CD Actual 45/cda45.iso/Linux/XFree86-4.0/doc/recordlib.TXT

Text File | 2000-03-09 | 35.8 KB | 1,255 lines

         X Record Extension Library

            Version 1.13

           X Consortium Standard

         X Version 11, Release 6.4






            Martha Zimet
          Network Computing Devices, Inc.






             edited by
               Stephen Gildea
            X Consortium
















































Copyright (C) 1994 Network Computing Devices, Inc.

Permission to use, copy, modify, distribute, and sell this
documentation for any purpose is hereby granted without fee,
provided that the above copyright notice and this permission
notice appear in all copies.  Network Computing Devices,
Inc.  makes no representations about the suitability for any
purpose of the information in this document.  This documen-
tation is provided "as is" without express or implied war-
ranty.

Copyright (C) 1995  X Consortium

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documenta-
tion files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or
sell copies of the Software, and to permit persons to whom
the Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall
be included in all copies or substantial portions of the
Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PUR-
POSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE X CONSOR-
TIUM BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of the X Con-
sortium and shall not be used in advertising or otherwise to
promote the sale, use or other dealings in this Software
without prior written authorization from the X Consortium.









X11, Release 6.4     X Record Extension Library, Version 1.13


1.  Record Extension Overview

The purpose of this extension is to support the recording and
reporting of all core X protocol and arbitrary X extension proto-
col.  This first section gives an overview of the Record exten-
sion.  The following sections describe how to use the Record
extension library.

1.1.  Synchronous Playback

Environment information is generally provided to an X-based play-
back mechanism, which might use the XTest extension to synthesize
input events.  This synchronization information defines the X
state prior to event synthesis (for example, location of the cur-
sor, window locations and sizes, installed colormap, window man-
ager running, and so on) and the consequences that occur after
the playback mechanism synthesizes the event.  If the user moves
the mouse into the icon window and presses and releases a mouse
button, the device events MotionNotify, ButtonPress, and Button-
Release are generated by the X server.    Because X follows an
event-driven model, there are consequences that follow from the
user actions, or device events, that are in the form of X proto-
col.  As a result of the previous user actions, the client could
generate requests such as ImageText8 and PolyLine to the X
server, or the X server could send non-device events such as
Expose and MapNotify to the client window.  Both the requests and
non-device events that result from user actions are known as con-
sequences, which can be used as a synchronization, or control
point, during playback.  That is, the playback mechanism does not
generate a specific synthesized event until its matching synchro-
nization condition occurs (for example, the window is mapped or
unmapped, the cursor changes, a text string displays, and so on)

Because it cannot be predicted what synchronization information
is required during playback, the Record extension makes no
assumptions about the intended use of the recorded data.  Facili-
ties exist to record any core X protocol or X extension protocol.
Therefore, Record does not enforce a specific synchronization
methodology.

1.2.  Design Approach

The design approach of the extension is to record core X protocol
and arbitrary X extension protocol entirely within the X server
itself.  When the extension has been requested to record specific
protocol by one or more recording clients, the protocol data is
formatted and returned to the recording clients.  The extension
provides a mechanism for capturing all events, including input
device events that do not go to any clients.

1.3.  Record Clients

The recommended communication model for a Record application is
to open two connections to the server--one connection for



                1





X Record Extension Library, Version 1.13     X11, Release 6.4


recording control and one connection for reading recorded proto-
col data.

Information about recording (for example, what clients to record,
what protocol to record for each client, and so on) is stored in
resources called record contexts (type XRecordContext).  Most
Record extension functions take a record context as an argument.
Although in theory it is possible to share record contexts
between applications, it is expected that applications will use
their own context when performing recording operations.

A client that wishes to record X protocol does so through the
library functions defined in section 3 "Library Extension
Requests".  A typical sequence of requests that a client would
make is as follows:

o    XRecordQueryVersion - query the extension protocol version.

o    XRecordCreateContext - request that the server create a
     record context for access by this client, and express inter-
     est in clients and protocol to be recorded.  This request
     returns an XRecordContext, which is an XID that is used by
     most other extension requests to identify the specified con-
     text.

o    XRecordEnableContext - begin the recording and reporting of
     protocol data.

o    XRecordDisableContext - end the recording and reporting of
     protocol data.

o    XRecordFreeContext - free the record context.

The header for this library is <X11/extensions/record.h>.  All
identifiers defined in the interface are supplied by this header
and are prefixed with "XRecord".  The Xtst library contains the
XRecord functions.

2.  Common Arguments

The Record extension functions XRecordCreateContext and XRecord-
RegisterClients allow applications to specify the following:

o    Individual clients or sets of clients to record

o    Ranges of core X protocol and X extension protocol to record
     for each client

Protocol in the ranges specified by the recording client will be
recorded by the server.  The device_events protocol type can be
specified by a recording client although it may not be sent to a
recorded client.  The device_events type differs from deliv-
ered_events, which also can be specified by a recording client;
delivered_events are actually delivered to one or more clients.



                2





X11, Release 6.4     X Record Extension Library, Version 1.13


These event types are discussed in section 2.3 "Protocol Ranges".

The Record extension functions XRecordCreateContext and XRecord-
RegisterClients have the common arguments datum_flags, clients,
and ranges, which specify whether server time and/or client
sequence number should precede protocol elements, the clients or
client set to record, and the protocol ranges to record, respec-
tively.  These are discussed in the following sections.

2.1.  Datum Flags

The datum_flags argument is a set of flags OR'ed together to
specify options for the record context.  Specify zero to disable
all the options.

The XRecordFromServerTime flag specifies that XRecordIntercept-
Data structures with a category of XRecordFromServer will have a
server_time field specific to each protocol element.

The XRecordFromClientTime flag specifies that XRecordIntercept-
Data structures with a category of XRecordFromClient will have a
server_time field specific to each protocol element.

The XRecordFromClientSequence flag specifies that XRecord-
InterceptData structures with a category of XRecordFromClient or
XRecordClientDied will have a valid client_seq field.

2.2.  Selecting Clients

The clients argument is a pointer to an array of
XRecordClientSpec.  XRecordClientSpec is an integral type that
holds a resource ID, a client resource ID base, or one of the
client set constants defined below.

Duplicate elements in the array are ignored by the functions, and
if any element in the array is not valid, a BadMatch error
results.  A resource ID references the client that created that
resource.  The client set may be one of the following constants:
XRecordCurrentClients, XRecordFutureClients, or
XRecordAllClients.

If the element in the array identifies a particular client, pro-
tocol specified by the ranges argument will be recorded by the
server.  The recorded protocol data will not be returned to the
recording client until the record context has been enabled.  This
is described in section 3.4 "Data Transfer".

If the element is XRecordCurrentClients, the protocol ranges
specified by the ranges argument, except for device_events, are
associated with each current client connection.  If the element
is XRecordFutureClients, the protocol ranges specified by the
ranges argument are associated with each new client connection.
If the element is XRecordAllClients, the protocol ranges speci-
fied by the ranges argument are associated with each current



                3





X Record Extension Library, Version 1.13     X11, Release 6.4


client connection and with each new client connection.

When the context is enabled, the data connection is unregistered
if it was registered.  If the context is enabled, XRecordCurrent-
Clients and XRecordAllClients silently exclude the recording data
connection.  It is an error to explicitly register the data con-
nection.

2.3.  Protocol Ranges

The functions XRecordCreateContext and XRecordRegisterClients
have another common argument, ranges, which is an array of point-
ers to XRecordRange structures.  Each structure contains ranges
of numeric values for each of the protocol types that can be
specified and recorded individually by the Record extension.  An
XRecordRange structure must be allocated by the Record library
using the XRecordAllocRange function.

The XRecordRange typedef is a structure with the following mem-
bers:

__
|
XRecordRange:
     XRecordRange8 core_requests/* core X requests */
     XRecordRange8 core_replies/* core X replies */
     XRecordExtRange ext_requests/* extension requests */
     XRecordExtRange ext_replies/* extension replies */
     XRecordRange8 delivered_events/* delivered core and ext events */
     XRecordRange8 device_events/* all core and ext device events */
     XRecordRange8 errors     /* core X and X ext errors */
     Bool client_started      /* connection setup reply from server */
     Bool client_died          /* notification of client disconnect */

|__

The types used in XRecordRange members are defined as follows.
The XRecordRange8 typedef is a structure with the following mem-
bers:

__
|
XRecordRange8:
     unsigned char first
     unsigned char last

|__

The XRecordRange16 typedef is a structure with the following mem-
bers:







                4





X11, Release 6.4     X Record Extension Library, Version 1.13

__
|
XRecordRange16:
     unsigned short first
     unsigned short last

|__

The XRecordExtRange typedef is a structure with the following
members:

__
|
XRecordExtRange:
     XRecordRange8 ext_major
     XRecordRange16 ext_minor

|__

If any of the values specified in XRecordRange is invalid, a Bad-
Value error results.

The core_requests member specifies the range of core X protocol
requests to record.  Core X protocol requests with a major opcode
that is between first and last, inclusive, will be recorded.  A
BadValue error results if the value of first is greater than the
value of last.    If the values of both first and last are zero, no
core X protocol requests will be recorded.

The core_replies member specifies the range of replies resulting
from core X protocol requests to record.  Replies that result
from core X protocol requests with a major opcode between first
and last, inclusive, will be recorded.    A BadValue error results
if the value of first is greater than the value of last.  If the
values of both first and last are zero, no core X protocol
replies will be recorded.

The ext_requests member specifies the range of X extension
requests to record.  X extension requests with a major opcode
between ext_major.first and ext_major.last, and with a minor
opcode between ext_minor.first and ext_minor.last, inclusive,
will be recorded.  A BadValue error results if the value of
ext_major.first is greater than the value of ext_major.last or if
the value of ext_minor.first is greater than the value of
ext_minor.last.  If the values of both ext_major.first and
ext_major.last are zero, no X extension requests will be
recorded.

The ext_replies member specifies the range of replies resulting
from X extension requests to record.  Replies that result from an
X extension request with a major opcode between ext_major.first
and ext_major.last, and a minor opcode that is between
ext_minor.first and ext_minor.last will be recorded.  A BadValue
error results if the value of ext_major.first is greater than the
value of ext_major.last or if the value of ext_minor.first is



                5





X Record Extension Library, Version 1.13     X11, Release 6.4


greater than the value of ext_minor.last.  If the values of both
ext_major.first and ext_major.last are zero, no X extension
replies will be recorded.

The delivered_events member specifies the range of both core X
events and X extension events to record.  These events are deliv-
ered to at least one client.  Core X events and X extension
events with a code value between first and last inclusive will be
recorded.  A BadValue error results if the value of first is
greater than the value of last.  If the values of first and last
are zero, no events will be recorded.

The device_events member specifies the range of both core X
device events and X extension device events to record.    These
events may or may not be delivered to a client.  Core X device
events and X extension device events with a code value between
first and last inclusive that are not delivered to any clients
will be recorded.  A BadValue error results if the value of first
is greater than the value of last.  A BadValue error results if
first is less than two or last is less than two, except that if
first and last are zero, no events will be recorded.

The errors member specifies the range of both core X errors and X
extension errors to record.  Core X errors and X extension errors
with a code value between first and last inclusive will be
recorded.  A BadValue error results if the value of first is
greater than the value of last.  If the values of first and last
are zero, no errors will be recorded.

A value of True for the client_started member specifies the con-
nection setup reply from the server to new clients.  If False,
the connection setup reply is not specified by this XRecordRange.

A value of True for the client_died member specifies notification
when a client disconnects.  If False, notification when a client
disconnects is not specified by this XRecordRange.

3.  Library Extension Requests

Recording operations are accessed by programs through the use of
new protocol requests.    The following functions are provided as
extensions to Xlib.  An Xlib error results if an extension
request is made to an X server that does not support the Record
extension.  Note that any of the extension protocol requests may
generate BadAlloc or BadLength errors.

3.1.  Query Extension Version

An application uses the XRecordQueryVersion function to determine
the version of the Record extension protocol supported by an X
server.






                6





X11, Release 6.4     X Record Extension Library, Version 1.13

__
|
Status
XRecordQueryVersion(Display *display, int *cmajor_return, int *cminor_return)


display   Specifies the connection to the X server.

cmajor_return
      Returns the extension protocol major version in use.

cminor_return
      Returns the extension protocol minor version in use.
|__

The XRecordQueryVersion function returns the major and minor pro-
tocol version numbers supported by the server.    XRecordQuery-
Version returns nonzero (success) only if the returned version
numbers are common to both the library and the server; otherwise,
it returns zero.

3.2.  Create and Modify Context

An application uses the XRecordCreateContext function to create a
record context.  At the time the record context is created by the
recording client, the clients to be recorded and the protocol to
record for each client may be specified.

__
|
XRecordContext
XRecordCreateContext(Display *display, int datum_flags, XRecordClientSpec *clients, int nclients,
              XRecordRange **ranges, int nranges)


display   Specifies the connection to the X server.

datum_flags
      Specifies whether detailed time or sequence info should
      be sent.

clients   Specifies the clients to record.

nclients  Specifies the number of clients.

ranges      Specifies the protocol ranges to record.

nranges   Specifies the number of protocol ranges.
|__

The XRecordCreateContext function creates a record context and
returns an XRecordContext, which is then used in the other Record
library calls.    This request is typically executed by the record-
ing client over its control connection to the X server.  The
datum_flags specifies whether server time and/or client sequence



                7





X Record Extension Library, Version 1.13     X11, Release 6.4


number should precede protocol elements recorded by context (see
section 2.1).  When a clients element identifies a particular
client, the client is added to the context and the protocol to
record for that client is set to the union of all ranges.  When a
clients element is XRecordCurrentClients, XRecordFutureClients,
or XRecordAllClients, the actions described in section 2.2
"Selecting Clients" are performed.

XRecordCreateContext returns zero if the request failed.
XRecordCreateContext can generate BadIDChoice, BadMatch, and Bad-
Value errors.

The ranges argument is an XRecordRange* array, that is, an array
of pointers.  The structures the elements point to shall be allo-
cated by calling XRecordAllocRange.

__
|
XRecordRange *
XRecordAllocRange(void)

|__

The XRecordAllocRange function allocates and returns an XRecor-
dRange structure.  The structure is initialized to specify no
protocol.  The function returns NULL if the structure allocation
fails.    The application can free the structure by calling XFree.

3.2.1.    Additions

An application uses the XRecordRegisterClients function to modify
a previously created record context, by adding clients or modify-
ing the recorded protocol, typically over its control connection
to the X server.























                8





X11, Release 6.4     X Record Extension Library, Version 1.13

__
|
Status
XRecordRegisterClients(Display *display, XRecordContext context, int datum_flags,
        XRecordClientSpec *clients, int nclients, XRecordRange **ranges, int nranges)


display   Specifies the connection to the X server.

context   Specifies the record context to modify.

datum_flags
      Specifies whether detailed time or sequence info should
      be sent.

clients   Specifies the clients to record.

nclients  Specifies the number of clients.

ranges      Specifies the protocol ranges to record.

nranges   Specifies the number of protocol ranges.
|__

The datum_flags specifies whether server time and/or client
sequence number should precede protocol elements for all clients
recorded by context (see section 2.1).    When a clients element
identifies a particular client and the client is not yet targeted
for recording in the given context, the client is added to the
set of clients to record, and the protocol to record for that
client is set to the union of all ranges.  When the client is
already targeted for recording, the protocol to record for that
client is set to the union of all ranges.  When the element is
XRecordCurrentClients, XRecordFutureClients, or
XRecordAllClients, the actions described in section 2.2 "Select-
ing Clients" are performed.

XRecordRegisterClients returns zero if the request failed; other-
wise, it returns nonzero.

XRecordRegisterClients can generate XRecordBadContext, BadMatch,
and BadValue errors.

3.2.2.    Deletions

An application uses the XRecordUnregisterClients function to
delete clients from a previously created record context, typi-
cally over its control connection to the X server.










                9





X Record Extension Library, Version 1.13     X11, Release 6.4

__
|
Status
XRecordUnregisterClients(Display *display, XRecordContext context, RecordClientSpec *clients,
          int nclients)


display   Specifies the connection to the X server.

context   Specifies the record context to modify.

clients   Specifies the clients to stop recording.

nclients  Specifies the number of clients.
|__

When an element in clients identifies a particular client, and
the specified client is already targeted for recording in the
given context, the client and the set of protocol to record for
that client are deleted from the context.  If the specified
client is not targeted for recording, then no action is per-
formed.

When the element is XRecordCurrentClients, all clients currently
targeted for recording in context and their corresponding sets of
protocol to record are deleted from context.

When the item is XRecordFutureClients, any future client connec-
tions will not automatically be targeted for recording in con-
text.

When the element is XRecordAllClients, all clients currently tar-
geted for recording in context and their corresponding sets of
protocol to record are deleted from context.  Any future client
connections will not automatically be targeted for recording in
context.

XRecordUnregisterClients returns zero if the request failed; oth-
erwise, it returns nonzero.

XRecordUnregisterClients can generate XRecordBadContext,
BadMatch, and BadValue errors.

3.3.  Query Context State

An application uses the XRecordGetContext function to query the
current state of a record context, typically over its control
connection to the X server.










                10





X11, Release 6.4     X Record Extension Library, Version 1.13

__
|
Status
XRecordGetContext(Display *display, XRecordContext context, XRecordState **state_return)


display   Specifies the connection to the X server.

context   Specifies the record context to query.

state_return
      Specifies the address of a variable into which the
      function stores a pointer to the current state of the
      record context.
|__

The XRecordState typedef returned by XRecordGetContext is a
structure with the following members:

__
|
XRecordState:
     Bool enabled
     int datum_flags
     unsigned long nclients
     XRecordClientInfo **client_info

|__

The enabled member is set to the state of data transfer and is
True when the recording client has asked that recorded data be
sent; otherwise it is False.  The datum_flags member is set to
the value of these flags for this context.  The nclients member
is set to the number of XRecordClientInfo structures returned.
The client_info member is an array of pointers to XRecordCli-
entInfo structures that contain the protocol to record for each
targeted client.  The XRecordClientInfo typedef is a structure
with the following members:

__
|
XRecordClientInfo:
     XRecordClientSpec client
     unsigned long nranges
     XRecordRange **ranges

|__

The client member either identifies a client targeted for record-
ing or is set to XRecordFutureClients to describe how future
clients will be automatically targeted for recording.  The
nranges member is set to the number of protocol ranges to be
recorded for the specified client.  The ranges member is an array
of pointers to XRecordRange structures, which specify the proto-
col ranges to record.



                11





X Record Extension Library, Version 1.13     X11, Release 6.4


XRecordGetContext returns zero if the request failed; otherwise,
it returns nonzero.  The context argument must specify a valid
XRecordContext or a XRecordBadContext error results.

Recording clients should use the XRecordFreeState function to
free the state data returned by XRecordGetContext.

__
|
void
XRecordFreeState(XRecordState *state)


state      Specifies the structure that is to be freed.
|__

XRecordFreeState frees the data pointed to by state.  If the
argument does not match an XRecordState pointer returned from a
successful call to XRecordGetContext, or if XRecordFreeState has
already been called with it, the behavior is undefined.

3.4.  Data Transfer

An application uses the XRecordEnableContext and XRecordDisable-
Context functions to change the state of data transfer between
the X server and the recording client.    These functions allow the
application to start recording and reporting of protocol data and
to stop recording and reporting of protocol data, respectively.

3.4.1.    Enable Context

To direct the X server to record and report protocol, a program
uses XRecordEnableContext, typically over its data connection to
the X server.  The reporting of recorded protocol back to the
recording client is handled by the following data structures and
procedure definitions.    Each recorded protocol element is
reported to the recording client through an XRecordInterceptData
typedef, a structure with the following members:

__
|
XRecordInterceptData:
  XID id_base
  Time server_time
  unsigned long client_seq
  int category
  Bool client_swapped
  unsigned char *data
  unsigned long data_len

|__

The id_base member is set to the resource identifier base sent to
the client in the connection setup reply and therefore identifies



                12





X11, Release 6.4     X Record Extension Library, Version 1.13


the client being recorded, except when the recorded protocol data
is a device event that may have not been delivered to a client.
In this case, id_base is set to zero.  The server_time member is
set to the time of the server when the protocol was recorded.  It
is the time that was attached to this protocol element in the
reply, if so specified by datum_flags, or else the time from the
header of the reply that contained this protocol element.  The
client_seq member is the sequence number of the recorded client's
most recent request processed by the server at the time this pro-
tocol element was recorded, if this information were included in
the recorded data; otherwise client_seq is 0.  The category mem-
ber is set to one of the following values: XRecordStartOfData,
XRecordFromServer, XRecordFromClient, XRecordClientStarted,
XRecordClientDied, or XRecordEndOfData.  XRecordStartOfData is
immediately sent as the first reply to confirm that the context
is enabled.  XRecordFromClient indicates the protocol data is
from the recorded client to the server (requests).  XRecordFrom-
Server indicates the protocol data is from the server to the
recorded client (replies, errors, events, or device events).
XRecordClientStarted indicates that the protocol data is the con-
nection setup reply from the server.  XRecordClientDied indicates
that the recorded client has closed its connection to the X
server; there is no protocol data.  XRecordEndOfData indicates
that the context has been disabled and that this is the last
datum.    It does not correspond to any protocol or state change in
a recorded client.  There is no protocol data.

The client_swapped member is set to True if the byte order of the
client being recorded is swapped relative to the recording
client; otherwise, it is set to False.    All recorded protocol
data is returned in the byte order of the recorded client.
Therefore, recording clients are responsible for all byte swap-
ping, if required.  Device events are in the byte order of the
recording client.  For replies of category XRecordStartOfData and
XRecordEndOfData, client_swapped is set according to the byte
order of the server relative to the recording client.

The data member contains the actual recorded protocol data.  When
category is set to XRecordStartOfData, XRecordClientDied, or
XRecordEndOfData, no protocol data are contained in data.

For the core X events KeyPress, KeyRelease, ButtonPress, and
ButtonRelease, the fields of a device event that contain valid
information are time and detail.  For the core X event
MotionNotify, the fields of a device event that contain valid
information are time, root, root-x and root-y.    The time field
refers to the time the event was generated by the device.

For the extension input device events DeviceKeyPress,
DeviceKeyRelease, DeviceButtonPress, and DeviceButtonRelease, the
fields of a device event that contain valid information are
device, time, and detail.  For DeviceMotionNotify, the valid
device event fields are device and time.  For the extension input
device events ProximityIn and ProximityOut, the fields of a



                13





X Record Extension Library, Version 1.13     X11, Release 6.4


device event that contain valid information are device and time.
For the extension input device event DeviceValuator, the fields
of a device event that contain valid information are device,
num_valuators, first_valuator, and valuators.  The time field
refers to the time the event was generated by the device.

The data_len member is set to the length of the actual recorded
protocol data in 4-byte units.

When the context has been enabled, protocol data the recording
client has previously expressed interest in is recorded and
returned to the recording client via multiple replies.    Because
the X server batches the recorded data, more than one protocol
element may be contained in the same reply packet.  When a reply
is received, a procedure of type XRecordInterceptProc is called
for each protocol element in the reply.

__
|
typedef void(*XRecordInterceptProc)
     (XPointer closure, XRecordInterceptData *recorded_data)


closure   Pointer that was passed in when the context was
      enabled.

recorded_data
      A protocol element recorded by the server extension.
|__

This callback may use the control display connection (or any dis-
play connection other than the data connection).

Recording clients should use the XRecordFreeData function to free
the XRecordInterceptData structure.

__
|
Status
XRecordEnableContext(Display *display, XRecordContext context, XRecordInterceptProc callback,
            XPointer closure)


display   Specifies the connection to the X server.

context   Specifies the record context to enable.

callback  Specifies the function to be called for each protocol
      element received.

closure   Specifies data passed to callback.
|__

XRecordEnableContext enables data transfer between the recording



                14





X11, Release 6.4     X Record Extension Library, Version 1.13


client and the X server.  All core and extension protocol
received from or sent to targeted clients that the recording
client has expressed interest in will be recorded and reported to
the recording client.

XRecordEnableContext returns zero if the request failed; other-
wise, it returns nonzero.  The context argument must specify a
valid XRecordContext or a XRecordBadContext error results.  The
error BadMatch results when data transfer is already enabled on
the given context.

3.4.2.    Enable Context Asynchronously

Because XRecordEnableContext does not return until XRecordDis-
ableContext is executed on the control connection, a nonblocking
interface in addition to XRecordEnableContext is provided.  This
interface also enables data transfer; however, it does not block.

This interface is defined as follows:

__
|
Status
XRecordEnableContextAsync(Display *display, XRecordContext context,
               XRecordInterceptProc callback, XPointer closure)


display   Specifies the connection to the X server.

context   Specifies the record context to enable.

callback  Specifies the function to be called for each protocol
      element received.

closure   Data passed to callback.
|__

XRecordEnableContextAsync enables data transfer between the
recording client and the X server just as XRecordEnableContext
does.  Unlike XRecordEnableContext, it does not wait for the con-
text to be disabled before returning; XRecordEnableContextAsync
returns as soon as the XRecordStartOfData reply has been received
and processed.

XRecordEnableContextAsync returns zero if it could not allocate
the necessary memory and nonzero if it sent the request success-
fully to the server.  The context argument must specify a valid
XRecordContext or a XRecordBadContext error results.  The error
BadMatch results when data transfer is already enabled.

Each time it reads data from the server connection, Xlib will
check for incoming replies and call callback as necessary.  The
application may direct Xlib explicitly to check for Record data
with the XRecordProcessReplies function.



                15





X Record Extension Library, Version 1.13     X11, Release 6.4

__
|
void
XRecordProcessReplies(Display *display)


display    Specifies the connection to the X server.
|__

XRecordProcessReplies will check for any replies that have not
yet been processed by the application.    The asynchronous callback
will be called as appropriate.    XRecordProcessReplies returns
when all immediately available replies have been processed.  It
does not block.


To free the data passed to the XRecordInterceptProc callback, use
XRecordFreeData.

__
|
void
XRecordFreeData(XRecordInterceptData *data)


data      Specifies the structure that is to be freed.
|__

XRecordFreeData frees the data pointed to by data.  If the argu-
ment does not match an XRecordInterceptData pointer earlier
passed to an XRecordInterceptProc callback or if XRecordFreeData
has already been called with it, the behavior is undefined.

3.4.3.    Disable Context

To direct the X server to halt the reporting of recorded proto-
col, the program executes XRecordDisableContext, typically over
its control connection to the X server.

__
|
Status
XRecordDisableContext(Display *display, XRecordContext context)


display   Specifies the connection to the X server.

context   Specifies the record context to disable.
|__

The XRecordDisableContext function disables context, stopping all
recording over its data connection.  Any complete protocol ele-
ments for context that were buffered in the server will be sent
to the recording client rather than being discarded.  If a pro-
gram attempts to disable an XRecordContext that has not been



                16





X11, Release 6.4     X Record Extension Library, Version 1.13


enabled, no action will take place.

XRecordDisableContext returns zero if the request failed; other-
wise, it returns nonzero.  The context argument must specify a
valid XRecordContext or an XRecordBadContext error results.

3.5.  ID Base Mask

To determine the mask the server uses for the client ID base, use
XRecordIdBaseMask.

__
|
XID
XRecordIdBaseMask(Display *display)


display   Specifies the connection to the X server.
|__

The XRecordIdBaseMask function returns the resource ID mask
passed to the client by the server at connection setup.

3.6.  Free Context

Before terminating, the program should request that the server
free the record context.  This is done with the XRecordFreeCon-
text function, typically over the record client's control connec-
tion to the X server.

__
|
Status
XRecordFreeContext(Display *display, XRecordContext context)


display   Specifies the connection to the X server.

context   Specifies the record context to free.
|__

The XRecordFreeContext function frees the given context for the
requesting client.  Freeing a record context releases the clients
targeted for recording and their respective protocol ranges to
record.  If protocol data is being reported to the recording
client, generally over the data connection to the X server, the
reporting ceases as if XRecordDisableContext had been called on
the given context.  When a program terminates without freeing its
record context, the X server will automatically free that context
on behalf of the client.

XRecordFreeContext returns zero if the request failed; other-
wise,it returns nonzero.  The context argument must specify a
valid XRecordContext or a XRecordBadContext error results.



                17