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| 1 | |
| 2 /* pnginfo.h - header file for PNG reference library | |
| 3 * | |
| 4 * Copyright (c) 1998-2013 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 1.6.1 [March 28, 2013] | |
| 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 are set by png_set_IHDR, called from the application on | |
| 74 * write, but the are never actually used by the write code. | |
| 75 */ | |
| 76 png_byte channels; /* number of data channels per pixel (1, 2, 3, 4) */ | |
| 77 png_byte pixel_depth; /* number of bits per pixel */ | |
| 78 png_byte spare_byte; /* to align the data, and for future use */ | |
| 79 | |
| 80 #ifdef PNG_READ_SUPPORTED | |
| 81 /* This is never set during write */ | |
| 82 png_byte signature[8]; /* magic bytes read by libpng from start of file */ | |
| 83 #endif | |
| 84 | |
| 85 /* The rest of the data is optional. If you are reading, check the | |
| 86 * valid field to see if the information in these are valid. If you | |
| 87 * are writing, set the valid field to those chunks you want written, | |
| 88 * and initialize the appropriate fields below. | |
| 89 */ | |
| 90 | |
| 91 #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED) | |
| 92 /* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are | |
| 93 * defined. When COLORSPACE is switched on all the colorspace-defining | |
| 94 * chunks should be enabled, when GAMMA is switched on all the gamma-defining | |
| 95 * chunks should be enabled. If this is not done it becomes possible to read | |
| 96 * inconsistent PNG files and assign a probably incorrect interpretation to | |
| 97 * the information. (In other words, by carefully choosing which chunks to | |
| 98 * recognize the system configuration can select an interpretation for PNG | |
| 99 * files containing ambiguous data and this will result in inconsistent | |
| 100 * behavior between different libpng builds!) | |
| 101 */ | |
| 102 png_colorspace colorspace; | |
| 103 #endif | |
| 104 | |
| 105 #ifdef PNG_iCCP_SUPPORTED | |
| 106 /* iCCP chunk data. */ | |
| 107 png_charp iccp_name; /* profile name */ | |
| 108 png_bytep iccp_profile; /* International Color Consortium profile data */ | |
| 109 png_uint_32 iccp_proflen; /* ICC profile data length */ | |
| 110 #endif | |
| 111 | |
| 112 #ifdef PNG_TEXT_SUPPORTED | |
| 113 /* The tEXt, and zTXt chunks contain human-readable textual data in | |
| 114 * uncompressed, compressed, and optionally compressed forms, respectively. | |
| 115 * The data in "text" is an array of pointers to uncompressed, | |
| 116 * null-terminated C strings. Each chunk has a keyword that describes the | |
| 117 * textual data contained in that chunk. Keywords are not required to be | |
| 118 * unique, and the text string may be empty. Any number of text chunks may | |
| 119 * be in an image. | |
| 120 */ | |
| 121 int num_text; /* number of comments read or comments to write */ | |
| 122 int max_text; /* current size of text array */ | |
| 123 png_textp text; /* array of comments read or comments to write */ | |
| 124 #endif /* PNG_TEXT_SUPPORTED */ | |
| 125 | |
| 126 #ifdef PNG_tIME_SUPPORTED | |
| 127 /* The tIME chunk holds the last time the displayed image data was | |
| 128 * modified. See the png_time struct for the contents of this struct. | |
| 129 */ | |
| 130 png_time mod_time; | |
| 131 #endif | |
| 132 | |
| 133 #ifdef PNG_sBIT_SUPPORTED | |
| 134 /* The sBIT chunk specifies the number of significant high-order bits | |
| 135 * in the pixel data. Values are in the range [1, bit_depth], and are | |
| 136 * only specified for the channels in the pixel data. The contents of | |
| 137 * the low-order bits is not specified. Data is valid if | |
| 138 * (valid & PNG_INFO_sBIT) is non-zero. | |
| 139 */ | |
| 140 png_color_8 sig_bit; /* significant bits in color channels */ | |
| 141 #endif | |
| 142 | |
| 143 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \ | |
| 144 defined(PNG_READ_BACKGROUND_SUPPORTED) | |
| 145 /* The tRNS chunk supplies transparency data for paletted images and | |
| 146 * other image types that don't need a full alpha channel. There are | |
| 147 * "num_trans" transparency values for a paletted image, stored in the | |
| 148 * same order as the palette colors, starting from index 0. Values | |
| 149 * for the data are in the range [0, 255], ranging from fully transparent | |
| 150 * to fully opaque, respectively. For non-paletted images, there is a | |
| 151 * single color specified that should be treated as fully transparent. | |
| 152 * Data is valid if (valid & PNG_INFO_tRNS) is non-zero. | |
| 153 */ | |
| 154 png_bytep trans_alpha; /* alpha values for paletted image */ | |
| 155 png_color_16 trans_color; /* transparent color for non-palette image */ | |
| 156 #endif | |
| 157 | |
| 158 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) | |
| 159 /* The bKGD chunk gives the suggested image background color if the | |
| 160 * display program does not have its own background color and the image | |
| 161 * is needs to composited onto a background before display. The colors | |
| 162 * in "background" are normally in the same color space/depth as the | |
| 163 * pixel data. Data is valid if (valid & PNG_INFO_bKGD) is non-zero. | |
| 164 */ | |
| 165 png_color_16 background; | |
| 166 #endif | |
| 167 | |
| 168 #ifdef PNG_oFFs_SUPPORTED | |
| 169 /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards | |
| 170 * and downwards from the top-left corner of the display, page, or other | |
| 171 * application-specific co-ordinate space. See the PNG_OFFSET_ defines | |
| 172 * below for the unit types. Valid if (valid & PNG_INFO_oFFs) non-zero. | |
| 173 */ | |
| 174 png_int_32 x_offset; /* x offset on page */ | |
| 175 png_int_32 y_offset; /* y offset on page */ | |
| 176 png_byte offset_unit_type; /* offset units type */ | |
| 177 #endif | |
| 178 | |
| 179 #ifdef PNG_pHYs_SUPPORTED | |
| 180 /* The pHYs chunk gives the physical pixel density of the image for | |
| 181 * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_ | |
| 182 * defines below). Data is valid if (valid & PNG_INFO_pHYs) is non-zero. | |
| 183 */ | |
| 184 png_uint_32 x_pixels_per_unit; /* horizontal pixel density */ | |
| 185 png_uint_32 y_pixels_per_unit; /* vertical pixel density */ | |
| 186 png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */ | |
| 187 #endif | |
| 188 | |
| 189 #ifdef PNG_hIST_SUPPORTED | |
| 190 /* The hIST chunk contains the relative frequency or importance of the | |
| 191 * various palette entries, so that a viewer can intelligently select a | |
| 192 * reduced-color palette, if required. Data is an array of "num_palette" | |
| 193 * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST) | |
| 194 * is non-zero. | |
| 195 */ | |
| 196 png_uint_16p hist; | |
| 197 #endif | |
| 198 | |
| 199 #ifdef PNG_pCAL_SUPPORTED | |
| 200 /* The pCAL chunk describes a transformation between the stored pixel | |
| 201 * values and original physical data values used to create the image. | |
| 202 * The integer range [0, 2^bit_depth - 1] maps to the floating-point | |
| 203 * range given by [pcal_X0, pcal_X1], and are further transformed by a | |
| 204 * (possibly non-linear) transformation function given by "pcal_type" | |
| 205 * and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_ | |
| 206 * defines below, and the PNG-Group's PNG extensions document for a | |
| 207 * complete description of the transformations and how they should be | |
| 208 * implemented, and for a description of the ASCII parameter strings. | |
| 209 * Data values are valid if (valid & PNG_INFO_pCAL) non-zero. | |
| 210 */ | |
| 211 png_charp pcal_purpose; /* pCAL chunk description string */ | |
| 212 png_int_32 pcal_X0; /* minimum value */ | |
| 213 png_int_32 pcal_X1; /* maximum value */ | |
| 214 png_charp pcal_units; /* Latin-1 string giving physical units */ | |
| 215 png_charpp pcal_params; /* ASCII strings containing parameter values */ | |
| 216 png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */ | |
| 217 png_byte pcal_nparams; /* number of parameters given in pcal_params */ | |
| 218 #endif | |
| 219 | |
| 220 /* New members added in libpng-1.0.6 */ | |
| 221 png_uint_32 free_me; /* flags items libpng is responsible for freeing */ | |
| 222 | |
| 223 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED | |
| 224 /* Storage for unknown chunks that the library doesn't recognize. */ | |
| 225 png_unknown_chunkp unknown_chunks; | |
| 226 | |
| 227 /* The type of this field is limited by the type of | |
| 228 * png_struct::user_chunk_cache_max, else overflow can occur. | |
| 229 */ | |
| 230 int unknown_chunks_num; | |
| 231 #endif | |
| 232 | |
| 233 #ifdef PNG_sPLT_SUPPORTED | |
| 234 /* Data on sPLT chunks (there may be more than one). */ | |
| 235 png_sPLT_tp splt_palettes; | |
| 236 int splt_palettes_num; /* Match type returned by png_get API */ | |
| 237 #endif | |
| 238 | |
| 239 #ifdef PNG_sCAL_SUPPORTED | |
| 240 /* The sCAL chunk describes the actual physical dimensions of the | |
| 241 * subject matter of the graphic. The chunk contains a unit specification | |
| 242 * a byte value, and two ASCII strings representing floating-point | |
| 243 * values. The values are width and height corresponsing to one pixel | |
| 244 * in the image. Data values are valid if (valid & PNG_INFO_sCAL) is | |
| 245 * non-zero. | |
| 246 */ | |
| 247 png_byte scal_unit; /* unit of physical scale */ | |
| 248 png_charp scal_s_width; /* string containing height */ | |
| 249 png_charp scal_s_height; /* string containing width */ | |
| 250 #endif | |
| 251 | |
| 252 #ifdef PNG_INFO_IMAGE_SUPPORTED | |
| 253 /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) | |
| 254 non-zero */ | |
| 255 /* Data valid if (valid & PNG_INFO_IDAT) non-zero */ | |
| 256 png_bytepp row_pointers; /* the image bits */ | |
| 257 #endif | |
| 258 | |
| 259 }; | |
| 260 #endif /* PNGINFO_H */ | |
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