Fix documentation of xcb_poll_for_event()

[free-sw/xcb/libxcb] / src / xcb.h

/*
 * Copyright (C) 2001-2006 Bart Massey, Jamey Sharp, and Josh Triplett.
 * All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the names of the authors or their
 * institutions shall not be used in advertising or otherwise to promote the
 * sale, use or other dealings in this Software without prior written
 * authorization from the authors.
 */

#ifndef __XCB_H__
#define __XCB_H__
#include <sys/types.h>

#if defined(__solaris__)
#include <inttypes.h>
#else
#include <stdint.h>
#endif

#ifndef _WIN32
#include <sys/uio.h>
#else
#include "xcb_windefs.h"
#endif
#include <pthread.h>


#ifdef __cplusplus
extern "C" {
#endif

/**
 * @file xcb.h
 */

/**
 * @defgroup XCB_Core_API XCB Core API
 * @brief Core API of the XCB library.
 *
 * @{
 */

/* Pre-defined constants */

/** Current protocol version */
#define X_PROTOCOL 11

/** Current minor version */
#define X_PROTOCOL_REVISION 0

/** X_TCP_PORT + display number = server port for TCP transport */
#define X_TCP_PORT 6000

/** xcb connection errors because of socket, pipe and other stream errors. */
#define XCB_CONN_ERROR 1

/** xcb connection shutdown because of extension not supported */
#define XCB_CONN_CLOSED_EXT_NOTSUPPORTED 2

/** malloc(), calloc() and realloc() error upon failure, for eg ENOMEM */
#define XCB_CONN_CLOSED_MEM_INSUFFICIENT 3

/** Connection closed, exceeding request length that server accepts. */
#define XCB_CONN_CLOSED_REQ_LEN_EXCEED 4

/** Connection closed, error during parsing display string. */
#define XCB_CONN_CLOSED_PARSE_ERR 5

/** Connection closed because the server does not have a screen matching the display. */
#define XCB_CONN_CLOSED_INVALID_SCREEN 6

#define XCB_TYPE_PAD(T,I) (-(I) & (sizeof(T) > 4 ? 3 : sizeof(T) - 1))

/* Opaque structures */

/**
 * @brief XCB Connection structure.
 *
 * A structure that contain all data that  XCB needs to communicate with an X server.
 */
typedef struct xcb_connection_t xcb_connection_t;  /**< Opaque structure containing all data that  XCB needs to communicate with an X server. */


/* Other types */

/**
 * @brief Generic iterator.
 *
 * A generic iterator structure.
 */
typedef struct {
    void *data;   /**< Data of the current iterator */
    int rem;    /**< remaining elements */
    int index;  /**< index of the current iterator */
} xcb_generic_iterator_t;

/**
 * @brief Generic reply.
 *
 * A generic reply structure.
 */
typedef struct {
    uint8_t   response_type;  /**< Type of the response */
    uint8_t  pad0;           /**< Padding */
    uint16_t sequence;       /**< Sequence number */
    uint32_t length;         /**< Length of the response */
} xcb_generic_reply_t;

/**
 * @brief Generic event.
 *
 * A generic event structure.
 */
typedef struct {
    uint8_t   response_type;  /**< Type of the response */
    uint8_t  pad0;           /**< Padding */
    uint16_t sequence;       /**< Sequence number */
    uint32_t pad[7];         /**< Padding */
    uint32_t full_sequence;  /**< full sequence */
} xcb_generic_event_t;

/**
 * @brief GE event
 *
 * An event as sent by the XGE extension. The length field specifies the
 * number of 4-byte blocks trailing the struct.
 */
typedef struct {
    uint8_t  response_type;  /**< Type of the response */
    uint8_t  pad0;           /**< Padding */
    uint16_t sequence;       /**< Sequence number */
    uint32_t length;
    uint16_t event_type;
    uint16_t pad1;
    uint32_t pad[5];         /**< Padding */
    uint32_t full_sequence;  /**< full sequence */
} xcb_ge_event_t;

/**
 * @brief Generic error.
 *
 * A generic error structure.
 */
typedef struct {
    uint8_t   response_type;  /**< Type of the response */
    uint8_t   error_code;     /**< Error code */
    uint16_t sequence;       /**< Sequence number */
    uint32_t resource_id;     /** < Resource ID for requests with side effects only */
    uint16_t minor_code;      /** < Minor opcode of the failed request */
    uint8_t major_code;       /** < Major opcode of the failed request */
    uint8_t pad0;
    uint32_t pad[5];         /**< Padding */
    uint32_t full_sequence;  /**< full sequence */
} xcb_generic_error_t;

/**
 * @brief Generic cookie.
 *
 * A generic cookie structure.
 */
typedef struct {
    unsigned int sequence;  /**< Sequence number */
} xcb_void_cookie_t;


/* Include the generated xproto header. */
#include "xproto.h"


/** XCB_NONE is the universal null resource or null atom parameter value for many core X requests */
#define XCB_NONE 0L

/** XCB_COPY_FROM_PARENT can be used for many xcb_create_window parameters */
#define XCB_COPY_FROM_PARENT 0L

/** XCB_CURRENT_TIME can be used in most requests that take an xcb_timestamp_t */
#define XCB_CURRENT_TIME 0L

/** XCB_NO_SYMBOL fills in unused entries in xcb_keysym_t tables */
#define XCB_NO_SYMBOL 0L


/* xcb_auth.c */

/**
 * @brief Container for authorization information.
 *
 * A container for authorization information to be sent to the X server.
 */
typedef struct xcb_auth_info_t {
    int   namelen;  /**< Length of the string name (as returned by strlen). */
    char *name;     /**< String containing the authentication protocol name, such as "MIT-MAGIC-COOKIE-1" or "XDM-AUTHORIZATION-1". */
    int   datalen;  /**< Length of the data member. */
    char *data;   /**< Data interpreted in a protocol-specific manner. */
} xcb_auth_info_t;


/* xcb_out.c */

/**
 * @brief Forces any buffered output to be written to the server.
 * @param c: The connection to the X server.
 * @return > @c 0 on success, <= @c 0 otherwise.
 *
 * Forces any buffered output to be written to the server. Blocks
 * until the write is complete.
 */
int xcb_flush(xcb_connection_t *c);

/**
 * @brief Returns the maximum request length that this server accepts.
 * @param c: The connection to the X server.
 * @return The maximum request length field.
 *
 * In the absence of the BIG-REQUESTS extension, returns the
 * maximum request length field from the connection setup data, which
 * may be as much as 65535. If the server supports BIG-REQUESTS, then
 * the maximum request length field from the reply to the
 * BigRequestsEnable request will be returned instead.
 *
 * Note that this length is measured in four-byte units, making the
 * theoretical maximum lengths roughly 256kB without BIG-REQUESTS and
 * 16GB with.
 */
uint32_t xcb_get_maximum_request_length(xcb_connection_t *c);

/**
 * @brief Prefetch the maximum request length without blocking.
 * @param c: The connection to the X server.
 *
 * Without blocking, does as much work as possible toward computing
 * the maximum request length accepted by the X server.
 *
 * Invoking this function may cause a call to xcb_big_requests_enable,
 * but will not block waiting for the reply.
 * xcb_get_maximum_request_length will return the prefetched data
 * after possibly blocking while the reply is retrieved.
 *
 * Note that in order for this function to be fully non-blocking, the
 * application must previously have called
 * xcb_prefetch_extension_data(c, &xcb_big_requests_id) and the reply
 * must have already arrived.
 */
void xcb_prefetch_maximum_request_length(xcb_connection_t *c);


/* xcb_in.c */

/**
 * @brief Returns the next event or error from the server.
 * @param c: The connection to the X server.
 * @return The next event from the server.
 *
 * Returns the next event or error from the server, or returns null in
 * the event of an I/O error. Blocks until either an event or error
 * arrive, or an I/O error occurs.
 */
xcb_generic_event_t *xcb_wait_for_event(xcb_connection_t *c);

/**
 * @brief Returns the next event or error from the server.
 * @param c: The connection to the X server.
 * @return The next event from the server.
 *
 * Returns the next event or error from the server, if one is
 * available, or returns @c NULL otherwise. If no event is available, that
 * might be because an I/O error like connection close occurred while
 * attempting to read the next event, in which case the connection is
 * shut down when this function returns.
 */
xcb_generic_event_t *xcb_poll_for_event(xcb_connection_t *c);

/**
 * @brief Returns the next event without reading from the connection.
 * @param c: The connection to the X server.
 * @return The next already queued event from the server.
 *
 * This is a version of xcb_poll_for_event that only examines the
 * event queue for new events. The function doesn't try to read new
 * events from the connection if no queued events are found.
 *
 * This function is useful for callers that know in advance that all
 * interesting events have already been read from the connection. For
 * example, callers might use xcb_wait_for_reply and be interested
 * only of events that preceded a specific reply.
 */
xcb_generic_event_t *xcb_poll_for_queued_event(xcb_connection_t *c);

/**
 * @brief Return the error for a request, or NULL if none can ever arrive.
 * @param c: The connection to the X server.
 * @param cookie: The request cookie.
 * @return The error for the request, or NULL if none can ever arrive.
 *
 * The xcb_void_cookie_t cookie supplied to this function must have resulted
 * from a call to xcb_[request_name]_checked().  This function will block
 * until one of two conditions happens.  If an error is received, it will be
 * returned.  If a reply to a subsequent request has already arrived, no error
 * can arrive for this request, so this function will return NULL.
 *
 * Note that this function will perform a sync if needed to ensure that the
 * sequence number will advance beyond that provided in cookie; this is a
 * convenience to avoid races in determining whether the sync is needed.
 */
xcb_generic_error_t *xcb_request_check(xcb_connection_t *c, xcb_void_cookie_t cookie);

/**
 * @brief Discards the reply for a request.
 * @param c: The connection to the X server.
 * @param sequence: The request sequence number from a cookie.
 *
 * Discards the reply for a request. Additionally, any error generated
 * by the request is also discarded (unless it was an _unchecked request
 * and the error has already arrived).
 *
 * This function will not block even if the reply is not yet available.
 *
 * Note that the sequence really does have to come from an xcb cookie;
 * this function is not designed to operate on socket-handoff replies.
 */
void xcb_discard_reply(xcb_connection_t *c, unsigned int sequence);


/* xcb_ext.c */

/**
 * @typedef typedef struct xcb_extension_t xcb_extension_t
 */
typedef struct xcb_extension_t xcb_extension_t;  /**< Opaque structure used as key for xcb_get_extension_data_t. */

/**
 * @brief Caches reply information from QueryExtension requests.
 * @param c: The connection.
 * @param ext: The extension data.
 * @return A pointer to the xcb_query_extension_reply_t for the extension.
 *
 * This function is the primary interface to the "extension cache",
 * which caches reply information from QueryExtension
 * requests. Invoking this function may cause a call to
 * xcb_query_extension to retrieve extension information from the
 * server, and may block until extension data is received from the
 * server.
 *
 * The result must not be freed. This storage is managed by the cache
 * itself.
 */
const xcb_query_extension_reply_t *xcb_get_extension_data(xcb_connection_t *c, xcb_extension_t *ext);

/**
 * @brief Prefetch of extension data into the extension cache
 * @param c: The connection.
 * @param ext: The extension data.
 *
 * This function allows a "prefetch" of extension data into the
 * extension cache. Invoking the function may cause a call to
 * xcb_query_extension, but will not block waiting for the
 * reply. xcb_get_extension_data will return the prefetched data after
 * possibly blocking while it is retrieved.
 */
void xcb_prefetch_extension_data(xcb_connection_t *c, xcb_extension_t *ext);


/* xcb_conn.c */

/**
 * @brief Access the data returned by the server.
 * @param c: The connection.
 * @return A pointer to an xcb_setup_t structure.
 *
 * Accessor for the data returned by the server when the xcb_connection_t
 * was initialized. This data includes
 * - the server's required format for images,
 * - a list of available visuals,
 * - a list of available screens,
 * - the server's maximum request length (in the absence of the
 * BIG-REQUESTS extension),
 * - and other assorted information.
 *
 * See the X protocol specification for more details.
 *
 * The result must not be freed.
 */
const xcb_setup_t *xcb_get_setup(xcb_connection_t *c);

/**
 * @brief Access the file descriptor of the connection.
 * @param c: The connection.
 * @return The file descriptor.
 *
 * Accessor for the file descriptor that was passed to the
 * xcb_connect_to_fd call that returned @p c.
 */
int xcb_get_file_descriptor(xcb_connection_t *c);

/**
 * @brief Test whether the connection has shut down due to a fatal error.
 * @param c: The connection.
 * @return > 0 if the connection is in an error state; 0 otherwise.
 *
 * Some errors that occur in the context of an xcb_connection_t
 * are unrecoverable. When such an error occurs, the
 * connection is shut down and further operations on the
 * xcb_connection_t have no effect.
 *
 * @return XCB_CONN_ERROR, because of socket errors, pipe errors or other stream errors.
 * @return XCB_CONN_CLOSED_EXT_NOTSUPPORTED, when extension not supported.
 * @return XCB_CONN_CLOSED_MEM_INSUFFICIENT, when memory not available.
 * @return XCB_CONN_CLOSED_REQ_LEN_EXCEED, exceeding request length that server accepts.
 * @return XCB_CONN_CLOSED_PARSE_ERR, error during parsing display string.
 * @return XCB_CONN_CLOSED_INVALID_SCREEN, because the server does not have a screen matching the display.
 */
int xcb_connection_has_error(xcb_connection_t *c);

/**
 * @brief Connects to the X server.
 * @param fd: The file descriptor.
 * @param auth_info: Authentication data.
 * @return A newly allocated xcb_connection_t structure.
 *
 * Connects to an X server, given the open socket @p fd and the
 * xcb_auth_info_t @p auth_info. The file descriptor @p fd is
 * bidirectionally connected to an X server. If the connection
 * should be unauthenticated, @p auth_info must be @c
 * NULL.
 */
xcb_connection_t *xcb_connect_to_fd(int fd, xcb_auth_info_t *auth_info);

/**
 * @brief Closes the connection.
 * @param c: The connection.
 *
 * Closes the file descriptor and frees all memory associated with the
 * connection @c c.
 */
void xcb_disconnect(xcb_connection_t *c);


/* xcb_util.c */

/**
 * @brief Parses a display string name in the form documented by X(7x).
 * @param name: The name of the display.
 * @param host: A pointer to a malloc'd copy of the hostname.
 * @param display: A pointer to the display number.
 * @param screen: A pointer to the screen number.
 * @return 0 on failure, non 0 otherwise.
 *
 * Parses the display string name @p display_name in the form
 * documented by X(7x). Has no side effects on failure. If
 * @p displayname is @c NULL or empty, it uses the environment
 * variable DISPLAY. @p hostp is a pointer to a newly allocated string
 * that contain the host name. @p displayp is set to the display
 * number and @p screenp to the preferred screen number. @p screenp
 * can be @c NULL. If @p displayname does not contain a screen number,
 * it is set to @c 0.
 */
int xcb_parse_display(const char *name, char **host, int *display, int *screen);

/**
 * @brief Connects to the X server.
 * @param displayname: The name of the display.
 * @param screenp: A pointer to a preferred screen number.
 * @return A newly allocated xcb_connection_t structure.
 *
 * Connects to the X server specified by @p displayname. If @p
 * displayname is @c NULL, uses the value of the DISPLAY environment
 * variable. If a particular screen on that server is preferred, the
 * int pointed to by @p screenp (if not @c NULL) will be set to that
 * screen; otherwise the screen will be set to 0.
 */
xcb_connection_t *xcb_connect(const char *displayname, int *screenp);

/**
 * @brief Connects to the X server, using an authorization information.
 * @param display: The name of the display.
 * @param auth: The authorization information.
 * @param screen: A pointer to a preferred screen number.
 * @return A newly allocated xcb_connection_t structure.
 *
 * Connects to the X server specified by @p displayname, using the
 * authorization @p auth. If a particular screen on that server is
 * preferred, the int pointed to by @p screenp (if not @c NULL) will
 * be set to that screen; otherwise @p screenp will be set to 0.
 */
xcb_connection_t *xcb_connect_to_display_with_auth_info(const char *display, xcb_auth_info_t *auth, int *screen);


/* xcb_xid.c */

/**
 * @brief Allocates an XID for a new object.
 * @param c: The connection.
 * @return A newly allocated XID.
 *
 * Allocates an XID for a new object. Typically used just prior to
 * various object creation functions, such as xcb_create_window.
 */
uint32_t xcb_generate_id(xcb_connection_t *c);


/**
 * @}
 */

#ifdef __cplusplus
}
#endif


#endif /* __XCB_H__ */