xcb_query_extension_unchecked3
Check if extension is present
Part of xcb_query_extension(3).
Usage
Request function
xcb_query_extension_cookie_t xcb_query_extension(xcb_connection_t
*conn,
uint16_t
name_len,
const
char
*name);
Reply datastructure
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;
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.
Overview
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.
Releases
6 releases since Debian 9 (Stretch); the text changed 4 times.