1 2 /* pnginfo.h - header file for PNG reference library 3 * 4 * Copyright (c) 1998-2011 Glenn Randers-Pehrson 5 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) 6 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) 7 * 8 * Last changed in libpng 1.5.0 [January 6, 2011] 9 * 10 * This code is released under the libpng license. 11 * For conditions of distribution and use, see the disclaimer 12 * and license in png.h 13 */ 14 15 /* png_info is a structure that holds the information in a PNG file so 16 * that the application can find out the characteristics of the image. 17 * If you are reading the file, this structure will tell you what is 18 * in the PNG file. If you are writing the file, fill in the information 19 * you want to put into the PNG file, using png_set_*() functions, then 20 * call png_write_info(). 21 * 22 * The names chosen should be very close to the PNG specification, so 23 * consult that document for information about the meaning of each field. 24 * 25 * With libpng < 0.95, it was only possible to directly set and read the 26 * the values in the png_info_struct, which meant that the contents and 27 * order of the values had to remain fixed. With libpng 0.95 and later, 28 * however, there are now functions that abstract the contents of 29 * png_info_struct from the application, so this makes it easier to use 30 * libpng with dynamic libraries, and even makes it possible to use 31 * libraries that don't have all of the libpng ancillary chunk-handing 32 * functionality. In libpng-1.5.0 this was moved into a separate private 33 * file that is not visible to applications. 34 * 35 * The following members may have allocated storage attached that should be 36 * cleaned up before the structure is discarded: palette, trans, text, 37 * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile, 38 * splt_palettes, scal_unit, row_pointers, and unknowns. By default, these 39 * are automatically freed when the info structure is deallocated, if they were 40 * allocated internally by libpng. This behavior can be changed by means 41 * of the png_data_freer() function. 42 * 43 * More allocation details: all the chunk-reading functions that 44 * change these members go through the corresponding png_set_* 45 * functions. A function to clear these members is available: see 46 * png_free_data(). The png_set_* functions do not depend on being 47 * able to point info structure members to any of the storage they are 48 * passed (they make their own copies), EXCEPT that the png_set_text 49 * functions use the same storage passed to them in the text_ptr or 50 * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns 51 * functions do not make their own copies. 52 */ 53 #ifndef PNGINFO_H 54 #define PNGINFO_H 55 56 struct png_info_def 57 { 58 /* the following are necessary for every PNG file */ 59 png_uint_32 width; /* width of image in pixels (from IHDR) */ 60 png_uint_32 height; /* height of image in pixels (from IHDR) */ 61 png_uint_32 valid; /* valid chunk data (see PNG_INFO_ below) */ 62 png_size_t rowbytes; /* bytes needed to hold an untransformed row */ 63 png_colorp palette; /* array of color values (valid & PNG_INFO_PLTE) */ 64 png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */ 65 png_uint_16 num_trans; /* number of transparent palette color (tRNS) */ 66 png_byte bit_depth; /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */ 67 png_byte color_type; /* see PNG_COLOR_TYPE_ below (from IHDR) */ 68 /* The following three should have been named *_method not *_type */ 69 png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */ 70 png_byte filter_type; /* must be PNG_FILTER_TYPE_BASE (from IHDR) */ 71 png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */ 72 73 /* The following is informational only on read, and not used on writes. */ 74 png_byte channels; /* number of data channels per pixel (1, 2, 3, 4) */ 75 png_byte pixel_depth; /* number of bits per pixel */ 76 png_byte spare_byte; /* to align the data, and for future use */ 77 png_byte signature[8]; /* magic bytes read by libpng from start of file */ 78 79 /* The rest of the data is optional. If you are reading, check the 80 * valid field to see if the information in these are valid. If you 81 * are writing, set the valid field to those chunks you want written, 82 * and initialize the appropriate fields below. 83 */ 84 85 #if defined(PNG_gAMA_SUPPORTED) 86 /* The gAMA chunk describes the gamma characteristics of the system 87 * on which the image was created, normally in the range [1.0, 2.5]. 88 * Data is valid if (valid & PNG_INFO_gAMA) is non-zero. 89 */ 90 png_fixed_point gamma; 91 #endif 92 93 #ifdef PNG_sRGB_SUPPORTED 94 /* GR-P, 0.96a */ 95 /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */ 96 png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */ 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 /* PNG_TEXT_SUPPORTED */ 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_hIST_SUPPORTED 177 /* The hIST chunk contains the relative frequency or importance of the 178 * various palette entries, so that a viewer can intelligently select a 179 * reduced-color palette, if required. Data is an array of "num_palette" 180 * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST) 181 * is non-zero. 182 */ 183 png_uint_16p hist; 184 #endif 185 186 #ifdef PNG_cHRM_SUPPORTED 187 /* The cHRM chunk describes the CIE color characteristics of the monitor 188 * on which the PNG was created. This data allows the viewer to do gamut 189 * mapping of the input image to ensure that the viewer sees the same 190 * colors in the image as the creator. Values are in the range 191 * [0.0, 0.8]. Data valid if (valid & PNG_INFO_cHRM) non-zero. 192 */ 193 png_fixed_point x_white; 194 png_fixed_point y_white; 195 png_fixed_point x_red; 196 png_fixed_point y_red; 197 png_fixed_point x_green; 198 png_fixed_point y_green; 199 png_fixed_point x_blue; 200 png_fixed_point y_blue; 201 #endif 202 203 #ifdef PNG_pCAL_SUPPORTED 204 /* The pCAL chunk describes a transformation between the stored pixel 205 * values and original physical data values used to create the image. 206 * The integer range [0, 2^bit_depth - 1] maps to the floating-point 207 * range given by [pcal_X0, pcal_X1], and are further transformed by a 208 * (possibly non-linear) transformation function given by "pcal_type" 209 * and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_ 210 * defines below, and the PNG-Group's PNG extensions document for a 211 * complete description of the transformations and how they should be 212 * implemented, and for a description of the ASCII parameter strings. 213 * Data values are valid if (valid & PNG_INFO_pCAL) non-zero. 214 */ 215 png_charp pcal_purpose; /* pCAL chunk description string */ 216 png_int_32 pcal_X0; /* minimum value */ 217 png_int_32 pcal_X1; /* maximum value */ 218 png_charp pcal_units; /* Latin-1 string giving physical units */ 219 png_charpp pcal_params; /* ASCII strings containing parameter values */ 220 png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */ 221 png_byte pcal_nparams; /* number of parameters given in pcal_params */ 222 #endif 223 224 /* New members added in libpng-1.0.6 */ 225 png_uint_32 free_me; /* flags items libpng is responsible for freeing */ 226 227 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \ 228 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED) 229 /* Storage for unknown chunks that the library doesn't recognize. */ 230 png_unknown_chunkp unknown_chunks; 231 int unknown_chunks_num; 232 #endif 233 234 #ifdef PNG_iCCP_SUPPORTED 235 /* iCCP chunk data. */ 236 png_charp iccp_name; /* profile name */ 237 png_bytep iccp_profile; /* International Color Consortium profile data */ 238 png_uint_32 iccp_proflen; /* ICC profile data length */ 239 png_byte iccp_compression; /* Always zero */ 240 #endif 241 242 #ifdef PNG_sPLT_SUPPORTED 243 /* Data on sPLT chunks (there may be more than one). */ 244 png_sPLT_tp splt_palettes; 245 png_uint_32 splt_palettes_num; 246 #endif 247 248 #ifdef PNG_sCAL_SUPPORTED 249 /* The sCAL chunk describes the actual physical dimensions of the 250 * subject matter of the graphic. The chunk contains a unit specification 251 * a byte value, and two ASCII strings representing floating-point 252 * values. The values are width and height corresponsing to one pixel 253 * in the image. Data values are valid if (valid & PNG_INFO_sCAL) is 254 * non-zero. 255 */ 256 png_byte scal_unit; /* unit of physical scale */ 257 png_charp scal_s_width; /* string containing height */ 258 png_charp scal_s_height; /* string containing width */ 259 #endif 260 261 #ifdef PNG_INFO_IMAGE_SUPPORTED 262 /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) 263 non-zero */ 264 /* Data valid if (valid & PNG_INFO_IDAT) non-zero */ 265 png_bytepp row_pointers; /* the image bits */ 266 #endif 267 268 }; 269 #endif /* PNGINFO_H */ 270