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Diffstat (limited to 'contrib/libpng/png.c')
| -rw-r--r-- | contrib/libpng/png.c | 2362 |
1 files changed, 0 insertions, 2362 deletions
diff --git a/contrib/libpng/png.c b/contrib/libpng/png.c deleted file mode 100644 index 764f47c..0000000 --- a/contrib/libpng/png.c +++ /dev/null @@ -1,2362 +0,0 @@ - -/* png.c - location for general purpose libpng functions - * - * Last changed in libpng 1.5.1 [February 3, 2011] - * Copyright (c) 1998-2011 Glenn Randers-Pehrson - * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) - * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) - * - * This code is released under the libpng license. - * For conditions of distribution and use, see the disclaimer - * and license in png.h - */ - -#include "pngpriv.h" - -/* Generate a compiler error if there is an old png.h in the search path. */ -typedef png_libpng_version_1_5_1 Your_png_h_is_not_version_1_5_1; - -/* Tells libpng that we have already handled the first "num_bytes" bytes - * of the PNG file signature. If the PNG data is embedded into another - * stream we can set num_bytes = 8 so that libpng will not attempt to read - * or write any of the magic bytes before it starts on the IHDR. - */ - -#ifdef PNG_READ_SUPPORTED -void PNGAPI -png_set_sig_bytes(png_structp png_ptr, int num_bytes) -{ - png_debug(1, "in png_set_sig_bytes"); - - if (png_ptr == NULL) - return; - - if (num_bytes > 8) - png_error(png_ptr, "Too many bytes for PNG signature"); - - png_ptr->sig_bytes = (png_byte)(num_bytes < 0 ? 0 : num_bytes); -} - -/* Checks whether the supplied bytes match the PNG signature. We allow - * checking less than the full 8-byte signature so that those apps that - * already read the first few bytes of a file to determine the file type - * can simply check the remaining bytes for extra assurance. Returns - * an integer less than, equal to, or greater than zero if sig is found, - * respectively, to be less than, to match, or be greater than the correct - * PNG signature (this is the same behaviour as strcmp, memcmp, etc). - */ -int PNGAPI -png_sig_cmp(png_const_bytep sig, png_size_t start, png_size_t num_to_check) -{ - png_byte png_signature[8] = {137, 80, 78, 71, 13, 10, 26, 10}; - - if (num_to_check > 8) - num_to_check = 8; - - else if (num_to_check < 1) - return (-1); - - if (start > 7) - return (-1); - - if (start + num_to_check > 8) - num_to_check = 8 - start; - - return ((int)(png_memcmp(&sig[start], &png_signature[start], num_to_check))); -} - -#endif /* PNG_READ_SUPPORTED */ - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -/* Function to allocate memory for zlib */ -PNG_FUNCTION(voidpf /* PRIVATE */, -png_zalloc,(voidpf png_ptr, uInt items, uInt size),PNG_ALLOCATED) -{ - png_voidp ptr; - png_structp p=(png_structp)png_ptr; - png_uint_32 save_flags=p->flags; - png_alloc_size_t num_bytes; - - if (png_ptr == NULL) - return (NULL); - - if (items > PNG_UINT_32_MAX/size) - { - png_warning (p, "Potential overflow in png_zalloc()"); - return (NULL); - } - num_bytes = (png_alloc_size_t)items * size; - - p->flags|=PNG_FLAG_MALLOC_NULL_MEM_OK; - ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes); - p->flags=save_flags; - - return ((voidpf)ptr); -} - -/* Function to free memory for zlib */ -void /* PRIVATE */ -png_zfree(voidpf png_ptr, voidpf ptr) -{ - png_free((png_structp)png_ptr, (png_voidp)ptr); -} - -/* Reset the CRC variable to 32 bits of 1's. Care must be taken - * in case CRC is > 32 bits to leave the top bits 0. - */ -void /* PRIVATE */ -png_reset_crc(png_structp png_ptr) -{ - png_ptr->crc = crc32(0, Z_NULL, 0); -} - -/* Calculate the CRC over a section of data. We can only pass as - * much data to this routine as the largest single buffer size. We - * also check that this data will actually be used before going to the - * trouble of calculating it. - */ -void /* PRIVATE */ -png_calculate_crc(png_structp png_ptr, png_const_bytep ptr, png_size_t length) -{ - int need_crc = 1; - - if (png_ptr->chunk_name[0] & 0x20) /* ancillary */ - { - if ((png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_MASK) == - (PNG_FLAG_CRC_ANCILLARY_USE | PNG_FLAG_CRC_ANCILLARY_NOWARN)) - need_crc = 0; - } - - else /* critical */ - { - if (png_ptr->flags & PNG_FLAG_CRC_CRITICAL_IGNORE) - need_crc = 0; - } - - if (need_crc) - png_ptr->crc = crc32(png_ptr->crc, ptr, (uInt)length); -} - -/* Allocate the memory for an info_struct for the application. We don't - * really need the png_ptr, but it could potentially be useful in the - * future. This should be used in favour of malloc(png_sizeof(png_info)) - * and png_info_init() so that applications that want to use a shared - * libpng don't have to be recompiled if png_info changes size. - */ -PNG_FUNCTION(png_infop,PNGAPI -png_create_info_struct,(png_structp png_ptr),PNG_ALLOCATED) -{ - png_infop info_ptr; - - png_debug(1, "in png_create_info_struct"); - - if (png_ptr == NULL) - return (NULL); - -#ifdef PNG_USER_MEM_SUPPORTED - info_ptr = (png_infop)png_create_struct_2(PNG_STRUCT_INFO, - png_ptr->malloc_fn, png_ptr->mem_ptr); -#else - info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); -#endif - if (info_ptr != NULL) - png_info_init_3(&info_ptr, png_sizeof(png_info)); - - return (info_ptr); -} - -/* This function frees the memory associated with a single info struct. - * Normally, one would use either png_destroy_read_struct() or - * png_destroy_write_struct() to free an info struct, but this may be - * useful for some applications. - */ -void PNGAPI -png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr) -{ - png_infop info_ptr = NULL; - - png_debug(1, "in png_destroy_info_struct"); - - if (png_ptr == NULL) - return; - - if (info_ptr_ptr != NULL) - info_ptr = *info_ptr_ptr; - - if (info_ptr != NULL) - { - png_info_destroy(png_ptr, info_ptr); - -#ifdef PNG_USER_MEM_SUPPORTED - png_destroy_struct_2((png_voidp)info_ptr, png_ptr->free_fn, - png_ptr->mem_ptr); -#else - png_destroy_struct((png_voidp)info_ptr); -#endif - *info_ptr_ptr = NULL; - } -} - -/* Initialize the info structure. This is now an internal function (0.89) - * and applications using it are urged to use png_create_info_struct() - * instead. - */ - -void PNGAPI -png_info_init_3(png_infopp ptr_ptr, png_size_t png_info_struct_size) -{ - png_infop info_ptr = *ptr_ptr; - - png_debug(1, "in png_info_init_3"); - - if (info_ptr == NULL) - return; - - if (png_sizeof(png_info) > png_info_struct_size) - { - png_destroy_struct(info_ptr); - info_ptr = (png_infop)png_create_struct(PNG_STRUCT_INFO); - *ptr_ptr = info_ptr; - } - - /* Set everything to 0 */ - png_memset(info_ptr, 0, png_sizeof(png_info)); -} - -void PNGAPI -png_data_freer(png_structp png_ptr, png_infop info_ptr, - int freer, png_uint_32 mask) -{ - png_debug(1, "in png_data_freer"); - - if (png_ptr == NULL || info_ptr == NULL) - return; - - if (freer == PNG_DESTROY_WILL_FREE_DATA) - info_ptr->free_me |= mask; - - else if (freer == PNG_USER_WILL_FREE_DATA) - info_ptr->free_me &= ~mask; - - else - png_warning(png_ptr, - "Unknown freer parameter in png_data_freer"); -} - -void PNGAPI -png_free_data(png_structp png_ptr, png_infop info_ptr, png_uint_32 mask, - int num) -{ - png_debug(1, "in png_free_data"); - - if (png_ptr == NULL || info_ptr == NULL) - return; - -#ifdef PNG_TEXT_SUPPORTED - /* Free text item num or (if num == -1) all text items */ - if ((mask & PNG_FREE_TEXT) & info_ptr->free_me) - { - if (num != -1) - { - if (info_ptr->text && info_ptr->text[num].key) - { - png_free(png_ptr, info_ptr->text[num].key); - info_ptr->text[num].key = NULL; - } - } - - else - { - int i; - for (i = 0; i < info_ptr->num_text; i++) - png_free_data(png_ptr, info_ptr, PNG_FREE_TEXT, i); - png_free(png_ptr, info_ptr->text); - info_ptr->text = NULL; - info_ptr->num_text=0; - } - } -#endif - -#ifdef PNG_tRNS_SUPPORTED - /* Free any tRNS entry */ - if ((mask & PNG_FREE_TRNS) & info_ptr->free_me) - { - png_free(png_ptr, info_ptr->trans_alpha); - info_ptr->trans_alpha = NULL; - info_ptr->valid &= ~PNG_INFO_tRNS; - } -#endif - -#ifdef PNG_sCAL_SUPPORTED - /* Free any sCAL entry */ - if ((mask & PNG_FREE_SCAL) & info_ptr->free_me) - { -#if defined(PNG_FIXED_POINT_SUPPORTED) && !defined(PNG_FLOATING_POINT_SUPPORTED) - png_free(png_ptr, info_ptr->scal_s_width); - png_free(png_ptr, info_ptr->scal_s_height); - info_ptr->scal_s_width = NULL; - info_ptr->scal_s_height = NULL; -#endif - info_ptr->valid &= ~PNG_INFO_sCAL; - } -#endif - -#ifdef PNG_pCAL_SUPPORTED - /* Free any pCAL entry */ - if ((mask & PNG_FREE_PCAL) & info_ptr->free_me) - { - png_free(png_ptr, info_ptr->pcal_purpose); - png_free(png_ptr, info_ptr->pcal_units); - info_ptr->pcal_purpose = NULL; - info_ptr->pcal_units = NULL; - if (info_ptr->pcal_params != NULL) - { - int i; - for (i = 0; i < (int)info_ptr->pcal_nparams; i++) - { - png_free(png_ptr, info_ptr->pcal_params[i]); - info_ptr->pcal_params[i] = NULL; - } - png_free(png_ptr, info_ptr->pcal_params); - info_ptr->pcal_params = NULL; - } - info_ptr->valid &= ~PNG_INFO_pCAL; - } -#endif - -#ifdef PNG_iCCP_SUPPORTED - /* Free any iCCP entry */ - if ((mask & PNG_FREE_ICCP) & info_ptr->free_me) - { - png_free(png_ptr, info_ptr->iccp_name); - png_free(png_ptr, info_ptr->iccp_profile); - info_ptr->iccp_name = NULL; - info_ptr->iccp_profile = NULL; - info_ptr->valid &= ~PNG_INFO_iCCP; - } -#endif - -#ifdef PNG_sPLT_SUPPORTED - /* Free a given sPLT entry, or (if num == -1) all sPLT entries */ - if ((mask & PNG_FREE_SPLT) & info_ptr->free_me) - { - if (num != -1) - { - if (info_ptr->splt_palettes) - { - png_free(png_ptr, info_ptr->splt_palettes[num].name); - png_free(png_ptr, info_ptr->splt_palettes[num].entries); - info_ptr->splt_palettes[num].name = NULL; - info_ptr->splt_palettes[num].entries = NULL; - } - } - - else - { - if (info_ptr->splt_palettes_num) - { - int i; - for (i = 0; i < (int)info_ptr->splt_palettes_num; i++) - png_free_data(png_ptr, info_ptr, PNG_FREE_SPLT, i); - - png_free(png_ptr, info_ptr->splt_palettes); - info_ptr->splt_palettes = NULL; - info_ptr->splt_palettes_num = 0; - } - info_ptr->valid &= ~PNG_INFO_sPLT; - } - } -#endif - -#ifdef PNG_UNKNOWN_CHUNKS_SUPPORTED - if (png_ptr->unknown_chunk.data) - { - png_free(png_ptr, png_ptr->unknown_chunk.data); - png_ptr->unknown_chunk.data = NULL; - } - - if ((mask & PNG_FREE_UNKN) & info_ptr->free_me) - { - if (num != -1) - { - if (info_ptr->unknown_chunks) - { - png_free(png_ptr, info_ptr->unknown_chunks[num].data); - info_ptr->unknown_chunks[num].data = NULL; - } - } - - else - { - int i; - - if (info_ptr->unknown_chunks_num) - { - for (i = 0; i < info_ptr->unknown_chunks_num; i++) - png_free_data(png_ptr, info_ptr, PNG_FREE_UNKN, i); - - png_free(png_ptr, info_ptr->unknown_chunks); - info_ptr->unknown_chunks = NULL; - info_ptr->unknown_chunks_num = 0; - } - } - } -#endif - -#ifdef PNG_hIST_SUPPORTED - /* Free any hIST entry */ - if ((mask & PNG_FREE_HIST) & info_ptr->free_me) - { - png_free(png_ptr, info_ptr->hist); - info_ptr->hist = NULL; - info_ptr->valid &= ~PNG_INFO_hIST; - } -#endif - - /* Free any PLTE entry that was internally allocated */ - if ((mask & PNG_FREE_PLTE) & info_ptr->free_me) - { - png_zfree(png_ptr, info_ptr->palette); - info_ptr->palette = NULL; - info_ptr->valid &= ~PNG_INFO_PLTE; - info_ptr->num_palette = 0; - } - -#ifdef PNG_INFO_IMAGE_SUPPORTED - /* Free any image bits attached to the info structure */ - if ((mask & PNG_FREE_ROWS) & info_ptr->free_me) - { - if (info_ptr->row_pointers) - { - int row; - for (row = 0; row < (int)info_ptr->height; row++) - { - png_free(png_ptr, info_ptr->row_pointers[row]); - info_ptr->row_pointers[row] = NULL; - } - png_free(png_ptr, info_ptr->row_pointers); - info_ptr->row_pointers = NULL; - } - info_ptr->valid &= ~PNG_INFO_IDAT; - } -#endif - - if (num != -1) - mask &= ~PNG_FREE_MUL; - - info_ptr->free_me &= ~mask; -} - -/* This is an internal routine to free any memory that the info struct is - * pointing to before re-using it or freeing the struct itself. Recall - * that png_free() checks for NULL pointers for us. - */ -void /* PRIVATE */ -png_info_destroy(png_structp png_ptr, png_infop info_ptr) -{ - png_debug(1, "in png_info_destroy"); - - png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1); - -#ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED - if (png_ptr->num_chunk_list) - { - png_free(png_ptr, png_ptr->chunk_list); - png_ptr->chunk_list = NULL; - png_ptr->num_chunk_list = 0; - } -#endif - - png_info_init_3(&info_ptr, png_sizeof(png_info)); -} -#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ - -/* This function returns a pointer to the io_ptr associated with the user - * functions. The application should free any memory associated with this - * pointer before png_write_destroy() or png_read_destroy() are called. - */ -png_voidp PNGAPI -png_get_io_ptr(png_structp png_ptr) -{ - if (png_ptr == NULL) - return (NULL); - - return (png_ptr->io_ptr); -} - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -# ifdef PNG_STDIO_SUPPORTED -/* Initialize the default input/output functions for the PNG file. If you - * use your own read or write routines, you can call either png_set_read_fn() - * or png_set_write_fn() instead of png_init_io(). If you have defined - * PNG_NO_STDIO, you must use a function of your own because "FILE *" isn't - * necessarily available. - */ -void PNGAPI -png_init_io(png_structp png_ptr, png_FILE_p fp) -{ - png_debug(1, "in png_init_io"); - - if (png_ptr == NULL) - return; - - png_ptr->io_ptr = (png_voidp)fp; -} -# endif - -# ifdef PNG_TIME_RFC1123_SUPPORTED -/* Convert the supplied time into an RFC 1123 string suitable for use in - * a "Creation Time" or other text-based time string. - */ -png_const_charp PNGAPI -png_convert_to_rfc1123(png_structp png_ptr, png_const_timep ptime) -{ - static PNG_CONST char short_months[12][4] = - {"Jan", "Feb", "Mar", "Apr", "May", "Jun", - "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"}; - - if (png_ptr == NULL) - return (NULL); - - if (png_ptr->time_buffer == NULL) - { - png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, (png_uint_32)(29* - png_sizeof(char))); - } - -# ifdef USE_FAR_KEYWORD - { - char near_time_buf[29]; - png_snprintf6(near_time_buf, 29, "%d %s %d %02d:%02d:%02d +0000", - ptime->day % 32, short_months[(ptime->month - 1) % 12], - ptime->year, ptime->hour % 24, ptime->minute % 60, - ptime->second % 61); - png_memcpy(png_ptr->time_buffer, near_time_buf, - 29*png_sizeof(char)); - } -# else - png_snprintf6(png_ptr->time_buffer, 29, "%d %s %d %02d:%02d:%02d +0000", - ptime->day % 32, short_months[(ptime->month - 1) % 12], - ptime->year, ptime->hour % 24, ptime->minute % 60, - ptime->second % 61); -# endif - return png_ptr->time_buffer; -} -# endif /* PNG_TIME_RFC1123_SUPPORTED */ - -#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ - -png_const_charp PNGAPI -png_get_copyright(png_const_structp png_ptr) -{ - PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ -#ifdef PNG_STRING_COPYRIGHT - return PNG_STRING_COPYRIGHT -#else -# ifdef __STDC__ - return PNG_STRING_NEWLINE \ - "libpng version 1.5.1 - February 3, 2011" PNG_STRING_NEWLINE \ - "Copyright (c) 1998-2011 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \ - "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \ - "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \ - PNG_STRING_NEWLINE; -# else - return "libpng version 1.5.1 - February 3, 2011\ - Copyright (c) 1998-2011 Glenn Randers-Pehrson\ - Copyright (c) 1996-1997 Andreas Dilger\ - Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc."; -# endif -#endif -} - -/* The following return the library version as a short string in the - * format 1.0.0 through 99.99.99zz. To get the version of *.h files - * used with your application, print out PNG_LIBPNG_VER_STRING, which - * is defined in png.h. - * Note: now there is no difference between png_get_libpng_ver() and - * png_get_header_ver(). Due to the version_nn_nn_nn typedef guard, - * it is guaranteed that png.c uses the correct version of png.h. - */ -png_const_charp PNGAPI -png_get_libpng_ver(png_const_structp png_ptr) -{ - /* Version of *.c files used when building libpng */ - return png_get_header_ver(png_ptr); -} - -png_const_charp PNGAPI -png_get_header_ver(png_const_structp png_ptr) -{ - /* Version of *.h files used when building libpng */ - PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ - return PNG_LIBPNG_VER_STRING; -} - -png_const_charp PNGAPI -png_get_header_version(png_const_structp png_ptr) -{ - /* Returns longer string containing both version and date */ - PNG_UNUSED(png_ptr) /* Silence compiler warning about unused png_ptr */ -#ifdef __STDC__ - return PNG_HEADER_VERSION_STRING -# ifndef PNG_READ_SUPPORTED - " (NO READ SUPPORT)" -# endif - PNG_STRING_NEWLINE; -#else - return PNG_HEADER_VERSION_STRING; -#endif -} - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -# ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED -int PNGAPI -png_handle_as_unknown(png_structp png_ptr, png_const_bytep chunk_name) -{ - /* Check chunk_name and return "keep" value if it's on the list, else 0 */ - int i; - png_bytep p; - if (png_ptr == NULL || chunk_name == NULL || png_ptr->num_chunk_list<=0) - return 0; - - p = png_ptr->chunk_list + png_ptr->num_chunk_list*5 - 5; - for (i = png_ptr->num_chunk_list; i; i--, p -= 5) - if (!png_memcmp(chunk_name, p, 4)) - return ((int)*(p + 4)); - return 0; -} -# endif -#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ - -#ifdef PNG_READ_SUPPORTED -/* This function, added to libpng-1.0.6g, is untested. */ -int PNGAPI -png_reset_zstream(png_structp png_ptr) -{ - if (png_ptr == NULL) - return Z_STREAM_ERROR; - - return (inflateReset(&png_ptr->zstream)); -} -#endif /* PNG_READ_SUPPORTED */ - -/* This function was added to libpng-1.0.7 */ -png_uint_32 PNGAPI -png_access_version_number(void) -{ - /* Version of *.c files used when building libpng */ - return((png_uint_32)PNG_LIBPNG_VER); -} - - - -#if defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) -# ifdef PNG_SIZE_T -/* Added at libpng version 1.2.6 */ - PNG_EXTERN png_size_t PNGAPI png_convert_size PNGARG((size_t size)); -png_size_t PNGAPI -png_convert_size(size_t size) -{ - if (size > (png_size_t)-1) - PNG_ABORT(); /* We haven't got access to png_ptr, so no png_error() */ - - return ((png_size_t)size); -} -# endif /* PNG_SIZE_T */ - -/* Added at libpng version 1.2.34 and 1.4.0 (moved from pngset.c) */ -# ifdef PNG_CHECK_cHRM_SUPPORTED - -int /* PRIVATE */ -png_check_cHRM_fixed(png_structp png_ptr, - png_fixed_point white_x, png_fixed_point white_y, png_fixed_point red_x, - png_fixed_point red_y, png_fixed_point green_x, png_fixed_point green_y, - png_fixed_point blue_x, png_fixed_point blue_y) -{ - int ret = 1; - unsigned long xy_hi,xy_lo,yx_hi,yx_lo; - - png_debug(1, "in function png_check_cHRM_fixed"); - - if (png_ptr == NULL) - return 0; - - if (white_x < 0 || white_y <= 0 || - red_x < 0 || red_y < 0 || - green_x < 0 || green_y < 0 || - blue_x < 0 || blue_y < 0) - { - png_warning(png_ptr, - "Ignoring attempt to set negative chromaticity value"); - ret = 0; - } - if (white_x > (png_fixed_point)PNG_UINT_31_MAX || - white_y > (png_fixed_point)PNG_UINT_31_MAX || - red_x > (png_fixed_point)PNG_UINT_31_MAX || - red_y > (png_fixed_point)PNG_UINT_31_MAX || - green_x > (png_fixed_point)PNG_UINT_31_MAX || - green_y > (png_fixed_point)PNG_UINT_31_MAX || - blue_x > (png_fixed_point)PNG_UINT_31_MAX || - blue_y > (png_fixed_point)PNG_UINT_31_MAX ) - { - png_warning(png_ptr, - "Ignoring attempt to set chromaticity value exceeding 21474.83"); - ret = 0; - } - if (white_x > 100000L - white_y) - { - png_warning(png_ptr, "Invalid cHRM white point"); - ret = 0; - } - - if (red_x > 100000L - red_y) - { - png_warning(png_ptr, "Invalid cHRM red point"); - ret = 0; - } - - if (green_x > 100000L - green_y) - { - png_warning(png_ptr, "Invalid cHRM green point"); - ret = 0; - } - - if (blue_x > 100000L - blue_y) - { - png_warning(png_ptr, "Invalid cHRM blue point"); - ret = 0; - } - - png_64bit_product(green_x - red_x, blue_y - red_y, &xy_hi, &xy_lo); - png_64bit_product(green_y - red_y, blue_x - red_x, &yx_hi, &yx_lo); - - if (xy_hi == yx_hi && xy_lo == yx_lo) - { - png_warning(png_ptr, - "Ignoring attempt to set cHRM RGB triangle with zero area"); - ret = 0; - } - - return ret; -} -# endif /* PNG_CHECK_cHRM_SUPPORTED */ - -void /* PRIVATE */ -png_check_IHDR(png_structp png_ptr, - png_uint_32 width, png_uint_32 height, int bit_depth, - int color_type, int interlace_type, int compression_type, - int filter_type) -{ - int error = 0; - - /* Check for width and height valid values */ - if (width == 0) - { - png_warning(png_ptr, "Image width is zero in IHDR"); - error = 1; - } - - if (height == 0) - { - png_warning(png_ptr, "Image height is zero in IHDR"); - error = 1; - } - -# ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (width > png_ptr->user_width_max || width > PNG_USER_WIDTH_MAX) - -# else - if (width > PNG_USER_WIDTH_MAX) -# endif - { - png_warning(png_ptr, "Image width exceeds user limit in IHDR"); - error = 1; - } - -# ifdef PNG_SET_USER_LIMITS_SUPPORTED - if (height > png_ptr->user_height_max || height > PNG_USER_HEIGHT_MAX) -# else - if (height > PNG_USER_HEIGHT_MAX) -# endif - { - png_warning(png_ptr, "Image height exceeds user limit in IHDR"); - error = 1; - } - - if (width > PNG_UINT_31_MAX) - { - png_warning(png_ptr, "Invalid image width in IHDR"); - error = 1; - } - - if (height > PNG_UINT_31_MAX) - { - png_warning(png_ptr, "Invalid image height in IHDR"); - error = 1; - } - - if (width > (PNG_UINT_32_MAX - >> 3) /* 8-byte RGBA pixels */ - - 48 /* bigrowbuf hack */ - - 1 /* filter byte */ - - 7*8 /* rounding of width to multiple of 8 pixels */ - - 8) /* extra max_pixel_depth pad */ - png_warning(png_ptr, "Width is too large for libpng to process pixels"); - - /* Check other values */ - if (bit_depth != 1 && bit_depth != 2 && bit_depth != 4 && - bit_depth != 8 && bit_depth != 16) - { - png_warning(png_ptr, "Invalid bit depth in IHDR"); - error = 1; - } - - if (color_type < 0 || color_type == 1 || - color_type == 5 || color_type > 6) - { - png_warning(png_ptr, "Invalid color type in IHDR"); - error = 1; - } - - if (((color_type == PNG_COLOR_TYPE_PALETTE) && bit_depth > 8) || - ((color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_GRAY_ALPHA || - color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8)) - { - png_warning(png_ptr, "Invalid color type/bit depth combination in IHDR"); - error = 1; - } - - if (interlace_type >= PNG_INTERLACE_LAST) - { - png_warning(png_ptr, "Unknown interlace method in IHDR"); - error = 1; - } - - if (compression_type != PNG_COMPRESSION_TYPE_BASE) - { - png_warning(png_ptr, "Unknown compression method in IHDR"); - error = 1; - } - -# ifdef PNG_MNG_FEATURES_SUPPORTED - /* Accept filter_method 64 (intrapixel differencing) only if - * 1. Libpng was compiled with PNG_MNG_FEATURES_SUPPORTED and - * 2. Libpng did not read a PNG signature (this filter_method is only - * used in PNG datastreams that are embedded in MNG datastreams) and - * 3. The application called png_permit_mng_features with a mask that - * included PNG_FLAG_MNG_FILTER_64 and - * 4. The filter_method is 64 and - * 5. The color_type is RGB or RGBA - */ - if ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) && - png_ptr->mng_features_permitted) - png_warning(png_ptr, "MNG features are not allowed in a PNG datastream"); - - if (filter_type != PNG_FILTER_TYPE_BASE) - { - if (!((png_ptr->mng_features_permitted & PNG_FLAG_MNG_FILTER_64) && - (filter_type == PNG_INTRAPIXEL_DIFFERENCING) && - ((png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) == 0) && - (color_type == PNG_COLOR_TYPE_RGB || - color_type == PNG_COLOR_TYPE_RGB_ALPHA))) - { - png_warning(png_ptr, "Unknown filter method in IHDR"); - error = 1; - } - - if (png_ptr->mode & PNG_HAVE_PNG_SIGNATURE) - { - png_warning(png_ptr, "Invalid filter method in IHDR"); - error = 1; - } - } - -# else - if (filter_type != PNG_FILTER_TYPE_BASE) - { - png_warning(png_ptr, "Unknown filter method in IHDR"); - error = 1; - } -# endif - - if (error == 1) - png_error(png_ptr, "Invalid IHDR data"); -} - -#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED) -/* ASCII to fp functions */ -/* Check an ASCII formated floating point value, see the more detailed - * comments in pngpriv.h - */ -/* The following is used internally to preserve the 'valid' flag */ -#define png_fp_add(state, flags) ((state) |= (flags)) -#define png_fp_set(state, value)\ - ((state) = (value) | ((state) & PNG_FP_WAS_VALID)) - -/* Internal type codes: bits above the base state! */ -#define PNG_FP_SIGN 0 /* [+-] */ -#define PNG_FP_DOT 4 /* . */ -#define PNG_FP_DIGIT 8 /* [0123456789] */ -#define PNG_FP_E 12 /* [Ee] */ - -int /* PRIVATE */ -png_check_fp_number(png_const_charp string, png_size_t size, int *statep, - png_size_tp whereami) -{ - int state = *statep; - png_size_t i = *whereami; - - while (i < size) - { - int type; - /* First find the type of the next character */ - { - char ch = string[i]; - - if (ch >= 48 && ch <= 57) - type = PNG_FP_DIGIT; - - else switch (ch) - { - case 43: case 45: type = PNG_FP_SIGN; break; - case 46: type = PNG_FP_DOT; break; - case 69: case 101: type = PNG_FP_E; break; - default: goto PNG_FP_End; - } - } - - /* Now deal with this type according to the current - * state, the type is arranged to not overlap the - * bits of the PNG_FP_STATE. - */ - switch ((state & PNG_FP_STATE) + type) - { - case PNG_FP_INTEGER + PNG_FP_SIGN: - if (state & PNG_FP_SAW_ANY) - goto PNG_FP_End; /* not a part of the number */ - - png_fp_add(state, PNG_FP_SAW_SIGN); - break; - - case PNG_FP_INTEGER + PNG_FP_DOT: - /* Ok as trailer, ok as lead of fraction. */ - if (state & PNG_FP_SAW_DOT) /* two dots */ - goto PNG_FP_End; - - else if (state & PNG_FP_SAW_DIGIT) /* trailing dot? */ - png_fp_add(state, PNG_FP_SAW_DOT); - - else - png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); - - break; - - case PNG_FP_INTEGER + PNG_FP_DIGIT: - if (state & PNG_FP_SAW_DOT) /* delayed fraction */ - png_fp_set(state, PNG_FP_FRACTION | PNG_FP_SAW_DOT); - - png_fp_add(state, PNG_FP_SAW_DIGIT + PNG_FP_WAS_VALID); - - break; - case PNG_FP_INTEGER + PNG_FP_E: - if ((state & PNG_FP_SAW_DIGIT) == 0) - goto PNG_FP_End; - - png_fp_set(state, PNG_FP_EXPONENT); - - break; - - /* case PNG_FP_FRACTION + PNG_FP_SIGN: - goto PNG_FP_End; ** no sign in exponent */ - - /* case PNG_FP_FRACTION + PNG_FP_DOT: - goto PNG_FP_End; ** Because SAW_DOT is always set */ - - case PNG_FP_FRACTION + PNG_FP_DIGIT: - png_fp_add(state, PNG_FP_SAW_DIGIT + PNG_FP_WAS_VALID); - break; - - case PNG_FP_FRACTION + PNG_FP_E: - /* This is correct because the trailing '.' on an - * integer is handled above - so we can only get here - * with the sequence ".E" (with no preceding digits). - */ - if ((state & PNG_FP_SAW_DIGIT) == 0) - goto PNG_FP_End; - - png_fp_set(state, PNG_FP_EXPONENT); - - break; - - case PNG_FP_EXPONENT + PNG_FP_SIGN: - if (state & PNG_FP_SAW_ANY) - goto PNG_FP_End; /* not a part of the number */ - - png_fp_add(state, PNG_FP_SAW_SIGN); - - break; - - /* case PNG_FP_EXPONENT + PNG_FP_DOT: - goto PNG_FP_End; */ - - case PNG_FP_EXPONENT + PNG_FP_DIGIT: - png_fp_add(state, PNG_FP_SAW_DIGIT + PNG_FP_WAS_VALID); - - break; - - /* case PNG_FP_EXPONEXT + PNG_FP_E: - goto PNG_FP_End; */ - - default: goto PNG_FP_End; /* I.e. break 2 */ - } - - /* The character seems ok, continue. */ - ++i; - } - -PNG_FP_End: - /* Here at the end, update the state and return the correct - * return code. - */ - *statep = state; - *whereami = i; - - return (state & PNG_FP_SAW_DIGIT) != 0; -} - - -/* The same but for a complete string. */ -int -png_check_fp_string(png_const_charp string, png_size_t size) -{ - int state=0; - png_size_t char_index=0; - - return png_check_fp_number(string, size, &state, &char_index) && - (char_index == size || string[char_index] == 0); -} -#endif /* pCAL or sCAL */ - -#ifdef PNG_READ_sCAL_SUPPORTED -# ifdef PNG_FLOATING_POINT_SUPPORTED -/* Utility used below - a simple accurate power of ten from an integral - * exponent. - */ -static double -png_pow10(int power) -{ - int recip = 0; - double d = 1; - - /* Handle negative exponent with a reciprocal at the end because - * 10 is exact whereas .1 is inexact in base 2 - */ - if (power < 0) - { - if (power < DBL_MIN_10_EXP) return 0; - recip = 1, power = -power; - } - - if (power > 0) - { - /* Decompose power bitwise. */ - double mult = 10; - do - { - if (power & 1) d *= mult; - mult *= mult; - power >>= 1; - } - while (power > 0); - - if (recip) d = 1/d; - } - /* else power is 0 and d is 1 */ - - return d; -} - -/* Function to format a floating point value in ASCII with a given - * precision. - */ -void /* PRIVATE */ -png_ascii_from_fp(png_structp png_ptr, png_charp ascii, png_size_t size, - double fp, unsigned int precision) -{ - /* We use standard functions from math.h, but not printf because - * that would require stdio. The caller must supply a buffer of - * sufficient size or we will png_error. The tests on size and - * the space in ascii[] consumed are indicated below. - */ - if (precision < 1) - precision = DBL_DIG; - - /* Enforce the limit of the implementation precision too. */ - if (precision > DBL_DIG+1) - precision = DBL_DIG+1; - - /* Basic sanity checks */ - if (size >= precision+5) /* See the requirements below. */ - { - if (fp < 0) - { - fp = -fp; - *ascii++ = 45; /* '-' PLUS 1 TOTAL 1*/ - --size; - } - - if (fp >= DBL_MIN && fp <= DBL_MAX) - { - int exp_b10; /* A base 10 exponent */ - double base; /* 10^exp_b10 */ - - /* First extract a base 10 exponent of the number, - * the calculation below rounds down when converting - * from base 2 to base 10 (multiply by log10(2) - - * 0.3010, but 77/256 is 0.3008, so exp_b10 needs to - * be increased. Note that the arithmetic shift - * performs a floor() unlike C arithmetic - using a - * C multiply would break the following for negative - * exponents. - */ - (void)frexp(fp, &exp_b10); /* exponent to base 2 */ - - exp_b10 = (exp_b10 * 77) >> 8; /* <= exponent to base 10 */ - - /* Avoid underflow here. */ - base = png_pow10(exp_b10); /* May underflow */ - - while (base < DBL_MIN || base < fp) - { - /* And this may overflow. */ - double test = png_pow10(exp_b10+1); - - if (test <= DBL_MAX) - ++exp_b10, base = test; - - else - break; - } - - /* Normalize fp and correct exp_b10, after this fp is in the - * range [.1,1) and exp_b10 is both the exponent and the digit - * *before* which the decimal point should be inserted - * (starting with 0 for the first digit). Note that this - * works even if 10^exp_b10 is out of range because of the - * test on DBL_MAX above. - */ - fp /= base; - while (fp >= 1) fp /= 10, ++exp_b10; - - /* Because of the code above fp may, at this point, be - * less than .1, this is ok because the code below can - * handle the leading zeros this generates, so no attempt - * is made to correct that here. - */ - - { - int czero, clead, cdigits; - char exponent[10]; - - /* Allow up to two leading zeros - this will not lengthen - * the number compared to using E-n. - */ - if (exp_b10 < 0 && exp_b10 > -3) /* PLUS 3 TOTAL 4 */ - { - czero = -exp_b10; /* PLUS 2 digits: TOTAL 3 */ - exp_b10 = 0; /* Dot added below before first output. */ - } - else - czero = 0; /* No zeros to add */ - - /* Generate the digit list, stripping trailing zeros and - * inserting a '.' before a digit if the exponent is 0. - */ - clead = czero; /* Count of leading zeros */ - cdigits = 0; /* Count of digits in list. */ - - do - { - double d; - - fp *= 10; - /* Use modf here, not floor and subtract, so that - * the separation is done in one step. At the end - * of the loop don't break the number into parts so - * that the final digit is rounded. - */ - if (cdigits+czero-clead+1 < (int)precision) - fp = modf(fp, &d); - - else - { - d = floor(fp + .5); - - if (d > 9) - { - /* Rounding up to 10, handle that here. */ - if (czero > 0) - { - --czero, d = 1; - if (cdigits == 0) --clead; - } - else - { - while (cdigits > 0 && d > 9) - { - int ch = *--ascii; - - if (exp_b10 != (-1)) - ++exp_b10; - - else if (ch == 46) - { - ch = *--ascii, ++size; - /* Advance exp_b10 to '1', so that the - * decimal point happens after the - * previous digit. - */ - exp_b10 = 1; - } - - --cdigits; - d = ch - 47; /* I.e. 1+(ch-48) */ - } - - /* Did we reach the beginning? If so adjust the - * exponent but take into account the leading - * decimal point. - */ - if (d > 9) /* cdigits == 0 */ - { - if (exp_b10 == (-1)) - { - /* Leading decimal point (plus zeros?), if - * we lose the decimal point here it must - * be reentered below. - */ - int ch = *--ascii; - - if (ch == 46) - ++size, exp_b10 = 1; - - /* Else lost a leading zero, so 'exp_b10' is - * still ok at (-1) - */ - } - else - ++exp_b10; - - /* In all cases we output a '1' */ - d = 1; - } - } - } - fp = 0; /* Guarantees termination below. */ - } - - if (d == 0) - { - ++czero; - if (cdigits == 0) ++clead; - } - else - { - /* Included embedded zeros in the digit count. */ - cdigits += czero - clead; - clead = 0; - - while (czero > 0) - { - /* exp_b10 == (-1) means we just output the decimal - * place - after the DP don't adjust 'exp_b10' any - * more! - */ - if (exp_b10 != (-1)) - { - if (exp_b10 == 0) *ascii++ = 46, --size; - /* PLUS 1: TOTAL 4 */ - --exp_b10; - } - *ascii++ = 48, --czero; - } - - if (exp_b10 != (-1)) - { - if (exp_b10 == 0) *ascii++ = 46, --size; /* counted - above */ - --exp_b10; - } - *ascii++ = (char)(48 + (int)d), ++cdigits; - } - } - while (cdigits+czero-clead < (int)precision && fp > DBL_MIN); - - /* The total output count (max) is now 4+precision */ - - /* Check for an exponent, if we don't need one we are - * done and just need to terminate the string. At - * this point exp_b10==(-1) is effectively if flag - it got - * to '-1' because of the decrement after outputing - * the decimal point above (the exponent required is - * *not* -1!) - */ - if (exp_b10 >= (-1) && exp_b10 <= 2) - { - /* The following only happens if we didn't output the - * leading zeros above for negative exponent, so this - * doest add to the digit requirement. Note that the - * two zeros here can only be output if the two leading - * zeros were *not* output, so this doesn't increase - * the output count. - */ - while (--exp_b10 >= 0) *ascii++ = 48; - - *ascii = 0; - - /* Total buffer requirement (including the '\0') is - * 5+precision - see check at the start. - */ - return; - } - - /* Here if an exponent is required, adjust size for - * the digits we output but did not count. The total - * digit output here so far is at most 1+precision - no - * decimal point and no leading or trailing zeros have - * been output. - */ - size -= cdigits; - - *ascii++ = 69, --size; /* 'E': PLUS 1 TOTAL 2+precision*/ - if (exp_b10 < 0) - { - *ascii++ = 45, --size; /* '-': PLUS 1 TOTAL 3+precision */ - exp_b10 = -exp_b10; - } - - cdigits = 0; - - while (exp_b10 > 0) - { - exponent[cdigits++] = (char)(48 + exp_b10 % 10); - exp_b10 /= 10; - } - - /* Need another size check here for the exponent digits, so - * this need not be considered above. - */ - if ((int)size > cdigits) - { - while (cdigits > 0) *ascii++ = exponent[--cdigits]; - - *ascii = 0; - - return; - } - } - } - else if (!(fp >= DBL_MIN)) - { - *ascii++ = 48; /* '0' */ - *ascii = 0; - return; - } - else - { - *ascii++ = 105; /* 'i' */ - *ascii++ = 110; /* 'n' */ - *ascii++ = 102; /* 'f' */ - *ascii = 0; - return; - } - } - - /* Here on buffer too small. */ - png_error(png_ptr, "ASCII conversion buffer too small"); -} - -# endif /* FLOATING_POINT */ - -# ifdef PNG_FIXED_POINT_SUPPORTED -/* Function to format a fixed point value in ASCII. - */ -void /* PRIVATE */ -png_ascii_from_fixed(png_structp png_ptr, png_charp ascii, png_size_t size, - png_fixed_point fp) -{ - /* Require space for 10 decimal digits, a decimal point, a minus sign and a - * trailing \0, 13 characters: - */ - if (size > 12) - { - png_uint_32 num; - - /* Avoid overflow here on the minimum integer. */ - if (fp < 0) - *ascii++ = 45, --size, num = -fp; - else - num = fp; - - if (num <= 0x80000000U) /* else overflowed */ - { - unsigned int ndigits = 0, first = 16/*flag value*/; - char digits[10]; - - while (num) - { - /* Split the low digit off num: */ - unsigned int tmp = num/10; - num -= tmp*10; - digits[ndigits++] = (char)(48 + num); - /* Record the first non-zero digit, note that this is a number - * starting at 1, it's not actually the array index. - */ - if (first == 16 && num > 0) - first = ndigits; - num = tmp; - } - - if (ndigits > 0) - { - while (ndigits > 5) *ascii++ = digits[--ndigits]; - /* The remaining digits are fractional digits, ndigits is '5' or - * smaller at this point. It is certainly not zero. Check for a - * non-zero fractional digit: - */ - if (first <= 5) - { - unsigned int i; - *ascii++ = 46; /* decimal point */ - /* ndigits may be <5 for small numbers, output leading zeros - * then ndigits digits to first: - */ - i = 5; - while (ndigits < i) *ascii++ = 48, --i; - while (ndigits >= first) *ascii++ = digits[--ndigits]; - /* Don't output the trailing zeros! */ - } - } - else - *ascii++ = 48; - - /* And null terminate the string: */ - *ascii = 0; - return; - } - } - - /* Here on buffer too small. */ - png_error(png_ptr, "ASCII conversion buffer too small"); -} -# endif /* FIXED_POINT */ -#endif /* READ_SCAL */ - -#if defined(PNG_FLOATING_POINT_SUPPORTED) && \ - !defined(PNG_FIXED_POINT_MACRO_SUPPORTED) -png_fixed_point -png_fixed(png_structp png_ptr, double fp, png_const_charp text) -{ - double r = floor(100000 * fp + .5); - - if (r > 2147483647. || r < -2147483648.) - png_fixed_error(png_ptr, text); - - return (png_fixed_point)r; -} -#endif - -#if defined(PNG_READ_GAMMA_SUPPORTED) || \ - defined(PNG_INCH_CONVERSIONS_SUPPORTED) || defined(PNG__READ_pHYs_SUPPORTED) -/* muldiv functions */ -/* This API takes signed arguments and rounds the result to the nearest - * integer (or, for a fixed point number - the standard argument - to - * the nearest .00001). Overflow and divide by zero are signalled in - * the result, a boolean - true on success, false on overflow. - */ -int -png_muldiv(png_fixed_point_p res, png_fixed_point a, png_int_32 times, - png_int_32 divisor) -{ - /* Return a * times / divisor, rounded. */ - if (divisor != 0) - { - if (a == 0 || times == 0) - { - *res = 0; - return 1; - } - else - { -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = a; - r *= times; - r /= divisor; - r = floor(r+.5); - - /* A png_fixed_point is a 32 bit integer. */ - if (r <= 2147483647. && r >= -2147483648.) - { - *res = (png_fixed_point)r; - return 1; - } -#else - int negative = 0; - png_uint_32 A, T, D; - png_uint_32 s16, s32, s00; - - if (a < 0) - negative = 1, A = -a; - else - A = a; - - if (times < 0) - negative = !negative, T = -times; - else - T = times; - - if (divisor < 0) - negative = !negative, D = -divisor; - else - D = divisor; - - /* Following can't overflow because the arguments only - * have 31 bits each, however the result may be 32 bits. - */ - s16 = (A >> 16) * (T & 0xffff) + - (A & 0xffff) * (T >> 16); - /* Can't overflow because the a*times bit is only 30 - * bits at most. - */ - s32 = (A >> 16) * (T >> 16) + (s16 >> 16); - s00 = (A & 0xffff) * (T & 0xffff); - - s16 = (s16 & 0xffff) << 16; - s00 += s16; - - if (s00 < s16) - ++s32; /* carry */ - - if (s32 < D) /* else overflow */ - { - /* s32.s00 is now the 64 bit product, do a standard - * division, we know that s32 < D, so the maximum - * required shift is 31. - */ - int bitshift = 32; - png_fixed_point result = 0; /* NOTE: signed */ - - while (--bitshift >= 0) - { - png_uint_32 d32, d00; - - if (bitshift > 0) - d32 = D >> (32-bitshift), d00 = D << bitshift; - - else - d32 = 0, d00 = D; - - if (s32 > d32) - { - if (s00 < d00) --s32; /* carry */ - s32 -= d32, s00 -= d00, result += 1<<bitshift; - } - - else - if (s32 == d32 && s00 >= d00) - s32 = 0, s00 -= d00, result += 1<<bitshift; - } - - /* Handle the rounding. */ - if (s00 >= (D >> 1)) - ++result; - - if (negative) - result = -result; - - /* Check for overflow. */ - if ((negative && result <= 0) || (!negative && result >= 0)) - { - *res = result; - return 1; - } - } -#endif - } - } - - return 0; -} -#endif /* READ_GAMMA || INCH_CONVERSIONS */ - -#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED) -/* The following is for when the caller doesn't much care about the - * result. - */ -png_fixed_point -png_muldiv_warn(png_structp png_ptr, png_fixed_point a, png_int_32 times, - png_int_32 divisor) -{ - png_fixed_point result; - - if (png_muldiv(&result, a, times, divisor)) - return result; - - png_warning(png_ptr, "fixed point overflow ignored"); - return 0; -} -#endif - -#ifdef PNG_READ_GAMMA_SUPPORTED /* more fixed point functions for gammma */ -/* Calculate a reciprocal, return 0 on div-by-zero or overflow. */ -png_fixed_point -png_reciprocal(png_fixed_point a) -{ -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = floor(1E10/a+.5); - - if (r <= 2147483647. && r >= -2147483648.) - return (png_fixed_point)r; -#else - png_fixed_point res; - - if (png_muldiv(&res, 100000, 100000, a)) - return res; -#endif - - return 0; /* error/overflow */ -} - -/* A local convenience routine. */ -static png_fixed_point -png_product2(png_fixed_point a, png_fixed_point b) -{ - /* The required result is 1/a * 1/b; the following preserves accuracy. */ -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = a * 1E-5; - r *= b; - r = floor(r+.5); - - if (r <= 2147483647. && r >= -2147483648.) - return (png_fixed_point)r; -#else - png_fixed_point res; - - if (png_muldiv(&res, a, b, 100000)) - return res; -#endif - - return 0; /* overflow */ -} - -/* The inverse of the above. */ -png_fixed_point -png_reciprocal2(png_fixed_point a, png_fixed_point b) -{ - /* The required result is 1/a * 1/b; the following preserves accuracy. */ -#ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = 1E15/a; - r /= b; - r = floor(r+.5); - - if (r <= 2147483647. && r >= -2147483648.) - return (png_fixed_point)r; -#else - /* This may overflow because the range of png_fixed_point isn't symmetric, - * but this API is only used for the product of file and screen gamma so it - * doesn't matter that the smallest number it can produce is 1/21474, not - * 1/100000 - */ - png_fixed_point res = png_product2(a, b); - - if (res != 0) - return png_reciprocal(res); -#endif - - return 0; /* overflow */ -} -#endif /* READ_GAMMA */ - -#ifdef PNG_CHECK_cHRM_SUPPORTED -/* Added at libpng version 1.2.34 (Dec 8, 2008) and 1.4.0 (Jan 2, - * 2010: moved from pngset.c) */ -/* - * Multiply two 32-bit numbers, V1 and V2, using 32-bit - * arithmetic, to produce a 64 bit result in the HI/LO words. - * - * A B - * x C D - * ------ - * AD || BD - * AC || CB || 0 - * - * where A and B are the high and low 16-bit words of V1, - * C and D are the 16-bit words of V2, AD is the product of - * A and D, and X || Y is (X << 16) + Y. -*/ - -void /* PRIVATE */ -png_64bit_product (long v1, long v2, unsigned long *hi_product, - unsigned long *lo_product) -{ - int a, b, c, d; - long lo, hi, x, y; - - a = (v1 >> 16) & 0xffff; - b = v1 & 0xffff; - c = (v2 >> 16) & 0xffff; - d = v2 & 0xffff; - - lo = b * d; /* BD */ - x = a * d + c * b; /* AD + CB */ - y = ((lo >> 16) & 0xffff) + x; - - lo = (lo & 0xffff) | ((y & 0xffff) << 16); - hi = (y >> 16) & 0xffff; - - hi += a * c; /* AC */ - - *hi_product = (unsigned long)hi; - *lo_product = (unsigned long)lo; -} -#endif /* CHECK_cHRM */ - -#ifdef PNG_READ_GAMMA_SUPPORTED /* gamma table code */ -#ifndef PNG_FLOATING_ARITHMETIC_SUPPORTED -/* Fixed point gamma. - * - * To calculate gamma this code implements fast log() and exp() calls using only - * fixed point arithmetic. This code has sufficient precision for either 8 or - * 16 bit sample values. - * - * The tables used here were calculated using simple 'bc' programs, but C double - * precision floating point arithmetic would work fine. The programs are given - * at the head of each table. - * - * 8 bit log table - * This is a table of -log(value/255)/log(2) for 'value' in the range 128 to - * 255, so it's the base 2 logarithm of a normalized 8 bit floating point - * mantissa. The numbers are 32 bit fractions. - */ -static png_uint_32 -png_8bit_l2[128] = -{ -# if PNG_DO_BC - for (i=128;i<256;++i) { .5 - l(i/255)/l(2)*65536*65536; } -# endif - 4270715492U, 4222494797U, 4174646467U, 4127164793U, 4080044201U, 4033279239U, - 3986864580U, 3940795015U, 3895065449U, 3849670902U, 3804606499U, 3759867474U, - 3715449162U, 3671346997U, 3627556511U, 3584073329U, 3540893168U, 3498011834U, - 3455425220U, 3413129301U, 3371120137U, 3329393864U, 3287946700U, 3246774933U, - 3205874930U, 3165243125U, 3124876025U, 3084770202U, 3044922296U, 3005329011U, - 2965987113U, 2926893432U, 2888044853U, 2849438323U, 2811070844U, 2772939474U, - 2735041326U, 2697373562U, 2659933400U, 2622718104U, 2585724991U, 2548951424U, - 2512394810U, 2476052606U, 2439922311U, 2404001468U, 2368287663U, 2332778523U, - 2297471715U, 2262364947U, 2227455964U, 2192742551U, 2158222529U, 2123893754U, - 2089754119U, 2055801552U, 2022034013U, 1988449497U, 1955046031U, 1921821672U, - 1888774511U, 1855902668U, 1823204291U, 1790677560U, 1758320682U, 1726131893U, - 1694109454U, 1662251657U, 1630556815U, 1599023271U, 1567649391U, 1536433567U, - 1505374214U, 1474469770U, 1443718700U, 1413119487U, 1382670639U, 1352370686U, - 1322218179U, 1292211689U, 1262349810U, 1232631153U, 1203054352U, 1173618059U, - 1144320946U, 1115161701U, 1086139034U, 1057251672U, 1028498358U, 999877854U, - 971388940U, 943030410U, 914801076U, 886699767U, 858725327U, 830876614U, - 803152505U, 775551890U, 748073672U, 720716771U, 693480120U, 666362667U, - 639363374U, 612481215U, 585715177U, 559064263U, 532527486U, 506103872U, - 479792461U, 453592303U, 427502463U, 401522014U, 375650043U, 349885648U, - 324227938U, 298676034U, 273229066U, 247886176U, 222646516U, 197509248U, - 172473545U, 147538590U, 122703574U, 97967701U, 73330182U, 48790236U, - 24347096U, 0U -#if 0 - /* The following are the values for 16 bit tables - these work fine for the 8 - * bit conversions but produce very slightly larger errors in the 16 bit log - * (about 1.2 as opposed to 0.7 absolute error in the final value). To use - * these all the shifts below must be adjusted appropriately. - */ - 65166, 64430, 63700, 62976, 62257, 61543, 60835, 60132, 59434, 58741, 58054, - 57371, 56693, 56020, 55352, 54689, 54030, 53375, 52726, 52080, 51439, 50803, - 50170, 49542, 48918, 48298, 47682, 47070, 46462, 45858, 45257, 44661, 44068, - 43479, 42894, 42312, 41733, 41159, 40587, 40020, 39455, 38894, 38336, 37782, - 37230, 36682, 36137, 35595, 35057, 34521, 33988, 33459, 32932, 32408, 31887, - 31369, 30854, 30341, 29832, 29325, 28820, 28319, 27820, 27324, 26830, 26339, - 25850, 25364, 24880, 24399, 23920, 23444, 22970, 22499, 22029, 21562, 21098, - 20636, 20175, 19718, 19262, 18808, 18357, 17908, 17461, 17016, 16573, 16132, - 15694, 15257, 14822, 14390, 13959, 13530, 13103, 12678, 12255, 11834, 11415, - 10997, 10582, 10168, 9756, 9346, 8937, 8531, 8126, 7723, 7321, 6921, 6523, - 6127, 5732, 5339, 4947, 4557, 4169, 3782, 3397, 3014, 2632, 2251, 1872, 1495, - 1119, 744, 372 -#endif -}; - -static png_int_32 -png_log8bit(unsigned int x) -{ - unsigned int lg2 = 0; - /* Each time 'x' is multiplied by 2, 1 must be subtracted off the final log, - * because the log is actually negate that means adding 1. The final - * returned value thus has the range 0 (for 255 input) to 7.994 (for 1 - * input), return 7.99998 for the overflow (log 0) case - so the result is - * always at most 19 bits. - */ - if ((x &= 0xff) == 0) - return 0xffffffff; - - if ((x & 0xf0) == 0) - lg2 = 4, x <<= 4; - - if ((x & 0xc0) == 0) - lg2 += 2, x <<= 2; - - if ((x & 0x80) == 0) - lg2 += 1, x <<= 1; - - /* result is at most 19 bits, so this cast is safe: */ - return (png_int_32)((lg2 << 16) + ((png_8bit_l2[x-128]+32768)>>16)); -} - -/* The above gives exact (to 16 binary places) log2 values for 8 bit images, - * for 16 bit images we use the most significant 8 bits of the 16 bit value to - * get an approximation then multiply the approximation by a correction factor - * determined by the remaining up to 8 bits. This requires an additional step - * in the 16 bit case. - * - * We want log2(value/65535), we have log2(v'/255), where: - * - * value = v' * 256 + v'' - * = v' * f - * - * So f is value/v', which is equal to (256+v''/v') since v' is in the range 128 - * to 255 and v'' is in the range 0 to 255 f will be in the range 256 to less - * than 258. The final factor also needs to correct for the fact that our 8 bit - * value is scaled by 255, whereas the 16 bit values must be scaled by 65535. - * - * This gives a final formula using a calculated value 'x' which is value/v' and - * scaling by 65536 to match the above table: - * - * log2(x/257) * 65536 - * - * Since these numbers are so close to '1' we can use simple linear - * interpolation between the two end values 256/257 (result -368.61) and 258/257 - * (result 367.179). The values used below are scaled by a further 64 to give - * 16 bit precision in the interpolation: - * - * Start (256): -23591 - * Zero (257): 0 - * End (258): 23499 - */ -static png_int_32 -png_log16bit(png_uint_32 x) -{ - unsigned int lg2 = 0; - - /* As above, but now the input has 16 bits. */ - if ((x &= 0xffff) == 0) - return 0xffffffff; - - if ((x & 0xff00) == 0) - lg2 = 8, x <<= 8; - - if ((x & 0xf000) == 0) - lg2 += 4, x <<= 4; - - if ((x & 0xc000) == 0) - lg2 += 2, x <<= 2; - - if ((x & 0x8000) == 0) - lg2 += 1, x <<= 1; - - /* Calculate the base logarithm from the top 8 bits as a 28 bit fractional - * value. - */ - lg2 <<= 28; - lg2 += (png_8bit_l2[(x>>8)-128]+8) >> 4; - - /* Now we need to interpolate the factor, this requires a division by the top - * 8 bits. Do this with maximum precision. - */ - x = ((x << 16) + (x >> 9)) / (x >> 8); - - /* Since we divided by the top 8 bits of 'x' there will be a '1' at 1<<24, - * the value at 1<<16 (ignoring this) will be 0 or 1; this gives us exactly - * 16 bits to interpolate to get the low bits of the result. Round the - * answer. Note that the end point values are scaled by 64 to retain overall - * precision and that 'lg2' is current scaled by an extra 12 bits, so adjust - * the overall scaling by 6-12. Round at every step. - */ - x -= 1U << 24; - - if (x <= 65536U) /* <= '257' */ - lg2 += ((23591U * (65536U-x)) + (1U << (16+6-12-1))) >> (16+6-12); - - else - lg2 -= ((23499U * (x-65536U)) + (1U << (16+6-12-1))) >> (16+6-12); - - /* Safe, because the result can't have more than 20 bits: */ - return (png_int_32)((lg2 + 2048) >> 12); -} - -/* The 'exp()' case must invert the above, taking a 20 bit fixed point - * logarithmic value and returning a 16 or 8 bit number as appropriate. In - * each case only the low 16 bits are relevant - the fraction - since the - * integer bits (the top 4) simply determine a shift. - * - * The worst case is the 16 bit distinction between 65535 and 65534, this - * requires perhaps spurious accuracty in the decoding of the logarithm to - * distinguish log2(65535/65534.5) - 10^-5 or 17 bits. There is little chance - * of getting this accuracy in practice. - * - * To deal with this the following exp() function works out the exponent of the - * frational part of the logarithm by using an accurate 32 bit value from the - * top four fractional bits then multiplying in the remaining bits. - */ -static png_uint_32 -png_32bit_exp[16] = -{ -# if PNG_DO_BC - for (i=0;i<16;++i) { .5 + e(-i/16*l(2))*2^32; } -# endif - /* NOTE: the first entry is deliberately set to the maximum 32 bit value. */ - 4294967295U, 4112874773U, 3938502376U, 3771522796U, 3611622603U, 3458501653U, - 3311872529U, 3171459999U, 3037000500U, 2908241642U, 2784941738U, 2666869345U, - 2553802834U, 2445529972U, 2341847524U, 2242560872U -}; - -/* Adjustment table; provided to explain the numbers in the code below. */ -#if PNG_DO_BC -for (i=11;i>=0;--i){ print i, " ", (1 - e(-(2^i)/65536*l(2))) * 2^(32-i), "\n"} - 11 44937.64284865548751208448 - 10 45180.98734845585101160448 - 9 45303.31936980687359311872 - 8 45364.65110595323018870784 - 7 45395.35850361789624614912 - 6 45410.72259715102037508096 - 5 45418.40724413220722311168 - 4 45422.25021786898173001728 - 3 45424.17186732298419044352 - 2 45425.13273269940811464704 - 1 45425.61317555035558641664 - 0 45425.85339951654943850496 -#endif - -static png_uint_32 -png_exp(png_fixed_point x) -{ - if (x > 0 && x <= 0xfffff) /* Else overflow or zero (underflow) */ - { - /* Obtain a 4 bit approximation */ - png_uint_32 e = png_32bit_exp[(x >> 12) & 0xf]; - - /* Incorporate the low 12 bits - these decrease the returned value by - * multiplying by a number less than 1 if the bit is set. The multiplier - * is determined by the above table and the shift. Notice that the values - * converge on 45426 and this is used to allow linear interpolation of the - * low bits. - */ - if (x & 0x800) - e -= (((e >> 16) * 44938U) + 16U) >> 5; - - if (x & 0x400) - e -= (((e >> 16) * 45181U) + 32U) >> 6; - - if (x & 0x200) - e -= (((e >> 16) * 45303U) + 64U) >> 7; - - if (x & 0x100) - e -= (((e >> 16) * 45365U) + 128U) >> 8; - - if (x & 0x080) - e -= (((e >> 16) * 45395U) + 256U) >> 9; - - if (x & 0x040) - e -= (((e >> 16) * 45410U) + 512U) >> 10; - - /* And handle the low 6 bits in a single block. */ - e -= (((e >> 16) * 355U * (x & 0x3fU)) + 256U) >> 9; - - /* Handle the upper bits of x. */ - e >>= x >> 16; - return e; - } - - /* Check for overflow */ - if (x <= 0) - return png_32bit_exp[0]; - - /* Else underflow */ - return 0; -} - -static png_byte -png_exp8bit(png_fixed_point lg2) -{ - /* Get a 32 bit value: */ - png_uint_32 x = png_exp(lg2); - - /* Convert the 32 bit value to 0..255 by multiplying by 256-1, note that the - * second, rounding, step can't overflow because of the first, subtraction, - * step. - */ - x -= x >> 8; - return (png_byte)((x + 0x7fffffU) >> 24); -} - -static png_uint_16 -png_exp16bit(png_fixed_point lg2) -{ - /* Get a 32 bit value: */ - png_uint_32 x = png_exp(lg2); - - /* Convert the 32 bit value to 0..65535 by multiplying by 65536-1: */ - x -= x >> 16; - return (png_uint_16)((x + 32767U) >> 16); -} -#endif /* FLOATING_ARITHMETIC */ - -png_byte -png_gamma_8bit_correct(unsigned int value, png_fixed_point gamma_val) -{ - if (value > 0 && value < 255) - { -# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = floor(255*pow(value/255.,gamma_val*.00001)+.5); - return (png_byte)r; -# else - png_int_32 lg2 = png_log8bit(value); - png_fixed_point res; - - if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1)) - return png_exp8bit(res); - - /* Overflow. */ - value = 0; -# endif - } - - return (png_byte)value; -} - -png_uint_16 -png_gamma_16bit_correct(unsigned int value, png_fixed_point gamma_val) -{ - if (value > 0 && value < 65535) - { -# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - double r = floor(65535*pow(value/65535.,gamma_val*.00001)+.5); - return (png_uint_16)r; -# else - png_int_32 lg2 = png_log16bit(value); - png_fixed_point res; - - if (png_muldiv(&res, gamma_val, lg2, PNG_FP_1)) - return png_exp16bit(res); - - /* Overflow. */ - value = 0; -# endif - } - - return (png_uint_16)value; -} - -/* This does the right thing based on the bit_depth field of the - * png_struct, interpreting values as 8 or 16 bit. While the result - * is nominally a 16 bit value if bit depth is 8 then the result is - * 8 bit (as are the arguments.) - */ -png_uint_16 /* PRIVATE */ -png_gamma_correct(png_structp png_ptr, unsigned int value, - png_fixed_point gamma_val) -{ - if (png_ptr->bit_depth == 8) - return png_gamma_8bit_correct(value, gamma_val); - - else - return png_gamma_16bit_correct(value, gamma_val); -} - -/* This is the shared test on whether a gamma value is 'significant' - whether - * it is worth doing gamma correction. - */ -int /* PRIVATE */ -png_gamma_significant(png_fixed_point gamma_val) -{ - return gamma_val < PNG_FP_1 - PNG_GAMMA_THRESHOLD_FIXED || - gamma_val > PNG_FP_1 + PNG_GAMMA_THRESHOLD_FIXED; -} - -/* Internal function to build a single 16 bit table - the table consists of - * 'num' 256 entry subtables, where 'num' is determined by 'shift' - the amount - * to shift the input values right (or 16-number_of_signifiant_bits). - * - * The caller is responsible for ensuring that the table gets cleaned up on - * png_error (i.e. if one of the mallocs below fails) - i.e. the *table argument - * should be somewhere that will be cleaned. - */ -static void -png_build_16bit_table(png_structp png_ptr, png_uint_16pp *ptable, - PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) -{ - /* Various values derived from 'shift': */ - PNG_CONST unsigned int num = 1U << (8U - shift); - PNG_CONST unsigned int max = (1U << (16U - shift))-1U; - PNG_CONST unsigned int max_by_2 = 1U << (15U-shift); - unsigned int i; - - png_uint_16pp table = *ptable = - (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p)); - - for (i = 0; i < num; i++) - { - png_uint_16p sub_table = table[i] = - (png_uint_16p)png_malloc(png_ptr, 256 * png_sizeof(png_uint_16)); - - /* The 'threshold' test is repeated here because it can arise for one of - * the 16 bit tables even if the others don't hit it. - */ - if (png_gamma_significant(gamma_val)) - { - /* The old code would overflow at the end and this would cause the - * 'pow' function to return a result >1, resulting in an - * arithmetic error. This code follows the spec exactly; ig is - * the recovered input sample, it always has 8-16 bits. - * - * We want input * 65535/max, rounded, the arithmetic fits in 32 - * bits (unsigned) so long as max <= 32767. - */ - unsigned int j; - for (j = 0; j < 256; j++) - { - png_uint_32 ig = (j << (8-shift)) + i; -# ifdef PNG_FLOATING_ARITHMETIC_SUPPORTED - /* Inline the 'max' scaling operation: */ - double d = floor(65535*pow(ig/(double)max, gamma_val*.00001)+.5); - sub_table[j] = (png_uint_16)d; -# else - if (shift) - ig = (ig * 65535U + max_by_2)/max; - - sub_table[j] = png_gamma_16bit_correct(ig, gamma_val); -# endif - } - } - else - { - /* We must still build a table, but do it the fast way. */ - unsigned int j; - - for (j = 0; j < 256; j++) - { - png_uint_32 ig = (j << (8-shift)) + i; - - if (shift) - ig = (ig * 65535U + max_by_2)/max; - - sub_table[j] = (png_uint_16)ig; - } - } - } -} - -/* NOTE: this function expects the *inverse* of the overall gamma transformation - * required. - */ -static void -png_build_16to8_table(png_structp png_ptr, png_uint_16pp *ptable, - PNG_CONST unsigned int shift, PNG_CONST png_fixed_point gamma_val) -{ - PNG_CONST unsigned int num = 1U << (8U - shift); - PNG_CONST unsigned int max = (1U << (16U - shift))-1U; - unsigned int i; - png_uint_32 last; - - png_uint_16pp table = *ptable = - (png_uint_16pp)png_calloc(png_ptr, num * png_sizeof(png_uint_16p)); - - /* 'num' is the number of tables and also the number of low bits of low - * bits of the input 16 bit value used to select a table. Each table is - * itself index by the high 8 bits of the value. - */ - for (i = 0; i < num; i++) - table[i] = (png_uint_16p)png_malloc(png_ptr, - 256 * png_sizeof(png_uint_16)); - - /* 'gamma_val' is set to the reciprocal of the value calculated above, so - * pow(out,g) is an *input* value. 'last' is the last input value set. - * - * In the loop 'i' is used to find output values. Since the output is 8 - * bit there are only 256 possible values. The tables are set up to - * select the closest possible output value for each input by finding - * the input value at the boundary between each pair of output values - * and filling the table up to that boundary with the lower output - * value. - * - * The boundary values are 0.5,1.5..253.5,254.5. Since these are 9 bit - * values the code below uses a 16 bit value in i; the values start at - * 128.5 (for 0.5) and step by 257, for a total of 254 values (the last - * entries are filled with 255). Start i at 128 and fill all 'last' - * table entries <= 'max' - */ - last = 0; - for (i = 0; i < 255; ++i) /* 8 bit output value */ - { - /* Find the corresponding maximum input value */ - png_uint_16 out = (png_uint_16)(i * 257U); /* 16 bit output value */ - - /* Find the boundary value in 16 bits: */ - png_uint_32 bound = png_gamma_16bit_correct(out+128U, gamma_val); - - /* Adjust (round) to (16-shift) bits: */ - bound = (bound * max + 32768U)/65535U + 1U; - - while (last < bound) - { - table[last & (0xffU >> shift)][last >> (8U - shift)] = out; - last++; - } - } - - /* And fill in the final entries. */ - while (last < (num << 8)) - { - table[last & (0xff >> shift)][last >> (8U - shift)] = 65535U; - last++; - } -} - -/* Build a single 8 bit table: same as the 16 bit case but much simpler (and - * typically much faster). Note that libpng currently does no sBIT processing - * (apparently contrary to the spec) so a 256 entry table is always generated. - */ -static void -png_build_8bit_table(png_structp png_ptr, png_bytepp ptable, - PNG_CONST png_fixed_point gamma_val) -{ - unsigned int i; - png_bytep table = *ptable = (png_bytep)png_malloc(png_ptr, 256); - - if (png_gamma_significant(gamma_val)) for (i=0; i<256; i++) - table[i] = png_gamma_8bit_correct(i, gamma_val); - - else for (i=0; i<256; ++i) - table[i] = (png_byte)i; -} - -/* We build the 8- or 16-bit gamma tables here. Note that for 16-bit - * tables, we don't make a full table if we are reducing to 8-bit in - * the future. Note also how the gamma_16 tables are segmented so that - * we don't need to allocate > 64K chunks for a full 16-bit table. - */ -void /* PRIVATE */ -png_build_gamma_table(png_structp png_ptr, int bit_depth) -{ - png_debug(1, "in png_build_gamma_table"); - - if (bit_depth <= 8) - { - png_build_8bit_table(png_ptr, &png_ptr->gamma_table, - png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma, - png_ptr->screen_gamma) : PNG_FP_1); - -#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ - defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - if (png_ptr->transformations & ((PNG_BACKGROUND) | PNG_RGB_TO_GRAY)) - { - png_build_8bit_table(png_ptr, &png_ptr->gamma_to_1, - png_reciprocal(png_ptr->gamma)); - - png_build_8bit_table(png_ptr, &png_ptr->gamma_from_1, - png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : - png_ptr->gamma/* Probably doing rgb_to_gray */); - } -#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */ - } - else - { - png_byte shift, sig_bit; - - if (png_ptr->color_type & PNG_COLOR_MASK_COLOR) - { - sig_bit = png_ptr->sig_bit.red; - - if (png_ptr->sig_bit.green > sig_bit) - sig_bit = png_ptr->sig_bit.green; - - if (png_ptr->sig_bit.blue > sig_bit) - sig_bit = png_ptr->sig_bit.blue; - } - else - sig_bit = png_ptr->sig_bit.gray; - - /* 16 bit gamma code uses this equation: - * - * ov = table[(iv & 0xff) >> gamma_shift][iv >> 8] - * - * Where 'iv' is the input color value and 'ov' is the output value - - * pow(iv, gamma). - * - * Thus the gamma table consists of up to 256 256 entry tables. The table - * is selected by the (8-gamma_shift) most significant of the low 8 bits of - * the color value then indexed by the upper 8 bits: - * - * table[low bits][high 8 bits] - * - * So the table 'n' corresponds to all those 'iv' of: - * - * <all high 8 bit values><n << gamma_shift>..<(n+1 << gamma_shift)-1> - * - */ - if (sig_bit > 0 && sig_bit < 16U) - shift = (png_byte)(16U - sig_bit); /* shift == insignificant bits */ - - else - shift = 0; /* keep all 16 bits */ - - if (png_ptr->transformations & PNG_16_TO_8) - { - /* PNG_MAX_GAMMA_8 is the number of bits to keep - effectively - * the significant bits in the *input* when the output will - * eventually be 8 bits. By default it is 11. - */ - if (shift < (16U - PNG_MAX_GAMMA_8)) - shift = (16U - PNG_MAX_GAMMA_8); - } - - if (shift > 8U) - shift = 8U; /* Guarantees at least one table! */ - - png_ptr->gamma_shift = shift; - -#ifdef PNG_16BIT_SUPPORTED - if (png_ptr->transformations & (PNG_16_TO_8 | PNG_BACKGROUND)) -#endif - png_build_16to8_table(png_ptr, &png_ptr->gamma_16_table, shift, - png_ptr->screen_gamma > 0 ? png_product2(png_ptr->gamma, - png_ptr->screen_gamma) : PNG_FP_1); - -#ifdef PNG_16BIT_SUPPORTED - else - png_build_16bit_table(png_ptr, &png_ptr->gamma_16_table, shift, - png_ptr->screen_gamma > 0 ? png_reciprocal2(png_ptr->gamma, - png_ptr->screen_gamma) : PNG_FP_1); -#endif - -#if defined(PNG_READ_BACKGROUND_SUPPORTED) || \ - defined(PNG_READ_RGB_TO_GRAY_SUPPORTED) - if (png_ptr->transformations & (PNG_BACKGROUND | PNG_RGB_TO_GRAY)) - { - png_build_16bit_table(png_ptr, &png_ptr->gamma_16_to_1, shift, - png_reciprocal(png_ptr->gamma)); - - /* Notice that the '16 from 1' table should be full precision, however - * the lookup on this table still uses gamma_shift, so it can't be. - * TODO: fix this. - */ - png_build_16bit_table(png_ptr, &png_ptr->gamma_16_from_1, shift, - png_ptr->screen_gamma > 0 ? png_reciprocal(png_ptr->screen_gamma) : - png_ptr->gamma/* Probably doing rgb_to_gray */); - } -#endif /* PNG_READ_BACKGROUND_SUPPORTED || PNG_RGB_TO_GRAY_SUPPORTED */ - } -} -#endif /* READ_GAMMA */ -#endif /* defined(PNG_READ_SUPPORTED) || defined(PNG_WRITE_SUPPORTED) */ |