/*------------------------------------------------------------------------
 *  Copyright 2007-2010 (c) Jeff Brown <spadix@users.sourceforge.net>
 *
 *  This file is part of the ZBar Bar Code Reader.
 *
 *  The ZBar Bar Code Reader is free software; you can redistribute it
 *  and/or modify it under the terms of the GNU Lesser Public License as
 *  published by the Free Software Foundation; either version 2.1 of
 *  the License, or (at your option) any later version.
 *
 *  The ZBar Bar Code Reader is distributed in the hope that it will be
 *  useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 *  of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Lesser Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser Public License
 *  along with the ZBar Bar Code Reader; if not, write to the Free
 *  Software Foundation, Inc., 51 Franklin St, Fifth Floor,
 *  Boston, MA  02110-1301  USA
 *
 *  http://sourceforge.net/projects/zbar
 *------------------------------------------------------------------------*/
#ifndef _ZBAR_H_
#define _ZBAR_H_

/** @file
 * ZBar Barcode Reader C API definition
 */

/** @mainpage
 *
 * interface to the barcode reader is available at several levels.
 * most applications will want to use the high-level interfaces:
 *
 * @section high-level High-Level Interfaces
 *
 * these interfaces wrap all library functionality into an easy-to-use
 * package for a specific toolkit:
 * - the "GTK+ 2.x widget" may be used with GTK GUI applications.  a
 *   Python wrapper is included for PyGtk
 * - the @ref zbar::QZBar "Qt4 widget" may be used with Qt GUI
 *   applications
 * - the Processor interface (in @ref c-processor "C" or @ref
 *   zbar::Processor "C++") adds a scanning window to an application
 *   with no GUI.
 *
 * @section mid-level Intermediate Interfaces
 *
 * building blocks used to construct high-level interfaces:
 * - the ImageScanner (in @ref c-imagescanner "C" or @ref
 *   zbar::ImageScanner "C++") looks for barcodes in a library defined
 *   image object
 * - the Window abstraction (in @ref c-window "C" or @ref
 *   zbar::Window "C++") sinks library images, displaying them on the
 *   platform display
 * - the Video abstraction (in @ref c-video "C" or @ref zbar::Video
 *   "C++") sources library images from a video device
 *
 * @section low-level Low-Level Interfaces
 *
 * direct interaction with barcode scanning and decoding:
 * - the Scanner (in @ref c-scanner "C" or @ref zbar::Scanner "C++")
 *   looks for barcodes in a linear intensity sample stream
 * - the Decoder (in @ref c-decoder "C" or @ref zbar::Decoder "C++")
 *   extracts barcodes from a stream of bar and space widths
 */

#ifdef __cplusplus

/** C++ namespace for library interfaces */
namespace zbar {
    extern "C" {
#endif
        
        /** @name Global library interfaces */
        /*@{*/
        
        /** "color" of element: bar or space. */
        typedef enum zbar_color_e {
            ZBAR_SPACE = 0,    /**< light area or space between bars */
            ZBAR_BAR = 1,      /**< dark area or colored bar segment */
        } zbar_color_t;
        
        /** decoded symbol type. */
        typedef enum zbar_symbol_type_e {
            ZBAR_NONE        =      0,  /**< no symbol decoded */
            ZBAR_PARTIAL     =      1,  /**< intermediate status */
            ZBAR_EAN2        =      2,  /**< GS1 2-digit add-on */
            ZBAR_EAN5        =      5,  /**< GS1 5-digit add-on */
            ZBAR_EAN8        =      8,  /**< EAN-8 */
            ZBAR_UPCE        =      9,  /**< UPC-E */
            ZBAR_ISBN10      =     10,  /**< ISBN-10 (from EAN-13). @since 0.4 */
            ZBAR_UPCA        =     12,  /**< UPC-A */
            ZBAR_EAN13       =     13,  /**< EAN-13 */
            ZBAR_ISBN13      =     14,  /**< ISBN-13 (from EAN-13). @since 0.4 */
            ZBAR_COMPOSITE   =     15,  /**< EAN/UPC composite */
            ZBAR_I25         =     25,  /**< Interleaved 2 of 5. @since 0.4 */
            ZBAR_DATABAR     =     34,  /**< GS1 DataBar (RSS). @since 0.11 */
            ZBAR_DATABAR_EXP =     35,  /**< GS1 DataBar Expanded. @since 0.11 */
            ZBAR_CODABAR     =     38,  /**< Codabar. @since 0.11 */
            ZBAR_CODE39      =     39,  /**< Code 39. @since 0.4 */
            ZBAR_PDF417      =     57,  /**< PDF417. @since 0.6 */
            ZBAR_QRCODE      =     64,  /**< QR Code. @since 0.10 */
            ZBAR_CODE93      =     93,  /**< Code 93. @since 0.11 */
            ZBAR_CODE128     =    128,  /**< Code 128 */
            
            /** mask for base symbol type.
             * @deprecated in 0.11, remove this from existing code
             */
            ZBAR_SYMBOL      = 0x00ff,
            /** 2-digit add-on flag.
             * @deprecated in 0.11, a ::ZBAR_EAN2 component is used for
             * 2-digit GS1 add-ons
             */
            ZBAR_ADDON2      = 0x0200,
            /** 5-digit add-on flag.
             * @deprecated in 0.11, a ::ZBAR_EAN5 component is used for
             * 5-digit GS1 add-ons
             */
            ZBAR_ADDON5      = 0x0500,
            /** add-on flag mask.
             * @deprecated in 0.11, GS1 add-ons are represented using composite
             * symbols of type ::ZBAR_COMPOSITE; add-on components use ::ZBAR_EAN2
             * or ::ZBAR_EAN5
             */
            ZBAR_ADDON       = 0x0700,
        } zbar_symbol_type_t;
        
        /** decoded symbol coarse orientation.
         * @since 0.11
         */
        typedef enum zbar_orientation_e {
            ZBAR_ORIENT_UNKNOWN = -1,   /**< unable to determine orientation */
            ZBAR_ORIENT_UP,             /**< upright, read left to right */
            ZBAR_ORIENT_RIGHT,          /**< sideways, read top to bottom */
            ZBAR_ORIENT_DOWN,           /**< upside-down, read right to left */
            ZBAR_ORIENT_LEFT,           /**< sideways, read bottom to top */
        } zbar_orientation_t;
        
        /** error codes. */
        typedef enum zbar_error_e {
            ZBAR_OK = 0,                /**< no error */
            ZBAR_ERR_NOMEM,             /**< out of memory */
            ZBAR_ERR_INTERNAL,          /**< internal library error */
            ZBAR_ERR_UNSUPPORTED,       /**< unsupported request */
            ZBAR_ERR_INVALID,           /**< invalid request */
            ZBAR_ERR_SYSTEM,            /**< system error */
            ZBAR_ERR_LOCKING,           /**< locking error */
            ZBAR_ERR_BUSY,              /**< all resources busy */
            ZBAR_ERR_XDISPLAY,          /**< X11 display error */
            ZBAR_ERR_XPROTO,            /**< X11 protocol error */
            ZBAR_ERR_CLOSED,            /**< output window is closed */
            ZBAR_ERR_WINAPI,            /**< windows system error */
            ZBAR_ERR_NUM                /**< number of error codes */
        } zbar_error_t;
        
        /** decoder configuration options.
         * @since 0.4
         */
        typedef enum zbar_config_e {
            ZBAR_CFG_ENABLE = 0,        /**< enable symbology/feature */
            ZBAR_CFG_ADD_CHECK,         /**< enable check digit when optional */
            ZBAR_CFG_EMIT_CHECK,        /**< return check digit when present */
            ZBAR_CFG_ASCII,             /**< enable full ASCII character set */
            ZBAR_CFG_NUM,               /**< number of boolean decoder configs */
            
            ZBAR_CFG_MIN_LEN = 0x20,    /**< minimum data length for valid decode */
            ZBAR_CFG_MAX_LEN,           /**< maximum data length for valid decode */
            
            ZBAR_CFG_UNCERTAINTY = 0x40,/**< required video consistency frames */
            
            ZBAR_CFG_POSITION = 0x80,   /**< enable scanner to collect position data */
            
            ZBAR_CFG_X_DENSITY = 0x100, /**< image scanner vertical scan density */
            ZBAR_CFG_Y_DENSITY,         /**< image scanner horizontal scan density */
        } zbar_config_t;
        
        /** decoder symbology modifier flags.
         * @since 0.11
         */
        typedef enum zbar_modifier_e {
            /** barcode tagged as GS1 (EAN.UCC) reserved
             * (eg, FNC1 before first data character).
             * data may be parsed as a sequence of GS1 AIs
             */
            ZBAR_MOD_GS1 = 0,
            
            /** barcode tagged as AIM reserved
             * (eg, FNC1 after first character or digit pair)
             */
            ZBAR_MOD_AIM,
            
            /** number of modifiers */
            ZBAR_MOD_NUM,
        } zbar_modifier_t;
        
        /** retrieve runtime library version information.
         * @param major set to the running major version (unless NULL)
         * @param minor set to the running minor version (unless NULL)
         * @returns 0
         */
        extern int zbar_version(unsigned *major,
                                unsigned *minor);
        
        /** set global library debug level.
         * @param verbosity desired debug level.  higher values create more spew
         */
        extern void zbar_set_verbosity(int verbosity);
        
        /** increase global library debug level.
         * eg, for -vvvv
         */
        extern void zbar_increase_verbosity(void);
        
        /** retrieve string name for symbol encoding.
         * @param sym symbol type encoding
         * @returns the static string name for the specified symbol type,
         * or "UNKNOWN" if the encoding is not recognized
         */
        extern const char *zbar_get_symbol_name(zbar_symbol_type_t sym);
        
        /** retrieve string name for addon encoding.
         * @param sym symbol type encoding
         * @returns static string name for any addon, or the empty string
         * if no addons were decoded
         * @deprecated in 0.11
         */
        extern const char *zbar_get_addon_name(zbar_symbol_type_t sym);
        
        /** retrieve string name for configuration setting.
         * @param config setting to name
         * @returns static string name for config,
         * or the empty string if value is not a known config
         */
        extern const char *zbar_get_config_name(zbar_config_t config);
        
        /** retrieve string name for modifier.
         * @param modifier flag to name
         * @returns static string name for modifier,
         * or the empty string if the value is not a known flag
         */
        extern const char *zbar_get_modifier_name(zbar_modifier_t modifier);
        
        /** retrieve string name for orientation.
         * @param orientation orientation encoding
         * @returns the static string name for the specified orientation,
         * or "UNKNOWN" if the orientation is not recognized
         * @since 0.11
         */
        extern const char *zbar_get_orientation_name(zbar_orientation_t orientation);
        
        /** parse a configuration string of the form "[symbology.]config[=value]".
         * the config must match one of the recognized names.
         * the symbology, if present, must match one of the recognized names.
         * if symbology is unspecified, it will be set to 0.
         * if value is unspecified it will be set to 1.
         * @returns 0 if the config is parsed successfully, 1 otherwise
         * @since 0.4
         */
        extern int zbar_parse_config(const char *config_string,
                                     zbar_symbol_type_t *symbology,
                                     zbar_config_t *config,
                                     int *value);
        
        /** consistently compute fourcc values across architectures
         * (adapted from v4l2 specification)
         * @since 0.11
         */
#define zbar_fourcc(a, b, c, d)                 \
((unsigned long)(a) |                   \
((unsigned long)(b) << 8) |            \
((unsigned long)(c) << 16) |           \
((unsigned long)(d) << 24))
        
        /** parse a fourcc string into its encoded integer value.
         * @since 0.11
         */
        static inline unsigned long zbar_fourcc_parse (const char *format) {
            unsigned long fourcc = 0;
            if (format) {
                int i;
                for (i = 0; i < 4 && format[i]; i++)
                    fourcc |= ((unsigned long)format[i]) << (i * 8);
            }
            return(fourcc);
        }
        
        /** @internal type unsafe error API (don't use) */
        extern int _zbar_error_spew(const void *object,
                                    int verbosity);
        extern const char *_zbar_error_string(const void *object,
                                              int verbosity);
        extern zbar_error_t _zbar_get_error_code(const void *object);
        
        /*@}*/
        
        struct zbar_symbol_s;
        typedef struct zbar_symbol_s zbar_symbol_t;
        
        struct zbar_symbol_set_s;
        typedef struct zbar_symbol_set_s zbar_symbol_set_t;
        
        /*------------------------------------------------------------*/
        /** @name Symbol interface
         * decoded barcode symbol result object.  stores type, data, and image
         * location of decoded symbol.  all memory is owned by the library
         */
        /*@{*/
        
        /** @typedef zbar_symbol_t
         * opaque decoded symbol object.
         */
        
        /** symbol reference count manipulation.
         * increment the reference count when you store a new reference to the
         * symbol.  decrement when the reference is no longer used.  do not
         * refer to the symbol once the count is decremented and the
         * containing image has been recycled or destroyed.
         * @note the containing image holds a reference to the symbol, so you
         * only need to use this if you keep a symbol after the image has been
         * destroyed or reused.
         * @since 0.9
         */
        extern void zbar_symbol_ref(const zbar_symbol_t *symbol,
                                    int refs);
        
        /** retrieve type of decoded symbol.
         * @returns the symbol type
         */
        extern zbar_symbol_type_t zbar_symbol_get_type(const zbar_symbol_t *symbol);
        
        /** retrieve symbology boolean config settings.
         * @returns a bitmask indicating which configs were set for the detected
         * symbology during decoding.
         * @since 0.11
         */
        extern unsigned int zbar_symbol_get_configs(const zbar_symbol_t *symbol);
        
        /** retrieve symbology modifier flag settings.
         * @returns a bitmask indicating which characteristics were detected
         * during decoding.
         * @since 0.11
         */
        extern unsigned int zbar_symbol_get_modifiers(const zbar_symbol_t *symbol);
        
        /** retrieve data decoded from symbol.
         * @returns the data string
         */
        extern const char *zbar_symbol_get_data(const zbar_symbol_t *symbol);
        
        /** retrieve length of binary data.
         * @returns the length of the decoded data
         */
        extern unsigned int zbar_symbol_get_data_length(const zbar_symbol_t *symbol);
        
        /** retrieve a symbol confidence metric.
         * @returns an unscaled, relative quantity: larger values are better
         * than smaller values, where "large" and "small" are application
         * dependent.
         * @note expect the exact definition of this quantity to change as the
         * metric is refined.  currently, only the ordered relationship
         * between two values is defined and will remain stable in the future
         * @since 0.9
         */
        extern int zbar_symbol_get_quality(const zbar_symbol_t *symbol);
        
        /** retrieve current cache count.  when the cache is enabled for the
         * image_scanner this provides inter-frame reliability and redundancy
         * information for video streams.
         * @returns < 0 if symbol is still uncertain.
         * @returns 0 if symbol is newly verified.
         * @returns > 0 for duplicate symbols
         */
        extern int zbar_symbol_get_count(const zbar_symbol_t *symbol);
        
        /** retrieve the number of points in the location polygon.  the
         * location polygon defines the image area that the symbol was
         * extracted from.
         * @returns the number of points in the location polygon
         * @note this is currently not a polygon, but the scan locations
         * where the symbol was decoded
         */
        extern unsigned zbar_symbol_get_loc_size(const zbar_symbol_t *symbol);
        
        /** retrieve location polygon x-coordinates.
         * points are specified by 0-based index.
         * @returns the x-coordinate for a point in the location polygon.
         * @returns -1 if index is out of range
         */
        extern int zbar_symbol_get_loc_x(const zbar_symbol_t *symbol,
                                         unsigned index);
        
        /** retrieve location polygon y-coordinates.
         * points are specified by 0-based index.
         * @returns the y-coordinate for a point in the location polygon.
         * @returns -1 if index is out of range
         */
        extern int zbar_symbol_get_loc_y(const zbar_symbol_t *symbol,
                                         unsigned index);
        
        /** retrieve general orientation of decoded symbol.
         * @returns a coarse, axis-aligned indication of symbol orientation or
         * ::ZBAR_ORIENT_UNKNOWN if unknown
         * @since 0.11
         */
        extern zbar_orientation_t
        zbar_symbol_get_orientation(const zbar_symbol_t *symbol);
        
        /** iterate the set to which this symbol belongs (there can be only one).
         * @returns the next symbol in the set, or
         * @returns NULL when no more results are available
         */
        extern const zbar_symbol_t *zbar_symbol_next(const zbar_symbol_t *symbol);
        
        /** retrieve components of a composite result.
         * @returns the symbol set containing the components
         * @returns NULL if the symbol is already a physical symbol
         * @since 0.10
         */
        extern const zbar_symbol_set_t *
        zbar_symbol_get_components(const zbar_symbol_t *symbol);
        
        /** iterate components of a composite result.
         * @returns the first physical component symbol of a composite result
         * @returns NULL if the symbol is already a physical symbol
         * @since 0.10
         */
        extern const zbar_symbol_t *
        zbar_symbol_first_component(const zbar_symbol_t *symbol);
        
        /** print XML symbol element representation to user result buffer.
         * @see http://zbar.sourceforge.net/2008/barcode.xsd for the schema.
         * @param symbol is the symbol to print
         * @param buffer is the inout result pointer, it will be reallocated
         * with a larger size if necessary.
         * @param buflen is inout length of the result buffer.
         * @returns the buffer pointer
         * @since 0.6
         */
        extern char *zbar_symbol_xml(const zbar_symbol_t *symbol,
                                     char * *buffer,
                                     unsigned *buflen);
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Symbol Set interface
         * container for decoded result symbols associated with an image
         * or a composite symbol.
         * @since 0.10
         */
        /*@{*/
        
        /** @typedef zbar_symbol_set_t
         * opaque symbol iterator object.
         * @since 0.10
         */
        
        /** reference count manipulation.
         * increment the reference count when you store a new reference.
         * decrement when the reference is no longer used.  do not refer to
         * the object any longer once references have been released.
         * @since 0.10
         */
        extern void zbar_symbol_set_ref(const zbar_symbol_set_t *symbols,
                                        int refs);
        
        /** retrieve set size.
         * @returns the number of symbols in the set.
         * @since 0.10
         */
        extern int zbar_symbol_set_get_size(const zbar_symbol_set_t *symbols);
        
        /** set iterator.
         * @returns the first decoded symbol result in a set
         * @returns NULL if the set is empty
         * @since 0.10
         */
        extern const zbar_symbol_t *
        zbar_symbol_set_first_symbol(const zbar_symbol_set_t *symbols);
        
        /** raw result iterator.
         * @returns the first decoded symbol result in a set, *before* filtering
         * @returns NULL if the set is empty
         * @since 0.11
         */
        extern const zbar_symbol_t *
        zbar_symbol_set_first_unfiltered(const zbar_symbol_set_t *symbols);
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Image interface
         * stores image data samples along with associated format and size
         * metadata
         */
        /*@{*/
        
        struct zbar_image_s;
        /** opaque image object. */
        typedef struct zbar_image_s zbar_image_t;
        
        /** cleanup handler callback function.
         * called to free sample data when an image is destroyed.
         */
        typedef void (zbar_image_cleanup_handler_t)(zbar_image_t *image);
        
        /** data handler callback function.
         * called when decoded symbol results are available for an image
         */
        typedef void (zbar_image_data_handler_t)(zbar_image_t *image,
        const void *userdata);
        
        /** new image constructor.
         * @returns a new image object with uninitialized data and format.
         * this image should be destroyed (using zbar_image_destroy()) as
         * soon as the application is finished with it
         */
        extern zbar_image_t *zbar_image_create(void);
        
        /** image destructor.  all images created by or returned to the
         * application should be destroyed using this function.  when an image
         * is destroyed, the associated data cleanup handler will be invoked
         * if available
         * @note make no assumptions about the image or the data buffer.
         * they may not be destroyed/cleaned immediately if the library
         * is still using them.  if necessary, use the cleanup handler hook
         * to keep track of image data buffers
         */
        extern void zbar_image_destroy(zbar_image_t *image);
        
        /** image reference count manipulation.
         * increment the reference count when you store a new reference to the
         * image.  decrement when the reference is no longer used.  do not
         * refer to the image any longer once the count is decremented.
         * zbar_image_ref(image, -1) is the same as zbar_image_destroy(image)
         * @since 0.5
         */
        extern void zbar_image_ref(zbar_image_t *image,
                                   int refs);
        
        /** image format conversion.  refer to the documentation for supported
         * image formats
         * @returns a @em new image with the sample data from the original image
         * converted to the requested format.  the original image is
         * unaffected.
         * @note the converted image size may be rounded (up) due to format
         * constraints
         */
        extern zbar_image_t *zbar_image_convert(const zbar_image_t *image,
                                                unsigned long format);
        
        /** image format conversion with crop/pad.
         * if the requested size is larger than the image, the last row/column
         * are duplicated to cover the difference.  if the requested size is
         * smaller than the image, the extra rows/columns are dropped from the
         * right/bottom.
         * @returns a @em new image with the sample data from the original
         * image converted to the requested format and size.
         * @note the image is @em not scaled
         * @see zbar_image_convert()
         * @since 0.4
         */
        extern zbar_image_t *zbar_image_convert_resize(const zbar_image_t *image,
                                                       unsigned long format,
                                                       unsigned width,
                                                       unsigned height);
        
        /** retrieve the image format.
         * @returns the fourcc describing the format of the image sample data
         */
        extern unsigned long zbar_image_get_format(const zbar_image_t *image);
        
        /** retrieve a "sequence" (page/frame) number associated with this image.
         * @since 0.6
         */
        extern unsigned zbar_image_get_sequence(const zbar_image_t *image);
        
        /** retrieve the width of the image.
         * @returns the width in sample columns
         */
        extern unsigned zbar_image_get_width(const zbar_image_t *image);
        
        /** retrieve the height of the image.
         * @returns the height in sample rows
         */
        extern unsigned zbar_image_get_height(const zbar_image_t *image);
        
        /** retrieve both dimensions of the image.
         * fills in the width and height in samples
         */
        extern void zbar_image_get_size(const zbar_image_t *image,
                                        unsigned *width,
                                        unsigned *height);
        
        /** retrieve the crop rectangle.
         * fills in the image coordinates of the upper left corner and size
         * of an axis-aligned rectangular area of the image that will be scanned.
         * defaults to the full image
         * @since 0.11
         */
        extern void zbar_image_get_crop(const zbar_image_t *image,
                                        unsigned *x,
                                        unsigned *y,
                                        unsigned *width,
                                        unsigned *height);
        
        /** return the image sample data.  the returned data buffer is only
         * valid until zbar_image_destroy() is called
         */
        extern const void *zbar_image_get_data(const zbar_image_t *image);
        
        /** return the size of image data.
         * @since 0.6
         */
        extern unsigned long zbar_image_get_data_length(const zbar_image_t *img);
        
        /** retrieve the decoded results.
         * @returns the (possibly empty) set of decoded symbols
         * @returns NULL if the image has not been scanned
         * @since 0.10
         */
        extern const zbar_symbol_set_t *
        zbar_image_get_symbols(const zbar_image_t *image);
        
        /** associate the specified symbol set with the image, replacing any
         * existing results.  use NULL to release the current results from the
         * image.
         * @see zbar_image_scanner_recycle_image()
         * @since 0.10
         */
        extern void zbar_image_set_symbols(zbar_image_t *image,
                                           const zbar_symbol_set_t *symbols);
        
        /** image_scanner decode result iterator.
         * @returns the first decoded symbol result for an image
         * or NULL if no results are available
         */
        extern const zbar_symbol_t *
        zbar_image_first_symbol(const zbar_image_t *image);
        
        /** specify the fourcc image format code for image sample data.
         * refer to the documentation for supported formats.
         * @note this does not convert the data!
         * (see zbar_image_convert() for that)
         */
        extern void zbar_image_set_format(zbar_image_t *image,
                                          unsigned long format);
        
        /** associate a "sequence" (page/frame) number with this image.
         * @since 0.6
         */
        extern void zbar_image_set_sequence(zbar_image_t *image,
                                            unsigned sequence_num);
        
        /** specify the pixel size of the image.
         * @note this also resets the crop rectangle to the full image
         * (0, 0, width, height)
         * @note this does not affect the data!
         */
        extern void zbar_image_set_size(zbar_image_t *image,
                                        unsigned width,
                                        unsigned height);
        
        /** specify a rectangular region of the image to scan.
         * the rectangle will be clipped to the image boundaries.
         * defaults to the full image specified by zbar_image_set_size()
         */
        extern void zbar_image_set_crop(zbar_image_t *image,
                                        unsigned x,
                                        unsigned y,
                                        unsigned width,
                                        unsigned height);
        
        /** specify image sample data.  when image data is no longer needed by
         * the library the specific data cleanup handler will be called
         * (unless NULL)
         * @note application image data will not be modified by the library
         */
        extern void zbar_image_set_data(zbar_image_t *image,
                                        const void *data,
                                        unsigned long data_byte_length,
                                        zbar_image_cleanup_handler_t *cleanup_hndlr);
        
        /** built-in cleanup handler.
         * passes the image data buffer to free()
         */
        extern void zbar_image_free_data(zbar_image_t *image);
        
        /** associate user specified data value with an image.
         * @since 0.5
         */
        extern void zbar_image_set_userdata(zbar_image_t *image,
                                            void *userdata);
        
        /** return user specified data value associated with the image.
         * @since 0.5
         */
        extern void *zbar_image_get_userdata(const zbar_image_t *image);
        
        /** dump raw image data to a file for debug.
         * the data will be prefixed with a 16 byte header consisting of:
         *   - 4 bytes uint = 0x676d697a ("zimg")
         *   - 4 bytes format fourcc
         *   - 2 bytes width
         *   - 2 bytes height
         *   - 4 bytes size of following image data in bytes
         * this header can be dumped w/eg:
         * @verbatim
         od -Ax -tx1z -N16 -w4 [file]
         @endverbatim
         * for some formats the image can be displayed/converted using
         * ImageMagick, eg:
         * @verbatim
         display -size 640x480+16 [-depth ?] [-sampling-factor ?x?] \
         {GRAY,RGB,UYVY,YUV}:[file]
         @endverbatim
         *
         * @param image the image object to dump
         * @param filebase base filename, appended with ".XXXX.zimg" where
         * XXXX is the format fourcc
         * @returns 0 on success or a system error code on failure
         */
        extern int zbar_image_write(const zbar_image_t *image,
                                    const char *filebase);
        
        /** read back an image in the format written by zbar_image_write()
         * @note TBD
         */
        extern zbar_image_t *zbar_image_read(char *filename);
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Processor interface
         * @anchor c-processor
         * high-level self-contained image processor.
         * processes video and images for barcodes, optionally displaying
         * images to a library owned output window
         */
        /*@{*/
        
        struct zbar_processor_s;
        /** opaque standalone processor object. */
        typedef struct zbar_processor_s zbar_processor_t;
        
        /** constructor.
         * if threaded is set and threading is available the processor
         * will spawn threads where appropriate to avoid blocking and
         * improve responsiveness
         */
        extern zbar_processor_t *zbar_processor_create(int threaded);
        
        /** destructor.  cleans up all resources associated with the processor
         */
        extern void zbar_processor_destroy(zbar_processor_t *processor);
        
        /** (re)initialization.
         * opens a video input device and/or prepares to display output
         */
        extern int zbar_processor_init(zbar_processor_t *processor,
                                       const char *video_device,
                                       int enable_display);
        
        /** request a preferred size for the video image from the device.
         * the request may be adjusted or completely ignored by the driver.
         * @note must be called before zbar_processor_init()
         * @since 0.6
         */
        extern int zbar_processor_request_size(zbar_processor_t *processor,
                                               unsigned width,
                                               unsigned height);
        
        /** request a preferred video driver interface version for
         * debug/testing.
         * @note must be called before zbar_processor_init()
         * @since 0.6
         */
        extern int zbar_processor_request_interface(zbar_processor_t *processor,
                                                    int version);
        
        /** request a preferred video I/O mode for debug/testing.  You will
         * get errors if the driver does not support the specified mode.
         * @verbatim
         0 = auto-detect
         1 = force I/O using read()
         2 = force memory mapped I/O using mmap()
         3 = force USERPTR I/O (v4l2 only)
         @endverbatim
         * @note must be called before zbar_processor_init()
         * @since 0.7
         */
        extern int zbar_processor_request_iomode(zbar_processor_t *video,
                                                 int iomode);
        
        /** force specific input and output formats for debug/testing.
         * @note must be called before zbar_processor_init()
         */
        extern int zbar_processor_force_format(zbar_processor_t *processor,
                                               unsigned long input_format,
                                               unsigned long output_format);
        
        /** setup result handler callback.
         * the specified function will be called by the processor whenever
         * new results are available from the video stream or a static image.
         * pass a NULL value to disable callbacks.
         * @param processor the object on which to set the handler.
         * @param handler the function to call when new results are available.
         * @param userdata is set as with zbar_processor_set_userdata().
         * @returns the previously registered handler
         */
        extern zbar_image_data_handler_t *
        zbar_processor_set_data_handler(zbar_processor_t *processor,
                                        zbar_image_data_handler_t *handler,
                                        const void *userdata);
        
        /** associate user specified data value with the processor.
         * @since 0.6
         */
        extern void zbar_processor_set_userdata(zbar_processor_t *processor,
                                                void *userdata);
        
        /** return user specified data value associated with the processor.
         * @since 0.6
         */
        extern void *zbar_processor_get_userdata(const zbar_processor_t *processor);
        
        /** set config for indicated symbology (0 for all) to specified value.
         * @returns 0 for success, non-0 for failure (config does not apply to
         * specified symbology, or value out of range)
         * @see zbar_decoder_set_config()
         * @since 0.4
         */
        extern int zbar_processor_set_config(zbar_processor_t *processor,
                                             zbar_symbol_type_t symbology,
                                             zbar_config_t config,
                                             int value);
        
        /** parse configuration string using zbar_parse_config()
         * and apply to processor using zbar_processor_set_config().
         * @returns 0 for success, non-0 for failure
         * @see zbar_parse_config()
         * @see zbar_processor_set_config()
         * @since 0.4
         */
        static inline int zbar_processor_parse_config (zbar_processor_t *processor,
                                                       const char *config_string) {
            zbar_symbol_type_t sym;
            zbar_config_t cfg;
            int val;
            return(zbar_parse_config(config_string, &sym, &cfg, &val) ||
                   zbar_processor_set_config(processor, sym, cfg, val));
        }
        
        /** retrieve the current state of the ouput window.
         * @returns 1 if the output window is currently displayed, 0 if not.
         * @returns -1 if an error occurs
         */
        extern int zbar_processor_is_visible(zbar_processor_t *processor);
        
        /** show or hide the display window owned by the library.
         * the size will be adjusted to the input size
         */
        extern int zbar_processor_set_visible(zbar_processor_t *processor,
                                              int visible);
        
        /** control the processor in free running video mode.
         * only works if video input is initialized. if threading is in use,
         * scanning will occur in the background, otherwise this is only
         * useful wrapping calls to zbar_processor_user_wait(). if the
         * library output window is visible, video display will be enabled.
         */
        extern int zbar_processor_set_active(zbar_processor_t *processor,
                                             int active);
        
        /** retrieve decode results for last scanned image/frame.
         * @returns the symbol set result container or NULL if no results are
         * available
         * @note the returned symbol set has its reference count incremented;
         * ensure that the count is decremented after use
         * @since 0.10
         */
        extern const zbar_symbol_set_t *
        zbar_processor_get_results(const zbar_processor_t *processor);
        
        /** wait for input to the display window from the user
         * (via mouse or keyboard).
         * @returns >0 when input is received, 0 if timeout ms expired
         * with no input or -1 in case of an error
         */
        extern int zbar_processor_user_wait(zbar_processor_t *processor,
                                            int timeout);
        
        /** process from the video stream until a result is available,
         * or the timeout (in milliseconds) expires.
         * specify a timeout of -1 to scan indefinitely
         * (zbar_processor_set_active() may still be used to abort the scan
         * from another thread).
         * if the library window is visible, video display will be enabled.
         * @note that multiple results may still be returned (despite the
         * name).
         * @returns >0 if symbols were successfully decoded,
         * 0 if no symbols were found (ie, the timeout expired)
         * or -1 if an error occurs
         */
        extern int zbar_process_one(zbar_processor_t *processor,
                                    int timeout);
        
        /** process the provided image for barcodes.
         * if the library window is visible, the image will be displayed.
         * @returns >0 if symbols were successfully decoded,
         * 0 if no symbols were found or -1 if an error occurs
         */
        extern int zbar_process_image(zbar_processor_t *processor,
                                      zbar_image_t *image);
        
        /** display detail for last processor error to stderr.
         * @returns a non-zero value suitable for passing to exit()
         */
        static inline int
        zbar_processor_error_spew (const zbar_processor_t *processor,
                                   int verbosity) {
            return(_zbar_error_spew(processor, verbosity));
        }
        
        /** retrieve the detail string for the last processor error. */
        static inline const char *
        zbar_processor_error_string (const zbar_processor_t *processor,
                                     int verbosity) {
            return(_zbar_error_string(processor, verbosity));
        }
        
        /** retrieve the type code for the last processor error. */
        static inline zbar_error_t
        zbar_processor_get_error_code (const zbar_processor_t *processor) {
            return(_zbar_get_error_code(processor));
        }
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Video interface
         * @anchor c-video
         * mid-level video source abstraction.
         * captures images from a video device
         */
        /*@{*/
        
        struct zbar_video_s;
        /** opaque video object. */
        typedef struct zbar_video_s zbar_video_t;
        
        /** constructor. */
        extern zbar_video_t *zbar_video_create(void);
        
        /** destructor. */
        extern void zbar_video_destroy(zbar_video_t *video);
        
        /** open and probe a video device.
         * the device specified by platform specific unique name
         * (v4l device node path in *nix eg "/dev/video",
         *  DirectShow DevicePath property in windows).
         * @returns 0 if successful or -1 if an error occurs
         */
        extern int zbar_video_open(zbar_video_t *video,
                                   const char *device);
        
        /** retrieve file descriptor associated with open *nix video device
         * useful for using select()/poll() to tell when new images are
         * available (NB v4l2 only!!).
         * @returns the file descriptor or -1 if the video device is not open
         * or the driver only supports v4l1
         */
        extern int zbar_video_get_fd(const zbar_video_t *video);
        
        /** request a preferred size for the video image from the device.
         * the request may be adjusted or completely ignored by the driver.
         * @returns 0 if successful or -1 if the video device is already
         * initialized
         * @since 0.6
         */
        extern int zbar_video_request_size(zbar_video_t *video,
                                           unsigned width,
                                           unsigned height);
        
        /** request a preferred driver interface version for debug/testing.
         * @note must be called before zbar_video_open()
         * @since 0.6
         */
        extern int zbar_video_request_interface(zbar_video_t *video,
                                                int version);
        
        /** request a preferred I/O mode for debug/testing.  You will get
         * errors if the driver does not support the specified mode.
         * @verbatim
         0 = auto-detect
         1 = force I/O using read()
         2 = force memory mapped I/O using mmap()
         3 = force USERPTR I/O (v4l2 only)
         @endverbatim
         * @note must be called before zbar_video_open()
         * @since 0.7
         */
        extern int zbar_video_request_iomode(zbar_video_t *video,
                                             int iomode);
        
        /** retrieve current output image width.
         * @returns the width or 0 if the video device is not open
         */
        extern int zbar_video_get_width(const zbar_video_t *video);
        
        /** retrieve current output image height.
         * @returns the height or 0 if the video device is not open
         */
        extern int zbar_video_get_height(const zbar_video_t *video);
        
        /** initialize video using a specific format for debug.
         * use zbar_negotiate_format() to automatically select and initialize
         * the best available format
         */
        extern int zbar_video_init(zbar_video_t *video,
                                   unsigned long format);
        
        /** start/stop video capture.
         * all buffered images are retired when capture is disabled.
         * @returns 0 if successful or -1 if an error occurs
         */
        extern int zbar_video_enable(zbar_video_t *video,
                                     int enable);
        
        /** retrieve next captured image.  blocks until an image is available.
         * @returns NULL if video is not enabled or an error occurs
         */
        extern zbar_image_t *zbar_video_next_image(zbar_video_t *video);
        
        /** display detail for last video error to stderr.
         * @returns a non-zero value suitable for passing to exit()
         */
        static inline int zbar_video_error_spew (const zbar_video_t *video,
                                                 int verbosity) {
            return(_zbar_error_spew(video, verbosity));
        }
        
        /** retrieve the detail string for the last video error. */
        static inline const char *zbar_video_error_string (const zbar_video_t *video,
                                                           int verbosity) {
            return(_zbar_error_string(video, verbosity));
        }
        
        /** retrieve the type code for the last video error. */
        static inline zbar_error_t
        zbar_video_get_error_code (const zbar_video_t *video) {
            return(_zbar_get_error_code(video));
        }
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Window interface
         * @anchor c-window
         * mid-level output window abstraction.
         * displays images to user-specified platform specific output window
         */
        /*@{*/
        
        struct zbar_window_s;
        /** opaque window object. */
        typedef struct zbar_window_s zbar_window_t;
        
        /** constructor. */
        extern zbar_window_t *zbar_window_create(void);
        
        /** destructor. */
        extern void zbar_window_destroy(zbar_window_t *window);
        
        /** associate reader with an existing platform window.
         * This can be any "Drawable" for X Windows or a "HWND" for windows.
         * input images will be scaled into the output window.
         * pass NULL to detach from the resource, further input will be
         * ignored
         */
        extern int zbar_window_attach(zbar_window_t *window,
                                      void *x11_display_w32_hwnd,
                                      unsigned long x11_drawable);
        
        /** control content level of the reader overlay.
         * the overlay displays graphical data for informational or debug
         * purposes.  higher values increase the level of annotation (possibly
         * decreasing performance). @verbatim
         0 = disable overlay
         1 = outline decoded symbols (default)
         2 = also track and display input frame rate
         @endverbatim
         */
        extern void zbar_window_set_overlay(zbar_window_t *window,
                                            int level);
        
        /** retrieve current content level of reader overlay.
         * @see zbar_window_set_overlay()
         * @since 0.10
         */
        extern int zbar_window_get_overlay(const zbar_window_t *window);
        
        /** draw a new image into the output window. */
        extern int zbar_window_draw(zbar_window_t *window,
                                    zbar_image_t *image);
        
        /** redraw the last image (exposure handler). */
        extern int zbar_window_redraw(zbar_window_t *window);
        
        /** resize the image window (reconfigure handler).
         * this does @em not update the contents of the window
         * @since 0.3, changed in 0.4 to not redraw window
         */
        extern int zbar_window_resize(zbar_window_t *window,
                                      unsigned width,
                                      unsigned height);
        
        /** display detail for last window error to stderr.
         * @returns a non-zero value suitable for passing to exit()
         */
        static inline int zbar_window_error_spew (const zbar_window_t *window,
                                                  int verbosity) {
            return(_zbar_error_spew(window, verbosity));
        }
        
        /** retrieve the detail string for the last window error. */
        static inline const char *
        zbar_window_error_string (const zbar_window_t *window,
                                  int verbosity) {
            return(_zbar_error_string(window, verbosity));
        }
        
        /** retrieve the type code for the last window error. */
        static inline zbar_error_t
        zbar_window_get_error_code (const zbar_window_t *window) {
            return(_zbar_get_error_code(window));
        }
        
        /** select a compatible format between video input and output window.
         * the selection algorithm attempts to use a format shared by
         * video input and window output which is also most useful for
         * barcode scanning.  if a format conversion is necessary, it will
         * heuristically attempt to minimize the cost of the conversion
         */
        extern int zbar_negotiate_format(zbar_video_t *video,
                                         zbar_window_t *window);
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Image Scanner interface
         * @anchor c-imagescanner
         * mid-level image scanner interface.
         * reads barcodes from 2-D images
         */
        /*@{*/
        
        struct zbar_image_scanner_s;
        /** opaque image scanner object. */
        typedef struct zbar_image_scanner_s zbar_image_scanner_t;
        
        /** constructor. */
        extern zbar_image_scanner_t *zbar_image_scanner_create(void);
        
        /** destructor. */
        extern void zbar_image_scanner_destroy(zbar_image_scanner_t *scanner);
        
        /** setup result handler callback.
         * the specified function will be called by the scanner whenever
         * new results are available from a decoded image.
         * pass a NULL value to disable callbacks.
         * @returns the previously registered handler
         */
        extern zbar_image_data_handler_t *
        zbar_image_scanner_set_data_handler(zbar_image_scanner_t *scanner,
                                            zbar_image_data_handler_t *handler,
                                            const void *userdata);
        
        /** set config for indicated symbology (0 for all) to specified value.
         * @returns 0 for success, non-0 for failure (config does not apply to
         * specified symbology, or value out of range)
         * @see zbar_decoder_set_config()
         * @since 0.4
         */
        extern int zbar_image_scanner_set_config(zbar_image_scanner_t *scanner,
                                                 zbar_symbol_type_t symbology,
                                                 zbar_config_t config,
                                                 int value);
        
        /** parse configuration string using zbar_parse_config()
         * and apply to image scanner using zbar_image_scanner_set_config().
         * @returns 0 for success, non-0 for failure
         * @see zbar_parse_config()
         * @see zbar_image_scanner_set_config()
         * @since 0.4
         */
        static inline int
        zbar_image_scanner_parse_config (zbar_image_scanner_t *scanner,
                                         const char *config_string) {
            zbar_symbol_type_t sym;
            zbar_config_t cfg;
            int val;
            return(zbar_parse_config(config_string, &sym, &cfg, &val) ||
                   zbar_image_scanner_set_config(scanner, sym, cfg, val));
        }
        
        /** enable or disable the inter-image result cache (default disabled).
         * mostly useful for scanning video frames, the cache filters
         * duplicate results from consecutive images, while adding some
         * consistency checking and hysteresis to the results.
         * this interface also clears the cache
         */
        extern void zbar_image_scanner_enable_cache(zbar_image_scanner_t *scanner,
                                                    int enable);
        
        /** remove any previously decoded results from the image scanner and the
         * specified image.  somewhat more efficient version of
         * zbar_image_set_symbols(image, NULL) which may retain memory for
         * subsequent decodes
         * @since 0.10
         */
        extern void zbar_image_scanner_recycle_image(zbar_image_scanner_t *scanner,
                                                     zbar_image_t *image);
        
        /** retrieve decode results for last scanned image.
         * @returns the symbol set result container or NULL if no results are
         * available
         * @note the symbol set does not have its reference count adjusted;
         * ensure that the count is incremented if the results may be kept
         * after the next image is scanned
         * @since 0.10
         */
        extern const zbar_symbol_set_t *
        zbar_image_scanner_get_results(const zbar_image_scanner_t *scanner);
        
        /** scan for symbols in provided image.  The image format must be
         * "Y800" or "GRAY".
         * @returns >0 if symbols were successfully decoded from the image,
         * 0 if no symbols were found or -1 if an error occurs
         * @see zbar_image_convert()
         * @since 0.9 - changed to only accept grayscale images
         */
        extern int zbar_scan_image(zbar_image_scanner_t *scanner,
                                   zbar_image_t *image);
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Decoder interface
         * @anchor c-decoder
         * low-level bar width stream decoder interface.
         * identifies symbols and extracts encoded data
         */
        /*@{*/
        
        struct zbar_decoder_s;
        /** opaque decoder object. */
        typedef struct zbar_decoder_s zbar_decoder_t;
        
        /** decoder data handler callback function.
         * called by decoder when new data has just been decoded
         */
        typedef void (zbar_decoder_handler_t)(zbar_decoder_t *decoder);
        
        /** constructor. */
        extern zbar_decoder_t *zbar_decoder_create(void);
        
        /** destructor. */
        extern void zbar_decoder_destroy(zbar_decoder_t *decoder);
        
        /** set config for indicated symbology (0 for all) to specified value.
         * @returns 0 for success, non-0 for failure (config does not apply to
         * specified symbology, or value out of range)
         * @since 0.4
         */
        extern int zbar_decoder_set_config(zbar_decoder_t *decoder,
                                           zbar_symbol_type_t symbology,
                                           zbar_config_t config,
                                           int value);
        
        /** parse configuration string using zbar_parse_config()
         * and apply to decoder using zbar_decoder_set_config().
         * @returns 0 for success, non-0 for failure
         * @see zbar_parse_config()
         * @see zbar_decoder_set_config()
         * @since 0.4
         */
        static inline int zbar_decoder_parse_config (zbar_decoder_t *decoder,
                                                     const char *config_string) {
            zbar_symbol_type_t sym;
            zbar_config_t cfg;
            int val;
            return(zbar_parse_config(config_string, &sym, &cfg, &val) ||
                   zbar_decoder_set_config(decoder, sym, cfg, val));
        }
        
        /** retrieve symbology boolean config settings.
         * @returns a bitmask indicating which configs are currently set for the
         * specified symbology.
         * @since 0.11
         */
        extern unsigned int zbar_decoder_get_configs(const zbar_decoder_t *decoder,
                                                     zbar_symbol_type_t symbology);
        
        /** clear all decoder state.
         * any partial symbols are flushed
         */
        extern void zbar_decoder_reset(zbar_decoder_t *decoder);
        
        /** mark start of a new scan pass.
         * clears any intra-symbol state and resets color to ::ZBAR_SPACE.
         * any partially decoded symbol state is retained
         */
        extern void zbar_decoder_new_scan(zbar_decoder_t *decoder);
        
        /** process next bar/space width from input stream.
         * the width is in arbitrary relative units.  first value of a scan
         * is ::ZBAR_SPACE width, alternating from there.
         * @returns appropriate symbol type if width completes
         * decode of a symbol (data is available for retrieval)
         * @returns ::ZBAR_PARTIAL as a hint if part of a symbol was decoded
         * @returns ::ZBAR_NONE (0) if no new symbol data is available
         */
        extern zbar_symbol_type_t zbar_decode_width(zbar_decoder_t *decoder,
                                                    unsigned width);
        
        /** retrieve color of @em next element passed to
         * zbar_decode_width(). */
        extern zbar_color_t zbar_decoder_get_color(const zbar_decoder_t *decoder);
        
        /** retrieve last decoded data.
         * @returns the data string or NULL if no new data available.
         * the returned data buffer is owned by library, contents are only
         * valid between non-0 return from zbar_decode_width and next library
         * call
         */
        extern const char *zbar_decoder_get_data(const zbar_decoder_t *decoder);
        
        /** retrieve length of binary data.
         * @returns the length of the decoded data or 0 if no new data
         * available.
         */
        extern unsigned int
        zbar_decoder_get_data_length(const zbar_decoder_t *decoder);
        
        /** retrieve last decoded symbol type.
         * @returns the type or ::ZBAR_NONE if no new data available
         */
        extern zbar_symbol_type_t
        zbar_decoder_get_type(const zbar_decoder_t *decoder);
        
        /** retrieve modifier flags for the last decoded symbol.
         * @returns a bitmask indicating which characteristics were detected
         * during decoding.
         * @since 0.11
         */
        extern unsigned int zbar_decoder_get_modifiers(const zbar_decoder_t *decoder);
        
        /** retrieve last decode direction.
         * @returns 1 for forward and -1 for reverse
         * @returns 0 if the decode direction is unknown or does not apply
         * @since 0.11
         */
        extern int zbar_decoder_get_direction(const zbar_decoder_t *decoder);
        
        /** setup data handler callback.
         * the registered function will be called by the decoder
         * just before zbar_decode_width() returns a non-zero value.
         * pass a NULL value to disable callbacks.
         * @returns the previously registered handler
         */
        extern zbar_decoder_handler_t *
        zbar_decoder_set_handler(zbar_decoder_t *decoder,
                                 zbar_decoder_handler_t *handler);
        
        /** associate user specified data value with the decoder. */
        extern void zbar_decoder_set_userdata(zbar_decoder_t *decoder,
                                              void *userdata);
        
        /** return user specified data value associated with the decoder. */
        extern void *zbar_decoder_get_userdata(const zbar_decoder_t *decoder);
        
        /*@}*/
        
        /*------------------------------------------------------------*/
        /** @name Scanner interface
         * @anchor c-scanner
         * low-level linear intensity sample stream scanner interface.
         * identifies "bar" edges and measures width between them.
         * optionally passes to bar width decoder
         */
        /*@{*/
        
        struct zbar_scanner_s;
        /** opaque scanner object. */
        typedef struct zbar_scanner_s zbar_scanner_t;
        
        /** constructor.
         * if decoder is non-NULL it will be attached to scanner
         * and called automatically at each new edge
         * current color is initialized to ::ZBAR_SPACE
         * (so an initial BAR->SPACE transition may be discarded)
         */
        extern zbar_scanner_t *zbar_scanner_create(zbar_decoder_t *decoder);
        
        /** destructor. */
        extern void zbar_scanner_destroy(zbar_scanner_t *scanner);
        
        /** clear all scanner state.
         * also resets an associated decoder
         */
        extern zbar_symbol_type_t zbar_scanner_reset(zbar_scanner_t *scanner);
        
        /** mark start of a new scan pass. resets color to ::ZBAR_SPACE.
         * also updates an associated decoder.
         * @returns any decode results flushed from the pipeline
         * @note when not using callback handlers, the return value should
         * be checked the same as zbar_scan_y()
         * @note call zbar_scanner_flush() at least twice before calling this
         * method to ensure no decode results are lost
         */
        extern zbar_symbol_type_t zbar_scanner_new_scan(zbar_scanner_t *scanner);
        
        /** flush scanner processing pipeline.
         * forces current scanner position to be a scan boundary.
         * call multiple times (max 3) to completely flush decoder.
         * @returns any decode/scan results flushed from the pipeline
         * @note when not using callback handlers, the return value should
         * be checked the same as zbar_scan_y()
         * @since 0.9
         */
        extern zbar_symbol_type_t zbar_scanner_flush(zbar_scanner_t *scanner);
        
        /** process next sample intensity value.
         * intensity (y) is in arbitrary relative units.
         * @returns result of zbar_decode_width() if a decoder is attached,
         * otherwise @returns (::ZBAR_PARTIAL) when new edge is detected
         * or 0 (::ZBAR_NONE) if no new edge is detected
         */
        extern zbar_symbol_type_t zbar_scan_y(zbar_scanner_t *scanner,
                                              int y);
        
        /** process next sample from RGB (or BGR) triple. */
        static inline zbar_symbol_type_t zbar_scan_rgb24 (zbar_scanner_t *scanner,
                                                          unsigned char *rgb) {
            return(zbar_scan_y(scanner, rgb[0] + rgb[1] + rgb[2]));
        }
        
        /** retrieve last scanned width. */
        extern unsigned zbar_scanner_get_width(const zbar_scanner_t *scanner);
        
        /** retrieve sample position of last edge.
         * @since 0.10
         */
        extern unsigned zbar_scanner_get_edge(const zbar_scanner_t *scn,
                                              unsigned offset,
                                              int prec);
        
        /** retrieve last scanned color. */
        extern zbar_color_t zbar_scanner_get_color(const zbar_scanner_t *scanner);
        
        /*@}*/
        
#ifdef __cplusplus
    }
}

# include "zbar/Exception.h"
# include "zbar/Decoder.h"
# include "zbar/Scanner.h"
# include "zbar/Symbol.h"
# include "zbar/Image.h"
# include "zbar/ImageScanner.h"
# include "zbar/Video.h"
# include "zbar/Window.h"
# include "zbar/Processor.h"
#endif

#endif
