xcb_query_extension(3)

1xcb_query_extension(3)           XCB Requests           xcb_query_extension(3)
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NAME

6       xcb_query_extension - check if extension is present
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SYNOPSIS

9       #include <xcb/xproto.h>
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11   Request function
12       xcb_query_extension_cookie_t
13              xcb_query_extension(xcb_connection_t *conn, uint16_t name_len,
14              const char *name);
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16   Reply datastructure
17       typedef struct xcb_query_extension_reply_t {
18           uint8_t  response_type;
19           uint8_t  pad0;
20           uint16_t sequence;
21           uint32_t length;
22           uint8_t  present;
23           uint8_t  major_opcode;
24           uint8_t  first_event;
25           uint8_t  first_error;
26       } xcb_query_extension_reply_t;
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28   Reply function
29       xcb_query_extension_reply_t
30              *xcb_query_extension_reply(xcb_connection_t *conn,
31              xcb_query_extension_cookie_t cookie, xcb_generic_error_t **e);
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REQUEST ARGUMENTS

34       conn      The XCB connection to X11.
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36       name_len  The length of name in bytes.
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38       name      The name of the extension to query, for example "RANDR". This
39                 is case sensitive!
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REPLY FIELDS

42       response_type
43                 The type of this reply, in this case XCB_QUERY_EXTENSION.
44                 This field is also present in the xcb_generic_reply_t and can
45                 be used to tell replies apart from each other.
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47       sequence  The sequence number of the last request processed by the X11
48                 server.
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50       length    The length of the reply, in words (a word is 4 bytes).
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52       present   Whether the extension is present on this X11 server.
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54       major_opcode
55                 The major opcode for requests.
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57       first_event
58                 The first event code, if any.
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60       first_error
61                 The first error code, if any.
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DESCRIPTION

64       Determines if the specified extension is present on this X11 server.
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66       Every extension has a unique major_opcode to identify requests, the mi‐
67       nor opcodes and request formats are extension-specific. If the exten‐
68       sion provides events and errors, the first_event and first_error fields
69       in the reply are set accordingly.
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71       There should rarely be a need to use this request directly, XCB pro‐
72       vides the xcb_get_extension_data function instead.
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RETURN VALUE

75       Returns an xcb_query_extension_cookie_t. Errors have to be handled when
76       calling the reply function xcb_query_extension_reply.
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78       If you want to handle errors in the event loop instead, use
79       xcb_query_extension_unchecked. See xcb-requests(3) for details.
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ERRORS

82       This request does never generate any errors.
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AUTHOR

88       Generated from xproto.xml. Contact xcb@lists.freedesktop.org for cor‐
89       rections and improvements.
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93X Version 11                      libxcb 1.13           xcb_query_extension(3)