pngstruct.h 20 KB

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  1. /* pngstruct.h - header file for PNG reference library
  2. *
  3. * Copyright (c) 2018-2019 Cosmin Truta
  4. * Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson
  5. * Copyright (c) 1996-1997 Andreas Dilger
  6. * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.
  7. *
  8. * This code is released under the libpng license.
  9. * For conditions of distribution and use, see the disclaimer
  10. * and license in png.h
  11. */
  12. /* The structure that holds the information to read and write PNG files.
  13. * The only people who need to care about what is inside of this are the
  14. * people who will be modifying the library for their own special needs.
  15. * It should NOT be accessed directly by an application.
  16. */
  17. #ifndef PNGSTRUCT_H
  18. #define PNGSTRUCT_H
  19. /* zlib.h defines the structure z_stream, an instance of which is included
  20. * in this structure and is required for decompressing the LZ compressed
  21. * data in PNG files.
  22. */
  23. #ifndef ZLIB_CONST
  24. /* We must ensure that zlib uses 'const' in declarations. */
  25. # define ZLIB_CONST
  26. #endif
  27. #include "zlib.h"
  28. #ifdef const
  29. /* zlib.h sometimes #defines const to nothing, undo this. */
  30. # undef const
  31. #endif
  32. /* zlib.h has mediocre z_const use before 1.2.6, this stuff is for compatibility
  33. * with older builds.
  34. */
  35. #if ZLIB_VERNUM < 0x1260
  36. # define PNGZ_MSG_CAST(s) png_constcast(char*,s)
  37. # define PNGZ_INPUT_CAST(b) png_constcast(png_bytep,b)
  38. #else
  39. # define PNGZ_MSG_CAST(s) (s)
  40. # define PNGZ_INPUT_CAST(b) (b)
  41. #endif
  42. /* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
  43. * can handle at once. This type need be no larger than 16 bits (so maximum of
  44. * 65535), this define allows us to discover how big it is, but limited by the
  45. * maximum for size_t. The value can be overridden in a library build
  46. * (pngusr.h, or set it in CPPFLAGS) and it works to set it to a considerably
  47. * lower value (e.g. 255 works). A lower value may help memory usage (slightly)
  48. * and may even improve performance on some systems (and degrade it on others.)
  49. */
  50. #ifndef ZLIB_IO_MAX
  51. # define ZLIB_IO_MAX ((uInt)-1)
  52. #endif
  53. #ifdef PNG_WRITE_SUPPORTED
  54. /* The type of a compression buffer list used by the write code. */
  55. typedef struct png_compression_buffer
  56. {
  57. struct png_compression_buffer *next;
  58. png_byte output[1]; /* actually zbuf_size */
  59. } png_compression_buffer, *png_compression_bufferp;
  60. #define PNG_COMPRESSION_BUFFER_SIZE(pp)\
  61. (offsetof(png_compression_buffer, output) + (pp)->zbuffer_size)
  62. #endif
  63. /* Colorspace support; structures used in png_struct, png_info and in internal
  64. * functions to hold and communicate information about the color space.
  65. *
  66. * PNG_COLORSPACE_SUPPORTED is only required if the application will perform
  67. * colorspace corrections, otherwise all the colorspace information can be
  68. * skipped and the size of libpng can be reduced (significantly) by compiling
  69. * out the colorspace support.
  70. */
  71. #ifdef PNG_COLORSPACE_SUPPORTED
  72. /* The chromaticities of the red, green and blue colorants and the chromaticity
  73. * of the corresponding white point (i.e. of rgb(1.0,1.0,1.0)).
  74. */
  75. typedef struct png_xy
  76. {
  77. png_fixed_point redx, redy;
  78. png_fixed_point greenx, greeny;
  79. png_fixed_point bluex, bluey;
  80. png_fixed_point whitex, whitey;
  81. } png_xy;
  82. /* The same data as above but encoded as CIE XYZ values. When this data comes
  83. * from chromaticities the sum of the Y values is assumed to be 1.0
  84. */
  85. typedef struct png_XYZ
  86. {
  87. png_fixed_point red_X, red_Y, red_Z;
  88. png_fixed_point green_X, green_Y, green_Z;
  89. png_fixed_point blue_X, blue_Y, blue_Z;
  90. } png_XYZ;
  91. #endif /* COLORSPACE */
  92. #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
  93. /* A colorspace is all the above plus, potentially, profile information;
  94. * however at present libpng does not use the profile internally so it is only
  95. * stored in the png_info struct (if iCCP is supported.) The rendering intent
  96. * is retained here and is checked.
  97. *
  98. * The file gamma encoding information is also stored here and gamma correction
  99. * is done by libpng, whereas color correction must currently be done by the
  100. * application.
  101. */
  102. typedef struct png_colorspace
  103. {
  104. #ifdef PNG_GAMMA_SUPPORTED
  105. png_fixed_point gamma; /* File gamma */
  106. #endif
  107. #ifdef PNG_COLORSPACE_SUPPORTED
  108. png_xy end_points_xy; /* End points as chromaticities */
  109. png_XYZ end_points_XYZ; /* End points as CIE XYZ colorant values */
  110. png_uint_16 rendering_intent; /* Rendering intent of a profile */
  111. #endif
  112. /* Flags are always defined to simplify the code. */
  113. png_uint_16 flags; /* As defined below */
  114. } png_colorspace, * PNG_RESTRICT png_colorspacerp;
  115. typedef const png_colorspace * PNG_RESTRICT png_const_colorspacerp;
  116. /* General flags for the 'flags' field */
  117. #define PNG_COLORSPACE_HAVE_GAMMA 0x0001
  118. #define PNG_COLORSPACE_HAVE_ENDPOINTS 0x0002
  119. #define PNG_COLORSPACE_HAVE_INTENT 0x0004
  120. #define PNG_COLORSPACE_FROM_gAMA 0x0008
  121. #define PNG_COLORSPACE_FROM_cHRM 0x0010
  122. #define PNG_COLORSPACE_FROM_sRGB 0x0020
  123. #define PNG_COLORSPACE_ENDPOINTS_MATCH_sRGB 0x0040
  124. #define PNG_COLORSPACE_MATCHES_sRGB 0x0080 /* exact match on profile */
  125. #define PNG_COLORSPACE_INVALID 0x8000
  126. #define PNG_COLORSPACE_CANCEL(flags) (0xffff ^ (flags))
  127. #endif /* COLORSPACE || GAMMA */
  128. struct png_struct_def
  129. {
  130. #ifdef PNG_SETJMP_SUPPORTED
  131. jmp_buf jmp_buf_local; /* New name in 1.6.0 for jmp_buf in png_struct */
  132. png_longjmp_ptr longjmp_fn;/* setjmp non-local goto function. */
  133. jmp_buf *jmp_buf_ptr; /* passed to longjmp_fn */
  134. size_t jmp_buf_size; /* size of the above, if allocated */
  135. #endif
  136. png_error_ptr error_fn; /* function for printing errors and aborting */
  137. #ifdef PNG_WARNINGS_SUPPORTED
  138. png_error_ptr warning_fn; /* function for printing warnings */
  139. #endif
  140. png_voidp error_ptr; /* user supplied struct for error functions */
  141. png_rw_ptr write_data_fn; /* function for writing output data */
  142. png_rw_ptr read_data_fn; /* function for reading input data */
  143. png_voidp io_ptr; /* ptr to application struct for I/O functions */
  144. #ifdef PNG_READ_USER_TRANSFORM_SUPPORTED
  145. png_user_transform_ptr read_user_transform_fn; /* user read transform */
  146. #endif
  147. #ifdef PNG_WRITE_USER_TRANSFORM_SUPPORTED
  148. png_user_transform_ptr write_user_transform_fn; /* user write transform */
  149. #endif
  150. /* These were added in libpng-1.0.2 */
  151. #ifdef PNG_USER_TRANSFORM_PTR_SUPPORTED
  152. #if defined(PNG_READ_USER_TRANSFORM_SUPPORTED) || \
  153. defined(PNG_WRITE_USER_TRANSFORM_SUPPORTED)
  154. png_voidp user_transform_ptr; /* user supplied struct for user transform */
  155. png_byte user_transform_depth; /* bit depth of user transformed pixels */
  156. png_byte user_transform_channels; /* channels in user transformed pixels */
  157. #endif
  158. #endif
  159. png_uint_32 mode; /* tells us where we are in the PNG file */
  160. png_uint_32 flags; /* flags indicating various things to libpng */
  161. png_uint_32 transformations; /* which transformations to perform */
  162. png_uint_32 zowner; /* ID (chunk type) of zstream owner, 0 if none */
  163. z_stream zstream; /* decompression structure */
  164. #ifdef PNG_WRITE_SUPPORTED
  165. png_compression_bufferp zbuffer_list; /* Created on demand during write */
  166. uInt zbuffer_size; /* size of the actual buffer */
  167. int zlib_level; /* holds zlib compression level */
  168. int zlib_method; /* holds zlib compression method */
  169. int zlib_window_bits; /* holds zlib compression window bits */
  170. int zlib_mem_level; /* holds zlib compression memory level */
  171. int zlib_strategy; /* holds zlib compression strategy */
  172. #endif
  173. /* Added at libpng 1.5.4 */
  174. #ifdef PNG_WRITE_CUSTOMIZE_ZTXT_COMPRESSION_SUPPORTED
  175. int zlib_text_level; /* holds zlib compression level */
  176. int zlib_text_method; /* holds zlib compression method */
  177. int zlib_text_window_bits; /* holds zlib compression window bits */
  178. int zlib_text_mem_level; /* holds zlib compression memory level */
  179. int zlib_text_strategy; /* holds zlib compression strategy */
  180. #endif
  181. /* End of material added at libpng 1.5.4 */
  182. /* Added at libpng 1.6.0 */
  183. #ifdef PNG_WRITE_SUPPORTED
  184. int zlib_set_level; /* Actual values set into the zstream on write */
  185. int zlib_set_method;
  186. int zlib_set_window_bits;
  187. int zlib_set_mem_level;
  188. int zlib_set_strategy;
  189. #endif
  190. png_uint_32 width; /* width of image in pixels */
  191. png_uint_32 height; /* height of image in pixels */
  192. png_uint_32 num_rows; /* number of rows in current pass */
  193. png_uint_32 usr_width; /* width of row at start of write */
  194. size_t rowbytes; /* size of row in bytes */
  195. png_uint_32 iwidth; /* width of current interlaced row in pixels */
  196. png_uint_32 row_number; /* current row in interlace pass */
  197. png_uint_32 chunk_name; /* PNG_CHUNK() id of current chunk */
  198. png_bytep prev_row; /* buffer to save previous (unfiltered) row.
  199. * While reading this is a pointer into
  200. * big_prev_row; while writing it is separately
  201. * allocated if needed.
  202. */
  203. png_bytep row_buf; /* buffer to save current (unfiltered) row.
  204. * While reading, this is a pointer into
  205. * big_row_buf; while writing it is separately
  206. * allocated.
  207. */
  208. #ifdef PNG_WRITE_FILTER_SUPPORTED
  209. png_bytep try_row; /* buffer to save trial row when filtering */
  210. png_bytep tst_row; /* buffer to save best trial row when filtering */
  211. #endif
  212. size_t info_rowbytes; /* Added in 1.5.4: cache of updated row bytes */
  213. png_uint_32 idat_size; /* current IDAT size for read */
  214. png_uint_32 crc; /* current chunk CRC value */
  215. png_colorp palette; /* palette from the input file */
  216. png_uint_16 num_palette; /* number of color entries in palette */
  217. /* Added at libpng-1.5.10 */
  218. #ifdef PNG_CHECK_FOR_INVALID_INDEX_SUPPORTED
  219. int num_palette_max; /* maximum palette index found in IDAT */
  220. #endif
  221. png_uint_16 num_trans; /* number of transparency values */
  222. png_byte compression; /* file compression type (always 0) */
  223. png_byte filter; /* file filter type (always 0) */
  224. png_byte interlaced; /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
  225. png_byte pass; /* current interlace pass (0 - 6) */
  226. png_byte do_filter; /* row filter flags (see PNG_FILTER_ in png.h ) */
  227. png_byte color_type; /* color type of file */
  228. png_byte bit_depth; /* bit depth of file */
  229. png_byte usr_bit_depth; /* bit depth of users row: write only */
  230. png_byte pixel_depth; /* number of bits per pixel */
  231. png_byte channels; /* number of channels in file */
  232. #ifdef PNG_WRITE_SUPPORTED
  233. png_byte usr_channels; /* channels at start of write: write only */
  234. #endif
  235. png_byte sig_bytes; /* magic bytes read/written from start of file */
  236. png_byte maximum_pixel_depth;
  237. /* pixel depth used for the row buffers */
  238. png_byte transformed_pixel_depth;
  239. /* pixel depth after read/write transforms */
  240. #if ZLIB_VERNUM >= 0x1240
  241. png_byte zstream_start; /* at start of an input zlib stream */
  242. #endif /* Zlib >= 1.2.4 */
  243. #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
  244. png_uint_16 filler; /* filler bytes for pixel expansion */
  245. #endif
  246. #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) ||\
  247. defined(PNG_READ_ALPHA_MODE_SUPPORTED)
  248. png_byte background_gamma_type;
  249. png_fixed_point background_gamma;
  250. png_color_16 background; /* background color in screen gamma space */
  251. #ifdef PNG_READ_GAMMA_SUPPORTED
  252. png_color_16 background_1; /* background normalized to gamma 1.0 */
  253. #endif
  254. #endif /* bKGD */
  255. #ifdef PNG_WRITE_FLUSH_SUPPORTED
  256. png_flush_ptr output_flush_fn; /* Function for flushing output */
  257. png_uint_32 flush_dist; /* how many rows apart to flush, 0 - no flush */
  258. png_uint_32 flush_rows; /* number of rows written since last flush */
  259. #endif
  260. #ifdef PNG_READ_GAMMA_SUPPORTED
  261. int gamma_shift; /* number of "insignificant" bits in 16-bit gamma */
  262. png_fixed_point screen_gamma; /* screen gamma value (display_exponent) */
  263. png_bytep gamma_table; /* gamma table for 8-bit depth files */
  264. png_uint_16pp gamma_16_table; /* gamma table for 16-bit depth files */
  265. #if defined(PNG_READ_BACKGROUND_SUPPORTED) || \
  266. defined(PNG_READ_ALPHA_MODE_SUPPORTED) || \
  267. defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
  268. png_bytep gamma_from_1; /* converts from 1.0 to screen */
  269. png_bytep gamma_to_1; /* converts from file to 1.0 */
  270. png_uint_16pp gamma_16_from_1; /* converts from 1.0 to screen */
  271. png_uint_16pp gamma_16_to_1; /* converts from file to 1.0 */
  272. #endif /* READ_BACKGROUND || READ_ALPHA_MODE || RGB_TO_GRAY */
  273. #endif
  274. #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_sBIT_SUPPORTED)
  275. png_color_8 sig_bit; /* significant bits in each available channel */
  276. #endif
  277. #if defined(PNG_READ_SHIFT_SUPPORTED) || defined(PNG_WRITE_SHIFT_SUPPORTED)
  278. png_color_8 shift; /* shift for significant bit transformation */
  279. #endif
  280. #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) \
  281. || defined(PNG_READ_EXPAND_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
  282. png_bytep trans_alpha; /* alpha values for paletted files */
  283. png_color_16 trans_color; /* transparent color for non-paletted files */
  284. #endif
  285. png_read_status_ptr read_row_fn; /* called after each row is decoded */
  286. png_write_status_ptr write_row_fn; /* called after each row is encoded */
  287. #ifdef PNG_PROGRESSIVE_READ_SUPPORTED
  288. png_progressive_info_ptr info_fn; /* called after header data fully read */
  289. png_progressive_row_ptr row_fn; /* called after a prog. row is decoded */
  290. png_progressive_end_ptr end_fn; /* called after image is complete */
  291. png_bytep save_buffer_ptr; /* current location in save_buffer */
  292. png_bytep save_buffer; /* buffer for previously read data */
  293. png_bytep current_buffer_ptr; /* current location in current_buffer */
  294. png_bytep current_buffer; /* buffer for recently used data */
  295. png_uint_32 push_length; /* size of current input chunk */
  296. png_uint_32 skip_length; /* bytes to skip in input data */
  297. size_t save_buffer_size; /* amount of data now in save_buffer */
  298. size_t save_buffer_max; /* total size of save_buffer */
  299. size_t buffer_size; /* total amount of available input data */
  300. size_t current_buffer_size; /* amount of data now in current_buffer */
  301. int process_mode; /* what push library is currently doing */
  302. int cur_palette; /* current push library palette index */
  303. #endif /* PROGRESSIVE_READ */
  304. #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
  305. /* For the Borland special 64K segment handler */
  306. png_bytepp offset_table_ptr;
  307. png_bytep offset_table;
  308. png_uint_16 offset_table_number;
  309. png_uint_16 offset_table_count;
  310. png_uint_16 offset_table_count_free;
  311. #endif
  312. #ifdef PNG_READ_QUANTIZE_SUPPORTED
  313. png_bytep palette_lookup; /* lookup table for quantizing */
  314. png_bytep quantize_index; /* index translation for palette files */
  315. #endif
  316. /* Options */
  317. #ifdef PNG_SET_OPTION_SUPPORTED
  318. png_uint_32 options; /* On/off state (up to 16 options) */
  319. #endif
  320. #if PNG_LIBPNG_VER < 10700
  321. /* To do: remove this from libpng-1.7 */
  322. #ifdef PNG_TIME_RFC1123_SUPPORTED
  323. char time_buffer[29]; /* String to hold RFC 1123 time text */
  324. #endif
  325. #endif
  326. /* New members added in libpng-1.0.6 */
  327. png_uint_32 free_me; /* flags items libpng is responsible for freeing */
  328. #ifdef PNG_USER_CHUNKS_SUPPORTED
  329. png_voidp user_chunk_ptr;
  330. #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
  331. png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
  332. #endif
  333. #endif
  334. #ifdef PNG_SET_UNKNOWN_CHUNKS_SUPPORTED
  335. int unknown_default; /* As PNG_HANDLE_* */
  336. unsigned int num_chunk_list; /* Number of entries in the list */
  337. png_bytep chunk_list; /* List of png_byte[5]; the textual chunk name
  338. * followed by a PNG_HANDLE_* byte */
  339. #endif
  340. /* New members added in libpng-1.0.3 */
  341. #ifdef PNG_READ_RGB_TO_GRAY_SUPPORTED
  342. png_byte rgb_to_gray_status;
  343. /* Added in libpng 1.5.5 to record setting of coefficients: */
  344. png_byte rgb_to_gray_coefficients_set;
  345. /* These were changed from png_byte in libpng-1.0.6 */
  346. png_uint_16 rgb_to_gray_red_coeff;
  347. png_uint_16 rgb_to_gray_green_coeff;
  348. /* deleted in 1.5.5: rgb_to_gray_blue_coeff; */
  349. #endif
  350. /* New member added in libpng-1.6.36 */
  351. #if defined(PNG_READ_EXPAND_SUPPORTED) && \
  352. defined(PNG_ARM_NEON_IMPLEMENTATION)
  353. png_bytep riffled_palette; /* buffer for accelerated palette expansion */
  354. #endif
  355. /* New member added in libpng-1.0.4 (renamed in 1.0.9) */
  356. #if defined(PNG_MNG_FEATURES_SUPPORTED)
  357. /* Changed from png_byte to png_uint_32 at version 1.2.0 */
  358. png_uint_32 mng_features_permitted;
  359. #endif
  360. /* New member added in libpng-1.0.9, ifdef'ed out in 1.0.12, enabled in 1.2.0 */
  361. #ifdef PNG_MNG_FEATURES_SUPPORTED
  362. png_byte filter_type;
  363. #endif
  364. /* New members added in libpng-1.2.0 */
  365. /* New members added in libpng-1.0.2 but first enabled by default in 1.2.0 */
  366. #ifdef PNG_USER_MEM_SUPPORTED
  367. png_voidp mem_ptr; /* user supplied struct for mem functions */
  368. png_malloc_ptr malloc_fn; /* function for allocating memory */
  369. png_free_ptr free_fn; /* function for freeing memory */
  370. #endif
  371. /* New member added in libpng-1.0.13 and 1.2.0 */
  372. png_bytep big_row_buf; /* buffer to save current (unfiltered) row */
  373. #ifdef PNG_READ_QUANTIZE_SUPPORTED
  374. /* The following three members were added at version 1.0.14 and 1.2.4 */
  375. png_bytep quantize_sort; /* working sort array */
  376. png_bytep index_to_palette; /* where the original index currently is
  377. in the palette */
  378. png_bytep palette_to_index; /* which original index points to this
  379. palette color */
  380. #endif
  381. /* New members added in libpng-1.0.16 and 1.2.6 */
  382. png_byte compression_type;
  383. #ifdef PNG_USER_LIMITS_SUPPORTED
  384. png_uint_32 user_width_max;
  385. png_uint_32 user_height_max;
  386. /* Added in libpng-1.4.0: Total number of sPLT, text, and unknown
  387. * chunks that can be stored (0 means unlimited).
  388. */
  389. png_uint_32 user_chunk_cache_max;
  390. /* Total memory that a zTXt, sPLT, iTXt, iCCP, or unknown chunk
  391. * can occupy when decompressed. 0 means unlimited.
  392. */
  393. png_alloc_size_t user_chunk_malloc_max;
  394. #endif
  395. /* New member added in libpng-1.0.25 and 1.2.17 */
  396. #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
  397. /* Temporary storage for unknown chunk that the library doesn't recognize,
  398. * used while reading the chunk.
  399. */
  400. png_unknown_chunk unknown_chunk;
  401. #endif
  402. /* New member added in libpng-1.2.26 */
  403. size_t old_big_row_buf_size;
  404. #ifdef PNG_READ_SUPPORTED
  405. /* New member added in libpng-1.2.30 */
  406. png_bytep read_buffer; /* buffer for reading chunk data */
  407. png_alloc_size_t read_buffer_size; /* current size of the buffer */
  408. #endif
  409. #ifdef PNG_SEQUENTIAL_READ_SUPPORTED
  410. uInt IDAT_read_size; /* limit on read buffer size for IDAT */
  411. #endif
  412. #ifdef PNG_IO_STATE_SUPPORTED
  413. /* New member added in libpng-1.4.0 */
  414. png_uint_32 io_state;
  415. #endif
  416. /* New member added in libpng-1.5.6 */
  417. png_bytep big_prev_row;
  418. /* New member added in libpng-1.5.7 */
  419. void (*read_filter[PNG_FILTER_VALUE_LAST-1])(png_row_infop row_info,
  420. png_bytep row, png_const_bytep prev_row);
  421. #ifdef PNG_READ_SUPPORTED
  422. #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
  423. png_colorspace colorspace;
  424. #endif
  425. #endif
  426. };
  427. #endif /* PNGSTRUCT_H */