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