xcb_query_tree_children_length(3)

1xcb_query_tree(3)                XCB Requests                xcb_query_tree(3)
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NAME

6       xcb_query_tree - query the window tree
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SYNOPSIS

9       #include <xcb/xproto.h>
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11   Request function
12       xcb_query_tree_cookie_t xcb_query_tree(xcb_connection_t *conn,
13              xcb_window_t window);
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15   Reply datastructure
16       typedef struct xcb_query_tree_reply_t {
17           uint8_t      response_type;
18           uint8_t      pad0;
19           uint16_t     sequence;
20           uint32_t     length;
21           xcb_window_t root;
22           xcb_window_t parent;
23           uint16_t     children_len;
24           uint8_t      pad1[14];
25       } xcb_query_tree_reply_t;
26
27   Reply function
28       xcb_query_tree_reply_t *xcb_query_tree_reply(xcb_connection_t *conn,
29              xcb_query_tree_cookie_t cookie, xcb_generic_error_t **e);
30
31   Reply accessors
32       xcb_window_t *xcb_query_tree_children(const xcb_query_tree_request_t
33              *reply);
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35       int xcb_query_tree_children_length(const xcb_query_tree_reply_t
36              *reply);
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38       xcb_generic_iterator_t xcb_query_tree_children_end(const
39              xcb_query_tree_reply_t *reply);
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REQUEST ARGUMENTS

42       conn      The XCB connection to X11.
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44       window    The window to query.
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REPLY FIELDS

47       response_type
48                 The type of this reply, in this case XCB_QUERY_TREE. This
49                 field is also present in the xcb_generic_reply_t and can be
50                 used to tell replies apart from each other.
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52       sequence  The sequence number of the last request processed by the X11
53                 server.
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55       length    The length of the reply, in words (a word is 4 bytes).
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57       root      The root window of window.
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59       parent    The parent window of window.
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61       children_len
62                 The number of child windows.
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DESCRIPTION

65       Gets the root window ID, parent window ID and list of children windows
66       for the specified window. The children are listed in bottom-to-top
67       stacking order.
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RETURN VALUE

70       Returns an xcb_query_tree_cookie_t. Errors have to be handled when
71       calling the reply function xcb_query_tree_reply.
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73       If you want to handle errors in the event loop instead, use
74       xcb_query_tree_unchecked. See xcb-requests(3) for details.
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ERRORS

77       This request does never generate any errors.
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EXAMPLE

80       /*
81        * Displays the root, parent and children of the specified window.
82        *
83        */
84       void my_example(xcb_connection_t *conn, xcb_window_t window) {
85           xcb_query_tree_cookie_t cookie;
86           xcb_query_tree_reply_t *reply;
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88           cookie = xcb_query_tree(conn, window);
89           if ((reply = xcb_query_tree_reply(conn, cookie, NULL))) {
90               printf("root = 0x%08x\n", reply->root);
91               printf("parent = 0x%08x\n", reply->parent);
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93               xcb_window_t *children = xcb_query_tree_children(reply);
94               for (int i = 0; i < xcb_query_tree_children_length(reply); i++)
95                   printf("child window = 0x%08x\n", children[i]);
96
97               free(reply);
98           }
99       }
100

AUTHOR

105       Generated from xproto.xml. Contact xcb@lists.freedesktop.org for cor‐
106       rections and improvements.
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110X Version 11                      libxcb 1.13                xcb_query_tree(3)