pnginfo.h (11362B)
1 /* pnginfo.h - internal structures for libpng 2 * 3 * Copyright (c) 2018-2025 Cosmin Truta 4 * Copyright (c) 1998-2002,2004,2006-2013,2018 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 13 #ifndef PNGPRIV_H 14 # error This file must not be included by applications; please include <png.h> 15 #endif 16 17 /* INTERNAL, PRIVATE definition of a PNG. 18 * 19 * png_info is a modifiable description of a PNG datastream. The fields inside 20 * this structure are accessed through png_get_<CHUNK>() functions and modified 21 * using png_set_<CHUNK>() functions. 22 * 23 * Some functions in libpng do directly access members of png_info. However, 24 * this should be avoided. png_struct objects contain members which hold 25 * caches, sometimes optimised, of the values from png_info objects, and 26 * png_info is not passed to the functions which read and write image data. 27 */ 28 #ifndef PNGINFO_H 29 #define PNGINFO_H 30 31 struct png_info_def 32 { 33 /* The following are necessary for every PNG file */ 34 png_uint_32 width; /* width of image in pixels (from IHDR) */ 35 png_uint_32 height; /* height of image in pixels (from IHDR) */ 36 png_uint_32 valid; /* valid chunk data (see PNG_INFO_ below) */ 37 size_t rowbytes; /* bytes needed to hold an untransformed row */ 38 png_colorp palette; /* array of color values (valid & PNG_INFO_PLTE) */ 39 png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */ 40 png_uint_16 num_trans; /* number of transparent palette color (tRNS) */ 41 png_byte bit_depth; /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */ 42 png_byte color_type; /* see PNG_COLOR_TYPE_ below (from IHDR) */ 43 /* The following three should have been named *_method not *_type */ 44 png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */ 45 png_byte filter_type; /* must be PNG_FILTER_TYPE_BASE (from IHDR) */ 46 png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */ 47 48 /* The following are set by png_set_IHDR, called from the application on 49 * write, but the are never actually used by the write code. 50 */ 51 png_byte channels; /* number of data channels per pixel (1, 2, 3, 4) */ 52 png_byte pixel_depth; /* number of bits per pixel */ 53 png_byte spare_byte; /* to align the data, and for future use */ 54 55 #ifdef PNG_READ_SUPPORTED 56 /* This is never set during write */ 57 png_byte signature[8]; /* magic bytes read by libpng from start of file */ 58 #endif 59 60 /* The rest of the data is optional. If you are reading, check the 61 * valid field to see if the information in these are valid. If you 62 * are writing, set the valid field to those chunks you want written, 63 * and initialize the appropriate fields below. 64 */ 65 66 #ifdef PNG_cICP_SUPPORTED 67 /* cICP chunk data */ 68 png_byte cicp_colour_primaries; 69 png_byte cicp_transfer_function; 70 png_byte cicp_matrix_coefficients; 71 png_byte cicp_video_full_range_flag; 72 #endif 73 74 #ifdef PNG_iCCP_SUPPORTED 75 /* iCCP chunk data. */ 76 png_charp iccp_name; /* profile name */ 77 png_bytep iccp_profile; /* International Color Consortium profile data */ 78 png_uint_32 iccp_proflen; /* ICC profile data length */ 79 #endif 80 81 #ifdef PNG_cLLI_SUPPORTED 82 png_uint_32 maxCLL; /* cd/m2 (nits) * 10,000 */ 83 png_uint_32 maxFALL; 84 #endif 85 86 #ifdef PNG_mDCV_SUPPORTED 87 png_uint_16 mastering_red_x; /* CIE (xy) x * 50,000 */ 88 png_uint_16 mastering_red_y; 89 png_uint_16 mastering_green_x; 90 png_uint_16 mastering_green_y; 91 png_uint_16 mastering_blue_x; 92 png_uint_16 mastering_blue_y; 93 png_uint_16 mastering_white_x; 94 png_uint_16 mastering_white_y; 95 png_uint_32 mastering_maxDL; /* cd/m2 (nits) * 10,000 */ 96 png_uint_32 mastering_minDL; 97 #endif 98 99 #ifdef PNG_TEXT_SUPPORTED 100 /* The tEXt, and zTXt chunks contain human-readable textual data in 101 * uncompressed, compressed, and optionally compressed forms, respectively. 102 * The data in "text" is an array of pointers to uncompressed, 103 * null-terminated C strings. Each chunk has a keyword that describes the 104 * textual data contained in that chunk. Keywords are not required to be 105 * unique, and the text string may be empty. Any number of text chunks may 106 * be in an image. 107 */ 108 int num_text; /* number of comments read or comments to write */ 109 int max_text; /* current size of text array */ 110 png_textp text; /* array of comments read or comments to write */ 111 #endif /* TEXT */ 112 113 #ifdef PNG_tIME_SUPPORTED 114 /* The tIME chunk holds the last time the displayed image data was 115 * modified. See the png_time struct for the contents of this struct. 116 */ 117 png_time mod_time; 118 #endif 119 120 #ifdef PNG_sBIT_SUPPORTED 121 /* The sBIT chunk specifies the number of significant high-order bits 122 * in the pixel data. Values are in the range [1, bit_depth], and are 123 * only specified for the channels in the pixel data. The contents of 124 * the low-order bits is not specified. Data is valid if 125 * (valid & PNG_INFO_sBIT) is non-zero. 126 */ 127 png_color_8 sig_bit; /* significant bits in color channels */ 128 #endif 129 130 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \ 131 defined(PNG_READ_BACKGROUND_SUPPORTED) 132 /* The tRNS chunk supplies transparency data for paletted images and 133 * other image types that don't need a full alpha channel. There are 134 * "num_trans" transparency values for a paletted image, stored in the 135 * same order as the palette colors, starting from index 0. Values 136 * for the data are in the range [0, 255], ranging from fully transparent 137 * to fully opaque, respectively. For non-paletted images, there is a 138 * single color specified that should be treated as fully transparent. 139 * Data is valid if (valid & PNG_INFO_tRNS) is non-zero. 140 */ 141 png_bytep trans_alpha; /* alpha values for paletted image */ 142 png_color_16 trans_color; /* transparent color for non-palette image */ 143 #endif 144 145 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) 146 /* The bKGD chunk gives the suggested image background color if the 147 * display program does not have its own background color and the image 148 * is needs to composited onto a background before display. The colors 149 * in "background" are normally in the same color space/depth as the 150 * pixel data. Data is valid if (valid & PNG_INFO_bKGD) is non-zero. 151 */ 152 png_color_16 background; 153 #endif 154 155 #ifdef PNG_oFFs_SUPPORTED 156 /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards 157 * and downwards from the top-left corner of the display, page, or other 158 * application-specific co-ordinate space. See the PNG_OFFSET_ defines 159 * below for the unit types. Valid if (valid & PNG_INFO_oFFs) non-zero. 160 */ 161 png_int_32 x_offset; /* x offset on page */ 162 png_int_32 y_offset; /* y offset on page */ 163 png_byte offset_unit_type; /* offset units type */ 164 #endif 165 166 #ifdef PNG_pHYs_SUPPORTED 167 /* The pHYs chunk gives the physical pixel density of the image for 168 * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_ 169 * defines below). Data is valid if (valid & PNG_INFO_pHYs) is non-zero. 170 */ 171 png_uint_32 x_pixels_per_unit; /* horizontal pixel density */ 172 png_uint_32 y_pixels_per_unit; /* vertical pixel density */ 173 png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */ 174 #endif 175 176 #ifdef PNG_eXIf_SUPPORTED 177 png_uint_32 num_exif; /* Added at libpng-1.6.31 */ 178 png_bytep exif; 179 #endif 180 181 #ifdef PNG_hIST_SUPPORTED 182 /* The hIST chunk contains the relative frequency or importance of the 183 * various palette entries, so that a viewer can intelligently select a 184 * reduced-color palette, if required. Data is an array of "num_palette" 185 * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST) 186 * is non-zero. 187 */ 188 png_uint_16p hist; 189 #endif 190 191 #ifdef PNG_pCAL_SUPPORTED 192 /* The pCAL chunk describes a transformation between the stored pixel 193 * values and original physical data values used to create the image. 194 * The integer range [0, 2^bit_depth - 1] maps to the floating-point 195 * range given by [pcal_X0, pcal_X1], and are further transformed by a 196 * (possibly non-linear) transformation function given by "pcal_type" 197 * and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_ 198 * defines below, and the PNG-Group's PNG extensions document for a 199 * complete description of the transformations and how they should be 200 * implemented, and for a description of the ASCII parameter strings. 201 * Data values are valid if (valid & PNG_INFO_pCAL) non-zero. 202 */ 203 png_charp pcal_purpose; /* pCAL chunk description string */ 204 png_int_32 pcal_X0; /* minimum value */ 205 png_int_32 pcal_X1; /* maximum value */ 206 png_charp pcal_units; /* Latin-1 string giving physical units */ 207 png_charpp pcal_params; /* ASCII strings containing parameter values */ 208 png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */ 209 png_byte pcal_nparams; /* number of parameters given in pcal_params */ 210 #endif 211 212 /* New members added in libpng-1.0.6 */ 213 png_uint_32 free_me; /* flags items libpng is responsible for freeing */ 214 215 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED 216 /* Storage for unknown chunks that the library doesn't recognize. */ 217 png_unknown_chunkp unknown_chunks; 218 219 /* The type of this field is limited by the type of 220 * png_struct::user_chunk_cache_max, else overflow can occur. 221 */ 222 int unknown_chunks_num; 223 #endif 224 225 #ifdef PNG_sPLT_SUPPORTED 226 /* Data on sPLT chunks (there may be more than one). */ 227 png_sPLT_tp splt_palettes; 228 int splt_palettes_num; /* Match type returned by png_get API */ 229 #endif 230 231 #ifdef PNG_sCAL_SUPPORTED 232 /* The sCAL chunk describes the actual physical dimensions of the 233 * subject matter of the graphic. The chunk contains a unit specification 234 * a byte value, and two ASCII strings representing floating-point 235 * values. The values are width and height corresponding to one pixel 236 * in the image. Data values are valid if (valid & PNG_INFO_sCAL) is 237 * non-zero. 238 */ 239 png_byte scal_unit; /* unit of physical scale */ 240 png_charp scal_s_width; /* string containing height */ 241 png_charp scal_s_height; /* string containing width */ 242 #endif 243 244 #ifdef PNG_INFO_IMAGE_SUPPORTED 245 /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) 246 non-zero */ 247 /* Data valid if (valid & PNG_INFO_IDAT) non-zero */ 248 png_bytepp row_pointers; /* the image bits */ 249 #endif 250 251 #ifdef PNG_cHRM_SUPPORTED 252 png_xy cHRM; 253 #endif 254 255 #ifdef PNG_gAMA_SUPPORTED 256 png_fixed_point gamma; 257 #endif 258 259 #ifdef PNG_sRGB_SUPPORTED 260 int rendering_intent; 261 #endif 262 #ifdef PNG_APNG_SUPPORTED 263 png_uint_32 num_frames; /* including default image */ 264 png_uint_32 num_plays; 265 png_uint_32 next_frame_width; 266 png_uint_32 next_frame_height; 267 png_uint_32 next_frame_x_offset; 268 png_uint_32 next_frame_y_offset; 269 png_uint_16 next_frame_delay_num; 270 png_uint_16 next_frame_delay_den; 271 png_byte next_frame_dispose_op; 272 png_byte next_frame_blend_op; 273 #endif 274 275 }; 276 #endif /* PNGINFO_H */