259 lines
11 KiB
Plaintext
259 lines
11 KiB
Plaintext
xcb/proto
|
|
|
|
Description
|
|
===========
|
|
|
|
xcb/proto is a set of XML files describing the X Window System protocol
|
|
It is designed for use with libxcb, the X C binding
|
|
<http://xcb.freedesktop.org/>. xcb/proto consists of:
|
|
|
|
xcb.xsd An XML Schema defining the data format for describing the X
|
|
protocol.
|
|
|
|
*.py Code generator helpers that read the protocol descriptions
|
|
into python structures. See libxcb for example usage.
|
|
|
|
*.xml XML descriptions of the core X protocol and many extensions.
|
|
|
|
|
|
Generating C bindings
|
|
=====================
|
|
|
|
See libxcb <http://cgit.freedesktop.org/xcb/libxcb/>.
|
|
|
|
|
|
Protocol Description Format
|
|
===========================
|
|
|
|
Root element
|
|
------------
|
|
|
|
<xcb header="string" extension-name="string" extension-xname="string">
|
|
top-level elements
|
|
</xcb>
|
|
|
|
This is the root element of a protocol description. The attributes are all
|
|
various forms of the extension name. header is the basename of the XML
|
|
protocol description file, which will be used as the basename for generated
|
|
bindings as well. extension-name is the name of the extension in InterCaps,
|
|
which will be used in the names of functions. extension-xname is the name
|
|
of the extension as passed to QueryExtension.
|
|
|
|
As an example, the XML-XCB description for the GO-FASTER extension would use
|
|
the root element <xcb header="gofaster" extension-name="GoFaster"
|
|
extension-xname="GO-FASTER">; as a result, C bindings will be put in
|
|
gofaster.h and gofaster.c, extension functions will be named
|
|
XCBGoFasterFunctionName, and the extension initialization will call
|
|
QueryExtension with the name "GO-FASTER".
|
|
|
|
This element can contain any number of the elements listed in the section
|
|
"Top-Level Elements" below.
|
|
|
|
|
|
Top-Level Elements
|
|
------------------
|
|
|
|
<import>header_name</import>
|
|
|
|
The import element allows the protocol description to reference types
|
|
declared in another extension. The content is be the basename of the
|
|
extension XML file, which is also the header attribute of the extension's
|
|
root node. Note that types from xproto are automatically available, without
|
|
explicitly importing them.
|
|
|
|
<struct name="identifier">structure contents</struct>
|
|
|
|
This element represents a data structure. The name attribute gives the name
|
|
of the structure. The content represents the fields of the structure, and
|
|
consists of one or more of the field, pad, and list elements described in
|
|
the section "Structure Contents" below.
|
|
|
|
<union name="identifier">structure contents</union>
|
|
|
|
This element represents a union of data types, which can hold one value of
|
|
any of those types. The name attribute gives the name of the union. The
|
|
content represents the fields of the union, and consists of one or more of
|
|
the field and pad elements described in the section "Structure Contents
|
|
below".
|
|
|
|
<xidtype name="identifier" />
|
|
|
|
This element represents an identifier for a particular type of resource.
|
|
The name attribute gives the name of the new type.
|
|
|
|
<enum name="identifier">
|
|
<item name="identifier">[optional expression]</item>
|
|
...
|
|
</enum>
|
|
|
|
The enum element represents an enumeration type, which can take on any of
|
|
the values given by the contained item elements. The name attribute on the
|
|
enum gives the name of the enumerated type.
|
|
|
|
The item element represents one possible value of an enumerated type. The
|
|
name attribute on the item gives the name of that value, and the optional
|
|
content is an expression giving the numeric value. If the expression is
|
|
omitted, the value will be one more than that of the previous item, or 0 for
|
|
the first item.
|
|
|
|
<typedef oldname="identifier" newname="identifier" />
|
|
|
|
The typedef element declares the type given by the newname attribute to be
|
|
an alias for the type given by the oldname attribute.
|
|
|
|
<request name="identifier" opcode="integer" [combine-adjacent="true"]>
|
|
structure contents
|
|
[<reply>structure contents</reply>]
|
|
</request>
|
|
|
|
The request element represents an X protocol request. The name attribute
|
|
gives the name of the request, and the opcode attribute gives the numeric
|
|
request code. The content of the request element represents the fields in
|
|
the request, and consists of one or more of any of the elements listed in
|
|
the "Structure Contents" section below. Note that for requests in the core
|
|
protocol, the first field in the request goes into the one-byte gap between
|
|
the major opcode and the length; if the request does not have any data in
|
|
that gap, put a one byte pad as the first element. Extension requests
|
|
always have this gap filled with the minor opcode.
|
|
|
|
The optional reply element is present if the request has a reply. The
|
|
content of the reply element represents the fields in the reply, and
|
|
consists of zero or more of the field, pad, and list elements listed in the
|
|
"Structure Contents" section below. Note that the first field in the reply
|
|
always goes into the one-byte gap between the response type and the sequence
|
|
number; if the reply does not have any data in that gap, put a one byte pad
|
|
as the first element.
|
|
|
|
If the optional combine-adjacent attribute is true, multiple adjacent
|
|
requests of the same type may be combined into a single request without
|
|
affecting the semantics of the requests.
|
|
|
|
<event name="identifier" number="integer" [no-sequence-number="true"]>
|
|
structure contents
|
|
</event>
|
|
|
|
This element represents an X protocol event. The name attribute gives the
|
|
name of the event, and the number attribute gives the event number. The
|
|
content of the event element represents the fields in the event, and
|
|
consists of zero or more of the field, pad, and list elements listed in the
|
|
"Structure Contents" section below.
|
|
|
|
If the optional no-sequence-number attribute is true, the event does not
|
|
include a sequence number. This is a special-case for the KeymapNotify
|
|
event in the core protocol, and should not be used in any other event.
|
|
|
|
<error name="identifier" number="integer">
|
|
structure contents
|
|
</error>
|
|
|
|
This element represents an X protocol error. The name attribute gives the
|
|
name of the error, and the number attribute gives the error number. The
|
|
content of the error element represents the fields in the error, and
|
|
consists of zero or more of the field, pad, and list elements listed in the
|
|
"Structure Contents" section below.
|
|
|
|
<eventcopy name="identifier" number="identifier" ref="identifier" />
|
|
|
|
This element creates an alias for the event named in the ref attribute, with
|
|
the new name given in the name attribute, and the new event number given in
|
|
the number attribute.
|
|
|
|
<errorcopy name="identifier" number="identifier" ref="identifier" />
|
|
|
|
This element creates an alias for the error named in the ref attribute, with
|
|
the new name given in the name attribute, and the new error number given in
|
|
the number attribute.
|
|
|
|
|
|
Structure Contents
|
|
------------------
|
|
|
|
Note: "type" attributes below refer to types defined by previous elements,
|
|
either in the current extension, xproto, or one of the imported extensions.
|
|
The type name must refer to only one possible type; if more than one type
|
|
matches, an error occurs. To avoid this, the type may be explicitly prefixed
|
|
with a namespace, which should be the value of the header attribute on the
|
|
protocol description containing the desired type. The namespace and type are
|
|
separated by a single colon. For example, to refer to the PIXMAP type defined
|
|
in glx rather than the one defined in xproto, use type="glx:PIXMAP" rather
|
|
than type="PIXMAP".
|
|
|
|
Note: Most of the below may optionally contain an enum, altenum, or mask
|
|
attribute, which follows the above rules for "type". "enum" is an exhaustive
|
|
enum; the value is restricted to one of the constants named in the enum.
|
|
"altenum" may be one of the values contained in the enum, but it need not be.
|
|
"mask" refers to an enum to be used as a bitmask.
|
|
|
|
<pad bytes="integer" />
|
|
|
|
This element declares some padding in a data structure. The bytes
|
|
attribute declares the number of bytes of padding.
|
|
|
|
<field type="identifier" name="identifier" />
|
|
|
|
This element represents a field in a data structure. The type attribute
|
|
declares the data type of the field, and the name attribute gives the name
|
|
of the field.
|
|
|
|
<list type="identifier" name="identifier">expression</list>
|
|
|
|
This element represents an array or list of fields in a data structure. The
|
|
type attribute declares the data type of the field, and the name attribute
|
|
gives the name of the field. The content is an expression giving the length
|
|
of the list in terms of other fields in the structure. See the section
|
|
"Expressions" for details on the expression representation.
|
|
|
|
<localfield type="identifier" name="identifier" />
|
|
|
|
This element represents a parameter in a request that is not sent over the
|
|
wire. The field can be referenced in the length expressions of lists or in
|
|
an exprfield. The type attribute declares the data type of the field, and
|
|
the name attribute gives the name of the field.
|
|
|
|
<exprfield type="identifier" name="identifier">expression</exprfield>
|
|
|
|
This element represents a field in a request that is calculated rather than
|
|
supplied by the caller. The type attribute declares the data type of the
|
|
field, and the name attribute gives the name of the field. The content is
|
|
the expression giving the value of the field. See the section "Expressions"
|
|
for details on the expression representation.
|
|
|
|
<valueparam value-mask-type="identifier" value-mask-name="identifier"
|
|
value-list-name="identifier" />
|
|
|
|
This element represents a BITMASK/LISTofVALUE parameter pair: a bitmask
|
|
defining the set of values included, and a list containing these values.
|
|
value-mask-type gives the type of the bitmask; this must be CARD16 or
|
|
CARD32. value-mask-name gives the field name of the bitmask, and
|
|
value-list-name gives the field name of the list of values.
|
|
|
|
|
|
Expressions
|
|
-----------
|
|
|
|
Expressions consist of a tree of <op> elements with leaves consisting of
|
|
<fieldref> or <value> elements.
|
|
|
|
<op op="operator">expression expression</op>
|
|
|
|
The op element represents an operator, with the op attribute specifying
|
|
which operator. The supported operations are +, -, *, /, &, and
|
|
<<, and their semantics are identical to the corresponding operators
|
|
in C. The two operand expressions may be other expression elements.
|
|
|
|
<fieldref>identifier</fieldref>
|
|
|
|
The fieldref element represents a reference to the value of another field in
|
|
the structure containing this expression. The identifier is the value of
|
|
the "name" attribute on the referenced field.
|
|
|
|
<value>integer</value>
|
|
|
|
The value element represents a literal integer value in an expression. The
|
|
integer may be expressed in decimal or hexadecimal.
|
|
|
|
<bit>integer</bit>
|
|
|
|
The bit element represents a literal bitmask value in an expression.
|
|
The integer must be in the range 0..31, expanding to (1<<n) in C.
|