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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 */ |