xcb_query_extension - Man Page
check if extension is present
Synopsis
#include <xcb/xproto.h>
Request function
xcb_query_extension_cookie_t xcb_query_extension(xcb_connection_t *conn, uint16_t name_len, const char *name);
Reply datastructure
typedef struct xcb_query_extension_reply_t {
uint8_t response_type;
uint8_t pad0;
uint16_t sequence;
uint32_t length;
uint8_t present;
uint8_t major_opcode;
uint8_t first_event;
uint8_t first_error;
} xcb_query_extension_reply_t;Reply function
xcb_query_extension_reply_t *xcb_query_extension_reply(xcb_connection_t *conn, xcb_query_extension_cookie_t cookie, xcb_generic_error_t **e);
Request Arguments
- conn
The XCB connection to X11.
- name_len
The length of name in bytes.
- name
The name of the extension to query, for example "RANDR". This is case sensitive!
Reply Fields
- response_type
The type of this reply, in this case XCB_QUERY_EXTENSION. This field is also present in the xcb_generic_reply_t and can be used to tell replies apart from each other.
- sequence
The sequence number of the last request processed by the X11 server.
- length
The length of the reply, in words (a word is 4 bytes).
- present
Whether the extension is present on this X11 server.
- major_opcode
The major opcode for requests.
- first_event
The first event code, if any.
- first_error
The first error code, if any.
Description
Determines if the specified extension is present on this X11 server.
Every extension has a unique major_opcode to identify requests, the minor opcodes and request formats are extension-specific. If the extension provides events and errors, the first_event and first_error fields in the reply are set accordingly.
There should rarely be a need to use this request directly, XCB provides the xcb_get_extension_data function instead.
Return Value
Returns an xcb_query_extension_cookie_t. Errors have to be handled when calling the reply function xcb_query_extension_reply.
If you want to handle errors in the event loop instead, use xcb_query_extension_unchecked. See xcb-requests(3) for details.
Errors
This request does never generate any errors.
See Also
xcb-requests(3), xcb_get_extension_data(3), xdpyinfo(1)
Author
Generated from xproto.xml. Contact xcb@lists.freedesktop.org for corrections and improvements.
Referenced By
The man pages xcb_query_extension_reply(3) and xcb_query_extension_unchecked(3) are aliases of xcb_query_extension(3).