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xcb_query_tree
Section: XCB Requests (3)Updated: libxcb 1.12
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NAME
xcb_query_tree - query the window treeSYNOPSIS
#include <xcb/xproto.h>Request function
- xcb_query_tree_cookie_t xcb_query_tree(xcb_connection_t *conn, xcb_window_t window);
Reply datastructure
typedef struct xcb_query_tree_reply_t {
uint8_t response_type;
uint8_t pad0;
uint16_t sequence;
uint32_t length;
xcb_window_t root;
xcb_window_t parent;
uint16_t children_len;
uint8_t pad1[14];
} xcb_query_tree_reply_t;
Reply function
- xcb_query_tree_reply_t *xcb_query_tree_reply(xcb_connection_t *conn, xcb_query_tree_cookie_t cookie, xcb_generic_error_t **e);
Reply accessors
- xcb_window_t *xcb_query_tree_children(const xcb_query_tree_request_t *reply);
- int xcb_query_tree_children_length(const xcb_query_tree_reply_t *reply);
- xcb_generic_iterator_t xcb_query_tree_children_end(const xcb_query_tree_reply_t *reply);
REQUEST ARGUMENTS
- conn
- The XCB connection to X11.
- window
- The window to query.
REPLY FIELDS
- response_type
- The type of this reply, in this case XCB_QUERY_TREE. 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).
- root
- The root window of window.
- parent
- The parent window of window.
- children_len
- The number of child windows.
DESCRIPTION
Gets the root window ID, parent window ID and list of children windows for the specified window. The children are listed in bottom-to-top stacking order.RETURN VALUE
Returns an xcb_query_tree_cookie_t. Errors have to be handled when calling the reply function xcb_query_tree_reply.If you want to handle errors in the event loop instead, use xcb_query_tree_unchecked. See xcb-requests(3) for details.
ERRORS
This request does never generate any errors.EXAMPLE
/*
* Displays the root, parent and children of the specified window.
*
*/
void my_example(xcb_connection_t *conn, xcb_window_t window) {
xcb_query_tree_cookie_t cookie;
xcb_query_tree_reply_t *reply;
cookie = xcb_query_tree(conn, window);
if ((reply = xcb_query_tree_reply(conn, cookie, NULL))) {
printf("root = 0x%08x\n", reply->root);
printf("parent = 0x%08x\n", reply->parent);
xcb_window_t *children = xcb_query_tree_children(reply);
for (int i = 0; i < xcb_query_tree_children_length(reply); i++)
printf("child window = 0x%08x\n", children[i]);
free(reply);
}
}