xref: /dports/graphics/djvulibre/djvulibre-3.5.28/libdjvu/ddjvuapi.h

/*
//C- -------------------------------------------------------------------
//C- DjVuLibre-3.5
//C- Copyright (c) 2002  Leon Bottou and Yann Le Cun.
//C- Copyright (c) 2001  AT&T
//C-
//C- This software is subject to, and may be distributed under, the
//C- GNU General Public License, either Version 2 of the license,
//C- or (at your option) any later version. The license should have
//C- accompanied the software or you may obtain a copy of the license
//C- from the Free Software Foundation at http://www.fsf.org .
//C-
//C- This program is distributed in the hope that it will be useful,
//C- but WITHOUT ANY WARRANTY; without even the implied warranty of
//C- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//C- GNU General Public License for more details.
//C-
//C- DjVuLibre-3.5 is derived from the DjVu(r) Reference Library from
//C- Lizardtech Software.  Lizardtech Software has authorized us to
//C- replace the original DjVu(r) Reference Library notice by the following
//C- text (see doc/lizard2002.djvu and doc/lizardtech2007.djvu):
//C-
//C-  ------------------------------------------------------------------
//C- | DjVu (r) Reference Library (v. 3.5)
//C- | Copyright (c) 1999-2001 LizardTech, Inc. All Rights Reserved.
//C- | The DjVu Reference Library is protected by U.S. Pat. No.
//C- | 6,058,214 and patents pending.
//C- |
//C- | This software is subject to, and may be distributed under, the
//C- | GNU General Public License, either Version 2 of the license,
//C- | or (at your option) any later version. The license should have
//C- | accompanied the software or you may obtain a copy of the license
//C- | from the Free Software Foundation at http://www.fsf.org .
//C- |
//C- | The computer code originally released by LizardTech under this
//C- | license and unmodified by other parties is deemed "the LIZARDTECH
//C- | ORIGINAL CODE."  Subject to any third party intellectual property
//C- | claims, LizardTech grants recipient a worldwide, royalty-free,
//C- | non-exclusive license to make, use, sell, or otherwise dispose of
//C- | the LIZARDTECH ORIGINAL CODE or of programs derived from the
//C- | LIZARDTECH ORIGINAL CODE in compliance with the terms of the GNU
//C- | General Public License.   This grant only confers the right to
//C- | infringe patent claims underlying the LIZARDTECH ORIGINAL CODE to
//C- | the extent such infringement is reasonably necessary to enable
//C- | recipient to make, have made, practice, sell, or otherwise dispose
//C- | of the LIZARDTECH ORIGINAL CODE (or portions thereof) and not to
//C- | any greater extent that may be necessary to utilize further
//C- | modifications or combinations.
//C- |
//C- | The LIZARDTECH ORIGINAL CODE is provided "AS IS" WITHOUT WARRANTY
//C- | OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
//C- | TO ANY WARRANTY OF NON-INFRINGEMENT, OR ANY IMPLIED WARRANTY OF
//C- | MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
//C- +------------------------------------------------------------------
*/

#ifndef DDJVUAPI_H
#define DDJVUAPI_H

#ifdef __cplusplus
extern "C" {
#endif
#if 0
}
#endif

#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>

#ifndef DDJVUAPI
# ifdef _WIN32
#  ifdef DDJVUAPI_EXPORT
#   define DDJVUAPI __declspec(dllexport)
#  else
#   define DDJVUAPI __declspec(dllimport)
#  endif
# endif
#endif
#ifndef DDJVUAPI
# define DDJVUAPI /**/
#endif

#ifndef TRUE
# define TRUE  (1)
#endif

#ifndef FALSE
# define FALSE (0)
#endif



/* -------------------------------------------------- */
/* DDJVU API                                          */
/* -------------------------------------------------- */

/* The DDJVU API provides for efficiently decoding and
   displaying DjVu documents.  It provides for displaying
   images without waiting for the complete DjVu data. Images
   can be displayed as soon as sufficient data is
   available. A higher quality image might later be
   displayed when further data is available.  The DjVu
   library achieves this using a complicated scheme
   involving multiple threads. The DDJVU API hides this
   complexity with a familiar event model.
*/

/* Compiler symbol DDJVUAPI_VERSION tracks
   backward compatible additions to the DDJVU API.

   Version   Change
   -----------------------------
     24    Added:
              miniexp_lstring()
              miniexp_to_lstr()
     23    Added:
              miniexp_mutate()
     22    Changed
              miniexp strings accept unicode escapes
              deprecated miniexp_io_t::p_print7bits
              added miniexp_io_t::p_flags
     21    Added:
              reentrant version of miniexp input/output
     20    Added:
              ddjvu_get_version_string()
              ddjvu_format_set_white()
              ddjvu_anno_get_xmp()
     19    Added:
              ddjvu_document_create_by_filename_utf8()
     18    Added:
              ddjvu_document_get_{anno,pagedump,filedump}()
           Modifed (binary compatible):
              ddjvu_document_get_{fileinfo,pageinfo}()
              ddjvu_document_save() [--pages, --indirect=]
           Deprecated:
              ddjvu_document_search_pageno()
              ddjvu_page_get_{short,long}_description()
     17    Added:
              ddjvu_page_get_initial_rotation(), ddjvu_code_get_version()
              ddjvu_document_{get_filenum,get_fileinfo}}()
              ddjvu_document_{search_pageno,check_pagedata}()
              ddjvu_rectmapper_t and related functions.
     16    Added:
              miniexp.h and related functions.
     15    Added:
              ddjvu_document_get_pageinfo()
              ddjvu_document_print()
     14    Initial version.
*/

#define DDJVUAPI_VERSION 23

typedef struct ddjvu_context_s    ddjvu_context_t;
typedef union  ddjvu_message_s    ddjvu_message_t;
typedef struct ddjvu_job_s        ddjvu_job_t;
typedef struct ddjvu_document_s   ddjvu_document_t;
typedef struct ddjvu_page_s       ddjvu_page_t;
typedef struct ddjvu_format_s     ddjvu_format_t;
typedef struct ddjvu_rect_s       ddjvu_rect_t;
typedef struct ddjvu_rectmapper_s ddjvu_rectmapper_t;


/* GENERAL CONVENTIONS:

   - all strings use locale encoding (unless specified otherwise).
   - all filenames are unencoded byte strings,
   - all errors are signaled with error event messages,
   - all functions returning a pointer might return a null pointer.

   HEADER:
   Always use the following idiom to include this file.

     #include <libdjvu/ddjvuapi.h>
     #include <libdjvu/miniexp.h>

   This file does not declare functions ddjvu_get_DjVuImage()
   and djvu_get_DjVuDocument() unless you include files
   "DjVuImage.h" and "DjVuDocument.h" before this file.

   PREREQUISITES:
   - Please read the djvu man page: <"tools/djvu.1">.
   - Please browse the file format specifications
     <"doc/djvu3changes.txt"> and <"doc/djvu3spec.djvu">.
*/



/* -------------------------------------------------- */
/* DDJVU_CONTEXT_T                                    */
/* -------------------------------------------------- */

/* There is usually only one <ddjvu_context_t> object.
   This object holds global data structures such as the
   cache of decoded pages, or the list of pending
   event messages.
 */



/* ddjvu_get_version_string() ---
   Returns a string that described the underlying code. */

DDJVUAPI const char*
ddjvu_get_version_string(void);


/* ddjvu_context_create ---
   Creates a <ddjvu_context_t> object.
   Argument <programname> is the name of the calling executable. */

DDJVUAPI ddjvu_context_t *
ddjvu_context_create(const char *programname);


/* ddjvu_context_release ---
   Release a reference to a <ddjvu_context_t> object.
   The calling program should no longer reference this object.
   The object itself will be destroyed as soon as no other object
   or thread needs it. */

DDJVUAPI void
ddjvu_context_release(ddjvu_context_t *context);





/* ------- CACHE ------- */

/* ddjvu_cache_set_size ---
   Sets the maximum size of the cache of decoded page data.
   The argument is expressed in bytes. */

DDJVUAPI void
ddjvu_cache_set_size(ddjvu_context_t *context,
                     unsigned long cachesize);


/* ddjvu_cache_get_size ---
   Returns the maximum size of the cache. */

DDJVUAPI unsigned long
ddjvu_cache_get_size(ddjvu_context_t *context);


/* ddjvu_cache_clear ---
   Clears all cached data. */

DDJVUAPI void
ddjvu_cache_clear(ddjvu_context_t *context);



/* ------- MESSAGE QUEUE ------- */

/* Messages produced by the ddjvu api accumulate into
   the message queue. Processing messages is not optional!
   A typical message handling routine looks like this:

   void handle_ddjvu_messages(ddjvu_context_t *ctx, int wait)
   {
     const ddjvu_message_t *msg;
     if (wait)
       ddjvu_message_wait(ctx);
     while ((msg = ddjvu_message_peek(ctx)))
     {
       switch(msg->m_any.tag)
       {
       case DDJVU_ERROR:      .... ; break;
       case DDJVU_INFO:       .... ; break;
       case DDJVU_NEWSTREAM:  .... ; break;
       ....
       default: break;
       }
       ddjvu_message_pop(ctx);
     }
   }
*/


/* ddjvu_message_peek ---
   Returns a pointer to the next DDJVU message.
   This function returns 0 if no message is available.
   It does not remove the message from the queue. */

DDJVUAPI ddjvu_message_t *
ddjvu_message_peek(ddjvu_context_t *context);


/* ddjvu_message_wait ---
   Returns a pointer to the next DDJVU message.
   This function waits until a message is available.
   It does not remove the message from the queue. */

DDJVUAPI ddjvu_message_t *
ddjvu_message_wait(ddjvu_context_t *context);


/* ddjvu_message_pop ---
   Removes one message from the queue.
   This function must be called after processing the message.
   Pointers returned by previous calls to <ddjvu_message_peek>
   or <ddjvu_message_wait> are no longer valid after
   calling <ddjvu_message_pop>. */

DDJVUAPI void
ddjvu_message_pop(ddjvu_context_t *context);


/* ddjvu_message_set_callback ---
   Defines a callback function invoked whenever
   a new message is posted to the ddjvuapi message queue,
   and returns a pointer to the previous callback function.
   This callback function can be called at any time
   while other code is executing. Do not call ddjvuapi
   functions from this callback. It should simply signal
   the main application event loop that new ddjvuapi messages
   are available.  Under WIN32, this is usually achieved
   by posting a user window message.  Under UNIX, this is
   usually achieved using a pipe: the callback writes
   a single byte into the pipe; the main application loop
   monitors the reading end of the pipe and detects
   the presence of data. */

typedef void
(*ddjvu_message_callback_t)(ddjvu_context_t *context, void *closure);

DDJVUAPI void
ddjvu_message_set_callback(ddjvu_context_t *context,
                           ddjvu_message_callback_t callback,
                           void *closure);



/* -------------------------------------------------- */
/* DDJVU_JOB_T                                        */
/* -------------------------------------------------- */


/* Many essential ddjvuapi functions initiate asynchronous operations.
   These "jobs" run in seperate threads and report their
   progress by posting messages into the ddjvu context event queue.
   Jobs are sometimes represented by a ddjvu_job_t object. */

/* ddjvu_job_status ---
   Returns the status of the specified job. */

typedef enum {
  DDJVU_JOB_NOTSTARTED, /* operation was not even started */
  DDJVU_JOB_STARTED,    /* operation is in progress */
  DDJVU_JOB_OK,         /* operation terminated successfully */
  DDJVU_JOB_FAILED,     /* operation failed because of an error */
  DDJVU_JOB_STOPPED     /* operation was interrupted by user */
} ddjvu_status_t;

DDJVUAPI ddjvu_status_t
ddjvu_job_status(ddjvu_job_t *job);

#define ddjvu_job_done(job) \
    (ddjvu_job_status(job) >= DDJVU_JOB_OK)
#define ddjvu_job_error(job) \
    (ddjvu_job_status(job) >= DDJVU_JOB_FAILED)


/* ddjvu_job_stop ---
   Attempts to cancel the specified job.
   This is a best effort function.
   There no guarantee that the job will
   actually stop.
 */

DDJVUAPI void
ddjvu_job_stop(ddjvu_job_t *job);


/* ddjvu_job_set_user_data ---
   ddjvu_job_get_user_data ---
   Each job can store an arbitrary pointer
   that callers can use for any purpose. These two
   functions provide for accessing or setting this pointer.
   This pointer is cleared when the job is released */

DDJVUAPI void
ddjvu_job_set_user_data(ddjvu_job_t *job, void *userdata);

DDJVUAPI void *
ddjvu_job_get_user_data(ddjvu_job_t *job);


/* ddjvu_job_release ---
   Releases a reference to a job object and clears its user
   data field.  This does not cause the job to stop executing.
   The calling program should no longer reference this object.
   The object itself will be destroyed as soon as no
   other object or thread needs it.
*/

DDJVUAPI void
ddjvu_job_release(ddjvu_job_t *job);



/* -------------------------------------------------- */
/* DDJVU_MESSAGE_T                                    */
/* -------------------------------------------------- */


/* ddjvu_message_t ---
   This union type represents messages delivered by the
   DDJVU API. Each member of the union pertains to a
   specific kind of message.  Member <m_any> represents the
   information common to all kinds of messages.  Given a
   pointer <p> to a <djvu_message_t>, the message kind can
   be accessed as <"p->m_any.tag">. */


/* ddjvu_message_tag_t ---
   This enumerated type identifies each kind of
   message delivered by the DDJVU API.  */

typedef enum {
  DDJVU_ERROR,
  DDJVU_INFO,
  DDJVU_NEWSTREAM,
  DDJVU_DOCINFO,
  DDJVU_PAGEINFO,
  DDJVU_RELAYOUT,
  DDJVU_REDISPLAY,
  DDJVU_CHUNK,
  DDJVU_THUMBNAIL,
  DDJVU_PROGRESS,
} ddjvu_message_tag_t;


/* ddjvu_message_t::m_any ---
   This structure is a member of the union <djvu_message_t>.
   It represents the information common to all kinds of
   messages.  Member <tag> indicates the kind of message.
   Members <context>, <document>, <page>, and <job> indicate
   the origin of the message.  These fields contain null
   pointers when they are not relevant.
   These fields are also cleared when the corresponding
   object is released with <ddjvu_{job,page,document}_release>.
   If the message has not yet been passed to the user
   with <ddjvu_message_{peek,wait}>, it is silently
   removed from the message queue. */

typedef struct ddjvu_message_any_s {
  ddjvu_message_tag_t   tag;
  ddjvu_context_t      *context;
  ddjvu_document_t     *document;
  ddjvu_page_t         *page;
  ddjvu_job_t          *job;
} ddjvu_message_any_t;


/* ddjvu_message_t::m_error ---
   Error messages are generated whenever the decoder or the
   DDJVU API encounters an error condition.  All errors are
   reported as error messages because they can occur
   asynchronously.  Member <message> is the error message.
   Members <function>, <filename> and <lineno>
   indicates the place where the error was detected. */

struct ddjvu_message_error_s {  /* ddjvu_message_t::m_error */
  ddjvu_message_any_t   any;
  const char           *message;
  const char           *function;
  const char           *filename;
  int                   lineno;
};


/* ddjvu_message_t::m_info ---
   This messages provides informational text indicating
   the progress of the decoding process. This might
   be displayed in the browser status bar. */

struct ddjvu_message_info_s {   /* ddjvu_message_t::m_info */
  ddjvu_message_any_t  any;
  const char          *message;
};




/* -------------------------------------------------- */
/* DDJVU_DOCUMENT_T                                    */
/* -------------------------------------------------- */


/* ddjvu_document_create ---
   Creates a decoder for a DjVu document and starts
   decoding.  This function returns immediately.  The
   decoding job then generates messages to request the raw
   data and to indicate the state of the decoding process.

   Argument <url> specifies an optional URL for the document.
   The URL follows the usual syntax (<"protocol://machine/path">).
   It should not end with a slash. It only serves two purposes:
   - The URL is used as a key for the cache of decoded pages.
   - The URL is used to document <m_newstream> messages.

   Setting argument <cache> to <TRUE> indicates that decoded pages
   should be cached when possible.  This only works when
   argument <url> is not the null pointer.

   It is important to understand that the URL is not used to
   access the data.  The document generates <m_newstream>
   messages to indicate which data is needed.  The caller must
   then provide the raw data using <ddjvu_stream_write>
   and <ddjvu_stream_close>.

   Localized characters in argument <url> should be in
   urlencoded UTF-8 (like "%2A"). What is happening for non
   ascii characters is unclear (probably UTF-8). */

DDJVUAPI ddjvu_document_t *
ddjvu_document_create(ddjvu_context_t *context,
                      const char *url,
                      int cache);


/* ddjvu_document_create_by_filename ---
   Creates a document for a DjVu document stored in a file.
   The document will directly access the specified DjVu file
   or related files without generating <m_newstream> messages.
   The standard function expects the filename in locale encoding.
   The utf8 variant expects an utf8 encoded filename. */

DDJVUAPI ddjvu_document_t *
ddjvu_document_create_by_filename(ddjvu_context_t *context,
                                  const char *filename,
                                  int cache);

DDJVUAPI ddjvu_document_t *
ddjvu_document_create_by_filename_utf8(ddjvu_context_t *context,
                                       const char *filename,
                                       int cache);

/* ddjvu_document_job ---
   Access the job object in charge of decoding the document header.
   In fact <ddjvu_document_t> is a subclass of <ddjvu_job_t>
   and this function is a type cast. */

DDJVUAPI ddjvu_job_t *
ddjvu_document_job(ddjvu_document_t *document);


/* ddjvu_document_release ---
   Release a reference to a <ddjvu_document_t> object.
   The calling program should no longer reference this object.
   The object itself will be destroyed as soon as no other object
   or thread needs it. */

#define ddjvu_document_release(document) \
   ddjvu_job_release(ddjvu_document_job(document))


/* ddjvu_document_set_user_data ---
   ddjvu_document_get_user_data ---
   Each <ddjvu_document_t> object can store an arbitray pointer
   that callers can use for any purpose. These two functions
   provide for accessing or setting this pointer. */

#define ddjvu_document_set_user_data(document,userdata) \
   ddjvu_job_set_user_data(ddjvu_document_job(document),userdata)
#define ddjvu_document_get_user_data(document) \
   ddjvu_job_get_user_data(ddjvu_document_job(document))

/* ddjvu_document_decoding_status ---
   ddjvu_document_decoding_done, ddjvu_document_decoding_error ---
   This function returns the status of the document header decoding job */

#define ddjvu_document_decoding_status(document) \
   ddjvu_job_status(ddjvu_document_job(document))
#define ddjvu_document_decoding_done(document) \
   (ddjvu_document_decoding_status(document) >= DDJVU_JOB_OK)
#define ddjvu_document_decoding_error(document) \
   (ddjvu_document_decoding_status(document) >= DDJVU_JOB_FAILED)


/* ------- STREAMS ------- */


/* ddjvu_message_t::m_newstream ---
   Newstream messages are generated whenever the decoder
   needs to access raw DjVu data.  The caller must then
   provide the requested data using <ddjvu_stream_write>
   and <ddjvu_stream_close>.

   In the case of indirect documents, a single decoder
   might simultaneously request several streams of data.
   Each stream is identified by a small integer <streamid>.

   The first <m_newstream> message always has member
   <streamid> set to zero and member <name> set to the null
   pointer.  It indicates that the decoder needs to access
   the data in the main DjVu file.  In fact, data can be
   written to stream <0> as soon as the <ddjvu_document_t>
   object is created.

   Further <m_newstream> messages are generated to access
   the auxiliary files of indirect or indexed DjVu
   documents.  Member <name> then provides the basename of
   the auxiliary file.

   Member <url> is set according to the url argument
   provided to function <ddjvu_document_create>.  The first
   newstream message always contain the url passed to
   <ddjvu_document_create>.  Subsequent newstream messages
   contain the url of the auxiliary files for indirect or
   indexed DjVu documents. */

struct ddjvu_message_newstream_s { /* ddjvu_message_t::m_newstream */
  ddjvu_message_any_t  any;
  int                  streamid;
  const char          *name;
  const char          *url;
};


/* ddjvu_stream_write ---
   Provide raw data to the DjVu decoder.
   This function should be called as soon as the data is available,
   for instance when receiving DjVu data from a network connection.
 */

DDJVUAPI void
ddjvu_stream_write(ddjvu_document_t *document,
                   int streamid,
                   const char *data,
                   unsigned long datalen );


/* ddjvu_stream_close ---
   Indicates that no more data will be provided on a
   particular stream.  Argument <stop> most likely should be
   set to <FALSE>. Setting argument <stop> to <TRUE>
   indicates that the user has interrupted the data transfer
   (for instance by pressing the stop button of a browser)
   and that the decoding threads should be stopped as
   soon as feasible. */

DDJVUAPI void
ddjvu_stream_close(ddjvu_document_t *document,
                   int streamid,
                   int stop );



/* ------- QUERIES ------- */


/* ddjvu_message_t::m_docinfo ---
   The <m_docinfo> message indicates that basic information
   about the document has been obtained and decoded.
   Not much can be done before this happens.
   Call <ddjvu_document_decoding_status> to determine
   whether the operation was successful. */

struct ddjvu_message_docinfo_s {
  ddjvu_message_any_t  any;
};


/* ddjvu_document_get_type ---
   Returns the type of a DjVu document.
   This function might return <DDJVU_DOCTYPE_UNKNOWN>
   when called before receiving a <m_docinfo> message. */

typedef enum {
  DDJVU_DOCTYPE_UNKNOWN=0,
  DDJVU_DOCTYPE_SINGLEPAGE,
  DDJVU_DOCTYPE_BUNDLED,
  DDJVU_DOCTYPE_INDIRECT,
  DDJVU_DOCTYPE_OLD_BUNDLED, /* obsolete */
  DDJVU_DOCTYPE_OLD_INDEXED, /* obsolete */
} ddjvu_document_type_t;

DDJVUAPI ddjvu_document_type_t
ddjvu_document_get_type(ddjvu_document_t *document);


/* ddjvu_document_get_pagenum ---
   Returns the number of pages in a DjVu document.
   This function might return 1 when called
   before receiving a <m_docinfo> message */

DDJVUAPI int
ddjvu_document_get_pagenum(ddjvu_document_t *document);



/* ------- ADVANCED ------- */


/* ddjvu_document_get_filenum --
   Returns the number of component files.
   This function might return 0 when called
   before receiving a <m_docinfo> message */

DDJVUAPI int
ddjvu_document_get_filenum(ddjvu_document_t *document);


/* ddjvu_document_get_fileinfo --
   Returns information about component file <fileno>.
   This function might return <DDJVU_JOB_STARTED> when
   called before receiving a <m_docinfo> message.
   String pointers in the returned data structure
   might be null. Strings are UTF8 encoded and remain
   allocated as long as the ddjvu_document_t object exists.

   Changes for ddjvuapi=18
   - Redefined as a macro passing the structure size.
*/

typedef struct ddjvu_fileinfo_s {
  char  type;                   /* [P]age, [T]humbnails, [I]nclude. */
  int   pageno;                 /* Negative when not applicable. */
  int   size;                   /* Negative when unknown. */
  const char *id;               /* File identifier. */
  const char *name;             /* Name for indirect documents. */
  const char *title;            /* Page title. */
} ddjvu_fileinfo_t;

#define ddjvu_document_get_fileinfo(d,f,i) \
   ddjvu_document_get_fileinfo_imp(d,f,i,sizeof(ddjvu_fileinfo_t))

DDJVUAPI ddjvu_status_t
ddjvu_document_get_fileinfo_imp(ddjvu_document_t *document, int fileno,
                                ddjvu_fileinfo_t *info, unsigned int infosz);


/* ddjvu_document_search_pageno --- DEPRECATED. */

DDJVUAPI int ddjvu_document_search_pageno(ddjvu_document_t*, const char*);


/* ddjvu_document_check_pagedata ---
   Returns a non zero result if the data for page <pageno>
   is already in memory. When this is the case, functions
   <ddjvu_document_get_pageinfo> and <ddjvu_document_get_pagetext>
   return the information immediately.
   This function causes the emission of <m_pageinfo> messages
   with zero in the <m_any.page> field whenever a new file
   is completely downloaded. */

DDJVUAPI int
ddjvu_document_check_pagedata(ddjvu_document_t *document, int pageno);


/* ddjvu_document_get_pageinfo ---
   Attempts to obtain information about page <pageno>
   without decoding the page. If the information is available,
   the function returns <DDJVU_JOB_OK> and fills the <info> structure.
   Otherwise it starts fetching page data and returns <DDJVU_JOB_STARTED>.
   This function causes the emission of <m_pageinfo> messages
   with zero in the <m_any.page> field.
   Typical synchronous usage:

   ddjvu_status_t r;
   ddjvu_pageinfo_t info;
   while ((r=ddjvu_document_get_pageinfo(doc,pageno,&info))<DDJVU_JOB_OK)
     handle_ddjvu_messages(ctx, TRUE);
   if (r>=DDJVU_JOB_FAILED)
     signal_error();

   Changes for ddjvuapi=18
   - Redefined as a macro passing the structure size.
   - Added fields 'rotation' and 'version'.
*/

typedef struct ddjvu_pageinfo_s {
  int width;                    /* page width (in pixels) */
  int height;                   /* page height (in pixels) */
  int dpi;                      /* page resolution (in dots per inche) */
  int rotation;                 /* initial page orientation */
  int version;                  /* page version */
} ddjvu_pageinfo_t;

#define ddjvu_document_get_pageinfo(d,p,i) \
   ddjvu_document_get_pageinfo_imp(d,p,i,sizeof(ddjvu_pageinfo_t))

DDJVUAPI ddjvu_status_t
ddjvu_document_get_pageinfo_imp(ddjvu_document_t *document, int pageno,
                                ddjvu_pageinfo_t *info, unsigned int infosz );




/* ddjvu_document_get_pagedump --
   This function returns a UTF8 encoded text describing the contents
   of page <pageno> using the same format as command <djvudump>.
   The returned string must be deallocated using <free()>.
   It returns <0> when the information is not yet available.
   It may then cause then the emission of <m_pageinfo>
   messages with null <m_any.page>.
*/

DDJVUAPI char *
ddjvu_document_get_pagedump(ddjvu_document_t *document, int pageno);


/* ddjvu_document_get_filedump --
   This function returns a UTF8 encoded text describing the contents
   of file <fileno> using the same format as command <djvudump>.
   The returned string must be deallocated using <free()>.
   It returns <0> when the information is not yet available.
   It may then cause then the emission of <m_pageinfo>
   messages with null <m_any.page>.
*/

DDJVUAPI char *
ddjvu_document_get_filedump(ddjvu_document_t *document, int fileno);




/* -------------------------------------------------- */
/* DJVU_PAGE_T                                        */
/* -------------------------------------------------- */


/* ddjvu_page_create_by_pageno ---
   Each page of a document can be accessed by creating a
   <ddjvu_page_t> object with this function.  Argument
   <pageno> indicates the page number, starting with page
   <0> to <pagenum-1>. This function may return NULL
   when called before receiving the <m_docinfo> message.
   Calling this function also initiates the data transfer
   and the decoding threads for the specified page.
   Various messages will document the progress of these
   operations. Error messages will be generated if
   the page does not exists. */

DDJVUAPI ddjvu_page_t *
ddjvu_page_create_by_pageno(ddjvu_document_t *document,
                            int pageno);

/* ddjvu_page_create_by_pageid ---
   This function is similar to <ddjvu_page_create_by_pageno>
   but identifies the desired page by name instead of page
   number. */

DDJVUAPI ddjvu_page_t *
ddjvu_page_create_by_pageid(ddjvu_document_t *document,
                            const char *pageid);


/* ddjvu_page_job ---
   Access the job object in charge of decoding the document header.
   In fact <ddjvu_page_t> is a subclass of <ddjvu_job_t>
   and this function is a type cast. */

DDJVUAPI ddjvu_job_t *
ddjvu_page_job(ddjvu_page_t *page);


/* ddjvu_page_release ---
   Release a reference to a <ddjvu_page_t> object.
   The calling program should no longer reference this object.
   The object itself will be destroyed as soon as no other object
   or thread needs it. */

#define ddjvu_page_release(page) \
  ddjvu_job_release(ddjvu_page_job(page))


/* ddjvu_page_set_user_data ---
   ddjvu_page_get_user_data ---
   Each <ddjvu_paqge_t> object can store an arbitray pointer
   that callers can use for any purpose. These two functions
   provide for accessing or setting this pointer. */

#define ddjvu_page_set_user_data(page,userdata) \
   ddjvu_job_set_user_data(ddjvu_page_job(page),userdata)
#define ddjvu_page_get_user_data(page) \
   ddjvu_job_get_user_data(ddjvu_page_job(page))

/* ddjvu_page_decoding_status ---
   ddjvu_page_decoding_done ---
   ddjvu_page_decoding_error ---
   These calls return the status of the page decoding job. */

#define ddjvu_page_decoding_status(page) \
   ddjvu_job_status(ddjvu_page_job(page))
#define ddjvu_page_decoding_done(page) \
    (ddjvu_page_decoding_status(page) >= DDJVU_JOB_OK)
#define ddjvu_page_decoding_error(page) \
    (ddjvu_page_decoding_status(page) >= DDJVU_JOB_FAILED)


/* ------- MESSAGES ------- */


/* ddjvu_message_t::m_pageinfo ---
   The page decoding process generates this message
   - when basic page information is available and
     before any <m_relayout> or <m_redisplay> message,
   - when the page decoding thread terminates.
   You can distinguish both cases using
   function ddjvu_page_decoding_status().
   Messages <m_pageinfo> are also generated as a consequence of
   functions such as <ddjvu_document_get_pageinfo>.
   The field <m_any.page> of such message is null.
*/

struct ddjvu_message_pageinfo_s {  /* ddjvu_message_t::m_pageinfo */
  ddjvu_message_any_t  any;
};


/* ddjvu_message_t::m_relayout ---
   This message is generated when a DjVu viewer
   should recompute the layout of the page viewer
   because the page size and resolution information has
   been updated. */

struct ddjvu_message_relayout_s {  /* ddjvu_message_t::m_relayout */
  ddjvu_message_any_t  any;
};


/* ddjvu_message_t::m_redisplay ---
   This message is generated when a DjVu viewer
   should call <ddjvu_page_render> and redisplay
   the page. This happens, for instance, when newly
   decoded DjVu data provides a better image. */

struct ddjvu_message_redisplay_s { /* ddjvu_message_t::m_redisplay */
  ddjvu_message_any_t  any;
};


/* ddjvu_message_t::m_chunk ---
   This message indicates that an additional chunk
   of DjVu data has been decoded.  Member <chunkid>
   indicates the type of the DjVu chunk. */

struct ddjvu_message_chunk_s {     /* ddjvu_message_t::m_chunk */
  ddjvu_message_any_t  any;
  const char *chunkid;
};

/* About page messages --
   Both the <m_relayout> and <m_redisplay> messages are derived from the
   <m_chunk> message.  They are intended for driving a djvu image viewer.
   When receiving <m_relayout>, the viewer should get the image size, decide
   zoom factors, and place the image area, scrollbars, toolbars, and other gui
   objects.  When receiving <m_redisplay>, the viewer should invalidate the
   image area so that the gui toolkit calls the repaint event handler. This
   handler should call ddjvu_page_render() and paint the part of the
   image that needs repainting. */



/* ------- QUERIES ------- */

/* ddjvu_page_get_width ---
   Returns the page width in pixels. Calling this function
   before receiving a <m_pageinfo> message always yields <0>. */

DDJVUAPI int
ddjvu_page_get_width(ddjvu_page_t *page);


/* ddjvu_page_get_height---
   Returns the page height in pixels. Calling this function
   before receiving a <m_pageinfo> message always yields <0>. */

DDJVUAPI int
ddjvu_page_get_height(ddjvu_page_t *page);

/* ddjvu_page_get_resolution ---
   Returns the page resolution in pixels per inch  (dpi).
   Calling this function before receiving a <m_pageinfo>
   message yields a meaningless but plausible value. */

DDJVUAPI int
ddjvu_page_get_resolution(ddjvu_page_t *page);


/* ddjvu_page_get_gamma ---
   Returns the gamma of the display for which this page was designed.
   Calling this function before receiving a <m_pageinfo>
   message yields a meaningless but plausible value. */

DDJVUAPI double
ddjvu_page_get_gamma(ddjvu_page_t *page);


/* ddjvu_page_get_version ---
   Returns the version of the djvu file format.
   Calling this function before receiving a <m_pageinfo>
   message yields a meaningless but plausible value. */

DDJVUAPI int
ddjvu_page_get_version(ddjvu_page_t *page);

/* ddjvu_code_get_version ---
   Returns the version of the djvu file format
   implemented by this library. More or less graceful
   degradation might arise if this is smaller than
   the number returned by <ddjvu_page_get_version>. */

DDJVUAPI int
ddjvu_code_get_version(void);


/* ddjvu_page_get_type ---
   Returns the type of the page data.
   Calling this function before the termination of the
   decoding process might returns <DDJVU_PAGETYPE_UNKNOWN>. */

typedef enum {
  DDJVU_PAGETYPE_UNKNOWN,
  DDJVU_PAGETYPE_BITONAL,
  DDJVU_PAGETYPE_PHOTO,
  DDJVU_PAGETYPE_COMPOUND,
} ddjvu_page_type_t;

DDJVUAPI ddjvu_page_type_t
ddjvu_page_get_type(ddjvu_page_t *page);


/* ddjvu_page_get_{short,long}_description --- DEPRECATED */

DDJVUAPI char *ddjvu_page_get_short_description(ddjvu_page_t *);
DDJVUAPI char *ddjvu_page_get_long_description(ddjvu_page_t *);


/* ddjvu_page_set_rotation ---
   Changes the counter-clockwise rotation angle for a DjVu page.
   Calling this function before receiving a <m_pageinfo>
   message has no good effect. */

typedef enum {
  DDJVU_ROTATE_0   = 0,
  DDJVU_ROTATE_90  = 1,
  DDJVU_ROTATE_180 = 2,
  DDJVU_ROTATE_270 = 3,
} ddjvu_page_rotation_t;

DDJVUAPI void
ddjvu_page_set_rotation(ddjvu_page_t *page,
                        ddjvu_page_rotation_t rot);


/* ddjvu_page_get_rotation ---
   Returns the counter-clockwise rotation angle for the DjVu page.
   The rotation is automatically taken into account
   by <ddjvu_page_render>, <ddjvu_page_get_width>
   and <ddjvu_page_get_height>. */

DDJVUAPI ddjvu_page_rotation_t
ddjvu_page_get_rotation(ddjvu_page_t *page);


/* ddjvu_page_get_initial_rotation ---
   Returns the page rotation specified by the
   orientation flags in the DjVu file.
   [brain damage warning] This is useful because
   maparea coordinates in the annotation chunks
   are expressed relative to the rotated coordinates
   whereas text coordinates in the hidden text data
   are expressed relative to the unrotated coordinates. */

DDJVUAPI ddjvu_page_rotation_t
ddjvu_page_get_initial_rotation(ddjvu_page_t *page);



/* ------- RENDER ------- */


/* ddjvu_render_mode_t ---
   Various ways to render a page. */

typedef enum {
  DDJVU_RENDER_COLOR = 0,       /* color page or stencil */
  DDJVU_RENDER_BLACK,           /* stencil or color page */
  DDJVU_RENDER_COLORONLY,       /* color page or fail */
  DDJVU_RENDER_MASKONLY,        /* stencil or fail */
  DDJVU_RENDER_BACKGROUND,      /* color background layer */
  DDJVU_RENDER_FOREGROUND,      /* color foreground layer */
} ddjvu_render_mode_t;


/* ddjvu_rect_t ---
   This structure specifies the location of a rectangle.
   Coordinates are usually expressed in pixels relative to
   the BOTTOM LEFT CORNER (but see ddjvu_format_set_y_direction).
   Members <x> and <y> indicate the position of the bottom left
   corner of the rectangle Members <w> and <h> indicate the
   width and height of the rectangle. */

struct ddjvu_rect_s {
  int x, y;
  unsigned int w, h;
};


/* ddjvu_page_render --
   Renders a segment of a page with arbitrary scale.
   Argument <mode> indicates what image layers
   should be rendered.

   Conceptually this function renders the full page
   into a rectangle <pagerect> and copies the
   pixels specified by rectangle <renderrect>
   into the buffer starting at position <imagebuffer>.
   The actual code is much more efficient than that.

   The final image is written into buffer <imagebuffer>.
   Argument <pixelformat> specifies the expected pixel format.
   Argument <rowsize> specifies the number of BYTES from
   one row to the next in the buffer. The buffer must be
   large enough to accomodate the desired image.

   This function makes a best effort to compute an image
   that reflects the most recently decoded data.  It might
   return <FALSE> to indicate that no image could be
   computed at this point, and that nothing was written into
   the buffer. */

DDJVUAPI int
ddjvu_page_render(ddjvu_page_t *page,
                  const ddjvu_render_mode_t mode,
                  const ddjvu_rect_t *pagerect,
                  const ddjvu_rect_t *renderrect,
                  const ddjvu_format_t *pixelformat,
                  unsigned long rowsize,
                  char *imagebuffer );




/* -------------------------------------------------- */
/* COORDINATE TRANSFORMS                              */
/* -------------------------------------------------- */

/* ddjvu_rectmapper_create --
   Creates a <ddjvu_rectmapper_t> data structure
   representing an affine coordinate transformation that
   maps points from rectangle <input> to rectangle <output>.
   The transformation maintains the positions relative
   to the coordinates of the rectangle corners. */

DDJVUAPI ddjvu_rectmapper_t *
ddjvu_rectmapper_create(ddjvu_rect_t *input, ddjvu_rect_t *output);


/* ddjvu_rectmapper_modify ---
   Modifies the coordinate transform <mapper> by redefining
   which corners of the output rectangle match those of the
   input rectangle. This function first applies a counter-clockwise
   rotation of <rotation> quarter-turns, and then reverses the X
   (resp. Y) coordinates when <mirrorx> (resp. <mirrory>) is non zero. */

DDJVUAPI void
ddjvu_rectmapper_modify(ddjvu_rectmapper_t *mapper,
                        int rotation, int mirrorx, int mirrory);


/* ddjvu_rectmapper_release ---
   Destroys the <ddjvu_rect_mapper_t> structure
   returned by <ddjvu_rect_mapper_create>. */

DDJVUAPI void
ddjvu_rectmapper_release(ddjvu_rectmapper_t *mapper);

/* ddjvu_map_point, ddjvu_map_rect ---
   Applies the coordinate transform
   to a point or a rectangle */

DDJVUAPI void
ddjvu_map_point(ddjvu_rectmapper_t *mapper, int *x, int *y);

DDJVUAPI void
ddjvu_map_rect(ddjvu_rectmapper_t *mapper, ddjvu_rect_t *rect);


/* ddjvu_unmap_point, ddjvu_unmap_rect ---
   Applies the inverse coordinate transform
   to a point or a rectangle */

DDJVUAPI void
ddjvu_unmap_point(ddjvu_rectmapper_t *mapper, int *x, int *y);

DDJVUAPI void
ddjvu_unmap_rect(ddjvu_rectmapper_t *mapper, ddjvu_rect_t *rect);




/* -------------------------------------------------- */
/* DJVU_FORMAT_T                                      */
/* -------------------------------------------------- */


/* ddjvu_format_style_t ---
   Enumerated type for pixel formats. */

typedef enum {
  DDJVU_FORMAT_BGR24,           /* truecolor 24 bits in BGR order */
  DDJVU_FORMAT_RGB24,           /* truecolor 24 bits in RGB order */
  DDJVU_FORMAT_RGBMASK16,       /* truecolor 16 bits with masks */
  DDJVU_FORMAT_RGBMASK32,       /* truecolor 32 bits with masks */
  DDJVU_FORMAT_GREY8,           /* greylevel 8 bits */
  DDJVU_FORMAT_PALETTE8,        /* paletized 8 bits (6x6x6 color cube) */
  DDJVU_FORMAT_MSBTOLSB,        /* packed bits, msb on the left */
  DDJVU_FORMAT_LSBTOMSB,        /* packed bits, lsb on the left */
} ddjvu_format_style_t;


/* ddjvu_format_create ---
   Creates a <ddjvu_format_t> object describing a pixel format.
   Argument <style> describes the generic pixel format.
   Argument <args> is an array of <nargs> unsigned ints
   providing additionnal information:
   - When style is <RGBMASK*>, argument <nargs> must be <3> or <4>.
     The three first entries of array <args> are three contiguous
     bit masks for the red, green, and blue components of each pixel.
     The resulting color is then xored with the optional fourth entry.
   - When style is <PALETTE*>, argument <nargs> must be <216>
     and array <args> contains the 6*6*6 entries of a web
     color cube.
   - Otherwise <nargs> must be <0>. */

DDJVUAPI ddjvu_format_t *
ddjvu_format_create(ddjvu_format_style_t style,
                    int nargs, unsigned int *args);


/* ddjvu_format_set_row_order ---
   Sets a flag indicating whether the rows in the pixel buffer
   are stored starting from the top or the bottom of the image.
   Default ordering starts from the bottom of the image.
   This is the opposite of the X11 convention. */

DDJVUAPI void
ddjvu_format_set_row_order(ddjvu_format_t *format, int top_to_bottom);


/* ddjvu_format_set_y_direction ---
   Sets a flag indicating whether the y coordinates in the drawing
   area are oriented from bottom to top, or from top to botttom.
   The default is bottom to top, similar to PostScript.
   This is the opposite of the X11 convention. */

DDJVUAPI void
ddjvu_format_set_y_direction(ddjvu_format_t *format, int top_to_bottom);


/* ddjvu_format_set_ditherbits ---
   Specifies the final depth of the image on the screen.
   This is used to decide which dithering algorithm should be used.
   The default is usually appropriate. */

DDJVUAPI void
ddjvu_format_set_ditherbits(ddjvu_format_t *format, int bits);


/* ddjvu_format_set_gamma ---
   Sets the gamma of the display for which the pixels are
   intended.  This will be combined with the gamma stored in
   DjVu documents in order to compute a suitable color
   correction.  The default value is 2.2. */

DDJVUAPI void
ddjvu_format_set_gamma(ddjvu_format_t *format, double gamma);


/* ddjvu_format_set_white ---
   Sets the whitepoint of the display for which the pixels are
   intended.  This will be combined with the gamma stored in
   DjVu documents in order to compute a suitable color
   correction.  The default value is 0xff,0xff,0xff. */

DDJVUAPI void
ddjvu_format_set_white(ddjvu_format_t *format,
                       unsigned char b, unsigned char g, unsigned char r);

/* ddjvu_format_release ---
   Release a reference to a <ddjvu_format_t> object.
   The calling program should no longer reference this object. */

DDJVUAPI void
ddjvu_format_release(ddjvu_format_t *format);




/* -------------------------------------------------- */
/* THUMBNAILS                                         */
/* -------------------------------------------------- */


/* ddjvu_thumbnail_status ---
   Determine whether a thumbnail is available for page <pagenum>.
   Calling this function with non zero argument <start> initiates
   a thumbnail calculation job. Regardless of its success,
   the completion of the job is signalled by a subsequent
   <m_thumbnail> message. */

DDJVUAPI ddjvu_status_t
ddjvu_thumbnail_status(ddjvu_document_t *document, int pagenum, int start);


/* ddjvu_message_t::m_thumbnail ---
   This message is sent when additional thumbnails are available. */

struct ddjvu_message_thumbnail_s { /* ddjvu_message_t::m_thumbnail */
  ddjvu_message_any_t  any;
  int pagenum;
};


/* ddjvu_thumbnail_render ---
   Renders a thumbnail for page <pagenum>.
   Argument <imagebuffer> must be large enough to contain
   an image of size <*wptr> by <*hptr> using pixel format
   <pixelformat>. Argument <rowsize> specifies the number
   of BYTES from one row to the next in the buffer.
   This function returns <FALSE> when no thumbnail is available.
   Otherwise it returns <TRUE>, adjusts <*wptr> and <*hptr> to
   reflect the thumbnail size, and, if the pointer <imagebuffer>
   is non zero, writes the pixel data into the image buffer. */

DDJVUAPI int
ddjvu_thumbnail_render(ddjvu_document_t *document, int pagenum,
                       int *wptr, int *hptr,
                       const ddjvu_format_t *pixelformat,
                       unsigned long rowsize,
                       char *imagebuffer);



/* -------------------------------------------------- */
/* SAVE AND PRINT JOBS                                */
/* -------------------------------------------------- */


/* ddjvu_message_t::m_progress ---
   These messages are generated to indicate progress
   towards the completion of a print or save job. */

struct ddjvu_message_progress_s {
  ddjvu_message_any_t any;
  ddjvu_status_t status;
  int percent;
};

/* ddjvu_document_print ---
   Converts specified pages of a djvu document into postscript.
   This function works asynchronously in a separate thread.
   You can use the following idiom for synchronous operation:

     ddjvu_job_t *job = ddjvu_document_print(....);
     while (! ddjvu_job_done(job) )
       handle_ddjvu_messages(context, TRUE);

   The postscript data is written to stdio file <output>.
   Arguments <optc> and <optv> specify printing options.
   All options described on the <djvups> man page are
   recognized, except <"-help"> and <"-verbose">.
*/

DDJVUAPI ddjvu_job_t *
ddjvu_document_print(ddjvu_document_t *document, FILE *output,
                     int optc, const char * const * optv);


/* ddjvu_document_save ---
   Saves the djvu document as a bundled djvu file.
   This function works asynchronously in a separate thread.
   You can use the following idiom for synchronous operation:

     ddjvu_job_t *job = ddjvu_document_save(....);
     while (! ddjvu_job_done(job) )
       handle_ddjvu_messages(context, TRUE);

   The bundled djvu data is written to file <output>
   which must be seekable. Arguments <optc> and <optv>
   can be used to pass the following options:
   * Option "-pages=<pagespec>" specify a subset of pages
     using the same syntax as program <ddjvu>.
     Reordering or duplicating pages is prohibited.
   * Option "-indirect=<filename>" causes the creation
     of an indirect document with index file <filename>
     and auxiliary files in the same directory.
     The file name is UTF-8 encoded.
     When this option is specified, the argument <output>
     is ignored and should be NULL.
*/
DDJVUAPI ddjvu_job_t *
ddjvu_document_save(ddjvu_document_t *document, FILE *output,
                    int optc, const char * const * optv);




/* -------------------------------------------------- */
/* S-EXPRESSIONS                                      */
/* -------------------------------------------------- */


/* DjVu files can contain ancillary information such as
   document outline, hidden text, hyperlinks, and metadata.
   Program <djvused> provides for manipulating such
   information.  Like <djvused>, the DDJVU API represents
   this information using a lisp s-expressions.  See file
   <"libdjvu/miniexp.h"> for the s-expression documentation
   and manipulation functions.  See the <djvused> man page
   for the specification of the s-expressions representing
   outlines, hidden text and annotations. It often help
   to print s-expressions using function <miniexp_pprint>.

   WARNING: All strings in s-expression are UTF-8 encoded.
   Strings returned by miniexp_to_str might have to be
   converted to the locale encoding. */


/* miniexp_t --
   Opaque type representing s-expressions.
   The same definition also appears in
   file <"libdjvu/miniexp.h">. */

#ifndef MINIEXP_H
typedef struct miniexp_s* miniexp_t;
#endif

/* ddjvu_miniexp_release --
   This function controls the allocation of the
   s-expressions returned by functions from the DDJVU
   API. It indicates that the s-expression <expr> is no
   longer needed and can be deallocated as soon as
   necessary. Otherwise the s-expression remains allocated
   as long as the document object exists. */

DDJVUAPI void
ddjvu_miniexp_release(ddjvu_document_t *document, miniexp_t expr);


/* ddjvu_document_get_outline --
   This function tries to obtain the document outline.
   If this information is available, it returns a
   s-expression with the same syntax as function
   <print-outline> of program <djvused>.
   Otherwise it returns <miniexp_dummy> until
   the document header gets fully decoded.
   Typical synchronous usage:

    miniexp_t r;
    while ((r=ddjvu_document_get_outline(doc))==miniexp_dummy)
      handle_ddjvu_messages(ctx, TRUE);

   This function returns the empty list <miniexp_nil> when
   the document contains no outline information. It can also
   return symbols <failed> or <stopped> when an error occurs
   while accessing the desired information. */

DDJVUAPI miniexp_t
ddjvu_document_get_outline(ddjvu_document_t *document);


/* ddjvu_document_get_anno --
   This function returns the document-wide annotations.
   This corresponds to a proposed change in the djvu format.
   When no new-style document-wide annotations are available
   and <compat> is true, this function searches a shared
   annotation chunk and returns its contents.

   This function returns <miniexp_dummy> if the information
   is not yet available. It may then cause the emission
   of <m_pageinfo> messages with null <m_any.page>.

   This function returns the empty list <miniexp_nil> when
   the document does not contain page annotations. It can also
   return symbols <failed> or <stopped> when an error occurs
   while accessing the desired information. */

DDJVUAPI miniexp_t
ddjvu_document_get_anno(ddjvu_document_t *document, int compat);


/* ddjvu_document_get_pagetext --
   This function tries to obtain the text information for
   page <pageno>. If this information is available, it
   returns a s-expression with the same syntax as function
   <print-txt> of program <djvused>.  Otherwise it starts
   fetching the page data and returns <miniexp_dummy>.
   This function causes the emission of <m_pageinfo> messages
   with zero in the <m_any.page> field.
   Typical synchronous usage:

    miniexp_t r;
    while ((r=ddjvu_document_get_pagetext(doc,pageno,0))==miniexp_dummy)
      handle_ddjvu_messages(ctx, TRUE);

   This function returns the empty list <miniexp_nil> when
   the page contains no text information. It can also return
   symbols <failed> or <stopped> when an error occurs while
   accessing the desired information.

   Argument <maxdetail> controls the level of detail in the
   returned s-expression. Values "page", "column", "region", "para",
   "line", and "word" restrict the output to the specified granularity.
   All other values produce a s-expression that represents
   the hidden text data as finely as possible. */

DDJVUAPI miniexp_t
ddjvu_document_get_pagetext(ddjvu_document_t *document, int pageno,
                            const char *maxdetail);


/* ddjvu_document_get_pageanno --
   This function tries to obtain the annotations for
   page <pageno>. If this information is available, it
   returns a s-expression with the same syntax as function
   <print-ant> of program <djvused>.  Otherwise it starts
   fetching the page data and returns <miniexp_dummy>.
   This function causes the emission of <m_pageinfo> messages
   with zero in the <m_any.page> field.
   Typical synchronous usage:

     miniexp_t r;
     while ((r = ddjvu_document_get_pageanno(doc,pageno))==miniexp_dummy)
       handle_ddjvu_messages(ctx, TRUE);

   This function returns the empty list <miniexp_nil> when
   the page contains no annotations. It can also return
   symbols <failed> or <stopped> when an error occurs while
   accessing the desired information. */

DDJVUAPI miniexp_t
ddjvu_document_get_pageanno(ddjvu_document_t *document, int pageno);


/* --- Helper functions to parse annotations --- */

/* ddjvu_anno_get_bgcolor --
   Parse the annotations and extracts the desired
   background color as a color string ("#FFFFFF").
   See <(background ...)> in the djvused man page.
   Returns zero if this information is not specified. */

DDJVUAPI const char *
ddjvu_anno_get_bgcolor(miniexp_t annotations);


/* ddjvu_anno_get_zoom --
   Parse the annotations and extracts the desired zoom factor.
   See <(zoom ...)> in the djvused man page.
   Returns zero if this information is not specified. */

DDJVUAPI const char *
ddjvu_anno_get_zoom(miniexp_t annotations);


/* ddjvu_anno_get_mode --
   Parse the annotations and extracts the desired display mode.
   See <(mode ...)> in the djvused man page.
   Returns zero if this information is not specified. */

DDJVUAPI const char *
ddjvu_anno_get_mode(miniexp_t annotations);


/* ddjvu_anno_get_horizalign --
   Parse the annotations and extracts how the page
   image should be aligned horizontally.
   See <(align ...)> in the djvused man page.
   Returns zero if this information is not specified. */

DDJVUAPI const char *
ddjvu_anno_get_horizalign(miniexp_t annotations);


/* ddjvu_anno_get_vertalign --
   Parse the annotations and extracts how the page
   image should be aligned vertically.
   See <(align ...)> in the djvused man page.
   Returns zero if this information is not specified. */

DDJVUAPI const char *
ddjvu_anno_get_vertalign(miniexp_t annotations);


/* ddjvu_anno_get_hyperlinks --
   Parse the annotations and returns a zero terminated
   array of <(maparea ...)> s-expressions.
   The caller should free this array with function <free>.
   These s-expressions remain allocated as long
   as the annotations remain allocated.
   See also <(maparea ...)> in the djvused man page. */

DDJVUAPI miniexp_t *
ddjvu_anno_get_hyperlinks(miniexp_t annotations);


/* ddjvu_anno_get_metadata_keys --
   Parse the annotations and returns a zero terminated
   array of key symbols for the page metadata.
   The caller should free this array with function <free>.
   See also <(metadata ...)> in the djvused man page. */

DDJVUAPI miniexp_t *
ddjvu_anno_get_metadata_keys(miniexp_t annotations);


/* ddjvu_anno_get_metadata --
   Parse the annotations and returns the metadata string
   corresponding to the metadata key symbol <key>.
   The string remains allocated as long as the
   annotations s-expression remain allocated.
   Returns zero if no such key is present. */

DDJVUAPI const char *
ddjvu_anno_get_metadata(miniexp_t annotations, miniexp_t key);


/* ddjvu_anno_get_xmp --
   Parse the annotations and returns the xmp metadata string.
   The string remains allocated as long as the
   annotations s-expression remain allocated.
   Returns zero if no such key is present. */

DDJVUAPI const char *
ddjvu_anno_get_xmp(miniexp_t annotations);


/* -------------------------------------------------- */
/* DJVU_MESSAGE_T                                     */
/* -------------------------------------------------- */


/* We can now define the djvu_message_t union */

union ddjvu_message_s {
  struct ddjvu_message_any_s        m_any;
  struct ddjvu_message_error_s      m_error;
  struct ddjvu_message_info_s       m_info;
  struct ddjvu_message_newstream_s  m_newstream;
  struct ddjvu_message_docinfo_s    m_docinfo;
  struct ddjvu_message_pageinfo_s   m_pageinfo;
  struct ddjvu_message_chunk_s      m_chunk;
  struct ddjvu_message_relayout_s   m_relayout;
  struct ddjvu_message_redisplay_s  m_redisplay;
  struct ddjvu_message_thumbnail_s  m_thumbnail;
  struct ddjvu_message_progress_s   m_progress;
};


/* -------------------------------------------------- */
/* BACKDOORS                                          */
/* -------------------------------------------------- */

#ifdef __cplusplus
} // extern "C"
#endif

/* ddjvu_get_DjVuImage ---
   ddjvu_get_DjVuDocument ---
   These functions provide an access to the libdjvu objects
   associated with the ddjvuapi objects.  These backdoors can
   be useful for advanced manipulations.  These two functions
   are declared in C++ when file <"ddjvuapi.h"> is included
   after the libdjvu header files <"DjVuImage.h"> and
   <"DjVuDocument.h">. */

#ifdef __cplusplus
# ifndef NOT_USING_DJVU_NAMESPACE
#  ifdef _DJVUIMAGE_H
DDJVUAPI GP<DjVuImage>
ddjvu_get_DjVuImage(ddjvu_page_t *page);
#  endif
#  ifdef _DJVUDOCUMENT_H
DDJVUAPI GP<DjVuDocument>
ddjvu_get_DjVuDocument(ddjvu_document_t *document);
#  endif
# endif
#endif

#endif /* DDJVUAPI_H */