|
2296
|
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 */
|
