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/src/FreeImage/Source/LibPNG/pnginfo.h

https://bitbucket.org/cabalistic/ogredeps/
C++ Header | 269 lines | 103 code | 24 blank | 142 comment | 4 complexity | ff88045d7ea36a73a67b284c720fd6d8 MD5 | raw file
  1
  2/* pnginfo.h - header file for PNG reference library
  3 *
  4 * Copyright (c) 1998-2011 Glenn Randers-Pehrson
  5 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  6 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
  7 *
  8 * Last changed in libpng 1.5.0 [January 6, 2011]
  9 *
 10 * This code is released under the libpng license.
 11 * For conditions of distribution and use, see the disclaimer
 12 * and license in png.h
 13 */
 14
 15 /* png_info is a structure that holds the information in a PNG file so
 16 * that the application can find out the characteristics of the image.
 17 * If you are reading the file, this structure will tell you what is
 18 * in the PNG file.  If you are writing the file, fill in the information
 19 * you want to put into the PNG file, using png_set_*() functions, then
 20 * call png_write_info().
 21 *
 22 * The names chosen should be very close to the PNG specification, so
 23 * consult that document for information about the meaning of each field.
 24 *
 25 * With libpng < 0.95, it was only possible to directly set and read the
 26 * the values in the png_info_struct, which meant that the contents and
 27 * order of the values had to remain fixed.  With libpng 0.95 and later,
 28 * however, there are now functions that abstract the contents of
 29 * png_info_struct from the application, so this makes it easier to use
 30 * libpng with dynamic libraries, and even makes it possible to use
 31 * libraries that don't have all of the libpng ancillary chunk-handing
 32 * functionality.  In libpng-1.5.0 this was moved into a separate private
 33 * file that is not visible to applications.
 34 *
 35 * The following members may have allocated storage attached that should be
 36 * cleaned up before the structure is discarded: palette, trans, text,
 37 * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
 38 * splt_palettes, scal_unit, row_pointers, and unknowns.   By default, these
 39 * are automatically freed when the info structure is deallocated, if they were
 40 * allocated internally by libpng.  This behavior can be changed by means
 41 * of the png_data_freer() function.
 42 *
 43 * More allocation details: all the chunk-reading functions that
 44 * change these members go through the corresponding png_set_*
 45 * functions.  A function to clear these members is available: see
 46 * png_free_data().  The png_set_* functions do not depend on being
 47 * able to point info structure members to any of the storage they are
 48 * passed (they make their own copies), EXCEPT that the png_set_text
 49 * functions use the same storage passed to them in the text_ptr or
 50 * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
 51 * functions do not make their own copies.
 52 */
 53#ifndef PNGINFO_H
 54#define PNGINFO_H
 55
 56struct png_info_def
 57{
 58   /* the following are necessary for every PNG file */
 59   png_uint_32 width;  /* width of image in pixels (from IHDR) */
 60   png_uint_32 height; /* height of image in pixels (from IHDR) */
 61   png_uint_32 valid;  /* valid chunk data (see PNG_INFO_ below) */
 62   png_size_t rowbytes; /* bytes needed to hold an untransformed row */
 63   png_colorp palette;      /* array of color values (valid & PNG_INFO_PLTE) */
 64   png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */
 65   png_uint_16 num_trans;   /* number of transparent palette color (tRNS) */
 66   png_byte bit_depth;      /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */
 67   png_byte color_type;     /* see PNG_COLOR_TYPE_ below (from IHDR) */
 68   /* The following three should have been named *_method not *_type */
 69   png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */
 70   png_byte filter_type;    /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
 71   png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
 72
 73   /* The following is informational only on read, and not used on writes. */
 74   png_byte channels;       /* number of data channels per pixel (1, 2, 3, 4) */
 75   png_byte pixel_depth;    /* number of bits per pixel */
 76   png_byte spare_byte;     /* to align the data, and for future use */
 77   png_byte signature[8];   /* magic bytes read by libpng from start of file */
 78
 79   /* The rest of the data is optional.  If you are reading, check the
 80    * valid field to see if the information in these are valid.  If you
 81    * are writing, set the valid field to those chunks you want written,
 82    * and initialize the appropriate fields below.
 83    */
 84
 85#if defined(PNG_gAMA_SUPPORTED)
 86   /* The gAMA chunk describes the gamma characteristics of the system
 87    * on which the image was created, normally in the range [1.0, 2.5].
 88    * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.
 89    */
 90   png_fixed_point gamma;
 91#endif
 92
 93#ifdef PNG_sRGB_SUPPORTED
 94    /* GR-P, 0.96a */
 95    /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */
 96   png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */
 97#endif
 98
 99#ifdef PNG_TEXT_SUPPORTED
100   /* The tEXt, and zTXt chunks contain human-readable textual data in
101    * uncompressed, compressed, and optionally compressed forms, respectively.
102    * The data in "text" is an array of pointers to uncompressed,
103    * null-terminated C strings. Each chunk has a keyword that describes the
104    * textual data contained in that chunk.  Keywords are not required to be
105    * unique, and the text string may be empty.  Any number of text chunks may
106    * be in an image.
107    */
108   int num_text; /* number of comments read or comments to write */
109   int max_text; /* current size of text array */
110   png_textp text; /* array of comments read or comments to write */
111#endif /* PNG_TEXT_SUPPORTED */
112
113#ifdef PNG_tIME_SUPPORTED
114   /* The tIME chunk holds the last time the displayed image data was
115    * modified.  See the png_time struct for the contents of this struct.
116    */
117   png_time mod_time;
118#endif
119
120#ifdef PNG_sBIT_SUPPORTED
121   /* The sBIT chunk specifies the number of significant high-order bits
122    * in the pixel data.  Values are in the range [1, bit_depth], and are
123    * only specified for the channels in the pixel data.  The contents of
124    * the low-order bits is not specified.  Data is valid if
125    * (valid & PNG_INFO_sBIT) is non-zero.
126    */
127   png_color_8 sig_bit; /* significant bits in color channels */
128#endif
129
130#if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \
131defined(PNG_READ_BACKGROUND_SUPPORTED)
132   /* The tRNS chunk supplies transparency data for paletted images and
133    * other image types that don't need a full alpha channel.  There are
134    * "num_trans" transparency values for a paletted image, stored in the
135    * same order as the palette colors, starting from index 0.  Values
136    * for the data are in the range [0, 255], ranging from fully transparent
137    * to fully opaque, respectively.  For non-paletted images, there is a
138    * single color specified that should be treated as fully transparent.
139    * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
140    */
141   png_bytep trans_alpha;    /* alpha values for paletted image */
142   png_color_16 trans_color; /* transparent color for non-palette image */
143#endif
144
145#if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
146   /* The bKGD chunk gives the suggested image background color if the
147    * display program does not have its own background color and the image
148    * is needs to composited onto a background before display.  The colors
149    * in "background" are normally in the same color space/depth as the
150    * pixel data.  Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
151    */
152   png_color_16 background;
153#endif
154
155#ifdef PNG_oFFs_SUPPORTED
156   /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
157    * and downwards from the top-left corner of the display, page, or other
158    * application-specific co-ordinate space.  See the PNG_OFFSET_ defines
159    * below for the unit types.  Valid if (valid & PNG_INFO_oFFs) non-zero.
160    */
161   png_int_32 x_offset; /* x offset on page */
162   png_int_32 y_offset; /* y offset on page */
163   png_byte offset_unit_type; /* offset units type */
164#endif
165
166#ifdef PNG_pHYs_SUPPORTED
167   /* The pHYs chunk gives the physical pixel density of the image for
168    * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
169    * defines below).  Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
170    */
171   png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
172   png_uint_32 y_pixels_per_unit; /* vertical pixel density */
173   png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
174#endif
175
176#ifdef PNG_hIST_SUPPORTED
177   /* The hIST chunk contains the relative frequency or importance of the
178    * various palette entries, so that a viewer can intelligently select a
179    * reduced-color palette, if required.  Data is an array of "num_palette"
180    * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
181    * is non-zero.
182    */
183   png_uint_16p hist;
184#endif
185
186#ifdef PNG_cHRM_SUPPORTED
187   /* The cHRM chunk describes the CIE color characteristics of the monitor
188    * on which the PNG was created.  This data allows the viewer to do gamut
189    * mapping of the input image to ensure that the viewer sees the same
190    * colors in the image as the creator.  Values are in the range
191    * [0.0, 0.8].  Data valid if (valid & PNG_INFO_cHRM) non-zero.
192    */
193   png_fixed_point x_white;
194   png_fixed_point y_white;
195   png_fixed_point x_red;
196   png_fixed_point y_red;
197   png_fixed_point x_green;
198   png_fixed_point y_green;
199   png_fixed_point x_blue;
200   png_fixed_point y_blue;
201#endif
202
203#ifdef PNG_pCAL_SUPPORTED
204   /* The pCAL chunk describes a transformation between the stored pixel
205    * values and original physical data values used to create the image.
206    * The integer range [0, 2^bit_depth - 1] maps to the floating-point
207    * range given by [pcal_X0, pcal_X1], and are further transformed by a
208    * (possibly non-linear) transformation function given by "pcal_type"
209    * and "pcal_params" into "pcal_units".  Please see the PNG_EQUATION_
210    * defines below, and the PNG-Group's PNG extensions document for a
211    * complete description of the transformations and how they should be
212    * implemented, and for a description of the ASCII parameter strings.
213    * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
214    */
215   png_charp pcal_purpose;  /* pCAL chunk description string */
216   png_int_32 pcal_X0;      /* minimum value */
217   png_int_32 pcal_X1;      /* maximum value */
218   png_charp pcal_units;    /* Latin-1 string giving physical units */
219   png_charpp pcal_params;  /* ASCII strings containing parameter values */
220   png_byte pcal_type;      /* equation type (see PNG_EQUATION_ below) */
221   png_byte pcal_nparams;   /* number of parameters given in pcal_params */
222#endif
223
224/* New members added in libpng-1.0.6 */
225   png_uint_32 free_me;     /* flags items libpng is responsible for freeing */
226
227#if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
228 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
229   /* Storage for unknown chunks that the library doesn't recognize. */
230   png_unknown_chunkp unknown_chunks;
231   int unknown_chunks_num;
232#endif
233
234#ifdef PNG_iCCP_SUPPORTED
235   /* iCCP chunk data. */
236   png_charp iccp_name;     /* profile name */
237   png_bytep iccp_profile;  /* International Color Consortium profile data */
238   png_uint_32 iccp_proflen;  /* ICC profile data length */
239   png_byte iccp_compression; /* Always zero */
240#endif
241
242#ifdef PNG_sPLT_SUPPORTED
243   /* Data on sPLT chunks (there may be more than one). */
244   png_sPLT_tp splt_palettes;
245   png_uint_32 splt_palettes_num;
246#endif
247
248#ifdef PNG_sCAL_SUPPORTED
249   /* The sCAL chunk describes the actual physical dimensions of the
250    * subject matter of the graphic.  The chunk contains a unit specification
251    * a byte value, and two ASCII strings representing floating-point
252    * values.  The values are width and height corresponsing to one pixel
253    * in the image.  Data values are valid if (valid & PNG_INFO_sCAL) is
254    * non-zero.
255    */
256   png_byte scal_unit;         /* unit of physical scale */
257   png_charp scal_s_width;     /* string containing height */
258   png_charp scal_s_height;    /* string containing width */
259#endif
260
261#ifdef PNG_INFO_IMAGE_SUPPORTED
262   /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS)
263      non-zero */
264   /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
265   png_bytepp row_pointers;        /* the image bits */
266#endif
267
268};
269#endif /* PNGINFO_H */