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 *

 * Copyright (c) 1998-2013 Glenn Randers-Pehrson

 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)

 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

 *

 * Last changed in libpng 1.6.1 [March 28, 2013]

 *

 * This code is released under the libpng license.

 * For conditions of distribution and use, see the disclaimer

 * and license in png.h

 */

 * that the application can find out the characteristics of the image.

 * If you are reading the file, this structure will tell you what is

 * in the PNG file.  If you are writing the file, fill in the information

 * you want to put into the PNG file, using png_set_*() functions, then

 * call png_write_info().

 *

 * The names chosen should be very close to the PNG specification, so

 * consult that document for information about the meaning of each field.

 *

 * With libpng < 0.95, it was only possible to directly set and read the

 * the values in the png_info_struct, which meant that the contents and

 * order of the values had to remain fixed.  With libpng 0.95 and later,

 * however, there are now functions that abstract the contents of

 * png_info_struct from the application, so this makes it easier to use

 * libpng with dynamic libraries, and even makes it possible to use

 * libraries that don't have all of the libpng ancillary chunk-handing

 * functionality.  In libpng-1.5.0 this was moved into a separate private

 * file that is not visible to applications.

 *

 * The following members may have allocated storage attached that should be

 * cleaned up before the structure is discarded: palette, trans, text,

 * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,

 * splt_palettes, scal_unit, row_pointers, and unknowns.   By default, these

 * are automatically freed when the info structure is deallocated, if they were

 * allocated internally by libpng.  This behavior can be changed by means

 * of the png_data_freer() function.

 *

 * More allocation details: all the chunk-reading functions that

 * change these members go through the corresponding png_set_*

 * functions.  A function to clear these members is available: see

 * png_free_data().  The png_set_* functions do not depend on being

 * able to point info structure members to any of the storage they are

 * passed (they make their own copies), EXCEPT that the png_set_text

 * functions use the same storage passed to them in the text_ptr or

 * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns

 * functions do not make their own copies.

 */

#ifndef PNGINFO_H

#define PNGINFO_H

{

   /* The following are necessary for every PNG file */

   png_uint_32 width;  /* width of image in pixels (from IHDR) */

   png_uint_32 height; /* height of image in pixels (from IHDR) */

   png_uint_32 valid;  /* valid chunk data (see PNG_INFO_ below) */

   png_size_t rowbytes; /* bytes needed to hold an untransformed row */

   png_colorp palette;      /* array of color values (valid & PNG_INFO_PLTE) */

   png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */

   png_uint_16 num_trans;   /* number of transparent palette color (tRNS) */

   png_byte bit_depth;      /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */

   png_byte color_type;     /* see PNG_COLOR_TYPE_ below (from IHDR) */

   /* The following three should have been named *_method not *_type */

   png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */

   png_byte filter_type;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */

   png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */

    * write, but the are never actually used by the write code.

    */

   png_byte channels;       /* number of data channels per pixel (1, 2, 3, 4) */

   png_byte pixel_depth;    /* number of bits per pixel */

   png_byte spare_byte;     /* to align the data, and for future use */

   /* This is never set during write */

   png_byte signature[8];   /* magic bytes read by libpng from start of file */

#endif

    * valid field to see if the information in these are valid.  If you

    * are writing, set the valid field to those chunks you want written,

    * and initialize the appropriate fields below.

    */

   /* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are

    * defined.  When COLORSPACE is switched on all the colorspace-defining

    * chunks should be enabled, when GAMMA is switched on all the gamma-defining

    * chunks should be enabled.  If this is not done it becomes possible to read

    * inconsistent PNG files and assign a probably incorrect interpretation to

    * the information.  (In other words, by carefully choosing which chunks to

    * recognize the system configuration can select an interpretation for PNG

    * files containing ambiguous data and this will result in inconsistent

    * behavior between different libpng builds!)

    */

   png_colorspace colorspace;

#endif

   /* iCCP chunk data. */

   png_charp iccp_name;     /* profile name */

   png_bytep iccp_profile;  /* International Color Consortium profile data */

   png_uint_32 iccp_proflen;  /* ICC profile data length */

#endif

   /* The tEXt, and zTXt chunks contain human-readable textual data in

    * uncompressed, compressed, and optionally compressed forms, respectively.

    * The data in "text" is an array of pointers to uncompressed,

    * null-terminated C strings. Each chunk has a keyword that describes the

    * textual data contained in that chunk.  Keywords are not required to be

    * unique, and the text string may be empty.  Any number of text chunks may

    * be in an image.

    */

   int num_text; /* number of comments read or comments to write */

   int max_text; /* current size of text array */

   png_textp text; /* array of comments read or comments to write */

#endif /* PNG_TEXT_SUPPORTED */

   /* The tIME chunk holds the last time the displayed image data was

    * modified.  See the png_time struct for the contents of this struct.

    */

   png_time mod_time;

#endif

   /* The sBIT chunk specifies the number of significant high-order bits

    * in the pixel data.  Values are in the range [1, bit_depth], and are

    * only specified for the channels in the pixel data.  The contents of

    * the low-order bits is not specified.  Data is valid if

    * (valid & PNG_INFO_sBIT) is non-zero.

    */

   png_color_8 sig_bit; /* significant bits in color channels */

#endif

defined(PNG_READ_BACKGROUND_SUPPORTED)

   /* The tRNS chunk supplies transparency data for paletted images and

    * other image types that don't need a full alpha channel.  There are

    * "num_trans" transparency values for a paletted image, stored in the

    * same order as the palette colors, starting from index 0.  Values

    * for the data are in the range [0, 255], ranging from fully transparent

    * to fully opaque, respectively.  For non-paletted images, there is a

    * single color specified that should be treated as fully transparent.

    * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.

    */

   png_bytep trans_alpha;    /* alpha values for paletted image */

   png_color_16 trans_color; /* transparent color for non-palette image */

#endif

   /* The bKGD chunk gives the suggested image background color if the

    * display program does not have its own background color and the image

    * is needs to composited onto a background before display.  The colors

    * in "background" are normally in the same color space/depth as the

    * pixel data.  Data is valid if (valid & PNG_INFO_bKGD) is non-zero.

    */

   png_color_16 background;

#endif

   /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards

    * and downwards from the top-left corner of the display, page, or other

    * application-specific co-ordinate space.  See the PNG_OFFSET_ defines

    * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.

    */

   png_int_32 x_offset; /* x offset on page */

   png_int_32 y_offset; /* y offset on page */

   png_byte offset_unit_type; /* offset units type */

#endif

   /* The pHYs chunk gives the physical pixel density of the image for

    * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_

    * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.

    */

   png_uint_32 x_pixels_per_unit; /* horizontal pixel density */

   png_uint_32 y_pixels_per_unit; /* vertical pixel density */

   png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */

#endif

   /* The hIST chunk contains the relative frequency or importance of the

    * various palette entries, so that a viewer can intelligently select a

    * reduced-color palette, if required.  Data is an array of "num_palette"

    * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)

    * is non-zero.

    */

   png_uint_16p hist;

#endif

   /* The pCAL chunk describes a transformation between the stored pixel

    * values and original physical data values used to create the image.

    * The integer range [0, 2^bit_depth - 1] maps to the floating-point

    * range given by [pcal_X0, pcal_X1], and are further transformed by a

    * (possibly non-linear) transformation function given by "pcal_type"

    * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_

    * defines below, and the PNG-Group's PNG extensions document for a

    * complete description of the transformations and how they should be

    * implemented, and for a description of the ASCII parameter strings.

    * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.

    */

   png_charp pcal_purpose;  /* pCAL chunk description string */

   png_int_32 pcal_X0;      /* minimum value */

   png_int_32 pcal_X1;      /* maximum value */

   png_charp pcal_units;    /* Latin-1 string giving physical units */

   png_charpp pcal_params;  /* ASCII strings containing parameter values */

   png_byte pcal_type;      /* equation type (see PNG_EQUATION_ below) */

   png_byte pcal_nparams;   /* number of parameters given in pcal_params */

#endif

   png_uint_32 free_me;     /* flags items libpng is responsible for freeing */

   /* Storage for unknown chunks that the library doesn't recognize. */

   png_unknown_chunkp unknown_chunks;

    * png_struct::user_chunk_cache_max, else overflow can occur.

    */

   int                unknown_chunks_num;

#endif

   /* Data on sPLT chunks (there may be more than one). */

   png_sPLT_tp splt_palettes;

   int         splt_palettes_num; /* Match type returned by png_get API */

#endif

   /* The sCAL chunk describes the actual physical dimensions of the

    * subject matter of the graphic.  The chunk contains a unit specification

    * a byte value, and two ASCII strings representing floating-point

    * values.  The values are width and height corresponsing to one pixel

    * in the image.  Data values are valid if (valid & PNG_INFO_sCAL) is

    * non-zero.

    */

   png_byte scal_unit;         /* unit of physical scale */

   png_charp scal_s_width;     /* string containing height */

   png_charp scal_s_height;    /* string containing width */

#endif

   /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS)

      non-zero */

   /* Data valid if (valid & PNG_INFO_IDAT) non-zero */

   png_bytepp row_pointers;        /* the image bits */

#endif

#endif /* PNGINFO_H */