png_byte name[5];    png_byte *data;    png_size_t size;    /* libpng-using applications should NOT directly modify this byte. */    png_byte location; /* mode of operation at read time */}png_unknown_chunk;typedef png_unknown_chunk FAR * png_unknown_chunkp;typedef png_unknown_chunk FAR * FAR * png_unknown_chunkpp;#endif/* png_info is a structure that holds the information in a PNG file so * 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, 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 any case, the order of the parameters in png_info_struct should NOT * be changed for as long as possible to keep compatibility with applications * that use the old direct-access method with png_info_struct. * * 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. */typedef struct png_info_struct{   /* 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_uint_32 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 */   /* The following is informational only on read, and not used on writes. */   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 */   png_byte signature[8];   /* magic bytes read by libpng from start of file */   /* The rest of the data is optional.  If you are reading, check the    * 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.    */#if defined(PNG_gAMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED)   /* The gAMA chunk describes the gamma characteristics of the system    * on which the image was created, normally in the range [1.0, 2.5].    * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.    */   float gamma; /* gamma value of image, if (valid & PNG_INFO_gAMA) */#endif#if defined(PNG_sRGB_SUPPORTED)    /* GR-P, 0.96a */    /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */   png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */#endif#if defined(PNG_TEXT_SUPPORTED)   /* 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/to write */   int max_text; /* current size of text array */   png_textp text; /* array of comments read/to write */#endif /* PNG_TEXT_SUPPORTED */#if defined(PNG_tIME_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#if defined(PNG_sBIT_SUPPORTED)   /* 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#if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \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; /* transparent values for paletted image */   png_color_16 trans_values; /* transparent color for non-palette image */#endif#if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)   /* 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#if defined(PNG_oFFs_SUPPORTED)   /* 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#if defined(PNG_pHYs_SUPPORTED)   /* 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#if defined(PNG_hIST_SUPPORTED)   /* 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#ifdef PNG_cHRM_SUPPORTED   /* The cHRM chunk describes the CIE color characteristics of the monitor    * on which the PNG was created.  This data allows the viewer to do gamut    * mapping of the input image to ensure that the viewer sees the same    * colors in the image as the creator.  Values are in the range    * [0.0, 0.8].  Data valid if (valid & PNG_INFO_cHRM) non-zero.    */#ifdef PNG_FLOATING_POINT_SUPPORTED   float x_white;   float y_white;   float x_red;   float y_red;   float x_green;   float y_green;   float x_blue;   float y_blue;#endif#endif#if defined(PNG_pCAL_SUPPORTED)   /* 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/* New members added in libpng-1.0.6 */#ifdef PNG_FREE_ME_SUPPORTED   png_uint_32 free_me;     /* flags items libpng is responsible for freeing */#endif#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED)   /* storage for unknown chunks that the library doesn't recognize. */   png_unknown_chunkp unknown_chunks;   png_size_t unknown_chunks_num;#endif#if defined(PNG_iCCP_SUPPORTED)   /* iCCP chunk data. */   png_charp iccp_name;     /* profile name */   png_charp iccp_profile;  /* International Color Consortium profile data */                            /* Note to maintainer: should be png_bytep */   png_uint_32 iccp_proflen;  /* ICC profile data length */   png_byte iccp_compression; /* Always zero */#endif#if defined(PNG_sPLT_SUPPORTED)   /* data on sPLT chunks (there may be more than one). */   png_sPLT_tp splt_palettes;   png_uint_32 splt_palettes_num;#endif#if defined(PNG_sCAL_SUPPORTED)   /* 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.  This external representation is converted to double    * here.  Data values are valid if (valid & PNG_INFO_sCAL) is non-zero.    */   png_byte scal_unit;         /* unit of physical scale */#ifdef PNG_FLOATING_POINT_SUPPORTED   double scal_pixel_width;    /* width of one pixel */   double scal_pixel_height;   /* height of one pixel */#endif#ifdef PNG_FIXED_POINT_SUPPORTED   png_charp scal_s_width;     /* string containing height */   png_charp scal_s_height;    /* string containing width */#endif#endif#if defined(PNG_INFO_IMAGE_SUPPORTED)   /* 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#if defined(PNG_FIXED_POINT_SUPPORTED) && defined(PNG_gAMA_SUPPORTED)   png_fixed_point int_gamma; /* gamma of image, if (valid & PNG_INFO_gAMA) */#endif#if defined(PNG_cHRM_SUPPORTED) && defined(PNG_FIXED_POINT_SUPPORTED)   png_fixed_point int_x_white;   png_fixed_point int_y_white;   png_fixed_point int_x_red;   png_fixed_point int_y_red;   png_fixed_point int_x_green;   png_fixed_point int_y_green;   png_fixed_point int_x_blue;   png_fixed_point int_y_blue;#endif} png_info;typedef png_info FAR * png_infop;typedef png_info FAR * FAR * png_infopp;/* Maximum positive integer used in PNG is (2^31)-1 */#define PNG_UINT_31_MAX ((png_uint_32)0x7fffffffL)#define PNG_UINT_32_MAX ((png_uint_32)(-1))#define PNG_SIZE_MAX ((png_size_t)(-1))/* PNG_MAX_UINT is deprecated; use PNG_UINT_31_MAX instead. */#define PNG_MAX_UINT PNG_UINT_31_MAX/* These describe the color_type field in png_info. */