1 2 /* pnginfo.h - header file for PNG reference library 3 * 4 * Last changed in libpng 1.6.1 [March 28, 2013] 5 * Copyright (c) 1998-2002,2004,2006-2013 Glenn Randers-Pehrson 6 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 7 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 8 * 9 * This code is released under the libpng license. 10 * For conditions of distribution and use, see the disclaimer 11 * and license in png.h 12 */ 13 14 /* png_info is a structure that holds the information in a PNG file so 15 * that the application can find out the characteristics of the image. 16 * If you are reading the file, this structure will tell you what is 17 * in the PNG file. If you are writing the file, fill in the information 18 * you want to put into the PNG file, using png_set_*() functions, then 19 * call png_write_info(). 20 * 21 * The names chosen should be very close to the PNG specification, so 22 * consult that document for information about the meaning of each field. 23 * 24 * With libpng < 0.95, it was only possible to directly set and read the 25 * the values in the png_info_struct, which meant that the contents and 26 * order of the values had to remain fixed. With libpng 0.95 and later, 27 * however, there are now functions that abstract the contents of 28 * png_info_struct from the application, so this makes it easier to use 29 * libpng with dynamic libraries, and even makes it possible to use 30 * libraries that don't have all of the libpng ancillary chunk-handing 31 * functionality. In libpng-1.5.0 this was moved into a separate private 32 * file that is not visible to applications. 33 * 34 * The following members may have allocated storage attached that should be 35 * cleaned up before the structure is discarded: palette, trans, text, 36 * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile, 37 * splt_palettes, scal_unit, row_pointers, and unknowns. By default, these 38 * are automatically freed when the info structure is deallocated, if they were 39 * allocated internally by libpng. This behavior can be changed by means 40 * of the png_data_freer() function. 41 * 42 * More allocation details: all the chunk-reading functions that 43 * change these members go through the corresponding png_set_* 44 * functions. A function to clear these members is available: see 45 * png_free_data(). The png_set_* functions do not depend on being 46 * able to point info structure members to any of the storage they are 47 * passed (they make their own copies), EXCEPT that the png_set_text 48 * functions use the same storage passed to them in the text_ptr or 49 * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns 50 * functions do not make their own copies. 51 */ 52 #ifndef PNGINFO_H 53 #define PNGINFO_H 54 55 struct png_info_def 56 { 57 /* The following are necessary for every PNG file */ 58 png_uint_32 width; /* width of image in pixels (from IHDR) */ 59 png_uint_32 height; /* height of image in pixels (from IHDR) */ 60 png_uint_32 valid; /* valid chunk data (see PNG_INFO_ below) */ 61 png_size_t rowbytes; /* bytes needed to hold an untransformed row */ 62 png_colorp palette; /* array of color values (valid & PNG_INFO_PLTE) */ 63 png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */ 64 png_uint_16 num_trans; /* number of transparent palette color (tRNS) */ 65 png_byte bit_depth; /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */ 66 png_byte color_type; /* see PNG_COLOR_TYPE_ below (from IHDR) */ 67 /* The following three should have been named *_method not *_type */ 68 png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */ 69 png_byte filter_type; /* must be PNG_FILTER_TYPE_BASE (from IHDR) */ 70 png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */ 71 72 /* The following are set by png_set_IHDR, called from the application on 73 * write, but the are never actually used by the write code. 74 */ 75 png_byte channels; /* number of data channels per pixel (1, 2, 3, 4) */ 76 png_byte pixel_depth; /* number of bits per pixel */ 77 png_byte spare_byte; /* to align the data, and for future use */ 78 79 #ifdef PNG_READ_SUPPORTED 80 /* This is never set during write */ 81 png_byte signature[8]; /* magic bytes read by libpng from start of file */ 82 #endif 83 84 /* The rest of the data is optional. If you are reading, check the 85 * valid field to see if the information in these are valid. If you 86 * are writing, set the valid field to those chunks you want written, 87 * and initialize the appropriate fields below. 88 */ 89 90 #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED) 91 /* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are 92 * defined. When COLORSPACE is switched on all the colorspace-defining 93 * chunks should be enabled, when GAMMA is switched on all the gamma-defining 94 * chunks should be enabled. If this is not done it becomes possible to read 95 * inconsistent PNG files and assign a probably incorrect interpretation to 96 * the information. (In other words, by carefully choosing which chunks to 97 * recognize the system configuration can select an interpretation for PNG 98 * files containing ambiguous data and this will result in inconsistent 99 * behavior between different libpng builds!) 100 */ 101 png_colorspace colorspace; 102 #endif 103 104 #ifdef PNG_iCCP_SUPPORTED 105 /* iCCP chunk data. */ 106 png_charp iccp_name; /* profile name */ 107 png_bytep iccp_profile; /* International Color Consortium profile data */ 108 png_uint_32 iccp_proflen; /* ICC profile data length */ 109 #endif 110 111 #ifdef PNG_TEXT_SUPPORTED 112 /* The tEXt, and zTXt chunks contain human-readable textual data in 113 * uncompressed, compressed, and optionally compressed forms, respectively. 114 * The data in "text" is an array of pointers to uncompressed, 115 * null-terminated C strings. Each chunk has a keyword that describes the 116 * textual data contained in that chunk. Keywords are not required to be 117 * unique, and the text string may be empty. Any number of text chunks may 118 * be in an image. 119 */ 120 int num_text; /* number of comments read or comments to write */ 121 int max_text; /* current size of text array */ 122 png_textp text; /* array of comments read or comments to write */ 123 #endif /* TEXT */ 124 125 #ifdef PNG_tIME_SUPPORTED 126 /* The tIME chunk holds the last time the displayed image data was 127 * modified. See the png_time struct for the contents of this struct. 128 */ 129 png_time mod_time; 130 #endif 131 132 #ifdef PNG_sBIT_SUPPORTED 133 /* The sBIT chunk specifies the number of significant high-order bits 134 * in the pixel data. Values are in the range [1, bit_depth], and are 135 * only specified for the channels in the pixel data. The contents of 136 * the low-order bits is not specified. Data is valid if 137 * (valid & PNG_INFO_sBIT) is non-zero. 138 */ 139 png_color_8 sig_bit; /* significant bits in color channels */ 140 #endif 141 142 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \ 143 defined(PNG_READ_BACKGROUND_SUPPORTED) 144 /* The tRNS chunk supplies transparency data for paletted images and 145 * other image types that don't need a full alpha channel. There are 146 * "num_trans" transparency values for a paletted image, stored in the 147 * same order as the palette colors, starting from index 0. Values 148 * for the data are in the range [0, 255], ranging from fully transparent 149 * to fully opaque, respectively. For non-paletted images, there is a 150 * single color specified that should be treated as fully transparent. 151 * Data is valid if (valid & PNG_INFO_tRNS) is non-zero. 152 */ 153 png_bytep trans_alpha; /* alpha values for paletted image */ 154 png_color_16 trans_color; /* transparent color for non-palette image */ 155 #endif 156 157 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) 158 /* The bKGD chunk gives the suggested image background color if the 159 * display program does not have its own background color and the image 160 * is needs to composited onto a background before display. The colors 161 * in "background" are normally in the same color space/depth as the 162 * pixel data. Data is valid if (valid & PNG_INFO_bKGD) is non-zero. 163 */ 164 png_color_16 background; 165 #endif 166 167 #ifdef PNG_oFFs_SUPPORTED 168 /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards 169 * and downwards from the top-left corner of the display, page, or other 170 * application-specific co-ordinate space. See the PNG_OFFSET_ defines 171 * below for the unit types. Valid if (valid & PNG_INFO_oFFs) non-zero. 172 */ 173 png_int_32 x_offset; /* x offset on page */ 174 png_int_32 y_offset; /* y offset on page */ 175 png_byte offset_unit_type; /* offset units type */ 176 #endif 177 178 #ifdef PNG_pHYs_SUPPORTED 179 /* The pHYs chunk gives the physical pixel density of the image for 180 * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_ 181 * defines below). Data is valid if (valid & PNG_INFO_pHYs) is non-zero. 182 */ 183 png_uint_32 x_pixels_per_unit; /* horizontal pixel density */ 184 png_uint_32 y_pixels_per_unit; /* vertical pixel density */ 185 png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */ 186 #endif 187 188 #ifdef PNG_hIST_SUPPORTED 189 /* The hIST chunk contains the relative frequency or importance of the 190 * various palette entries, so that a viewer can intelligently select a 191 * reduced-color palette, if required. Data is an array of "num_palette" 192 * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST) 193 * is non-zero. 194 */ 195 png_uint_16p hist; 196 #endif 197 198 #ifdef PNG_pCAL_SUPPORTED 199 /* The pCAL chunk describes a transformation between the stored pixel 200 * values and original physical data values used to create the image. 201 * The integer range [0, 2^bit_depth - 1] maps to the floating-point 202 * range given by [pcal_X0, pcal_X1], and are further transformed by a 203 * (possibly non-linear) transformation function given by "pcal_type" 204 * and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_ 205 * defines below, and the PNG-Group's PNG extensions document for a 206 * complete description of the transformations and how they should be 207 * implemented, and for a description of the ASCII parameter strings. 208 * Data values are valid if (valid & PNG_INFO_pCAL) non-zero. 209 */ 210 png_charp pcal_purpose; /* pCAL chunk description string */ 211 png_int_32 pcal_X0; /* minimum value */ 212 png_int_32 pcal_X1; /* maximum value */ 213 png_charp pcal_units; /* Latin-1 string giving physical units */ 214 png_charpp pcal_params; /* ASCII strings containing parameter values */ 215 png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */ 216 png_byte pcal_nparams; /* number of parameters given in pcal_params */ 217 #endif 218 219 /* New members added in libpng-1.0.6 */ 220 png_uint_32 free_me; /* flags items libpng is responsible for freeing */ 221 222 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED 223 /* Storage for unknown chunks that the library doesn't recognize. */ 224 png_unknown_chunkp unknown_chunks; 225 226 /* The type of this field is limited by the type of 227 * png_struct::user_chunk_cache_max, else overflow can occur. 228 */ 229 int unknown_chunks_num; 230 #endif 231 232 #ifdef PNG_sPLT_SUPPORTED 233 /* Data on sPLT chunks (there may be more than one). */ 234 png_sPLT_tp splt_palettes; 235 int splt_palettes_num; /* Match type returned by png_get API */ 236 #endif 237 238 #ifdef PNG_sCAL_SUPPORTED 239 /* The sCAL chunk describes the actual physical dimensions of the 240 * subject matter of the graphic. The chunk contains a unit specification 241 * a byte value, and two ASCII strings representing floating-point 242 * values. The values are width and height corresponsing to one pixel 243 * in the image. Data values are valid if (valid & PNG_INFO_sCAL) is 244 * non-zero. 245 */ 246 png_byte scal_unit; /* unit of physical scale */ 247 png_charp scal_s_width; /* string containing height */ 248 png_charp scal_s_height; /* string containing width */ 249 #endif 250 251 #ifdef PNG_INFO_IMAGE_SUPPORTED 252 /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) 253 non-zero */ 254 /* Data valid if (valid & PNG_INFO_IDAT) non-zero */ 255 png_bytepp row_pointers; /* the image bits */ 256 #endif 257 258 }; 259 #endif /* PNGINFO_H */ 260
