reactos/dll/3rdparty/libpng/pnginfo.h

   1
   2 /* pnginfo.h - header file for PNG reference library
   3  *
   4  * Last changed in libpng 1.6.1 [March 28, 2013]
   5  * Copyright (c) 1998-2002,2004,2006-2013 Glenn Randers-Pehrson
   6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
   7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
   8  *
   9  * This code is released under the libpng license.
  10  * For conditions of distribution and use, see the disclaimer
  11  * and license in png.h
  12  */
  13
  14  /* png_info is a structure that holds the information in a PNG file so
  15  * that the application can find out the characteristics of the image.
  16  * If you are reading the file, this structure will tell you what is
  17  * in the PNG file.  If you are writing the file, fill in the information
  18  * you want to put into the PNG file, using png_set_*() functions, then
  19  * call png_write_info().
  20  *
  21  * The names chosen should be very close to the PNG specification, so
  22  * consult that document for information about the meaning of each field.
  23  *
  24  * With libpng < 0.95, it was only possible to directly set and read the
  25  * the values in the png_info_struct, which meant that the contents and
  26  * order of the values had to remain fixed.  With libpng 0.95 and later,
  27  * however, there are now functions that abstract the contents of
  28  * png_info_struct from the application, so this makes it easier to use
  29  * libpng with dynamic libraries, and even makes it possible to use
  30  * libraries that don't have all of the libpng ancillary chunk-handing
  31  * functionality.  In libpng-1.5.0 this was moved into a separate private
  32  * file that is not visible to applications.
  33  *
  34  * The following members may have allocated storage attached that should be
  35  * cleaned up before the structure is discarded: palette, trans, text,
  36  * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
  37  * splt_palettes, scal_unit, row_pointers, and unknowns.   By default, these
  38  * are automatically freed when the info structure is deallocated, if they were
  39  * allocated internally by libpng.  This behavior can be changed by means
  40  * of the png_data_freer() function.
  41  *
  42  * More allocation details: all the chunk-reading functions that
  43  * change these members go through the corresponding png_set_*
  44  * functions.  A function to clear these members is available: see
  45  * png_free_data().  The png_set_* functions do not depend on being
  46  * able to point info structure members to any of the storage they are
  47  * passed (they make their own copies), EXCEPT that the png_set_text
  48  * functions use the same storage passed to them in the text_ptr or
  49  * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
  50  * functions do not make their own copies.
  51  */
  52 #ifndef PNGINFO_H
  53 #define PNGINFO_H
  54
  55 struct png_info_def
  56 {
  57    /* The following are necessary for every PNG file */
  58    png_uint_32 width;  /* width of image in pixels (from IHDR) */
  59    png_uint_32 height; /* height of image in pixels (from IHDR) */
  60    png_uint_32 valid;  /* valid chunk data (see PNG_INFO_ below) */
  61    png_size_t rowbytes; /* bytes needed to hold an untransformed row */
  62    png_colorp palette;      /* array of color values (valid & PNG_INFO_PLTE) */
  63    png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */
  64    png_uint_16 num_trans;   /* number of transparent palette color (tRNS) */
  65    png_byte bit_depth;      /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */
  66    png_byte color_type;     /* see PNG_COLOR_TYPE_ below (from IHDR) */
  67    /* The following three should have been named *_method not *_type */
  68    png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */
  69    png_byte filter_type;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
  70    png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
  71
  72    /* The following are set by png_set_IHDR, called from the application on
  73     * write, but the are never actually used by the write code.
  74     */
  75    png_byte channels;       /* number of data channels per pixel (1, 2, 3, 4) */
  76    png_byte pixel_depth;    /* number of bits per pixel */
  77    png_byte spare_byte;     /* to align the data, and for future use */
  78
  79 #ifdef PNG_READ_SUPPORTED
  80    /* This is never set during write */
  81    png_byte signature[8];   /* magic bytes read by libpng from start of file */
  82 #endif
  83
  84    /* The rest of the data is optional.  If you are reading, check the
  85     * valid field to see if the information in these are valid.  If you
  86     * are writing, set the valid field to those chunks you want written,
  87     * and initialize the appropriate fields below.
  88     */
  89
  90 #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
  91    /* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are
  92     * defined.  When COLORSPACE is switched on all the colorspace-defining
  93     * chunks should be enabled, when GAMMA is switched on all the gamma-defining
  94     * chunks should be enabled.  If this is not done it becomes possible to read
  95     * inconsistent PNG files and assign a probably incorrect interpretation to
  96     * the information.  (In other words, by carefully choosing which chunks to
  97     * recognize the system configuration can select an interpretation for PNG
  98     * files containing ambiguous data and this will result in inconsistent
  99     * behavior between different libpng builds!)
 100     */
 101    png_colorspace colorspace;
 102 #endif
 103
 104 #ifdef PNG_iCCP_SUPPORTED
 105    /* iCCP chunk data. */
 106    png_charp iccp_name;     /* profile name */
 107    png_bytep iccp_profile;  /* International Color Consortium profile data */
 108    png_uint_32 iccp_proflen;  /* ICC profile data length */
 109 #endif
 110
 111 #ifdef PNG_TEXT_SUPPORTED
 112    /* The tEXt, and zTXt chunks contain human-readable textual data in
 113     * uncompressed, compressed, and optionally compressed forms, respectively.
 114     * The data in "text" is an array of pointers to uncompressed,
 115     * null-terminated C strings. Each chunk has a keyword that describes the
 116     * textual data contained in that chunk.  Keywords are not required to be
 117     * unique, and the text string may be empty.  Any number of text chunks may
 118     * be in an image.
 119     */
 120    int num_text; /* number of comments read or comments to write */
 121    int max_text; /* current size of text array */
 122    png_textp text; /* array of comments read or comments to write */
 123 #endif /* TEXT */
 124
 125 #ifdef PNG_tIME_SUPPORTED
 126    /* The tIME chunk holds the last time the displayed image data was
 127     * modified.  See the png_time struct for the contents of this struct.
 128     */
 129    png_time mod_time;
 130 #endif
 131
 132 #ifdef PNG_sBIT_SUPPORTED
 133    /* The sBIT chunk specifies the number of significant high-order bits
 134     * in the pixel data.  Values are in the range [1, bit_depth], and are
 135     * only specified for the channels in the pixel data.  The contents of
 136     * the low-order bits is not specified.  Data is valid if
 137     * (valid & PNG_INFO_sBIT) is non-zero.
 138     */
 139    png_color_8 sig_bit; /* significant bits in color channels */
 140 #endif
 141
 142 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \
 143 defined(PNG_READ_BACKGROUND_SUPPORTED)
 144    /* The tRNS chunk supplies transparency data for paletted images and
 145     * other image types that don't need a full alpha channel.  There are
 146     * "num_trans" transparency values for a paletted image, stored in the
 147     * same order as the palette colors, starting from index 0.  Values
 148     * for the data are in the range [0, 255], ranging from fully transparent
 149     * to fully opaque, respectively.  For non-paletted images, there is a
 150     * single color specified that should be treated as fully transparent.
 151     * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
 152     */
 153    png_bytep trans_alpha;    /* alpha values for paletted image */
 154    png_color_16 trans_color; /* transparent color for non-palette image */
 155 #endif
 156
 157 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
 158    /* The bKGD chunk gives the suggested image background color if the
 159     * display program does not have its own background color and the image
 160     * is needs to composited onto a background before display.  The colors
 161     * in "background" are normally in the same color space/depth as the
 162     * pixel data.  Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
 163     */
 164    png_color_16 background;
 165 #endif
 166
 167 #ifdef PNG_oFFs_SUPPORTED
 168    /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
 169     * and downwards from the top-left corner of the display, page, or other
 170     * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
 171     * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
 172     */
 173    png_int_32 x_offset; /* x offset on page */
 174    png_int_32 y_offset; /* y offset on page */
 175    png_byte offset_unit_type; /* offset units type */
 176 #endif
 177
 178 #ifdef PNG_pHYs_SUPPORTED
 179    /* The pHYs chunk gives the physical pixel density of the image for
 180     * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
 181     * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
 182     */
 183    png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
 184    png_uint_32 y_pixels_per_unit; /* vertical pixel density */
 185    png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
 186 #endif
 187
 188 #ifdef PNG_eXIf_SUPPORTED
 189    int num_exif;  /* Added at libpng-1.6.31 */
 190    png_bytep exif;
 191 # ifdef PNG_READ_eXIf_SUPPORTED
 192    png_bytep eXIf_buf;  /* Added at libpng-1.6.32 */
 193 # endif
 194 #endif
 195
 196 #ifdef PNG_hIST_SUPPORTED
 197    /* The hIST chunk contains the relative frequency or importance of the
 198     * various palette entries, so that a viewer can intelligently select a
 199     * reduced-color palette, if required.  Data is an array of "num_palette"
 200     * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
 201     * is non-zero.
 202     */
 203    png_uint_16p hist;
 204 #endif
 205
 206 #ifdef PNG_pCAL_SUPPORTED
 207    /* The pCAL chunk describes a transformation between the stored pixel
 208     * values and original physical data values used to create the image.
 209     * The integer range [0, 2^bit_depth - 1] maps to the floating-point
 210     * range given by [pcal_X0, pcal_X1], and are further transformed by a
 211     * (possibly non-linear) transformation function given by "pcal_type"
 212     * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
 213     * defines below, and the PNG-Group's PNG extensions document for a
 214     * complete description of the transformations and how they should be
 215     * implemented, and for a description of the ASCII parameter strings.
 216     * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
 217     */
 218    png_charp pcal_purpose;  /* pCAL chunk description string */
 219    png_int_32 pcal_X0;      /* minimum value */
 220    png_int_32 pcal_X1;      /* maximum value */
 221    png_charp pcal_units;    /* Latin-1 string giving physical units */
 222    png_charpp pcal_params;  /* ASCII strings containing parameter values */
 223    png_byte pcal_type;      /* equation type (see PNG_EQUATION_ below) */
 224    png_byte pcal_nparams;   /* number of parameters given in pcal_params */
 225 #endif
 226
 227 /* New members added in libpng-1.0.6 */
 228    png_uint_32 free_me;     /* flags items libpng is responsible for freeing */
 229
 230 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
 231    /* Storage for unknown chunks that the library doesn't recognize. */
 232    png_unknown_chunkp unknown_chunks;
 233
 234    /* The type of this field is limited by the type of
 235     * png_struct::user_chunk_cache_max, else overflow can occur.
 236     */
 237    int                unknown_chunks_num;
 238 #endif
 239
 240 #ifdef PNG_sPLT_SUPPORTED
 241    /* Data on sPLT chunks (there may be more than one). */
 242    png_sPLT_tp splt_palettes;
 243    int         splt_palettes_num; /* Match type returned by png_get API */
 244 #endif
 245
 246 #ifdef PNG_sCAL_SUPPORTED
 247    /* The sCAL chunk describes the actual physical dimensions of the
 248     * subject matter of the graphic.  The chunk contains a unit specification
 249     * a byte value, and two ASCII strings representing floating-point
 250     * values.  The values are width and height corresponsing to one pixel
 251     * in the image.  Data values are valid if (valid & PNG_INFO_sCAL) is
 252     * non-zero.
 253     */
 254    png_byte scal_unit;         /* unit of physical scale */
 255    png_charp scal_s_width;     /* string containing height */
 256    png_charp scal_s_height;    /* string containing width */
 257 #endif
 258
 259 #ifdef PNG_INFO_IMAGE_SUPPORTED
 260    /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS)
 261       non-zero */
 262    /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
 263    png_bytepp row_pointers;        /* the image bits */
 264 #endif
 265
 266 };
 267 #endif /* PNGINFO_H */