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pnginfo.h
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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 values for paletted image */
142 png_bytep trans_alpha; /* alpha values for paletted image */
143 png_color_16 trans_color; /* transparent color for non-palette image */
144 #endif
145
146 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
147 /* The bKGD chunk gives the suggested image background color if the
148 * display program does not have its own background color and the image
149 * is needs to composited onto a background before display. The colors
150 * in "background" are normally in the same color space/depth as the
151 * pixel data. Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
152 */
153 png_color_16 background;
154 #endif
155
156 #ifdef PNG_oFFs_SUPPORTED
157 /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
158 * and downwards from the top-left corner of the display, page, or other
159 * application-specific co-ordinate space. See the PNG_OFFSET_ defines
160 * below for the unit types. Valid if (valid & PNG_INFO_oFFs) non-zero.
161 */
162 png_int_32 x_offset; /* x offset on page */
163 png_int_32 y_offset; /* y offset on page */
164 png_byte offset_unit_type; /* offset units type */
165 #endif
166
167 #ifdef PNG_pHYs_SUPPORTED
168 /* The pHYs chunk gives the physical pixel density of the image for
169 * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
170 * defines below). Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
171 */
172 png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
173 png_uint_32 y_pixels_per_unit; /* vertical pixel density */
174 png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
175 #endif
176
177 #ifdef PNG_hIST_SUPPORTED
178 /* The hIST chunk contains the relative frequency or importance of the
179 * various palette entries, so that a viewer can intelligently select a
180 * reduced-color palette, if required. Data is an array of "num_palette"
181 * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
182 * is non-zero.
183 */
184 png_uint_16p hist;
185 #endif
186
187 #ifdef PNG_cHRM_SUPPORTED
188 /* The cHRM chunk describes the CIE color characteristics of the monitor
189 * on which the PNG was created. This data allows the viewer to do gamut
190 * mapping of the input image to ensure that the viewer sees the same
191 * colors in the image as the creator. Values are in the range
192 * [0.0, 0.8]. Data valid if (valid & PNG_INFO_cHRM) non-zero.
193 */
194 png_fixed_point x_white;
195 png_fixed_point y_white;
196 png_fixed_point x_red;
197 png_fixed_point y_red;
198 png_fixed_point x_green;
199 png_fixed_point y_green;
200 png_fixed_point x_blue;
201 png_fixed_point y_blue;
202 #endif
203
204 #ifdef PNG_pCAL_SUPPORTED
205 /* The pCAL chunk describes a transformation between the stored pixel
206 * values and original physical data values used to create the image.
207 * The integer range [0, 2^bit_depth - 1] maps to the floating-point
208 * range given by [pcal_X0, pcal_X1], and are further transformed by a
209 * (possibly non-linear) transformation function given by "pcal_type"
210 * and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_
211 * defines below, and the PNG-Group's PNG extensions document for a
212 * complete description of the transformations and how they should be
213 * implemented, and for a description of the ASCII parameter strings.
214 * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
215 */
216 png_charp pcal_purpose; /* pCAL chunk description string */
217 png_int_32 pcal_X0; /* minimum value */
218 png_int_32 pcal_X1; /* maximum value */
219 png_charp pcal_units; /* Latin-1 string giving physical units */
220 png_charpp pcal_params; /* ASCII strings containing parameter values */
221 png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */
222 png_byte pcal_nparams; /* number of parameters given in pcal_params */
223 #endif
224
225 /* New members added in libpng-1.0.6 */
226 png_uint_32 free_me; /* flags items libpng is responsible for freeing */
227
228 #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \
229 defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED)
230 /* Storage for unknown chunks that the library doesn't recognize. */
231 png_unknown_chunkp unknown_chunks;
232 int unknown_chunks_num;
233 #endif
234
235 #ifdef PNG_iCCP_SUPPORTED
236 /* iCCP chunk data. */
237 png_charp iccp_name; /* profile name */
238 png_bytep iccp_profile; /* International Color Consortium profile data */
239 png_uint_32 iccp_proflen; /* ICC profile data length */
240 png_byte iccp_compression; /* Always zero */
241 #endif
242
243 #ifdef PNG_sPLT_SUPPORTED
244 /* Data on sPLT chunks (there may be more than one). */
245 png_sPLT_tp splt_palettes;
246 png_uint_32 splt_palettes_num;
247 #endif
248
249 #ifdef PNG_sCAL_SUPPORTED
250 /* The sCAL chunk describes the actual physical dimensions of the
251 * subject matter of the graphic. The chunk contains a unit specification
252 * a byte value, and two ASCII strings representing floating-point
253 * values. The values are width and height corresponsing to one pixel
254 * in the image. Data values are valid if (valid & PNG_INFO_sCAL) is
255 * non-zero.
256 */
257 png_byte scal_unit; /* unit of physical scale */
258 png_charp scal_s_width; /* string containing height */
259 png_charp scal_s_height; /* string containing width */
260 #endif
261
262 #ifdef PNG_INFO_IMAGE_SUPPORTED
263 /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS)
264 non-zero */
265 /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
266 png_bytepp row_pointers; /* the image bits */
267 #endif
268
269 };
270 #endif /* PNGINFO_H */
png_info_def::filter_type
png_byte filter_type
Definition: pnginfo.h:70
png_info_def::rowbytes
png_size_t rowbytes
Definition: pnginfo.h:62
png_info_def::palette
png_colorp palette
Definition: pnginfo.h:63
png_info_def::interlace_type
png_byte interlace_type
Definition: pnginfo.h:71
png_charp
char FAR * png_charp
Definition: pngconf.h:572
png_int_32
long png_int_32
Definition: pngconf.h:481
png_textp
png_text FAR * png_textp
Definition: png.h:610
png_info_def
Definition: pnginfo.h:56
png_info_def::compression_type
png_byte compression_type
Definition: pnginfo.h:69
png_info_def::color_type
png_byte color_type
Definition: pnginfo.h:67
png_bytepp
png_byte FAR *FAR * png_bytepp
Definition: pngconf.h:589
png_uint_32
unsigned long png_uint_32
Definition: pngconf.h:480
png_info_def::channels
png_byte channels
Definition: pnginfo.h:74
png_info_def::height
png_uint_32 height
Definition: pnginfo.h:60
png_byte
unsigned char png_byte
Definition: pngconf.h:485
png_uint_16
unsigned short png_uint_16
Definition: pngconf.h:483
png_uint_16p
png_uint_16 FAR * png_uint_16p
Definition: pngconf.h:568
png_info_def::signature
png_byte signature[8]
Definition: pnginfo.h:77
png_info_def::spare_byte
png_byte spare_byte
Definition: pnginfo.h:76
png_info_def::num_palette
png_uint_16 num_palette
Definition: pnginfo.h:64
png_time_struct
Definition: png.h:631
png_color_8_struct
Definition: png.h:540
png_info_def::bit_depth
png_byte bit_depth
Definition: pnginfo.h:66
png_bytep
png_byte FAR * png_bytep
Definition: pngconf.h:562
png_info_def::pixel_depth
png_byte pixel_depth
Definition: pnginfo.h:75
png_sPLT_tp
png_sPLT_t FAR * png_sPLT_tp
Definition: png.h:580
png_info_def::valid
png_uint_32 valid
Definition: pnginfo.h:61
png_fixed_point
png_int_32 png_fixed_point
Definition: pngconf.h:557
png_charpp
char FAR *FAR * png_charpp
Definition: pngconf.h:595
png_size_t
size_t png_size_t
Definition: pngconf.h:490
png_info_def::width
png_uint_32 width
Definition: pnginfo.h:59
png_unknown_chunkp
png_unknown_chunk FAR * png_unknown_chunkp
Definition: png.h:661
png_info_def::free_me
png_uint_32 free_me
Definition: pnginfo.h:226
png_info_def::num_trans
png_uint_16 num_trans
Definition: pnginfo.h:65
png_color_16_struct
Definition: png.h:528
png_colorp
png_color FAR * png_colorp
Definition: png.h:524