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:
      o Modern toolkits (in this case, GTK+ 2.x) have progressed to the point
        of implementing migration between screens of arbitrary depths
      o 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
      o The continued decline of legacy toolkits whose design would have
        required depth switching to support migration
      o The lack of depth switchin 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 implementated 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,
the size of the 'porthole' shown by each monitor is independent of the
overall size of the screen, and the porthole may be located anywhere within
the screen.

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

To extend RandR for this model, we separate out the monitor 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) monitor.
Monitor configuration is now done with full mode information instead of just
size and refresh rate, and these modes have names. These names should use
UTF-8 encoding, but there isn't any enforcement in the specification.
New modes may also be added by the user.

Additional requests and events are provided for this new functionality.

2. Acknowlegements

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

2. Screen change model

Screens may change dynamically, either under control of this
extension, or due to external events. Examples include: monitors being
swapped, you 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 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 enabel 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 stucture, 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).

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.

4. Errors

There are no new error types defined by this extension.

5. Protocol Types

RRCONFIGSTATUS {
	Success
	InvalidConfigTime
	InvalidTime
	Failed }
ROTATION {
	 Rotate_0
	 Rotate_90
	 Rotate_180
	 Rotate_270
	 Reflect_X
	 Reflect_Y }

RRSELECTMASK { RRScreenChangeNotifyMask
	       RRMonitorChangeNotifyMask (New in version 1.2) }

SIZEID { CARD16 }

MODEID { CARD16 or Disabled }

MONITOR { CARD16 }

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 {
	hsync_positive hsync_negative
	vsync_positive vsync_negative
	interlace double_scan
	csync csync_positive csync_negative
	hskew_present
	bcast
	pixel_multiplex
	double_clock
	clock_divide_by_2
}

MONITORMODE {
	name: STRING
	widthInPixels, heightInPixels: CARD16
	widthInMillimeters, heightInMillimeters: CARD32
	dotClock: CARD32
	hSyncStart, hSyncEnd, hTotal, hSkew: CARD16
	vSyncStart, vSyncEnd, vTotal: CARD16
	modeFlags: SETofMODEFLAG
}

REFRESH {
	rates: LISTofCARD16 }

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 RRMonitorChangeMask,
	RRMonitorChangeNotify events will be sent when a the configuration
	for a monitor associated with the screen changes, either through
	this protocol extension or due to detected external monitor changes.
	RRMonitorChangeNotify may also be sent when this request executes if
	the monitor configuration has changed since the client connected, to
	avoid race conditions.

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

	where:

	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 cooresponding 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 monitor configuration, permitting the subset of the screen
presented by multiple monitors to be configured. As a separate notion, the
size of the screen itself may be arbitrarily configured within a defined
range. As monitors are added and removed from the system, the set returned
by RRGetMonitorModes will change so that applications can detect dynamic
changes in the monitor 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.

RRGetMonitorModes
	window: WINDOW

	->

	root: WINDOW
	monitors: LISTofMONITORINFO

	where:

	MONITORINFO {
		timestamp: TIMESTAMP
		config-timestamp: TIMESTAMP
		x, y: INT16
		mode: MODEID
		rotation: ROTATION
		rotations: SETofROTATION
		default-mode: MODEID
		modes: LISTofMONITORMODE
	}

	Errors: Window

	RRGetMonitorModes returns information about the current and available
	configurations for all monitors connected to the screen associated
	with 'window'.

	'root' is the root window of the screen.
	
	'timestamp' indicates when the configuration was last set.
	
	'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. 
	
	'x' and 'y' indicate the position of this monitor within the screen
	region. They will be set to 0 when the monitor is disabled.
	
	'mode' indicates which mode is active, or 'Disabled' indicating
	that the monitor has been disabled and is not displaying the screen
	contents.

	'rotation' indicates the active rotation. It is set to Rotate_0
	when the monitor is disabled.
	
	'rotations' contains the set of rotations and reflections supported
	by the monitor.

	'default-mode' is the mode the monitor is set to at server
	reset time.

	'modes' is the list of possible displayed modes. Within each mode,
	the sizes are reported for rotation set to Rotate_0.

RRAddMonitorMode
	window: WINDOW
	monitor-index: MONITOR
	mode: MONITORMODE
	config-timestamp: TIMESTAMP
	timestamp: TIMESTAMP
	
	->

	Errors: Window, Value, Match, Name

	'window' and 'monitor-index' indicate which monitor is to be
	configured. If 'monitor-index' is out of range, a Value error is
	returned.

	'mode' provides a new mode for the monitor.  If the name of 'mode'
	names an existing mode, a Name error is returned. If 'mode' cannot be
	supported by the specified monitor, a Match error is returned. If
	some parameter of the mode is not valid in some other way, a Value
	error is returned.

	This request generates MonitorChangeNotify events.

RRDeleteMonitorMode
	window: WINDOW
	monitor-index: MONITOR
	name: STRING

	->

	Errors: Window, Value, Name

	'window' and 'monitor-index' indicate which monitor is to be
	configured. If 'monitor-index' is out of range, a Value error is
	returned.

	'name' specifies which mode to delete. If no mode of the specified
	name exists, a Name error is returned. The named mode must have
	been added with RRAddMonitorMode, else an Access error is returned.
	The named mode must not be active, else a Match error is returned.

RRSetMonitorMode
	window: WINDOW
	monitor-index: MONITOR
	timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	x, y: INT16
	mode: MODEID
	rotation: ROTATION

	->

	status: RRCONFIGSTATUS
	new-timestamp: TIMESTAMP
	config-timestamp: TIMESTAMP
	root: WINDOW
	monitor: MONITOR
	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 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' contains the index of desired mode or Disabled indicating the
	monitor should be disabled. If 'mode' is not one of these values, a
	Value error results.

	'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.

	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 monitor to the specified position, mode,
	rotation and reflection. The entire area of the monitor must fit
	within the screen size, else a Match error results. As an example,
	rotating the screen so that a single monitor fills the entire screen
	before and after may necessitate disabling the monitor, resizing the
	screen, then re-enabling the monitor 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.
	
	'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 monitor
	to allow correct subpixel rendering.

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 recabling a monitor, etc.

RRScreenChangeNotify

	rotation: ROTATION;		new rotation
	sequenceNumber: CARD16		low 16 bits of request's 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

RRMonitorChangeNotify

	sequenceNumber: CARD16		low 16 bits of request's seq. number
	timestamp: TIMESTAMP		time monitor was changed
	configTimestamp: TIMESTAMP	time config data was changed
	root: WINDOW			root window of screen
	window: WINDOW			window requesting notification
	monitor-index: MONITOR		monitor which changed
	mode: MODEID			new mode
	rotation: ROTATION;		new rotation
	subpixelOrder: SUBPIXELORDER	order of subpixels
	x: INT16			x position of monitor within screen
	y: INT16			y position of monitor within screen

	This event is generated whenever the monitor configuration is changed
	and sent to requesting clients. 'timestamp' indicates when the
	monitor 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 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 RRGetMonitorModes), the client MUST call
	RRGetMonitorModes 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 provied.
This document describes the version 1.0 of the specification, the
partial implementations have version numbers less than that.  Here's a
list of what each version before 1.0 implemented:

	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 out screens from monitors, 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.

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.

Most of the utility of this extension is subsumed by RandR version 1.2,
except for the gamma adjustments. If this features continue to be useful,
either some relationship between the screen indices used in the
XFree86-VidModeExtension and the screen/monitor pairs used int RandR or an
incorporation of this functionality into RandR might be needed.

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


	RRSELECTMASK
	0x0001	ScreenChangeNotifyMask
	0x0002	MonitorChangeNotifyMask		Added in version 1.2

	RRCONFIGSTATUS
	0x0 Success
	0x1 InvalidConfigTime
	0x2 InvalidTime
	0x3 Failed

	SIZEID
	0xffff	Disabled

	MONITORMODE (36)			Added in version 1.2
	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 (n)
	4	SETofMODEFLAG	mode flags
	
	A monitor mode specifies the complete CRTC timings for
	a specfic 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 location of the name in the encoding is specified separately
	
A.2 Protocol Requests


Opcodes 0x1 and 0x3 were used in the 0.0 protocols, and will return
errors if used in version 1.0.

	RRQueryVersion

	1	CARD8			major opcode
	1	0x01			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	0x02			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	0x04			RandR opcode
	2	3			length
	4	WINDOW			window
	2	SETofRRSELECTMASK	enable
	2	CARD16			pad


	RRGetScreenInfo

	1	CARD8			major opcode
	1	0x05			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	0x06			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
	4				unused
	4				unused
	4				unused
	4				unused
	
	
	RRSetScreenSize
	
	1	CARD8			major opcode
	1	0x07			RandR opcode
	2	5			length
	4	WINDOW			window
	2	CARD16			width
	2	CARD16			height
	4	CARD32			width in millimeters
	4	CARD32			height in millimeters
	

	RRGetMonitorModes
	
	1	CARD8			major opcode
	1	0x08			RandR opcode
	2	2			length
	4	WINDOW			window
	->
	1	1			Reply
	1				unused
	2	CARD16			sequence number
	4	i*6 + m*9 + (b+p)/4	reply length
	4	WINDOW			root
	2	CARD16			i = number of MONITORINFO following
	2	CARD16			m = number of SIZE following
	2	CARD16			b = size of name array following
	14				unused
	i*24	LISTofMONITORINFO	one per monitor
	m*36	LISTofMONITORMODE	for all monitors
	b	LISTofCARD*		list of mode names
	p	pad			pad(b)

	MONITORINFO
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		config-timestamp
	2	INT16			x
	2	INT16			y
	2	ROTATION		rotation
	2	MODEID			mode
	2	MODEID			default mode
	2	SETofROTATION		rotations
	2	CARD16			start offset in LISTofMONITORMODE
	2	CARD16			number of MONITORMODE

	RRAddMonitorMode
	1	CARD8			major opcode
	1	0x09			RandR opcode
	2	12+(b+p)/4		length
	4	WINDOW			window
	2	MONITOR			monitor index
	2				unused
	36	MONITORMODE		mode
	b	STRING			mode name
	p				pad(b)
	
	RRDeleteMonitorMode
	1	CARD8			major opcode
	1	0x0a			RandR opcode
	2	3+(b+p)/4		length
	4	WINDOW			window
	2	MONITOR			monitor index
	2	CARD16			mode name length
	b	STRING			mode name
	p				pad(b)
	
	RRSetMonitorMode

	1	CARD8			major opcode
	1	0x0b			RandR opcode
	2	7			length
	4	WINDOW			window
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		config timestamp
	2	MONITOR			monitor index
	2	INT16			x
	2	INT16			y
	2	MODEID			mode index
	2	ROTATION		rotation/reflection
	2				unused
	->
	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	MONITOR			monitor
	8				unused
	

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

	RRMonitorChangeNotify

	1	Base + 1		code
	1	0			sub-code
	2	CARD16			sequence number
	4	TIMESTAMP		timestamp
	4	TIMESTAMP		configuration timestamp
	4	WINDOW			root window
	4	WINDOW			request window
	2	MONITOR			monitor index
	2	MODEID			mode ID
	2	ROTATION		new rotation and reflection
	2	SUBPIXELORDER		new subpixel order
	2	INT16			x
	2	INT16			y

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.