pngcrush  1.8.13
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pnginfo.h
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1 
2 /* pnginfo.h - header file for PNG reference library
3  *
4  * Last changed in libpng 1.6.1 [March 28, 2013]
5  * Copyright (c) 1998-2002,2004,2006-2013 Glenn Randers-Pehrson
6  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
7  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
8  *
9  * This code is released under the libpng license.
10  * For conditions of distribution and use, see the disclaimer
11  * and license in png.h
12  */
13 
14  /* png_info is a structure that holds the information in a PNG file so
15  * that the application can find out the characteristics of the image.
16  * If you are reading the file, this structure will tell you what is
17  * in the PNG file. If you are writing the file, fill in the information
18  * you want to put into the PNG file, using png_set_*() functions, then
19  * call png_write_info().
20  *
21  * The names chosen should be very close to the PNG specification, so
22  * consult that document for information about the meaning of each field.
23  *
24  * With libpng < 0.95, it was only possible to directly set and read the
25  * the values in the png_info_struct, which meant that the contents and
26  * order of the values had to remain fixed. With libpng 0.95 and later,
27  * however, there are now functions that abstract the contents of
28  * png_info_struct from the application, so this makes it easier to use
29  * libpng with dynamic libraries, and even makes it possible to use
30  * libraries that don't have all of the libpng ancillary chunk-handing
31  * functionality. In libpng-1.5.0 this was moved into a separate private
32  * file that is not visible to applications.
33  *
34  * The following members may have allocated storage attached that should be
35  * cleaned up before the structure is discarded: palette, trans, text,
36  * pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
37  * splt_palettes, scal_unit, row_pointers, and unknowns. By default, these
38  * are automatically freed when the info structure is deallocated, if they were
39  * allocated internally by libpng. This behavior can be changed by means
40  * of the png_data_freer() function.
41  *
42  * More allocation details: all the chunk-reading functions that
43  * change these members go through the corresponding png_set_*
44  * functions. A function to clear these members is available: see
45  * png_free_data(). The png_set_* functions do not depend on being
46  * able to point info structure members to any of the storage they are
47  * passed (they make their own copies), EXCEPT that the png_set_text
48  * functions use the same storage passed to them in the text_ptr or
49  * itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
50  * functions do not make their own copies.
51  */
52 #ifndef PNGINFO_H
53 #define PNGINFO_H
54 
56 {
57  /* The following are necessary for every PNG file */
58  png_uint_32 width; /* width of image in pixels (from IHDR) */
59  png_uint_32 height; /* height of image in pixels (from IHDR) */
60  png_uint_32 valid; /* valid chunk data (see PNG_INFO_ below) */
61  png_size_t rowbytes; /* bytes needed to hold an untransformed row */
62  png_colorp palette; /* array of color values (valid & PNG_INFO_PLTE) */
63  png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */
64  png_uint_16 num_trans; /* number of transparent palette color (tRNS) */
65  png_byte bit_depth; /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */
66  png_byte color_type; /* see PNG_COLOR_TYPE_ below (from IHDR) */
67  /* The following three should have been named *_method not *_type */
68  png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */
69  png_byte filter_type; /* must be PNG_FILTER_TYPE_BASE (from IHDR) */
70  png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
71 
72  /* The following are set by png_set_IHDR, called from the application on
73  * write, but the are never actually used by the write code.
74  */
75  png_byte channels; /* number of data channels per pixel (1, 2, 3, 4) */
76  png_byte pixel_depth; /* number of bits per pixel */
77  png_byte spare_byte; /* to align the data, and for future use */
78 
79 #ifdef PNG_READ_SUPPORTED
80  /* This is never set during write */
81  png_byte signature[8]; /* magic bytes read by libpng from start of file */
82 #endif
83 
84  /* The rest of the data is optional. If you are reading, check the
85  * valid field to see if the information in these are valid. If you
86  * are writing, set the valid field to those chunks you want written,
87  * and initialize the appropriate fields below.
88  */
89 
90 #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED)
91  /* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are
92  * defined. When COLORSPACE is switched on all the colorspace-defining
93  * chunks should be enabled, when GAMMA is switched on all the gamma-defining
94  * chunks should be enabled. If this is not done it becomes possible to read
95  * inconsistent PNG files and assign a probably incorrect interpretation to
96  * the information. (In other words, by carefully choosing which chunks to
97  * recognize the system configuration can select an interpretation for PNG
98  * files containing ambiguous data and this will result in inconsistent
99  * behavior between different libpng builds!)
100  */
101  png_colorspace colorspace;
102 #endif
103 
104 #ifdef PNG_iCCP_SUPPORTED
105  /* iCCP chunk data. */
106  png_charp iccp_name; /* profile name */
107  png_bytep iccp_profile; /* International Color Consortium profile data */
108  png_uint_32 iccp_proflen; /* ICC profile data length */
109 #endif
110 
111 #ifdef PNG_TEXT_SUPPORTED
112  /* The tEXt, and zTXt chunks contain human-readable textual data in
113  * uncompressed, compressed, and optionally compressed forms, respectively.
114  * The data in "text" is an array of pointers to uncompressed,
115  * null-terminated C strings. Each chunk has a keyword that describes the
116  * textual data contained in that chunk. Keywords are not required to be
117  * unique, and the text string may be empty. Any number of text chunks may
118  * be in an image.
119  */
120  int num_text; /* number of comments read or comments to write */
121  int max_text; /* current size of text array */
122  png_textp text; /* array of comments read or comments to write */
123 #endif /* TEXT */
124 
125 #ifdef PNG_tIME_SUPPORTED
126  /* The tIME chunk holds the last time the displayed image data was
127  * modified. See the png_time struct for the contents of this struct.
128  */
129  png_time mod_time;
130 #endif
131 
132 #ifdef PNG_sBIT_SUPPORTED
133  /* The sBIT chunk specifies the number of significant high-order bits
134  * in the pixel data. Values are in the range [1, bit_depth], and are
135  * only specified for the channels in the pixel data. The contents of
136  * the low-order bits is not specified. Data is valid if
137  * (valid & PNG_INFO_sBIT) is non-zero.
138  */
139  png_color_8 sig_bit; /* significant bits in color channels */
140 #endif
141 
142 #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \
143 defined(PNG_READ_BACKGROUND_SUPPORTED)
144  /* The tRNS chunk supplies transparency data for paletted images and
145  * other image types that don't need a full alpha channel. There are
146  * "num_trans" transparency values for a paletted image, stored in the
147  * same order as the palette colors, starting from index 0. Values
148  * for the data are in the range [0, 255], ranging from fully transparent
149  * to fully opaque, respectively. For non-paletted images, there is a
150  * single color specified that should be treated as fully transparent.
151  * Data is valid if (valid & PNG_INFO_tRNS) is non-zero.
152  */
153  png_bytep trans_alpha; /* alpha values for paletted image */
154  png_color_16 trans_color; /* transparent color for non-palette image */
155 #endif
156 
157 #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
158  /* The bKGD chunk gives the suggested image background color if the
159  * display program does not have its own background color and the image
160  * is needs to composited onto a background before display. The colors
161  * in "background" are normally in the same color space/depth as the
162  * pixel data. Data is valid if (valid & PNG_INFO_bKGD) is non-zero.
163  */
164  png_color_16 background;
165 #endif
166 
167 #ifdef PNG_oFFs_SUPPORTED
168  /* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
169  * and downwards from the top-left corner of the display, page, or other
170  * application-specific co-ordinate space. See the PNG_OFFSET_ defines
171  * below for the unit types. Valid if (valid & PNG_INFO_oFFs) non-zero.
172  */
173  png_int_32 x_offset; /* x offset on page */
174  png_int_32 y_offset; /* y offset on page */
175  png_byte offset_unit_type; /* offset units type */
176 #endif
177 
178 #ifdef PNG_pHYs_SUPPORTED
179  /* The pHYs chunk gives the physical pixel density of the image for
180  * display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
181  * defines below). Data is valid if (valid & PNG_INFO_pHYs) is non-zero.
182  */
183  png_uint_32 x_pixels_per_unit; /* horizontal pixel density */
184  png_uint_32 y_pixels_per_unit; /* vertical pixel density */
185  png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */
186 #endif
187 
188 #ifdef PNG_eXIf_SUPPORTED
189  int num_exif; /* Added at libpng-1.6.31 */
190  png_bytep exif;
191 # ifdef PNG_READ_eXIf_SUPPORTED
192  png_bytep eXIf_buf; /* Added at libpng-1.6.32 */
193 # endif
194 #endif
195 
196 #ifdef PNG_hIST_SUPPORTED
197  /* The hIST chunk contains the relative frequency or importance of the
198  * various palette entries, so that a viewer can intelligently select a
199  * reduced-color palette, if required. Data is an array of "num_palette"
200  * values in the range [0,65535]. Data valid if (valid & PNG_INFO_hIST)
201  * is non-zero.
202  */
203  png_uint_16p hist;
204 #endif
205 
206 #ifdef PNG_pCAL_SUPPORTED
207  /* The pCAL chunk describes a transformation between the stored pixel
208  * values and original physical data values used to create the image.
209  * The integer range [0, 2^bit_depth - 1] maps to the floating-point
210  * range given by [pcal_X0, pcal_X1], and are further transformed by a
211  * (possibly non-linear) transformation function given by "pcal_type"
212  * and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_
213  * defines below, and the PNG-Group's PNG extensions document for a
214  * complete description of the transformations and how they should be
215  * implemented, and for a description of the ASCII parameter strings.
216  * Data values are valid if (valid & PNG_INFO_pCAL) non-zero.
217  */
218  png_charp pcal_purpose; /* pCAL chunk description string */
219  png_int_32 pcal_X0; /* minimum value */
220  png_int_32 pcal_X1; /* maximum value */
221  png_charp pcal_units; /* Latin-1 string giving physical units */
222  png_charpp pcal_params; /* ASCII strings containing parameter values */
223  png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */
224  png_byte pcal_nparams; /* number of parameters given in pcal_params */
225 #endif
226 
227 /* New members added in libpng-1.0.6 */
228  png_uint_32 free_me; /* flags items libpng is responsible for freeing */
229 
230 #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
231  /* Storage for unknown chunks that the library doesn't recognize. */
232  png_unknown_chunkp unknown_chunks;
233 
234  /* The type of this field is limited by the type of
235  * png_struct::user_chunk_cache_max, else overflow can occur.
236  */
237  int unknown_chunks_num;
238 #endif
239 
240 #ifdef PNG_sPLT_SUPPORTED
241  /* Data on sPLT chunks (there may be more than one). */
242  png_sPLT_tp splt_palettes;
243  int splt_palettes_num; /* Match type returned by png_get API */
244 #endif
245 
246 #ifdef PNG_sCAL_SUPPORTED
247  /* The sCAL chunk describes the actual physical dimensions of the
248  * subject matter of the graphic. The chunk contains a unit specification
249  * a byte value, and two ASCII strings representing floating-point
250  * values. The values are width and height corresponsing to one pixel
251  * in the image. Data values are valid if (valid & PNG_INFO_sCAL) is
252  * non-zero.
253  */
254  png_byte scal_unit; /* unit of physical scale */
255  png_charp scal_s_width; /* string containing height */
256  png_charp scal_s_height; /* string containing width */
257 #endif
258 
259 #ifdef PNG_INFO_IMAGE_SUPPORTED
260  /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS)
261  non-zero */
262  /* Data valid if (valid & PNG_INFO_IDAT) non-zero */
263  png_bytepp row_pointers; /* the image bits */
264 #endif
265 
266 };
267 #endif /* PNGINFO_H */
png_info_def::width
png_uint_32 width
Definition: pnginfo.h:58
png_info_def::spare_byte
png_byte spare_byte
Definition: pnginfo.h:77
png_info_def::height
png_uint_32 height
Definition: pnginfo.h:59
png_color_16_struct
Definition: png.h:519
png_charp
char * png_charp
Definition: pngconf.h:594
png_bytepp
png_byte ** png_bytepp
Definition: pngconf.h:611
png_sPLT_struct
Definition: png.h:564
png_info_def::color_type
png_byte color_type
Definition: pnginfo.h:66
png_bytep
png_byte * png_bytep
Definition: pngconf.h:584
png_info_def::palette
png_colorp palette
Definition: pnginfo.h:62
png_info_def::valid
png_uint_32 valid
Definition: pnginfo.h:60
png_text_struct
Definition: png.h:593
png_info_def::num_palette
png_uint_16 num_palette
Definition: pnginfo.h:63
png_info_def::bit_depth
png_byte bit_depth
Definition: pnginfo.h:65
png_info_def
Definition: pnginfo.h:55
png_info_def::rowbytes
png_size_t rowbytes
Definition: pnginfo.h:61
png_info_def::interlace_type
png_byte interlace_type
Definition: pnginfo.h:70
png_time_struct
Definition: png.h:631
png_info_def::num_trans
png_uint_16 num_trans
Definition: pnginfo.h:64
png_info_def::filter_type
png_byte filter_type
Definition: pnginfo.h:69
png_color_8_struct
Definition: png.h:531
png_color_struct
Definition: png.h:509
png_info_def::compression_type
png_byte compression_type
Definition: pnginfo.h:68
png_charpp
char ** png_charpp
Definition: pngconf.h:617
png_info_def::free_me
png_uint_32 free_me
Definition: pnginfo.h:228
png_uint_16p
png_uint_16 * png_uint_16p
Definition: pngconf.h:590
png_info_def::channels
png_byte channels
Definition: pnginfo.h:75
png_size_t
size_t png_size_t
Definition: pngconf.h:527
png_info_def::pixel_depth
png_byte pixel_depth
Definition: pnginfo.h:76
png_unknown_chunk_t
Definition: png.h:653
iccp_name
char iccp_name[80]
Definition: pngcrush.c:2210