Low Bandwidth X Extension

X Consortium Standard

Donna Converse

Jim Fulton

David Lemke

Ralph Mor

Keith Packard

Ray Tice

Dale Tonogai

   X Version 11, Release 7.7

   Version 1.0

   Copyright © 1996 X Consortium

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     __________________________________________________________

   Table of Contents

   Introduction
   Description

        Data Flow
        Tags
        Short-circuiting
        Graphics Re-encoding
        Motion events
        Event Squishing
        Master Client
        Multiplexing of Clients
        Swapping
        Delta cache
        Stream Compression
        Authentication Protocols

   C Library Interfaces

        Application Library Interfaces
        Proxy Library Interfaces

   Protocol

        Syntactic Conventions and Common Types
        Errors
        Requests
        Events
        Responses

   Algorithm Naming
   Encoding

        Errors
        Requests
        Events
        Re-encoding of X Events
        Responses

Introduction

   Low Bandwidth X (LBX) is a network-transparent protocol for
   running X Window System applications over transport channels
   whose bandwidth and latency are significantly worse than that
   used in local area networks. It combines a variety of caching
   and reencoding techniques to reduce the volume of data that
   must be sent over the wire. It can be used with existing
   clients by placing a proxy between the clients and server, so
   that the low bandwidth/high latency communication occurs
   between the proxy and server.

   This extension was designed and implemented by Jim Fulton,
   David Lemke, Keith Packard, and Dale Tonogai, all of Network
   Computing Devices (NCD). Chris Kent Kantarjiev (Xerox PARC)
   participated in early design discussions. Ralph Mor (X
   Consortium) designed and implemented additional sections. Donna
   Converse (X Consortium) authored the protocol description and
   encoding from design notes and the implementation. Ray Tice (X
   Consortium) resolved the open issues in the design and
   specification. Bob Scheifler (X Consortium) helped out in many
   areas.

   The extension name is "LBX".

Description

   The design center for LBX is to use a proxy as an intermediary
   between the client and server. The proxy reencodes and
   compresses requests, events, replies and errors, as well as the
   resulting data stream. Additionally, the proxy can cache
   information from the server to provide low-latency replies to
   clients. This reply generation by the proxy is known as
   short-circuiting. A proxy can handle multiple clients for a
   given server, but does not prevent clients from connecting
   directly to the server. The design allows the proxy to
   multiplex multiple clients into a single data stream to the
   server.

   Much of LBX is implemented as an extension. The compression and
   reencoding changes can be isolated to the transport and
   dispatch portions of the server, while short-circuiting
   requires minor changes to the server's colormap and property
   code.

   LBX employs several different compression and short-circuiting
   methods. Use of these methods is negotiable, and in some cases,
   the algorithm used by a given method is negotiable as well. LBX
   also provides for negotiation of extensions to LBX.

Data Flow

   The LBX data stream goes through a number of layers:
    1. Client requests
    2. Read by LBX and potential byte-swapping
    3. Request-specific compression
    4. Potential byte swapping
    5. Multiplexing of client request streams
    6. Delta replacement
    7. Stream compression

   Transport
    1. Stream decompression
    2. Delta substitution
    3. Demultiplexing of client request streams
    4. Potential byte swapping
    5. Reencoding
    6. Request processing

   The reverse process occurs with X server replies, events, and
   errors.

Tags

   Tags are used to support caching of large data items that are
   expected to be queried multiple times. Such things as the
   keyboard map and font metrics are often requested by multiple
   clients. Rather than send the data each time, the first time
   the data is sent it includes a tag. The proxy saves this data,
   so that subsequent requests can send only the tag to refer to
   that same data. The different types of tags are used for
   connection information, keyboard maps, modifier maps, fonts
   information and properties.

   Tag usage is negotiated as a boolean in the LbxStartProxy
   message. The proxy controls how many tags are stored in the
   proxy. The server may wish to observe the proxy's InvalidateTag
   behavior to limit how many tags are cached at any one time.
   Tagged data is not shared across types of tags, but the number
   space used for the tag ids is. The tag ids are generated by the
   server.

   The X server keeps track of what tags are known to the proxy.
   The proxy can invalidate a tag if no tag bearing replies of
   that type are pending. The proxy sends an LbxInvalidateTag
   message to release the tagged data. The proxy must not
   invalidate connection tags unless instructed to do so by the
   server.

   If the server wishes to discard tagged data, it must either
   have received an LbxInvalidateTag request from the proxy or
   send an LbxInvalidateTag event to the proxy for that tag.

Tag Substitution in Requests

   Many substitution requests have a tag field, followed by fields
   marked optional. For these requests, if the optional fields are
   present, the data in them is stored in the indicated tag,
   unless the tag is 0. If the optional fields are absent, the tag
   field indicates the tag that contains the data for the
   "optional" fields.

Property Tags

   Property data makes special use of tags. A common use of
   properties is for inter-client communication. If both clients
   use the proxy, it is wasteful to send the data to the server
   and then back, when the server may never need it.
   LbxChangeProperty request does the same work as the core
   ChangeProperty request, but it does not send the data. The
   reply to this request contains a tag id corresponding to the
   data. If the property information is used locally, the server
   responds to LbxGetProperty with the tag, and the property data
   need never be sent to the server. If the server does require
   the data, it can issue an LbxQueryTag message. The proxy can
   also send the data on at any time if it judges it appropriate
   (i.e., when the wire goes idle). Since the proxy owns the
   property data, it must not invalidate the tag before sending
   the data back to the server via an LbxTagData request.

Short-circuiting

   Short-circuiting is used to handle constant data. This includes
   atoms, color name/RGB mappings, and AllocColor calls. Atoms and
   color name/RGB mappings stay constant for the life of the
   server. AllocColor replies are constant for each colormap.
   Short-circuiting replaces round-trip requests with one-way
   requests, and can sometimes use one in place of many.

   Atoms are used heavily for ICCCM communication. Once the proxy
   knows the string to atom mapping, it has no need to send
   subsequent requests for this atom to the server.

   Colorname/RGB mappings are constant, so once the proxy sees the
   response from LookupColor , it need not forward any subsequent
   requests.

   Clients often use the same color cells, so once a read-only
   color allocation has occurred, the proxy knows what RGB values
   should be returned to the client. The proxy doesn't need to
   forward any AllocColor requests it can resolve, but it must
   tell the server to modify the color cell's reference count.
   LbxIncrementPixel is used to support this.

   For all three classes of short-circuiting, the proxy must still
   tell the server a request has occurred, so that the request
   sequence numbers stay in sync. This is done with
   LbxModifySequence .

   Sequence numbers cause the major complication with
   short-circuiting. X guarantees that any replies, events or
   errors generated by a previous request will be sent before
   those of a later request. This means that any requests that can
   be handled by the proxy must have their reply sent after any
   previous events or errors.

   If a proxy's applications do not require strict adherence to
   the X protocol ordering of errors or events, a proxy might
   provide further optimization by avoiding the overhead of
   maintaining this ordering, however, the resulting protocol is
   not strictly X11 compliant.

Graphics Re-encoding

   The LBX proxy attempts to reencode PolyPoint, PolyLine,
   PolySegment, PolyRectangle, PolyArc, FillPoly,
   PolyFillRectangle, PolyFillArc, CopyArea, CopyPlane, PolyText8,
   PolyText16, ImageText8, and ImageText16 requests. If the
   request can be reencoded, it may be replaced by an equivalent
   LBX form of the request. The requests are reencoded by
   attempting to reduce 2-byte coordinate, length, width and angle
   fields to 1 byte. Where applicable, the coordinate mode is also
   converted to Previous to improve the compressibility of the
   resulting data. In image requests, the image data may also be
   compressed.

Motion events

   To prevent clogging the wire with MotionNotify events, the
   server and proxy work together to control the number of events
   on the wire. This is done with the LbxAllowMotion request. The
   request adds an amount to an allowed motion count in the
   server, which is kept on a per-proxy basis. Every motion notify
   event sent to the proxy decrements the allowed motion counter.
   If the allowed motion count is less than or equal to zero,
   motion events not required by the X protocol definition are not
   sent to the proxy. The allowed motion counter has a minimum
   value of -2^31.

Event Squishing

   In the core protocol, all events are padded as needed to be 32
   bytes long. The LBX extension reduces traffic by removing
   padding at the end of events, and implying the event length
   from its type. This is known as squishing.

Master Client

   When the initial X connection between the proxy and the server
   is converted to LBX mode, the proxy itself becomes the master
   client. New client requests and some tag messages are sent in
   the context of the master client.

Multiplexing of Clients

   The LBX proxy multiplexes the data streams of all its clients
   into one stream, and then splits them apart again when they are
   received. The LbxSwitch message is used to tell each end which
   client is using the wire at the time.

   The server should process delta requests in the order that they
   appear on the LBX connection. If the server does not maintain
   the interclient request order for requests sent by the proxy,
   it must still obey the semantics implied by the interclient
   request order so that the delta cache functions correctly.

   The server can affect the multiplexing of clients by the proxy
   using the LbxListenToOne and LbxListenToAll messages. This is
   useful during grabs, since the master connection can not be
   blocked during grabs like other clients. The proxy is
   responsible for tracking server grabs issued by its clients so
   that the proxy can multiplex the client streams in an order
   executable by the server.

   Replies must be ordered in the multiplexed data stream from the
   server to the proxy such that the reply carrying tagged data
   precedes replies that refer to that tagged data.

Swapping

   Swapping is handled as with any X extension, with one caveat.
   Since a proxy can be supporting clients with different byte
   orders, and they all share the same wire, the length fields of
   all messages between the server and proxy are expressed in the
   proxy byte order. This prevents any problems with length
   computation that may occur when clients are switched.

Delta cache

   LBX takes advantage of the fact that an X message may be very
   similar to one that has been previously sent. For example, a
   KeyPress event may differ from a previous KeyPress event in
   just a few bytes. By sending just the bytes that differ (or
   "deltas"), the number of bytes sent over the wire can be
   substantially reduced. Delta compaction is used on requests
   being sent by the proxy as well as on replies and events being
   sent by the server.

   The server and the proxy each keep per-proxy request and
   response caches. The response cache contains events, errors and
   replies. All messages are saved in the appropriate delta cache
   if they are of an appropriate type and more than 8 bytes long
   but fit within the delta cache. The number of entries in the
   delta cache and the maximum saved message size are negotiated
   in the LbxStartProxy request.

   The LBX requests that are never stored in the request delta
   cache are the LbxQueryVersion , LbxStartProxy , LbxSwitch ,
   LbxNewClient , LbxAllowMotion , LbxDelta , LbxQueryExtension ,
   LbxPutImage , LbxGetImage , LbxBeginLargeRequest ,
   LbxLargeRequestData , LbxEndLargeRequest and LbxInternAtoms
   requests. The responses that are never stored in the response
   cache are LbxSwitchEvent and LbxDeltaResponse . The message
   carried by a delta message is also cached, if it meets the
   other requirements. Messages after the LbxStartProxy request
   are cached starting at index 0, and incrementing the index,
   modulo the number of entries, thereafter. The request and
   response caches are independently indexed.

   If the current message is cachable and the same length as a
   message in the corresponding delta cache, a delta message may
   be substituted in place of the original message in the protocol
   stream.

Stream Compression

   Before being passed down to the transport layer messages can be
   passed through a general purpose data compressor. The choice of
   compression algorithm is negotiated with See LbxStartProxy. The
   proxy and server are not required to support any specific
   stream compressor. As an example, however, the X Consortium
   implementation of a ZLIB based compressor is described below.

Note

   The XC-ZLIB compressor is presented with a simple byte stream -
   the X and LBX message boundaries are not apparent. The data is
   broken up into fixed sized blocks. Each block is compressed
   using zlib 1.0 (by Gailly & Adler), then a two byte header is
   prepended, and then the entire packet is transmitted. The
   header has the following information:
      out[0] = (length & 0xfff) >> 8 | ((compflag) ? 0x80 : 0);
      out[1] = length & 0xff;

Authentication Protocols

   The current version of LBX does not support multipass
   authentication protocols for clients of the proxy. These
   authentication protocols return an Authenticate message in
   response to a connection setup request, and require additional
   authentication data from the client after the LbxNewClient
   request, and before the reply to LbxNewClient . One example of
   such a protocol is XC-QUERY-SECURITY-1.

C Library Interfaces

   The C Library routines for LBX are in the Xext library. The
   prototypes are located in a file named "XLbx.h".

Application Library Interfaces

   In a proxy environment, applications do not need to call these
   routines to take advantage of LBX. Clients can, however, obtain
   information about the LBX extension to the server using this
   interface. Use of this routine may be altered when connected
   through a proxy, as described in See C Library Interfaces.

XLbxQueryVersion

   To determine the version of LBX supported by the X server, call
   XLbxQueryVersion .

   Bool XLbxQueryVersion(Display * display, int *
   major_version_return, int * minor_version_return);

   display

   Specifies the connection to the X server.

   major_version_return

   Returns the extension major version number.

   minor_version_return

   Returns the extension minor version number.

   The XLbxQueryVersion function determines if the LBX extension
   is present. If the extension is not present, XLbxQueryVersion
   returns False ; otherwise, it returns True . If the extension
   is present, XLbxQueryVersion returns the major and minor
   version numbers of the extension as supported by the X server.

Proxy Library Interfaces

   The following interfaces are intended for use by the proxy.

XLbxQueryExtension

   To determine the dynamically assigned codes for the extension,
   use the Xlib function XQueryExtension or the LBX function
   XLbxQueryExtension .

   Bool XLbxQueryExtension(Display * display, int *
   major_opcode_return, int * first_event_return, int *
   first_error_return);

   display

   Specifies the connection to the X server.

   major_opcode_return

   Returns the major opcode.

   first_event_return

   Returns the first event code.

   first_error_return

   Returns the first error code.

   The XLbxQueryExtension function determines if the LBX extension
   is present. If the extension is not present, XLbxQueryExtension
   returns False ; otherwise, it returns True . If the extension
   is present, XLbxQueryExtension returns the major opcode for the
   extension to major_opcode_return, the base event type code to
   first_event_return, and the base error code to
   first_error_return; otherwise, the return values are undefined.

XLbxGetEventBase

   To determine the base event type code, use the Xlib function
   XQueryExtension or the LBX function XLbxGetEventBase.

   int XLbxGetEventBase(Display * display);

   display

   Specifies the connection to the X server.

   The XLbxGetEventBase function returns the base event type code
   if the extension is present; otherwise, it returns -1.

Protocol

Syntactic Conventions and Common Types

   Please refer to the X Window System Protocol specification, as
   this document uses the syntactic conventions established there
   and references types defined there.

   The following additional types are defined by this extension:

   DIFFITEM
   1      CARD8      offset
   1      CARD8      diff

   LBXANGLE: CARD8 or 2 BYTE
         where (in order of precedence):
         (0 <= in <= A(95)) && !(in % A(5))       out = 0x5a + (in
    /
   A(5))
         A(105) <= in <= A(360) && !(in % A(15))      out = 0x67 +
   (in / A(15))
         -A(100) <= in <= -A(5) && !(in % A(5))      out = 0xa6 +
   (in / A(5))
         -A(360) < in <= -A(105) && !(in % A(15))      out = 0x98
   +
   (in / A(15))
         -A(360) < in <= A(360)      out[0] = in >> 8; out[1] = in

   LBXARC:
         [x, y: LBXINT16,
         width, height: LBXCARD16,
         angle1, angle2: LBXANGLE]

   Within a list of arcs, after the first arc, x and y are
   relative to the corresponding fields of the prior arc.

   LBXCARD16: CARD8 or 2 BYTE
         where:
         0x0000 <= in < 0x00F0      CARD8
         0x00F0 <= in < 0x10F0      out[0] = 0xF0 | ((in - 0xF0) >
   >
   8)
               out[1] = in - 0xF0

   LBXGCANDDRAWENT
   [ gc-cache-index, drawable-cache-index: CARD4 ]

   LBXGCANDDRAWUPDATE
         drawable: DRAWABLE      /* present only if
   drawable-cache-index
    == 0 */
   gc: GC]      /* present only if gc-cache-index == 0 */

   LBXGCANDDRAWABLE
         cache-entries: LBXGCANDDRAWENT
         updates: LBXGCANDDRAWUPDATE

   LBXINT16: INT8 or 2 BYTE
         where:
         0xF790 <= in < 0xFF90      out[0] = 0x80 | (((in + 0x70)
   >>
   8) & 0x0F)
               out[1] = in + 0x70
         0xFF90 <= in < 0x0080      CARD8
         0x0080 <= in < 0x0880      out[0] = 0x80 | (((in - 0x80)
   >>
   8) & 0x0F)
               out[1] = in - 0x80

   LBXPINT16: CARD8 or 2 BYTE       /* for
   usually positive numbers */
         where:
         0xFE00 <= in < 0x0000      out[0] = 0xF0 | (((in + 0x1000
   )
   >> 8) & 0x0F)
               out[1] = in + 0x1000
         0x0000 <= in < 0x00F0       CARD8
         0x00F0 <= in < 0x0EF0      out[0] = 0xF0 | ((in - 0xF0) >
   >8)
               out[1] = in - 0xF0

   LBXPOINT: [x, y: LBXINT16]
         Within a list of points, after the first rectangle, x and
    y are
   relative to the corresponding fields of the prior point.

   LBXRECTANGLE:
         [x, y: LBXINT16,
         width, height: LBXCARD16]

   Within a list of rectangles, after the first rectangle, x and y
   are relative to the corresponding fields of the prior
   rectangle.

   MASK: CARD8

Errors

   As with the X11 protocol, when a request terminates with an
   error, the request has no side effects (that is, there is no
   partial execution).

   There is one error, LbxClient . This error indicates that the
   client field of an LBX request was invalid, or that the proxy's
   connection was in an invalid state for a start or stop proxy
   request.

Requests

   There is one request that is expected to be used only by the
   client: LbxQueryVersion

   There is one request that is expected to be used by the client
   or the proxy: LbxQueryExtension .

   The following requests are expected to be used only by the
   proxy, and are instigated by the proxy: LbxStartProxy ,
   LbxStopProxy , LbxNewClient , LbxSwitch , LbxCloseClient ,
   LbxModifySequence , LbxAllowMotion , LbxInvalidateTag ,
   LbxTagData and LbxQueryTag .

   All other requests are sent by the proxy to the LBX server and
   are instigated by reception of an X request from the client.
   They replace the X request.

Requests Initiated by the Proxy or by the Client

   LbxQueryVersion
   =>;
   majorVersion: CARD16
   minorVersion: CARD16

   This request returns the major and minor version numbers of the
   LBX protocol.

   The encoding of this request is on See LbxQueryVersion.

Requests Initiated or Substituted by the Proxy

   LbxQueryExtension
   nbytes : CARD32
   name : STRING8
   =>
   num-requests: CARD8
   present: BOOL
   major-opcode: CARD8
   first-event: CARD8
   first-error: CARD8
   reply-mask: LISTofMASK /* optional */
   event-mask:LISTofMASK /* optional */
   Errors: Alloc

   This request is identical to the QueryExtension request, with
   an additional field, and two optional additional fields. When
   the client issues an QueryExtension request, the proxy will
   substitute an LbxQueryExtension request.

   This request determines if the named extension is present. If
   so, the major opcode for the extension is returned, if it has
   one. Otherwise, zero is returned. Any minor opcode and the
   request formats are specific to the extension. If the extension
   involves additional event types, the base event type code is
   returned. Otherwise, zero is returned. The format of events is
   specific to the extension. If the extension involves additional
   error codes, the base error code is returned. Otherwise, zero
   is returned. The format of additional data in the errors is
   specific to the extension.

   In addition, the number of requests defined by the named
   extension is returned. If the number of requests is nonzero,
   and if the information is available, reply-mask and event-mask
   will be included in the reply. The reply-mask represents a
   bit-wise one-to-one correspondence with the extension requests.
   The least significant bit corresponds to the first request, and
   the next bit corresponds to the next request, and so on. Each
   element in the list contains eight meaningful bits, except for
   the last element, which contains eight or fewer meaningful
   bits. Unused bits are not guaranteed to be zero. The bit
   corresponding to a request is set if the request could generate
   a reply, otherwise it is zero. In the same way, the event-mask
   represents a bit-wise one-to-one correspondence with the
   extension requests. A bit is set if the corresponding request
   could result in the generation of one or more extension or X11
   events. If reply-mask is present in the reply, event-mask will
   also be present.

   The encoding of this request is on See LbxQueryExtension.

Control Requests Initiated by the Proxy

   LbxStartProxy
   options : LISTofOPTION
   =>
   choices: LISTofCHOICE
   Errors: LbxClient , Alloc
   where:
   OPTION [optcode: CARD8,
   len: OPTLEN,
   option: (See See StartProxy Options) ]
   CHOICE [optcode: CARD8,
   len: OPTLEN,
   choice: (See See StartProxy Options) ]

   Table 1. StartProxy Options
   optcode option choice default
   delta-proxy DELTAOPT DELTACHOICE entries=16, maxlen=64
   delta-server DELTAOPT DELTACHOICE entries=16, maxlen=64
   stream-comp LISTofNAMEDOPT INDEXEDCHOICE No Compression
   bitmap-comp LISTofSTRING8 LISTofINDEXEDOPT No Compression
   pixmap-comp LISTofPIXMAPMETHOD LISTofPIXMAPCHOICE No
   Compression
   use-squish BOOL BOOL True
   use-tags BOOL BOOL True
   colormap LISTofSTRING8 INDEXEDCHOICE No Colormap Grabbing
   extension NAMEDOPT INDEXEDCHOICE Extension Disabled

   DELTAOPT [minN, maxN, prefN: CARD8
   minMaxMsgLen, maxMaxMsgLen, prefMaxMsgLen: CARD8]
   DELTACHOICE [entries, maxlen: CARD8]
   INDEXEDCHOICE [index: CARD8,
   data: LISTofBYTE]
   INDEXEDOPT [index, opcode: CARD8]
   NAMEDOPT [name: STRING8,
   detail: LISTofBYTE]
   OPTLEN 1 or 3 CARD8
   where:
   (0 < in <= 0xFF): out = in
   (0 <= in<= 0xFFFF): out[0] = 0; out[1] = in >> 8; out[2] = in&
   0xFF;
   PIXMAPMETHOD [name: STRING8,
   format-mask: BITMASK,
   depths: LISTofCARD8]
   PIXMAPCHOICE [index, opcode: CARD8,
   format-mask: BITMASK,
   depths: LISTofCARD8]

   This request negotiates LBX protocol options, and switches the
   proxy-server connection from X11 protocol to LBX protocol.

   The proxy gives the preferred protocol options in the request.
   The server chooses from the given options and informs the proxy
   which to use. The options may be listed in any order, and the
   proxy may choose which options to negotiate. If an option is
   not successfully negotiated, the default is used.

   The server delta cache and proxy delta caches can be configured
   for number of entries, and the length of entries. (See See
   Delta cache for details.) The delta caches are configured using
   the delta-server and delta-proxy options. To configure a cache,
   the proxy sends the minimum, maximum and preferred values for
   the number of cache entries, ( minN, maxN, prefN ), and the
   length of the cache entries, ( minMaxMsgLen, maxMaxMsgLen,
   prefMaxMsgLen ). The server's reply fields, entries and maxlen
   , contains the values to use. These values must be within the
   ranges specified by the proxy. The server may also specify an
   entries value of 0 to disable delta caching. The cache entry
   lengths are specified in units of 4 bytes.

   The stream compression algorithm is selected using the
   stream-comp option. (Stream compression is described in See
   Stream Compression.) Each algorithm has a name that follows the
   naming conventions in See Algorithm Naming. To negotiate using
   the stream-comp option, the proxy lists its available
   compressors. For each candidate algorithm, the proxy sends the
   name in the name field, and uses the detail field to send any
   additional data specific to each compression algorithm. The
   reply contains a 0-based index into the list of algorithms to
   indicate which algorithm to use, followed by data specific to
   that algorithm.

   Bitmap compression is negotiated using the bitmap-comp option.
   The proxy sends a list of names of available algorithms, and
   the server reply lists the algorithms to use. For each bitmap
   algorithm in the reply, a 0-based index into the list of
   algorithms indicates the algorithm, and the opcode field gives
   the value for use in requests. The algorithm names follow the
   conventions in See Algorithm Naming.

   Pixmap compression is negotiated using the pixmap-comp option.
   The proxy sends a list of available algorithms. For each
   algorithm, the list includes, the name, a bitmask of supported
   formats, and a list of depths that the format supports. The
   server reply lists the algorithms to use. For each pixmap
   algorithm in the reply, the reply contains a 0-based index into
   the list of proxy algorithms, the opcode to use in requests
   when referring to this algorithm, a mask of valid formats, and
   a list of valid depths. Algorithm names follow the conventions
   in See Algorithm Naming.

   Squishing is negotiated using the use-squish option. If the
   proxy desires squishing, it sends a true value. The reply from
   the server indicates whether to do squishing, and will indicate
   squishing only if use-squish is set to true in the request.

   Tag caching, described in See Tags, is negotiated using the
   use-tag option. If the proxy desires tag caching, it sends a
   true value. The reply from the server indicates whether to do
   tag caching, and will demand caching only if use-tag is set to
   true in the request.

   The colormap option is used to negotiate what color matching
   algorithm will be used by the proxy when the proxy uses the
   LbxAllocColor request to allocate pixels in a grabbed colormap.
   To negotiate using the colormap option, the proxy lists the
   names of available colormap algorithms. The choice in the reply
   contains a 0-based index into the list of algorithms to
   indicate which algorithm to use, followed by data specific to
   that algorithm. If no colormap algorithm is successfully
   negotiated, then the LbxAllocColor , LbxGrabCmap , and
   LbxReleaseCmap requests will not be used.

   The extension option is used to control extensions to LBX.
   These extensions may, for example, enable other types of
   compression. To negotiate an extension, the name of the
   extension is sent, followed by any data specific to that
   extension. The extension name follows the conventions in See
   Algorithm Naming. The extension option may occur multiple times
   in the start proxy message, since multiple extensions can be
   negotiated. The reply to an extension option contains the
   zero-based index of the extension option, as counted in the
   LbxStartProxy message. This index is followed by
   extension-specific information. The server does not respond to
   extensions it does not recognize.

   An LbxClient error is returned when a client which is already
   communicating through an LBX proxy to the X server sends a
   LbxStartProxy request.

   The encoding for this request is on See LbxStartProxy.
   LbxStopProxy
   Errors: LbxClient

   This request terminates the connection between the proxy and X
   server, and terminates any clients connected through the proxy.

   The encoding for this request is on See LbxStopProxy.

   An LbxClient error is returned if the requesting client is not
   an LBX proxy.
   LbxNewClient
   byte-order : CARD8
   client-id : CARD32
   protocol-major-version : CARD16
   protocol-minor-version: CARD16
   authorization-protocol-name : STRING8
   authorization-protocol-data : STRING8
   =>
   Core X reply (if connection is rejected)

   OR

   success: BOOL
   change-type: {NoDeltas, NormalClientDeltas, AppGroupDeltas}
   protocol-major-version: CARD16
   protocol-minor-version: CARD16
   tag-id: CARD32
   length: CARD16
   connection-data: CONINFO or CONDIF or CONDIFROOT

   where:
   CONINFO: (the "additional data" portion of the core connection
   reply for successes)
   CONDIF: [resource-id-base: CARD32,
   root-input-masks: LISTofSETofEVENT]
   CONDIFROOT: [resource-id-base: CARD32,
   root: WINDOW
   root-visual: VISUALID
   default-colormap: COLORMAP
   white-pixel, black-pixel: CARD32
   root-input-masks: LISTofSETofEVENT]

   Errors: LbxClient, Alloc

   This request, which is sent by the proxy over the control
   connection, creates a new virtual connection to the server.

   Much of the information in the LbxNewClient request and reply
   is identical to the connection setup and reply information in
   the core X protocol.

   For the LbxNewClient request, the field unique to LBX is
   client-id. For the LbxNewClient reply, tag-id and change-type
   are fields unique to LBX, and the contents of connection-data
   may be different in LBX from the core X protocol (see below).

   The proxy assigns each virtual connection a unique identifier
   using the client-id field in the LbxNewClient request. This
   client-id is used in the LBX protocol to specify the current
   client (see the LbxSwitch request and the LbxSwitchEvent ).
   client-id 0 is reserved for the proxy control connection. An
   LbxClient error will result if the LbxNewClient request
   contains a client-id of 0 or an already in use client-id.

   If the server rejects this new virtual connection, the server
   sends a core X connection failure reply to the proxy. The
   current version of LBX does not support the return of an
   Authenticate reply.

   If the change-type field is set to NoDeltas , then
   connection-data is sent using the CONINFO structure, which is
   identical to the additional data of the core connection reply.
   If the tag-id is non-zero, then the connection-data is stored
   by the proxy using this tag value. Tagged connection data must
   be stored by the proxy, and can not be invalidated by the proxy
   until an LbxInvalidateTag event is received for that tag.

   When the change-type field is not set to NoDeltas , then
   connection data is sent as changes against connection
   information previously sent to the proxy. The tag-id field, if
   non-zero, has the tag of the previously sent data to apply the
   changes to. A zero tag-id indicates that the changes are with
   respect to the connection information sent when the proxy
   connected to the server.

   If the change-type field is set to NormalClientDeltas , then
   connection-data is sent using the CONDIF structure. The values
   in the CONDIF structure are substituted for the identically
   named fields of the connection information for the new
   connection.

   If the change-type field is set to AppGroupDeltas , then
   connection-data is sent using the CONDIFROOT structure. The
   root , root-visual , and default-colormap fields, when nonzero,
   are substituted for the corresponding fields in the reference
   connection information. The white-pixel and black-pixel fields
   are substituted only when the default-colormap field of the
   reply is non-zero. When default-colormap field of the reply is
   zero, so are white-pixel and black-pixel . The first entry in
   the root-input-masks field is the current-input-mask for the
   default root window. The remaining entries in root-input-masks
   are input masks for non-video screens, as defined by the X
   Print Extension. The number of non-video screens is one less
   than the number of entries in root-input-masks . These screens
   are at the end of screen list in the reference connection
   information.

   The encoding for this request is on See The description of this
   request is on page 13..
   LbxCloseClient
   client : CARD32
   Errors: LbxClient

   This requests the server to close down the connection
   represented by the specified proxy's client identifier. If the
   specified client wasn't previously registered with the server
   by a LbxNewClient request, the server will send the LbxClient
   error.

   The encoding for this request is on See The description of this
   request is on page 12..
   LbxSwitch
   client : CARD32
   Errors: LbxClient

   This request causes the X server to treat subsequent requests
   as being from a connection to the X server represented by the
   specified client identifier.

   If the client making the request is not the proxy, or if the
   client identifier sent in the request was not previously sent
   in a LbxNewClient request, an LbxClient error is returned.

   The encoding for this request is on See LbxSwitch.
   LbxSync
   =>

   The sync request causes the server to send a reply when all
   requests before the sync request have been processed.

   The encoding for this client is on See LbxSync.
   LbxModifySequence
   adjust : CARD32
   Errors: None

   This request advances the sequence number of the virtual client
   connection by the specified amount. The proxy sends the
   LbxModifySequence request to the server when it replies to a
   client request without forwarding the client request on to the
   X server.

   The encoding for this client is on See The description of this
   request is on page 13..
   LbxAllowMotion
   num : CARD32
   Errors: None

   This request controls the delivery of optional motion notify
   events, as described in See Motion events. The num field
   specifies an increase in the allowed number of motion notify
   events sent.

   The encoding for this request is on See The description of this
   request is on page 14..
   LbxInvalidateTag
   tag : CARD32

   The LBX proxy sends this notification to the X server when it
   refuses to store tagged data, or when it releases tagged data
   which was previously stored and which was not invalidated by a
   notification from the X server.

   The encoding for this request is on See LbxInvalidateTag.
   LbxTagData
   tag : CARD32
   real-length : CARD32
   data : LISTofBYTE

   This request specifies the data associated with a previously
   assigned tag. It is sent in two circumstances: in response to
   receiving a SendTagDataEvent , and spontaneously, when the
   proxy must rely on the server to store data which was not
   previously received from the server. The data is carried in the
   byte order and structure as would have originally been sent in
   the core protocol request.

   The encoding for this request is on See LbxTagData.
   LbxGrabCmap
   cmap : Colormap
   =>
   smart-grab : BOOL
   large-pixel: BOOL /* optional */
   auto-release: BOOL /* optional */
   three-channels : BOOL /* optional */
   bits-per-rgb: CARD4 /* optional */
   cells : LISTofCHAN /* optional */

   where:
   CHAN: LISTofLBXPIXEL
   LBXPIXEL: PIXELPRIVATE or PIXELPRIVATERANGE or
   PIXELALLOC or PIXELALLOCRANGE
   PIXEL: CARD8 or CARD16
   PIXELPRIVATE: [ pixel: PIXEL ]
   PIXELPRIVATERANGE: [ first-pixel, last-pixel: PIXEL]
   PIXELALLOC: [ pixel: PIXEL,
   color: COLORSINGLE or COLORTRIPLE]
   PIXELALLOCRANGE: [ first-pixel, last-pixel: PIXEL,
   colors: LISTofCOLORSINGLE or LISTofCOLORTRIPLE]
   COLORSINGLE: [ value: CARD8 or CARD16 ]
   COLORTRIPLE: [ r, g, b: COLORSINGLE]
   Errors: Colormap

   This request asks the server for control of allocating new
   colormap cells in the specified colormap. The server grants
   control by replying to this request. If no changes have
   occurred since the last time this proxy grabbed this colormap,
   then the smart-grab field of the reply is set to true, and the
   optional fields are not sent. Otherwise, the current contents
   of the colormap are placed in the reply, as described later in
   this section.

   Once the proxy has received the reply, it can use the
   LbxAllocColor request to allocate new colormap cells without
   the performance penalty of round trips. The proxy is still
   permitted to use the normal colormap and LbxIncrementPixel
   requests while the colormap is grabbed. The grab is valid
   across all virtual connections of the proxy.

   The LbxGrabCmap request is limited to colormaps for the visual
   types negotiated as part of the colormap algorithm negotiation
   in the start proxy request at connection setup.

   The server and other proxies may not allocate new colormap
   cells in the colormap while the colormap is grabbed by this
   proxy. If the server or another proxy needs to allocate new
   colormap cells, the server sends a Lbx ReleaseCmap event to the
   proxy holding the grab, which then issues an LbxReleaseCmap
   request.

   The server and other proxies may free colormap cells in a
   colormap grabbed by a proxy. The server will send an
   LbxFreeCells event to the proxy that currently has the colormap
   grabbed when the cell reference count reaches 0.

   If the colormap is a of a static visual type, such as
   StaticGray , StaticColor , GrayScale , or TrueColor , then the
   proxy's grab is immediately released by the server, and the
   proxy must use LbxIncrementPixel requests in place of
   LbxAllocColor requests for this colormap.

   If the cmap field does not refer to a valid colormap or the
   colormap is already grabbed by this proxy then a Colormap error
   is generated.

   The reply describes the contents of the colormap via several
   arguments and a descriptive list containing one or three
   channels, with each channel describing allocations in the
   colormap.

   The large-pixel argument, if True, specifies that PIXEL indices
   will be listed as CARD16 quantities instead of CARD8. The
   auto-release field, if True, indicates that this colormap is of
   a static visual type and the proxy's grab is immediately
   released by the server.

   If three-channels is False, a single channel is enclosed and
   color values are described using COLORTRIPLE, which has fields
   for red, green and blue. A single channel is used when the
   visual type is not DirectColor or TrueColor .

   If three-channels is True, separate red, green and blue channel
   lists are enclosed, for describing a DirectColor or TrueColor
   colormap. Color values for entries in each channel are sent
   using COLORSINGLE and the corresponding PIXEL value refers to
   the RGB subfield of the current channel, as defined by the
   corresponding red-mask, green-mask and blue-mask of the visual.

   The bits-per-rgb value is one less than the bits-per-rgb-value
   field of the visual that the colormap belongs to. If the value
   is 7 or less, then COLORSINGLE values in the descriptive list
   are sent using CARD8 fields. Otherwise these values are sent
   using CARD16 fields.

   The list describing current colormap allocations contains
   entries of the following types:

   An LBXPIXELPRIVATE entry indicates that the pixel in the pixel
   field is unavailable for allocation.

   An LBXPIXELPRIVATERANGE entry indicates that a contiguous range
   of pixels are unavailable for allocation. The range is
   first-pixel to last-pixel , and includes last-pixel .

   An LBXPIXELALLOC entry indicates that the pixel in the pixel
   field is allocated as a read-only pixel. The color field
   carries the color information of the pixel.

   An LBXPIXELALLOCRANGE entry indicates that a contiguous range
   of pixels are allocated as read-only. The range starts
   first-pixel to last-pixel , and includes last-pixel . These
   fields are followed by a list of COLORSINGLE or COLORTRIPLE,
   depending on the value of three-channels .

   A NEXTCHANNEL entry indicates that the next channel of the
   colormap will be described.

   A LISTEND entry indicates the end of the colormap description.

   All pixels not described in the reply are unallocated.

   The encoding for this request is on See LbxGrabCmap.
   LbxReleaseCmap
   cmap : Colormap

   This request releases the specified grabbed colormap. If the
   cmap field does not refer to a colormap, a BadColormap error is
   produced.

   The proxy must remember the state of the colormap when the
   LbxReleaseCmap request is issued if this proxy may at some
   future time issue another LbxGrabCmap request on this colormap
   before the state of the colormap changes.

   The encoding for this request is on See LbxReleaseCmap.
   LbxInternAtoms
   count : CARD16
   names: LISTofSTRING8
   =>
   atoms : LISTofATOM
   Errors: Alloc

   This request allows the proxy to intern a group of atoms in a
   single round trip. The server will create any atoms that do not
   exist.

   The encoding for this request is on See LbxInternAtoms.

Substitution Requests

   LbxAllocColor
   cmap : Colormap
   pixel : CARD32
   red , green , blue : CARD16

   This request is sent by a proxy that has given colormap grabbed
   to allocate a new read-only cell in the colormap. The proxy may
   substitute this request for the core AllocColor and
   AllocNamedColor requests.

   The pixel field identifies the colormap cell to allocate. The
   red , green , and blue fields are the hardware specific color
   values of the corresponding fields of the core AllocColor
   request. The mapping to hardware specific colormap values by
   the proxy is performed using the color algorithm negotiated by
   LbxStartProxy .

   For colormaps of static visual types, the LbxIncrementPixel
   request is used instead of LBX AllocColor .

   If the cmap field does not identify a grabbed colormap then a
   BadAccess error is produced. If the pixel field refers to a
   read-write entry, or the pixel field refers to a pixel outside
   of the range of this colormap, a BadAlloc error is produced.

   The encoding for this request is on See LbxAllocColor.
   LbxIncrementPixel
   cmap : COLORMAP
   pixel : CARD32
   Errors: None

   This request replaces the AllocColor request for read-only
   pixels currently allocated for the current client. If the
   visual type of the colormap is of a static type, this request
   may be used on currently unallocated pixels. The colormap is
   not required to be grabbed to use this request.

   The encoding for this request is on See The description of this
   request is on page 14..
   LbxDelta
   count : CARD8
   cache-index : CARD8
   diffs : LISTofDIFFITEM

   This request contains a minimal amount of information relative
   to a similar prior request. The information is in the form of a
   difference comparison to a prior request. The prior request is
   specified by an index to a cache, independently maintained by
   both the proxy and the server.

   The encoding for this request is on See The description of this
   request is on page 18..
   LbxGetModifierMapping
   =>
   keyspermod : CARD8
   tag : CARD32
   keycodes : LISTofKEYCODE /* optional */

   This request is identical to the core GetModifierMapping
   request, with the addition of a tag being returned in the
   reply. See See Tag Substitution in Requests for a description
   of the tag field and optional fields.

   The encoding for this request is on See LbxGetModifierMapping.
   LbxGetKeyboardMapping
   firstKeyCode : KEYCODE
   count : CARD8
   =>
   keysperkeycode : CARD8
   tag : CARD32
   keysyms : LISTofKEYSYM /* optional */
   Errors: Value

   This request is identical to the X GetKeyboardMapping protocol
   request, with the addition that a tag is returned in the reply.
   See See Tag Substitution in Requests for a description of the
   tag field and optional fields.

   The encoding for this request is on See LbxGetKeyboardMapping.
   LbxGetWinAttrAndGeom
   window : WINDOW
   =>
   visual: VISUALID
   class: {InputOutput, InputOnly}
   bit-gravity: BITGRAVITY
   win-gravity: WINGRAVITY
   backing-store: {NotUseful, WhenMapped, Always}
   backing-planes: CARD32
   backing-pixel: CARD32
   save-under: BOOL
   colormap: COLORMAP or None
   map-is-installed: BOOL
   map-state: {Unmapped, Unviewable, Viewable}
   all-event-masks, your-event-mask: SETofEVENT
   do-not-propagate-mask: SETofDEVICEEVENT
   override-redirect: BOOL
   root: WINDOW
   depth: CARD8
   x, y: INT16
   width, height, border-width: CARD16
   Errors: Window

   GetWindowAttributes and GetGeometry are frequently used
   together in the X protocol. LbxGetWinAttrAndGeom allows the
   proxy to request the same information in one round trip.

   The encoding for this request is on See LbxGetWinAttrAndGeom.
   LbxQueryFont
   font : FONTABLE
   =>
   compression: BOOL
   tag: CARD32
   font-info: FONTINFO /* optional */
   char-infos: LISTofCHARINFO or LISTofLBXCHARINFO /* optional */
   where:
   LBXCHARINFO: [left-side-bearing: INT6
   right-side-bearing: INT7
   character-width: INT6
   ascent: INT6
   descent: INT7]
   Errors: Font,Alloc

   This request is used to replace the core QueryFont request and
   has identical semantics.

   See See Tag Substitution in Requests for a description of the
   tag field and optional fields.

   The compression field is True if the char-infos field is
   represented using LBXCHARINFO.

   The per-character information will be encoded in an LBXCHARINFO
   when, for every character, the character-width,
   left-side-bearing, and ascent can each be represented in not
   more than 6 bits, and the right-side-bearing and descent can
   each be represented in not more than 7 bits, and the attributes
   field is identical the attributes field of the max_bounds of
   the font_info field of the font.

   The encoding for this request is on See LbxQueryFont.
   LbxChangeProperty
   window : WINDOW
   property : ATOM
   type : ATOM
   format : {0,8,16,32}
   mode : {Replace, Prepend, Append}
   nUnits : CARD32
   =>
   tag: CARD32

   This request is sent to the server when the client sends an X
   ChangeProperty request through the proxy. The size of the data
   is sent with this request, but not the property data itself.
   The server reply contains a tag identifier for the data, which
   is stored in the proxy. The proxy must not discard this data
   before it is sent to the server, or invalidated by the server.
   This means that before issuing an LbxStopProxy request, or
   exiting, the proxy must send Lbx TagData requests for these
   items. If the server loses the connection before the
   information is sent back, the server should revert the property
   value to its last known value, if possible.

   If the mode field is Prepend or Append , the tag refers only to
   the prepended or appended data.

   If the tag in the reply is zero, then the change was ignored by
   the server, as defined in the security extension. The proxy
   should dump the associated data, since the server will never
   ask for it.

   The encoding for this request is on See LbxChangeProperty.
   LbxGetProperty
   window : WINDOW
   property : ATOM
   type : ATOM or AnyPropertyType
   long-offset : CARD32
   long-length : CARD32
   delete : CARD8
   =>
   type: ATOM or None
   format: {0, 8, 16, 32}
   bytes-after: CARD32
   nItems: CARD32
   tag: CARD32
   value: LISTofINT8 or LISTofINT16 or LISTofINT32

   This request may be used by the proxy as a substitution for a
   core GetProperty request. It allows tags to be used for
   property data that is unlikely to change often in value, but is
   likely to be fetched by multiple clients.

   The LbxGetProperty request has the same arguments as the core
   GetProperty request. The reply for LbxGetProperty has all of
   the fields from the core GetProperty reply, but has the
   additional fields of nItems and tag .

   In order to utilize tags in LbxGetProperty for a specific
   property, the server must first send the complete property data
   to the proxy and associate this data with a tag. More
   precisely, the server sends an LbxGetProperty reply with a new
   tag , nItems set to the number of items in the property, the
   size of the property data in the reply length field, and the
   complete property data in value. The proxy stores the property
   data in its tag cache and associates it with the specified tag.

   In response to future LbxGetProperty requests for the same
   property, if the server thinks that the proxy has the actual
   property data in its tag cache, it may choose to send an
   LbxGetProperty reply without the actual property data. In this
   case, the reply would include a non-zero tag , a zero reply
   length, and no data for value.

   If the server chooses not to generate a tagged reply to
   LbxGetProperty , or for some reason is unable to do so, it
   would send a reply with a tag of zero, the size of the property
   data in the reply length field, and the complete property data
   in value.

   The encoding for this request is on See LbxGetProperty.
   LbxPolyPoint
   gc-and-drawable: LBXGCANDDRAWABLE
   points : LISTofLBXPOINT
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolyPoint request. Not all PolyPoint
   requests can be represented as LbxPolyPoint requests.

   The proxy will convert the representation of the points to be
   relative to the previous point, as described by previous
   coordinate mode in the X protocol.

   The encoding for this request is on See LbxPolyPoint.
   LbxPolyLine
   gc-and-drawable: LBXGCANDDRAWABLE
   points : LISTofLBXPOINT
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolyLine request. Not all PolyLine
   requests can be represented as LbxPolyline requests.

   The proxy will convert the representation of the points to be
   relative to the previous point, as described by previous
   coordinate mode in the X protocol.

   The encoding for this request is on See The description of this
   request is on page 21..
   LbxPolySegment
   gc-and-drawable: LBXGCANDDRAWABLE
   segments : LISTofLBXSEGMENT

   where:
   LBXSEGEMENT; [x1, y1, x2, y2: LBXINT16]
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolySegment request. Not all
   PolySegment requests can be represented as LbxPolySegment
   requests.

   For segments other than the first segment of the request, [x1,
   y1] is relative to [x1, y1] of the previous segment. For all
   segments, [x2, y2] is relative to that segment's [x1, y1].

   The encoding for this request is on See LbxPolySegment.
   LbxPolyRectangle
   gc-and-drawable: LBXGCANDDRAWABLE
   rectangles : LISTofLBXRECTANGLE
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolyRectangle request. Not all
   PolyRectangle requests can be represented as LbxPolyRectangle
   requests.

   The encoding for this request is on See The description of this
   request is on page 22..
   LbxPolyArc
   gc-and-drawable: LBXGCANDDRAWABLE
   arcs : LISTofLBXARC
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolyArc request. Not all PolyArc
   requests can be represented as LbxPolyArc requests.

   The encoding for this request is on See LbxPolyArc.
   LbxPolyFillRectangle
   gc-and-drawable: LBXGCANDDRAWABLE
   rectangles : LISTofLBXRECTANGLE
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolyFillRectangle request. Not all
   PolyFillRectangle requests can be represented as
   LbxPolyFillRectangle requests.

   The encoding for this request is on See LbxPolyFillRectangle.
   LbxPolyFillArc
   gc-and-drawable: LBXGCANDDRAWABLE
   arcs : LISTofLBXARC
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the PolyFillArc request. Not all
   PolyFillArc requests can be represented as LbxPolyFillArc
   requests.

   The encoding for this request is on See The description of this
   request is on page 22..
   LbxFillPoly
   gc-and-drawable: LBXGCANDDRAWABLE
   shape : BYTE
   points : LISTofLBXPOINT
   Errors: Alloc and those given for the corresponding X request.

   This request replaces the FillPoly request. Not all FillPoly
   requests can be represented as LbxFillPoly requests.

   The proxy will convert the representation of the points to be
   relative to the previous point, as described by previous
   coordinate mode in the X protocol.

   The encoding for this request is on See LbxFillPoly.
   LbxCopyArea
   srcCache : CARD8 /* source drawable */
   gc-and-drawable: LBXGCANDDRAWABLE
   src-Drawable : CARD32
   src-x : LBXPINT16
   src-y : LBXPINT16
   width : LBXCARD16
   height : LBXCARD16
   dst-x : LBXPINT16
   dst-y : LBXPINT16
   Errors: Those given for the corresponding X request.

   This request replaces the CopyArea request for requests within
   its encoding range.

   The encoding for this request is on See LbxCopyArea.
   LbxCopyPlane
   bit-plane : CARD32
   src-cache : CARD8 /* cache reference for source drawable */
   gc-and-drawable: LBXGCANDDRAWABLE
   src-drawable : CARD32
   src-x : LBXPINT16
   src-y : LBXPINT16
   width : LBXCARD16
   height : LBXCARD16
   dst-x : LBXPINT16
   dst-y : LBXPINT16
   Errors: Those given for the corresponding X request.

   This request replaces the CopyPlane request for requests within
   its coding range.

   The encoding for this request is on See LbxCopyPlane.
   LbxPolyText8
   gc-and-drawable: LBXGCANDDRAWABLE
   x : LBXPINT16
   y : LBXPINT16
   items : LISTofTEXTITEM8
   Errors: Alloc , and those given for the corresponding X
   request.

   This request replaces the PolyText8 request for requests within
   its encoding range.

   The encoding for this request is on See The description of this
   request is on page 23..
   LbxPolyText16
   gc-and-drawable: LBXGCANDDRAWABLE
   x: LBXPINT16
   y : LBXPINT16
   items : LISTofTEXTITEM16
   Errors: Alloc , and those given for the corresponding X
   request.

   This request replaces the PolyText16 request for requests
   within its encoding range.

   The encoding for this request is on See The description of this
   request is on page 24..
   LbxImageText8
   gc-and-drawable: LBXGCANDDRAWABLE
   nChars : CARD8
   x : LBXPINT16
   y : LBXPINT16
   string : STRING8
   Errors: Alloc , and those given for the corresponding X
   request.

   This request replaces the ImageText8 request for requests
   within its encoding range.

   The encoding for this request is on See The description of this
   request is on page 24..
   LbxImageText16
   nChars : CARD8
   gc-and-drawable: LBXGCANDDRAWABLE
   x: LBXPINT16
   y : LBXPINT16
   string : STRING16
   Errors: Alloc , and those given for the corresponding X
   request.

   This request replaces the ImageText16 request for requests
   within its encoding range.

   The encoding for this request is on See The description of this
   request is on page 24..
   LbxPutImage
   compression-method : CARD8
   format : { Bitmap , XYPixmap , ZPixmap } /* packed */
   gc-and-drawable: LBXGCANDDRAWABLE
   width , height : LBXCARD16
   dst-x , dst-y : LBXPINT16
   depth : CARD8 /* packed */
   left-pad : CARD8 /* packed */
   pad-bytes : CARD8 /* packed */
   data :LISTofBYTE
   Errors: Alloc , Value

   When the request can be usefully compressed, this request
   replaces the PutImage request. The compression-method parameter
   contains the opcode of a compression method returned in the
   LbxStartProxy reply. The pad-bytes parameter gives the number
   of unused pad bytes that follow the compressed image data. All
   other parameters are as in the X request. If the specified
   compression method is not recognized, the server returns a
   Value error.

   The encoding for this request is on See LbxPutImage.
   LbxGetImage
   drawable : DRAWABLE
   x , y : INT16
   width , height : CARD16
   plane-mask : CARD32
   format : {XYPixmap, ZPixmap}
   =>
   depth: CARD8
   x-length: CARD32
   visual: VISUALID or None
   compression-method: CARD8
   data: LISTofBYTE
   Errors: Alloc,Match,Value

   This request can replace the GetImage request. The same
   semantics apply, with the following exceptions.

   The compression-method field contains the opcode of the
   compression method used in the reply. The compression opcodes
   are supplied in the LbxStartProxy reply. The x-length field
   contains the length of the uncompressed version of the reply in
   4 byte units.

   A Value error is returned if the format is not recognized by
   the X server. A Match error is returned under the same
   circumstances as described by the GetImage request.

   The encoding for this request is on See LbxGetImage.
   LbxBeginLargeRequest
   large-request-length : CARD32
   Errors: Alloc

   This request, along with the Lbx LargeRequestData and Lbx
   EndLargeRequest requests, is used to transport a large request
   in pieces. The smaller size of the resulting requests allows
   smoother multiplexing of clients on a single low bandwidth
   connection to the server. The resulting finer-grained
   multiplexing improves responsiveness for the other clients.

   After a LbxBeginLargeRequest request is sent, multiple
   LbxLargeRequestData requests are sent to transport all of the
   data in the large request, and finally an LbxEndLargeRequest
   request is sent. The large-request-length field expresses the
   total length of the transported large request, expressed as the
   number of bytes in the transported request divided by four.

   The encoding for this request is on See The description of this
   request is on page 25..
   LbxLargeRequestData
   data : LISTofBYTE
   Errors: Alloc

   This request is used to carry the segments of a larger request,
   as described in the definition of LbxBeginLargeRequest . The
   data must be carried in order, starting with the request
   header, and each segment must be multiples of 4 bytes long. If
   the LbxLargeRequestData is not preceded by a corresponding
   LbxBeginLargeRequest , a BadAlloc error is generated.

   The encoding for this request is on See The description of this
   request is on page 26..
   LbxEndLargeRequest
   Errors: Length, Alloc

   As described in the definition of LbxBeginLargeRequest ,
   LbxEndLargeRequest is used to signal the end of a series of
   LargeRequestData requests. If the total length of the data
   transported by the LbxLargeRequestData requests does not match
   the large-request-length field of the preceding
   LbxBeginLargeRequest request, then a Length error occurs. If
   the LbxEndLargeRequest is not preceded by a corresponding
   LbxBeginLargeRequest , a BadAlloc error is generated. The
   request is executed in order for that client as if it were the
   request after the request preceding LbxEndLargeRequest .

   The encoding for this request is on See LbxEndLargeRequest.

Events

   LbxSwitchEvent
   client : CARD32

   Notify the proxy that the subsequent replies, events, and
   errors are relative to the specified client.

   The encoding for this event is on See LbxSwitchEvent.
   LbxCloseEvent
   client : CARD32

   Notify the proxy that the specified client's connection to the
   server is closed.

   The encoding for this event is on See The description of this
   event is on page 27..
   LbxInvalidateTagEvent
   tag : CARD32
   tag-type : {Modmap, Keymap, Property, Font, ConnInfo}

   This message informs the proxy that the tag and the server data
   referenced by the tag are obsolete, and should be discarded.
   The tag type may be one of the following values:
   LbxTagTypeModmap , LbxTagTypeKeymap , LbxTagTypeProperty ,
   LbxTagTypeFont , LbxTagTypeConnInfo .

   The encoding for this event is on See LbxInvalidateTagEvent.
   LbxSendTagDataEvent
   tag : CARD32
   tag-type : {Property}

   The server sends this event to the proxy to request a copy of
   tagged data which is being stored by the proxy. The request
   contains a tag which was previously assigned to the data by the
   server. The proxy should respond to SendTagData by sending a
   TagData request to the server. The tag type may be one of the
   following values: LbxTagTypeProperty .

   The encoding for this event is on See LbxSendTagDataEvent.
   LbxListenToOne
   client : CARD32 or 0xffffffff

   When the server is grabbed, ListenToOne is sent to the proxy.
   As an X client, the proxy itself is unaffected by grabs, in
   order that it may respond to requests for data from the X
   server.

   When the client grabbing the server is managed through the
   proxy, the proxy will permit messages from itself and the
   grabbing client to be sent immediately to the server, and may
   buffer requests from other clients of the proxy. The client is
   identified in the event.

   When the client grabbing the server is not managed through the
   proxy, the client field in the event will be 0xffffffff . The
   proxy will communicate with the server, and it may buffer
   requests from other clients. The proxy will continue to handle
   new connections while the server is grabbed.

   The server will send ListenToAll to the proxy when the server
   is ungrabbed. There is no time-out for this interval in the
   protocol.

   The encoding for this event is on See The description of this
   event is on page 27..
   LbxListenToAll

   Notify the proxy that the server has been ungrabbed, and that
   the proxy may now send all buffered client requests on to the
   server.

   The encoding for this event is on See The description of this
   event is on page 27..
   LbxQuickMotionDeltaEvent
   deltaTime : CARD8
   deltaX : INT8
   deltaY : INT8

   This event is used as a replacement for the MotionNotify event
   when possible. The fields are used as deltas to the most recent
   MotionNotify event encoded as a MotionNotify event,
   LbxQuickMotionDeltaEvent , or LbxMotionDeltaEvent . Not every
   MotionNotify event can be encoded as a LbxQuickMotionDeltaEvent
   .

   The encoding for this event is on See LbxQuickMotionDeltaEvent.
   LbxMotionDeltaEvent
   deltaX : INT8
   deltaY : INT8
   deltaTime : CARD16
   deltaSequence : CARD16

   This event is used as a replacement for the MotionNotify event
   when possible. The fields are used as deltas to the most recent
   MotionNotify event encoded as a MotionNotify event,
   LbxQuickMotionDeltaEvent , or LbxMotionDeltaEvent . Not every
   MotionNotify event can be encoded as a LbxMotionDeltaEvent .

   The encoding for this event is on See LbxMotionDeltaEvent.
   LbxReleaseCmapEvent
   colormap : Colormap

   This event notifies the proxy that it must release the grab on
   this colormap via the ReleaseCmap request. See LbxReleaseCmap

   The encoding for this event is on See LbxReleaseCmapEvent.
   LbxFreeCellsEvent
   colormap : Colormap
   pixelStart, pixelEnd : CARD32

   The LbxFreeCells event is sent to a proxy that has a colormap
   grabbed to notify the proxy that the reference count of the
   described cells were decremented to zero by the server or
   another proxy. The reference count includes those by this
   proxy. The proxy must update its copy of the colormap state
   accordingly if the colormap is still grabbed, or if the proxy
   may in the future grab the colormap using smart-grab mode. See
   LbxGrabCmap

   The pixelStart and pixelEnd fields of the event denote a
   continuous range of cells that were freed.

   The encoding for this event is on See LbxFreeCellsEvent.

Responses

   Responses are messages from the server to the proxy that not,
   strictly speaking, events, replies or errors.
   LbxDeltaResponse
   count : CARD8
   cache-index : CARD8
   diffs : LISTofDIFFITEM

   This response carries an event, reply, or error that has been
   encoded relative to a message in the response delta cache. The
   cache-index field is the index into the cache. Each entry in
   diffs provides a byte offset and replacement value to use in
   reconstructing the response.

   The encoding for this event is on See LbxDeltaResponse.

Algorithm Naming

   To avoid potential clashes between different but similar
   algorithms for stream, bitmap, and pixmap compression, the
   following naming scheme will be adhered to:

   Each algorithm has a unique name, which is a STRING8, of the
   following form:

   <organization>-<some-descriptive-name>

   The organization field above is the organization name as
   registered in section 1 of the X Registry (the registry is
   provided as a free service by the X Consortium.) This prevents
   conflicts among different vendor's extensions.

   As an example, the X Consortium defines a zlib-based stream
   compression algorithm called XC-ZLIB.

Encoding

   The syntax and types used in the encoding are taken from the X
   protocol encoding. Where LBX defines new types, they are
   defined earlier in this document.

   As in the X protocol, in various cases, the number of bytes
   occupied by a component will be specified by a lowercase
   single-letter variable name instead of a specific numeric
   value, and often some other component will have its value
   specified as a simple numeric expression involving these
   variables. Components specified with such expressions are
   always interpreted as unsigned integers. The scope of such
   variables is always just the enclosing request, reply, error,
   event, or compound type structure.

   For unused bytes, the encode-form is:

   N            unused

   If the number of unused bytes is variable, the encode-form
   typically is:

   p            unused, p=pad(E)

   where E is some expression, and pad(E) is the number of bytes
   needed to round E up to a multiple of four.

   pad(E) = (4 - (E mod 4)) mod 4

   In many of the encodings, the length depends on many variable
   length fields. The variable L is used to indicate the number of
   padded 4 byte units needed to carry the request. Similarly, the
   variable Lpad indicates the number of bytes needed to pad the
   request to a 4 byte boundary.

   For counted lists there is a common encoding of NLISTofFOO:
NLISTofFOO
1      m      num items
m      LISTofFOO      items

   For cached GC and Drawables:

   LBXGCANDDRAWUPDATE
   4 or 0      DRAWBLE      optional drawable
   4 or 0      GC           optional GC

   LBXGCANDDRAWABLE
   8      LBXGCANDDRAWENT      cache-entries
   8                           unused
   m      LBXGCANDDRAWUPDATE   optional GC and Drawable

Errors

LbxClient
1      0          Error
1      CARD8      error-base + 0
2      CARD16     sequence number
4                 unused
2      CARD16     lbx opcode
1      CARD8      major opcode
21                unused

Requests

LbxQueryVersion
1      CARD8      opcode
1      0          lbx opcode
2      1          request length
=>
1      1          Reply
1                 unused
2      CARD16     sequence number
4      0          reply length
2      CARD16     major version
2      CARD16     minor version
20                unused

   The description of this request is on See LbxQueryVersion.
LbxStartProxy
1      CARD8                      opcode
1      1                          lbx opcode
2      L                          request length
n      NLISTofOPTION-REQUEST      options
p                                 unused, p=pad(n)

OPTION-REQUEST
1      OPTCODE                    option-code
m      OPTLEN                     option-request-byte-length, (b=m+a+1)
a      DELTAOPT or                option
       NLISTofNAMEDOPT or
       NLISTofSTR or
       NLISTofPIXMAPMETHOD or
       BOOL

   The encoding of the option field depends on the option-code.
   See See StartProxy Options.
1      OPTCODE                               option-code
0      LbxOptionDeltaProxy
1      LbxOptionDeltaServer
2      LbxOptionStreamCompression
3      LbxOptionBitmapCompression
4      LbxOptionPixmapCompression
5      LbxOptionMessageCompression              /* also known as squishi
ng */
6      LbxOptionUseTags
7      LbxOptionColormapAllocation
255    LbxOptionExtension

   OPTLEN has two possible encodings, depending on the size of the
   value carried:
OPTLEN
1      CARD8              b (0 < b <= 255)

OPTLEN
1      0                  long length header
1      c                  length0, c = b >> 8
1      d                  length1, d= b & #xff

DELTAOPT
1      CARD8      min-cache-size
1      CARD8      max-cache-size
1      CARD8      preferred-cache-size
1      CARD8      min-message-length
1      CARD8      max-message-length (in 4-byte units)
1      CARD8      preferred-message-length

NAMEDOPT
f      STR             type-name
1      g+1             option-data-length
g      LISTofBYTE      option-data (option specific)

PIXMAPMETHOD
h      STR              name
1      BITMASK          format mask
1      j                depth count
j      LISTofCARD8      depths

=>
=>

1      1                 Reply
1      CARD8             count

0xff      options in request cannot be decoded
2      CARD16            sequence number
4      (a+p-32)/4        reply length
a      LISTofCHOICE      options-reply
p            unused, if (n<24) p=24-n else p=pad(n)

CHOICE
1      CARD8                request-option-index
b      OPTLEN               reply-option-byte-length
c      DELTACHOICE or       choice
      INDEXEDCHOICE or
      NLISTofINDEXEDOPT or
      NLISTofPIXMAPCHOICE or
      BOOL or
      INDEXEDCHOICE

   The encoding of the choice field depends on the option-code.
   See See StartProxy Options.
DELTACHOICE
1      CARD8      preferred cache size
1      CARD8      preferred message length in 4-byte units

INDEXEDCHOICE
1      CARD8           index
d      LISTofBYTE      data

PIXMAPCHOICE
1      CARD8           index
1      CARD8           opcode
1      BITMASK         format mask
e      NLISTofCARD8    depths

   The description of this request is on See LbxStartProxy.
LbxStopProxy
1      CARD8      opcode
1      2          lbx opcode
2      1          request length

   The description of this request is on See LbxStopProxy.
LbxSwitch
1      CARD8      opcode
1      3          lbx opcode
2      2          request length
4      CARD32     client

   The description of this request is on See LbxSwitch.
LbxNewClient
1      CARD8      opcode
1      4          lbx opcode
2      L          request length
4      CARD32     client
The remaining bytes of the request are the core connection setup.
=>
If the connection is rejected, a core connection reply is sent. Otherwis
e the
reply has the form:
1      BOOL      success
1                change type
      0          no-deltas
      1          normal-client-deltas
      2          app-group-deltas
2      CARD16    major version
2      CARD16    minor version
2      1 + a     length
4      CARD32    tag id

   The remaining bytes depend on the value of change-type and
   length.

   For no-deltas, the remaining bytes are the "additional data"
   bytes of the core reply. (a = length of core reply, in 4 byte
   quantities).

   For normal-client-deltas, the additional bytes have the form,
   with a length (a = 1 +b):
4      CARD32                 resource id base
4b      LISTofSETofEVENT      root input masks

   For app-group-deltas, the additional bytes have the following
   form, with a length of (a = 1 + 4c):
4      CARD32                resource id base
4      WINDOW                root id base
4      VISUALID              visual
4      COLORMAP              colormap
4      CARD32                white pixel
4      CARD32                black pixel
4c     LISTofSETofEVENT      root input masks

   The description of this request is on See LbxNewClient.
LbxCloseClient
1      CARD8      opcode
1      5          lbx opcode
2      2          request length
4      CARD32     client

   The description of this request is on See LbxCloseClient.
LbxModifySequence
1      CARD8      opcode
1      6          lbx opcode
2      2          request length
4      CARD32     offset to sequence number

   The description of this request is on See LbxModifySequence.
LbxAllowMotion
1      CARD8      opcode
1      7          lbx opcode
2      2          request length
4      CARD32     number of MotionNotify events

   The description of this request is on See LbxAllowMotion.
LbxIncrementPixel
1      CARD8      opcode
1      8          lbx opcode
2      3          request length
4      COLORMAP   colormap
4      CARD32      pixel

   The description of this request is on See LbxIncrementPixel.
LbxDelta
1      CARD8              opcode
1      9                  lbx opcode
2      1+(2n +p+2)/4      request length
1      n                  count of diffs
1      CARD8              cache index
2n      LISTofDIFFITEM    offsets and differences
p                         unused, p=pad(2n + 2)

   The description of this request is on See LbxDelta.
LbxGetModifierMapping
1      CARD8      opcode
1      10         lbx opcode
2      1          request length
=>
1      1          Reply
1      n          keycodes-per-modifier
2      CARD16     sequence number
4      2n         reply length
4      CARD32     tag
20                unused
8n     LISTofKEYCODE      keycodes

   The description of this request is on See
   LbxGetModifierMapping.
LbxInvalidateTag
1      CARD8      opcode
1      12         lbx opcode
2      2          request length
4      CARD32     tag

   The description of this request is on See LbxInvalidateTag.
LbxPolyPoint
1      CARD8      opcode
1      13      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXPOINT      points (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxPolyPoint.
LbxPolyLine
1      CARD8      opcode
1      14      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXPOINT      points (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxPolyLine.
LbxPolySegment
1      CARD8      opcode
1      15      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXSEGMENT      segments (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxPolySegment.
LbxPolyRectangle
1      CARD8      opcode
1      16      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXRECTANGLE      rectangles (n is data-dependent)
p      0      unused, p=pad(m+n)

   The description of this request is on See LbxPolyRectangle.
LbxPolyArc
1      CARD8      opcode
1      17      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXARCS      arcs (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxPolyArc.
LbxFillPoly
1      CARD8      opcode
1      18      lbx opcode
2      1+(3+m+n+p)/4      request length
1      LBXGCANDDRAWENT      cache entries
1            shape
0      Complex
1      Nonconvex
2      Convex
1      p      pad byte count
m      LBXGCANDDRAWUPDATE      optional gc and drawable
n      LISTofLBXPOINT      points (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxFillPoly.
LbxPolyFillRectangle
1      CARD8      opcode
1      19      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXRECTANGLE      rectangles (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxPolyFillRectangle.
LbxPolyFillArc
1      CARD8      opcode
1      20      lbx opcode
2      1+(m+n+p)/4      request length
m      LBXGCANDDRAWABLE      cache entries
n      LISTofLBXARC      arcs (n is data-dependent)
p      0      unused, p=Lpad

   The description of this request is on See LbxPolyFillArc.
LbxGetKeyboardMapping
1      CARD8      opcode
1      21      lbx opcode
2      2      request length
1      KEYCODE      first keycode
1      m      count
2            unused
=>
1      1      Reply
1      n      keysyms-per-keycode
2      CARD16      sequence number
4      nm      reply length (m = count field from the request)
4      CARD32      tag
20            unused
4nm      LISTofKEYSYM      keysyms

   The description of this request is on See
   LbxGetKeyboardMapping.
LbxQueryFont
1      CARD8      opcode
1      22      lbx opcode
2      2      request length
4      FONTABLE      font
=>
1      1      Reply
1      BOOL      compression
2      CARD16      sequence number
4      L      reply length
4      CARD32      tag
20            unused
All of the following is conditional:
12      CHARINFO      min-bounds
4            unused
12      CHARINFO      max-bounds
4            unused
2      CARD16      min-char-or-byte2
2      CARD16      max-char-or-byte2
2      CARD16      default-char
2      n      number of FONTPROPs in properties
1            draw-direction
0      LeftToRight
1      RightToLeft
1      CARD8      min-byte1
1      CARD8      max-byte1
1      BOOL      all-chars-exist
2      INT16      font-ascent
2      INT16      font-descent
4      m      number of elements in char-infos
8n      LISTofFONTPROP      properties
and either
12m      LISTofCHARINFO      char-infos
or
m      LISTofLBXCHARINFO      char-infos

   The description of this request is on See LbxQueryFont.
LbxChangeProperty
1      CARD8      opcode
1      23      lbx opcode
2      6      request length
4      WINDOW      window
4      ATOM      property
4      ATOM      type
1      CARD8      format
1            mode
0      Replace
1      Preprend
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)
=>
1      1      Reply
1            unused
2      CARD16      sequence number
4      0      reply length
4      CARD32      tag
20            unused

   The description of this request is on See LbxChangeProperty.
LbxGetProperty
1      CARD8      opcode
1      24      lbx opcode
2      7      request length
4      WINDOW      window
4      ATOM      property
4      ATOM      type
0      AnyPropertyType
1      CARD8      delete
3            unused
4      CARD32      long-offset
4      CARD32      long-length
=>
1      1      Reply
1      CARD8      format
2      CARD16      sequence number
4      CARD32      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)
4      CARD32      tag
8            unused

   The description of this request is on See LbxGetProperty.
LbxTagData
1      CARD8      opcode
1      25      lbx opcode
2      3+(n+p)/4      request length
4      CARD32      tag
4      CARD32      length of data in bytes
n      LISTofBYTE      data
p            unused, p=pad(n)

   The description of this request is on See LbxTagData.
LbxCopyArea
1      CARD8      opcode
1      26      lbx opcode
2      L      request length
1      CARD8      source drawable cache entry
1      LBXGCANDDRAWENT      cache entries
4 or 0      DRAWABLE      optional source drawable
b      LBXGCANDDRAWUPDATE      optional gc and dest drawable
c      LBXPINT16      src-x
d      LBXPINT16      src-y
e      LBXPINT16      dst-x
f      LBXPINT16      dst-y
g      LBXCARD16      width
h      LBXCARD16      height
p            unused, p=Lpad

   The description of this request is on See LbxCopyArea.
LbxCopyPlane
1      CARD8      opcode
1      27      lbx opcode
2      L      request length
4      CARD32      bit plane
1      CARD8      source drawable cache entry
1      LBXGCANDDRAWENT      cache entries
4 or 0      DRAWABLE      optional source drawable
b      LBXGCANDDRAWUPDATE      optional gc and dest drawable
c      LBXPINT16      src-x
d      LBXPINT16      src-y
e      LBXPINT16      dst-x
f      LBXPINT16      dst-y
g      LBXCARD16      width
h      LBXCARD16      height
p            unused, p=Lpad

   The description of this request is on See LbxCopyPlane.
LbxPolyText8
1      CARD8      opcode
1      28      lbx opcode
2      L      request length
1      LBXGCANDDRAWENT      cache entries
a      LBXGCANDDRAWUPDATE      optional gc and drawable
b      LBXPINT16      x
c      LBXPINT16      y
n      LISTofTEXTITEM8      items
p            unused, p=Lpad

   The description of this request is on See LbxPolyText8.
LbxPolyText16
1      CARD8      opcode
1      29      lbx opcode
2      L      request length
1      LBXGCANDDRAWENT      cache entries
a      LBXGCANDDRAWUPDATE      optional gc and drawable
b      LBXPINT16      x
c      LBXPINT16      y
2n      LISTofTEXTITEM16      items
p            unused, p=Lpad

   The description of this request is on See LbxPolyText16.
LbxImageText8
1      CARD8      opcode
1      30      lbx opcode
2      L      request length
1      LBXGCANDDRAWENT      cache entries
a      LBXGCANDDRAWUPDATE      optional gc and drawable
b      LBXPINT16      x
c      LBXPINT16      y
n      STRING8      string
p            unused, p=Lpad

   The description of this request is on See LbxImageText8.
LbxImageText16
1      CARD8      opcode
1      31      lbx opcode
2      L      request length
1      LBXGCANDDRAWENT      cache entries
a      LBXGCANDDRAWUPDATE      optional gc and drawable
b      LBXPINT16      x
c      LBXPINT16      y
2n      STRING16      string
p            unused, p=Lpad

   The description of this request is on See LbxImageText16.
LbxQueryExtension
1      CARD8      opcode
1      32      lbx opcode
2      2+(n+p)/4      request length
4      n      length of extension name
n      STRING8      extension name
p            unused, p=pad(n)
=>
1      1      Reply
1      n      number of requests in the extension
2      CARD16      sequence number
4      0 or 2*(m + p)      reply length, m = (n+7)/8
1      BOOL      present
1      CARD8      major opcode
1      CARD8      first event
1      CARD8      first error
20            unused
m      LISTofMASK      optional reply-mask
p            unused, p=pad(m)
m      LISTofMASK      optional event-mask
p            unused, p=pad(m)

   The description of this request is on See LbxQueryExtension.
LbxPutImage
1      CARD8      opcode
1      33      lbx opcode
2      L      request length
1      CARD8      compression method
1      LBXGCANDDRAWENT      cache entries
a      PIPACKED            bit-packed
b      LBXGCANDDRAWUPDATE      optional gc and drawable
c      LBXCARD16      width
d      LBXCARD16      height
e      LBXPINT16      x
f      LBXPINT16      y
n      LISTofBYTE      compressed image data
p            unused, p=Lpad

   If there is no left padding and the depth is less than or equal
   to nine, PIPPACKED is encoded as follows:
PIPACKED
1      #x80 | (format << 5) | ((depth -1) << 2)

   Otherwise PIPACKED is defined as:
PIPACKED
1      (depth -1) << 2)
1      (format << 5) | left-pad

   The description of this request is on See LbxPutImage.
LbxGetImage
1      CARD8      opcode
1      34      lbx opcode
2      6      request length
4      DRAWABLE      drawable
2      INT16      x
2      INT16      y
2      CARD16      width
2      CARD16      height
4      CARD32      plane mask
1      CARD8      format
3            unused
=>
1      1      Reply
1      CARD8      depth
2      CARD16      sequence number
4      (n+p)/4      reply length
4      (m+p)/4      X reply length; if uncompressed, m=n
4      VISUALID      visual
0      None
1            compression method
15            unused
n      LISTofBYTE      data
p            unused, p=pad(n)

   The description of this request is on See LbxGetImage.
LbxBeginLargeRequest
1      CARD8      opcode
1      35      lbx opcode
2      2      request length
4      CARD32      large request length

   The description of this request is on See LbxBeginLargeRequest.
LbxLargeRequestData
1      CARD8      opcode
1      36      lbx opcode
2      1+n      request length
4n      LISTofBYTE      data

   The description of this request is on See LbxLargeRequestData.
LbxEndLargeRequest
1      CARD8      opcode
1      37      lbx opcode
2      1      request length

   The description of this request is on See LbxEndLargeRequest.
LbxInternAtoms
1      CARD8      opcode
1      38      lbx opcode
2      1+(2+m+n+p)/4      request length
2      m      num-atoms
n      LISTofLONGSTR      names
p            pad p=Lpad
=>
1      1      Reply
1            unused
2      CARD16      sequence number
4      a      reply length, a = MAX(m - 6, 0)
4*m      LISTofATOM      atoms
p            pad p = MAX(0, 4*(6 - m))

LONGSTR
2      c      string length
c      STRING8      string

   The description of this request is on See LbxInternAtoms.
LbxGetWinAttrAndGeom
1      CARD8      opcode
1      39      lbx opcode
2      2      request length
4      CARD32      window id
=>
1      1      Reply
1            backing store
0      NotUseful
1      WhenMapped
2      Always
2      CARD16      sequence number
4      7      reply length
4      VISUALID      visual id
2            class
1      InputOutput
2      InputOnly
1      BITGRAVITY      bit gravity
1      WINGRAVITY      window gravity
4      CARD32      backing bit planes
4      CARD32      backing pixel
1      BOOL      save under
1      BOOL      map installed
1            map state
0      Unmapped
1      Unviewable
2      Viewable
1      BOOL      override
4      COLORMAP      colormap
4      SETofEVENT      all events mask
4      SETofEVENT      your event mask
2      SETofDEVICEEVENT      do not propagate mask
2            unused
4      WINDOW      root
2      INT16      x
2      INT16      y
2      CARD16      width
2      CARD16      height
2      CARD16      border width
1      CARD8      depth
1            unused

   The description of this request is on See LbxGetWinAttrAndGeom.
LbxGrabCmap
1      CARD8      opcode
1      40      lbx opcode
2      2      request length
4      COLORMAP      colormap
=>

   If smart-grab is true, the reply is as follows:
1      1      Reply
1      #x80      flags
2      CARD16      sequence number
4      0      reply length
24            unused

If smart-grab is false, the reply is as follows:

1      1      Reply
1            flags (set of)
       #x40      auto-release
       #x20      three-channels
       #x10      two-byte-pixels
lower four bits specifies bits-per-pixel
2      CARD16      sequence number
4      L      reply length
m      CHAN or CHANNELS      cells (CHAN if !three-channels)
p      0      pad(m)

CHANNELS
a      CHAN      red
1      5            next channel
b      CHAN      green
1      5      next channel
c      CHAN      blue
1      0      list end

CHAN
d      LISTofLBXPIXEL

LBXPIXEL
e      PIXELPRIVATE or
      PIXELPRIVATERANGE or
      PIXELALLOC or
      PIXELALLOCRANGE

PIXELPRIVATE
1      1      pixel-private
f      PIXEL      pixel

PIXEL
f      CARD8 or CARD16      (CARD8 if !two-byte-pixels)

PIXELPRIVATERANGE
1      2      pixel-private-range
f      PIXEL      fist-pixel
f      PIXEL      last-pixel

PIXELALLOC
1      3      pixel-private
f      PIXEL      pixel
g      COLORSINGLE or COLORTRIPLE      color       (COLORSINGLE if
three-channels)

COLORSINGLE
h      CARD8 or CARD16      value (CARD8       if bits-per-rgb =< 7)

COLORTRIPLE
h      COLORSINGLE      red
h      COLORSINGLE      green
h      COLORSINGLE      blue

PIXELALLOCRANGE
1      4      pixel-private
f      PIXEL      first-pixel
f      PIXEL      last-pixel
j      LISTofCOLORSINGLE or       color       (COLORSINGLE if three-chan
nels)
      LISTofCOLORTRIPLE

   The description of this request is on See LbxGrabCmap.
LbxReleaseCmap
1      CARD8      opcode
1      41      lbx opcode
2      2      request length
4      COLORMAP      cmap

   The description of this request is on See LbxReleaseCmap.
LbxAllocColor
1      CARD8      opcode
1      42      lbx opcode
2      5      request length
4      COLORMAP      colormap
4      CARD32      pixel
2      CARD16      red
2      CARD16      green
2      CARD16            blue
2            unused

   The description of this request is on See LbxAllocColor.
LbxSync
1      CARD8      opcode
1      43      lbx opcode
2      1      request length
=>
1      1      Reply
1      n      unused
2      CARD16      sequence number
4      0      reply length
24            unused

   The description of this request is on See LbxSync.

Events

LbxSwitchEvent
1      base + 0      code
1      0      lbx type
2      CARD16      sequence number
4      CARD32      client
24            unused

   The description of this event is on See LbxSwitchEvent.
LbxCloseEvent
1      base + 0      code
1      1      lbx type
2      CARD16      sequence number
4      CARD32      client
24            unused

   The description of this event is on See LbxCloseEvent.
LbxInvalidateTagEvent
1      base + 0      code
1      3      lbx type
2      CARD16      sequence number
4      CARD32      tag
4            tag-type
1      LbxTagTypeModmap
2      LbxTagTypeKeymap
3      LbxTagTypeProperty
4      LbxTagTypeFont
5      LbxTagTypeConnInfo
20            unused

   The description of this event is on See LbxInvalidateTagEvent.
LbxSendTagDataEvent
1      base + 0      code
1      4      lbx type
2      CARD16      sequence number
4      CARD32      tag
4            tag-type
3      LbxTagTypeProperty
20            unused

   The description of this event is on See LbxSendTagDataEvent.
LbxListenToOne
1      base + 0      code
1      5      lbx type
2      CARD16      sequence number
4      CARD32      client
#xFFFFFFFF
a client not managed by the proxy
24            unused

   The description of this event is on See LbxListenToOne.
LbxListenToAll
1      base + 0      code
1      6      lbx type
2      CARD16      sequence number
28            unused

   The description of this event is on See LbxListenToAll.
LbxQuickMotionDeltaEvent
1      base + 1      code
1      CARD8      delta-time
1      INT8      delta-x
1      INT8      delta-y

   This event is not padded to 32 bytes.

   The description of this event is on See
   LbxQuickMotionDeltaEvent.
LbxMotionDeltaEvent
1      base + 0      code
1      7                  lbx type
1      INT8      delta-x
1      INT8      delta-y
2      CARD16      delta-time
2      CARD16      delta-sequence

   This event is not padded to 32 bytes.

   The description of this event is on See LbxMotionDeltaEvent.
LbxReleaseCmapEvent
1      base + 0      code
1      8                  lbx type
2      CARD16      sequence number
4      COLORMAP      colormap
24            unused

   The description of this event is on See LbxReleaseCmapEvent.
LbxFreeCellsEvent
1      base + 0      code
1      9                  lbx type
2      CARD16      sequence number
4      COLORMAP      colormap
4      PIXEL      pixel start
4      PIXEL      pixel end
16            unused

   The description of this event is on See LbxFreeCellsEvent.

Re-encoding of X Events

   The X protocol requires all X events to be 32 bytes. The LBX
   server reduces the number of bytes sent between the server and
   the proxy for some X events by not appending unused pad bytes
   to the event data. The offsets of X event data are unchanged.
   The proxy will pad the events to 32 bytes before passing them
   on to the client.

   LBX reencodes X event representations into the following sizes,
   if squishing is enabled:
KeyOrButton            32
EnterOrLeave           32
Keymap                 32
Expose                 20
GraphicsExposure       24
NoExposure             12
VisibilityNotify       12
CreateNotify           24
DestroyNotify          12
UnmapNotify            16
MapNotify              16
MapRequest             12
Reparent               24
ConfigureNotify        28
ConfigureRequest       28
GravityNotify          16
ResizeRequest          12
Circulate              20
Property      Notify   20
SelectionClear         20
SelectionRequest       28
SelectionNotify        24
Colormap      Notify   16
MappingNotify          8
ClientMessage          32
Unknown                32

Responses

LbxDeltaResponse
1      event_base + 0      event code
1      2      lbx type
2      1+(2+2n+p)/4      request length
1      n      count of diffs
1      CARD8      cache index
2n      LISTofDIFFITEM      offsets and differences
p            unused, p=pad(2n)

   The description of this response is on See LbxDeltaResponse.
