion

	1	CARD8			major opcode
	1	0			RandR opcode
	2	3			length
	4	CARD32			major version
	4	CARD32			minor version
      ▶
	1	1			Reply
        1				unused
	2	CARD16			sequence number
	4	0			reply length
	1	CARD32			major version
        1	CARD32			minor version
└───
┌───
    RRSetScreenConfig
	
	1	CARD8			major opcode
	1	2			RandR opcode
	2	6			length
	4	WINDOW			window on screen to be configured
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		config timestamp
	2	SIZEID			size index
	2	ROTATION		rotation/reflection
	2	CARD16			refresh rate (1.1 only)
	2	CARD16			pad
      ▶
	1	1			Reply
	1	RRCONFIGSTATUS		status
	2	CARD16			sequence number
	4	0			reply length
	4	TIMESTAMP		new timestamp
	4	TIMESTAMP		new configuration timestamp
	4	WINDOW			root
	2	SUBPIXELORDER		subpixel order defined in Render
	2	CARD16			pad4
	4	CARD32			pad5
	4	CARD32			pad6
└───
┌───
    RRSelectInput

	1	CARD8			major opcode
	1	4			RandR opcode
	2	3			length
	4	WINDOW			window
	2	SETofRRSELECTMASK	enable
	2	CARD16			pad
└───
┌───
    RRGetScreenInfo

	1	CARD8			major opcode
	1	5			RandR opcode
	2	2			length
	4	WINDOW			window
      ▶
	1	1			Reply
	1	CARD8			set of Rotations
	2	CARD16			sequence number
	4	0			reply length
	4	WINDOW			root window
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		config timestamp
	2	CARD16			number of SCREENSIZE following
	2	SIZEID			current size index
	2	ROTATION		current rotation and reflection
	2	CARD16			current rate (added in version 1.1)
	2	CARD16			length of rate info (number of CARD16s)
	2	CARD16			pad

	SCREENSIZE
	2	CARD16			width in pixels
	2	CARD16			height in pixels
	2	CARD16			width in millimeters
	2	CARD16			height in millimeters

	REFRESH
	2	CARD16			number of rates (n)
	2n	CARD16			rates
└───

A.2.1 Protocol Requests added with version 1.2

┌───
    RRGetScreenSizeRange
	1	CARD8			major opcode
	1	6			RandR opcode
	2	2			length
	4	WINDOW			window
      ▶
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	0			reply length
	2	CARD16			minWidth
	2	CARD16			minHeight
	2	CARD16			maxWidth
	2	CARD16			maxHeight
	16				unused
└───
┌───
    RRSetScreenSize
	1	CARD8			major opcode
	1	7			RandR opcode
	2	5			length
	4	WINDOW			window
	2	CARD16			width
	2	CARD16			height
	4	CARD32			width in millimeters
	4	CARD32			height in millimeters
└───
┌───
    RRGetScreenResources
	1	CARD8			major opcode
	1	8			RandR opcode
	2	2			length
	4	WINDOW			window
      ▶
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	c+o+11m+(b+p)/4		reply length
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		config-timestamp
	2	c			number of CRTCs
	2	o			number of outputs
	2	m			number of modeinfos
	2	b			total bytes in mode names
	8				unused
	4c	LISTofCRTC		crtcs
	4o	LISTofOUTPUT		outputs
	44m	LISTofMODEINFO		modeinfos
	b	STRING8			mode names
	p				unused, p=pad(b)
└───
┌───
    RRGetOutputInfo
	1	CARD8			major opcode
	1	9			RandR opcode
	2	3			length
	4	OUTPUT			output
	4	TIMESTAMP		config-timestamp
      ▶
	1	1			Reply
	1	RRCONFIGSTATUS		status
	2	CARD16			sequence number
	4	1+c+m+(n+p)/4		reply length
	4	TIMESTAMP		timestamp
	4	CRTC			current connected crtc
	4	SETofOUTPUTOPTION	current output options
	1	CONNECTION		connection
	1	SUBPIXELORDER		subpixel-order
	2	c			number of CRTCs
	2	m			number of modes
	2	o			number of clones
	2	n			length of name
	2				unused
	4	SETofOUTPUTOPTION	supported output options
	4c	LISTofCRTC		crtcs
	4m	LISTofMODE		modes
	n	STRING8			name
	p				unused, p=pad(n)
└───
┌───
    RRListOutputProperties
	1	CARD8			major opcode
	1	10			RandR opcode
	2	3			length
	4	OUTPUT			output
      ▶
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	n			reply length
	2	n			number of ATOMs in atoms
	22				unused
	4n	LISTofATOM		atoms
└───
┌───
    RRChangeOutputProperty
	1	CARD8			major opcode
	1	11			RandR opcode
	2	6+(n+p)/4		request length
	4	OUTPUT			output
	4	ATOM			property
	4	ATOM			type
	1	CARD8			format
	1				mode
		0	Replace
		1	Prepend
		2	Append
	2				unused
	4	CARD32			length of data in format units
					(= n for format = 8)
					(= n/2 for format = 16)
					(= n/4 for format = 32)
	n	LISTofBYTE		data
					(n is a multiple of 2 for format = 16)
					(n is a multiple of 4 for format = 32)
	p				unused, p=pad(n)
└───
┌───
    RRDeleteOutputProperty
	1	CARD8			major opcode
	1	12			RandR opcode
	2	3			request length
	4	OUTPUT			output
	4	ATOM			property
└───
┌───
    RRGetOutputProperty
	1	CARD8			major opcode
	1	13			RandR opcode
	2	7			request length
	4	OUTPUT			output
	4	ATOM			property
	4	ATOM			type
		0	AnyPropertyType
	4	CARD32			long-offset
	4	CARD32			long-length
	1	BOOL			delete
	3				unused
      ▶
	1	1			Reply
	1	CARD8			format
	2	CARD16			sequence number
	4	(n+p)/4			reply length
	4	ATOM			type
		0	None
	4	CARD32			bytes-after
	4	CARD32			length of value in format units
					(= 0 for format = 0)
					(= n for format = 8)
					(= n/2 for format = 16)
					(= n/4 for format = 32)
	12				unused
	n	LISTofBYTE		value
					(n is zero for format = 0)
					(n is a multiple of 2 for format = 16)
					(n is a multiple of 4 for format = 32)
	p				unused, p=pad(n)
└───
┌───
    RRCreateMode
	1	CARD8			major opcode
	1	14			RandR opcode
	2	13+(n+p)/4		length
	4	WINDOW			window
	44	MODEINFO		mode
	n	STRING8			mode name
	p				unused, p=pad(n)
      ▶
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	0			reply length
	4	MODE			mode
	20				unused
└───
┌───
    RRDestroyMode
	1	CARD8			major opcode
	1	15			RandR opcode
	2	2			length
	4	MODE			mode
└───
┌───
    RRAddOutputMode
	1	CARD8			major opcode
	1	16			RandR opcode
	2	3			length
	4	OUTPUT			output
	4	MODE			mode
└───
┌───
    RRDeleteOutputMode
	1	CARD8			major opcode
	1	17			RandR opcode
	2	3			length
	4	OUTPUT			output
	4	MODE			mode
└───
┌───
    RRGetCrtcInfo
	1	CARD8			major opcode
	1	18			RandR opcode
	2	3			length
	4	CRTC			crtc
	4	TIMESTAMP		config-timestamp
      ▶
	1	1			Reply
	1	RRCONFIGSTATUS		status
	2	CARD16			sequence number
	4	o+p			reply length
	4	TIMESTATMP		timestamp
	2	INT16			x
	2	INT16			y
	2	CARD16			width
	2	CARD16			height
	4	MODE			mode
	2	ROTATION		current rotation and reflection
	2	ROTATION		set of possible rotations
	2	o			number of outputs
	2	p			number of possible outputs
	4o	LISTofOUTPUT		outputs
	4p	LISTofOUTPUT		possible outputs
└───
┌───
    RRSetCrtcConfig
	1	CARD8			major opcode
	1	19			RandR opcode
	2	7+2n			length
	4	CRTC			crtc
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		config timestamp
	2	INT16			x
	2	INT16			y
	4	MODE			mode
	2	ROTATION		rotation/reflection
	2				unused
	8n	LISTofOUTPUTCONFIG	outputs
      ▶
	1	1			Reply
	1	RRCONFIGSTATUS		status
	2	CARD16			sequence number
	4	0			reply length
	4	TIMESTAMP		new timestamp
	20				unused
└───
┌───
    RRGetCrtcGammaSize
	1	CARD8			major opcode
	1	20			RandR opcode
	2	2			length
	4	CRTC			crtc
      ▶
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	0			reply length
	2	CARD16			size
	22				unused
└───
┌───
    RRGetCrtcGamma
	1	CARD8			major opcode
	1	21			RandR opcode
	2	2			length
	4	CRTC			crtc
      ▶
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	(6n+2)/4		reply length
	2	n			size
	20				unused
	2n	LISTofCARD16		red
	2n	LISTofCARD16		green
	2n	LISTofCARD16		blue
└───
┌───
    RRSetCrtcGamma
	1	CARD8			major opcode
	1	22			RandR opcode
	2	3+(6n+2)/4		length
	4	CRTC			crtc
	2	n			size
	2				unused
	2n	LISTofCARD16		red
	2n	LISTofCARD16		green
	2n	LISTofCARD16		blue
└───

A.3 Protocol Events

┌───
    RRScreenChangeNotify
	1	Base + 0		code
	1	ROTATION		new rotation and reflection
	2	CARD16			sequence number
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		configuration timestamp
	4	WINDOW			root window
	4	WINDOW			request window
	2	SIZEID			size ID
	2	SUBPIXELORDER		subpixel order defined in Render
	2	CARD16			width in pixels
	2	CARD16			height in pixels
	2	CARD16			width in millimeters
	2	CARD16			height in millimeters
└───

A.3.1 Protocol Events added with version 1.2

┌───
    RRCrtcChangeNotify
	1	Base + 1		code
	1	0			sub-code
	2	CARD16			sequence number
	4	TIMESTAMP		timestamp
	4	WINDOW			request window
	4	CRTC			crtc affected
	4	MODE			mode in use
	2	ROTATION		new rotation and reflection
	2				unused
	2	INT16			x
	2	INT16			y
	2	CARD16			width
	2	CARD16			height
└───
┌───
    RROutputChangeNotify
	1	Base + 1		code
	1	1			sub-code
	2	CARD16			sequence number
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		configuration timestamp
	4	WINDOW			request window
	4	OUTPUT			output affected
	4	CRTC			crtc in use
	4	MODE			mode in use
	2	ROTATION		rotation in use
	1	CONNECTION		connection status
	1	SUBPIXELORDER		subpixel order
└───
┌───
    RROutputPropertyNotify
	1	Base + 1		code
	1	2			sub-code
	2	CARD16			sequence number
	4	WINDOW			window
	4	OUTPUT			output
	4	ATOM			atom
	4	TIMESTAMP		time
	1				state
		0	NewValue
		1	Deleted
	11				unused
└───

A.4 Protocol Errors

┌───
    ERRORS
	Base + 0		Output
	Base + 1		Crtc
	Base + 2		Mode
└───
	
Bibliography

[RANDR] Gettys, Jim and Keith Packard, "The X Resize and Rotate
	Extension - RandR", Proceedings of the 2001 USENIX Annual
	Technical Conference, Boston, MA

[RENDER] 
	Packard, Keith, "The X Rendering Extension", work in progress,
	documents found in xc/specs/Render.