AshanGimhana's picture
Upload folder using huggingface_hub
9375c9a verified
<html><!-- Created using the cpp_pretty_printer from the dlib C++ library. See http://dlib.net for updates. --><head><title>dlib C++ Library - pnginfo.h</title></head><body bgcolor='white'><pre>
<font color='#009900'>/* pnginfo.h - header file for PNG reference library
*
* Copyright (c) 1998-2013 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
*
* Last changed in libpng 1.6.1 [March 28, 2013]
*
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
*/</font>
<font color='#009900'>/* png_info is a structure that holds the information in a PNG file so
* that the application can find out the characteristics of the image.
* If you are reading the file, this structure will tell you what is
* in the PNG file. If you are writing the file, fill in the information
* you want to put into the PNG file, using png_set_*() functions, then
* call png_write_info().
*
* The names chosen should be very close to the PNG specification, so
* consult that document for information about the meaning of each field.
*
* With libpng &lt; 0.95, it was only possible to directly set and read the
* the values in the png_info_struct, which meant that the contents and
* order of the values had to remain fixed. With libpng 0.95 and later,
* however, there are now functions that abstract the contents of
* png_info_struct from the application, so this makes it easier to use
* libpng with dynamic libraries, and even makes it possible to use
* libraries that don't have all of the libpng ancillary chunk-handing
* functionality. In libpng-1.5.0 this was moved into a separate private
* file that is not visible to applications.
*
* The following members may have allocated storage attached that should be
* cleaned up before the structure is discarded: palette, trans, text,
* pcal_purpose, pcal_units, pcal_params, hist, iccp_name, iccp_profile,
* splt_palettes, scal_unit, row_pointers, and unknowns. By default, these
* are automatically freed when the info structure is deallocated, if they were
* allocated internally by libpng. This behavior can be changed by means
* of the png_data_freer() function.
*
* More allocation details: all the chunk-reading functions that
* change these members go through the corresponding png_set_*
* functions. A function to clear these members is available: see
* png_free_data(). The png_set_* functions do not depend on being
* able to point info structure members to any of the storage they are
* passed (they make their own copies), EXCEPT that the png_set_text
* functions use the same storage passed to them in the text_ptr or
* itxt_ptr structure argument, and the png_set_rows and png_set_unknowns
* functions do not make their own copies.
*/</font>
<font color='#0000FF'>#ifndef</font> PNGINFO_H
<font color='#0000FF'>#define</font> PNGINFO_H
<font color='#0000FF'>struct</font> <b><a name='png_info_def'></a>png_info_def</b>
<b>{</b>
<font color='#009900'>/* The following are necessary for every PNG file */</font>
png_uint_32 width; <font color='#009900'>/* width of image in pixels (from IHDR) */</font>
png_uint_32 height; <font color='#009900'>/* height of image in pixels (from IHDR) */</font>
png_uint_32 valid; <font color='#009900'>/* valid chunk data (see PNG_INFO_ below) */</font>
png_size_t rowbytes; <font color='#009900'>/* bytes needed to hold an untransformed row */</font>
png_colorp palette; <font color='#009900'>/* array of color values (valid &amp; PNG_INFO_PLTE) */</font>
png_uint_16 num_palette; <font color='#009900'>/* number of color entries in "palette" (PLTE) */</font>
png_uint_16 num_trans; <font color='#009900'>/* number of transparent palette color (tRNS) */</font>
png_byte bit_depth; <font color='#009900'>/* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */</font>
png_byte color_type; <font color='#009900'>/* see PNG_COLOR_TYPE_ below (from IHDR) */</font>
<font color='#009900'>/* The following three should have been named *_method not *_type */</font>
png_byte compression_type; <font color='#009900'>/* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */</font>
png_byte filter_type; <font color='#009900'>/* must be PNG_FILTER_TYPE_BASE (from IHDR) */</font>
png_byte interlace_type; <font color='#009900'>/* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */</font>
<font color='#009900'>/* The following are set by png_set_IHDR, called from the application on
* write, but the are never actually used by the write code.
*/</font>
png_byte channels; <font color='#009900'>/* number of data channels per pixel (1, 2, 3, 4) */</font>
png_byte pixel_depth; <font color='#009900'>/* number of bits per pixel */</font>
png_byte spare_byte; <font color='#009900'>/* to align the data, and for future use */</font>
<font color='#0000FF'>#ifdef</font> PNG_READ_SUPPORTED
<font color='#009900'>/* This is never set during write */</font>
png_byte signature[<font color='#979000'>8</font>]; <font color='#009900'>/* magic bytes read by libpng from start of file */</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* The rest of the data is optional. If you are reading, check the
* valid field to see if the information in these are valid. If you
* are writing, set the valid field to those chunks you want written,
* and initialize the appropriate fields below.
*/</font>
<font color='#0000FF'>#if</font> defined<font face='Lucida Console'>(</font>PNG_COLORSPACE_SUPPORTED<font face='Lucida Console'>)</font> <font color='#5555FF'>|</font><font color='#5555FF'>|</font> defined<font face='Lucida Console'>(</font>PNG_GAMMA_SUPPORTED<font face='Lucida Console'>)</font>
<font color='#009900'>/* png_colorspace only contains 'flags' if neither GAMMA or COLORSPACE are
* defined. When COLORSPACE is switched on all the colorspace-defining
* chunks should be enabled, when GAMMA is switched on all the gamma-defining
* chunks should be enabled. If this is not done it becomes possible to read
* inconsistent PNG files and assign a probably incorrect interpretation to
* the information. (In other words, by carefully choosing which chunks to
* recognize the system configuration can select an interpretation for PNG
* files containing ambiguous data and this will result in inconsistent
* behavior between different libpng builds!)
*/</font>
png_colorspace colorspace;
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_iCCP_SUPPORTED
<font color='#009900'>/* iCCP chunk data. */</font>
png_charp iccp_name; <font color='#009900'>/* profile name */</font>
png_bytep iccp_profile; <font color='#009900'>/* International Color Consortium profile data */</font>
png_uint_32 iccp_proflen; <font color='#009900'>/* ICC profile data length */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_TEXT_SUPPORTED
<font color='#009900'>/* The tEXt, and zTXt chunks contain human-readable textual data in
* uncompressed, compressed, and optionally compressed forms, respectively.
* The data in "text" is an array of pointers to uncompressed,
* null-terminated C strings. Each chunk has a keyword that describes the
* textual data contained in that chunk. Keywords are not required to be
* unique, and the text string may be empty. Any number of text chunks may
* be in an image.
*/</font>
<font color='#0000FF'><u>int</u></font> num_text; <font color='#009900'>/* number of comments read or comments to write */</font>
<font color='#0000FF'><u>int</u></font> max_text; <font color='#009900'>/* current size of text array */</font>
png_textp text; <font color='#009900'>/* array of comments read or comments to write */</font>
<font color='#0000FF'>#endif</font> <font color='#009900'>/* PNG_TEXT_SUPPORTED */</font>
<font color='#0000FF'>#ifdef</font> PNG_tIME_SUPPORTED
<font color='#009900'>/* The tIME chunk holds the last time the displayed image data was
* modified. See the png_time struct for the contents of this struct.
*/</font>
png_time mod_time;
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_sBIT_SUPPORTED
<font color='#009900'>/* The sBIT chunk specifies the number of significant high-order bits
* in the pixel data. Values are in the range [1, bit_depth], and are
* only specified for the channels in the pixel data. The contents of
* the low-order bits is not specified. Data is valid if
* (valid &amp; PNG_INFO_sBIT) is non-zero.
*/</font>
png_color_8 sig_bit; <font color='#009900'>/* significant bits in color channels */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#if</font> defined<font face='Lucida Console'>(</font>PNG_tRNS_SUPPORTED<font face='Lucida Console'>)</font> <font color='#5555FF'>|</font><font color='#5555FF'>|</font> defined<font face='Lucida Console'>(</font>PNG_READ_EXPAND_SUPPORTED<font face='Lucida Console'>)</font> <font color='#5555FF'>|</font><font color='#5555FF'>|</font> \
<b><a name='defined'></a>defined</b><font face='Lucida Console'>(</font>PNG_READ_BACKGROUND_SUPPORTED<font face='Lucida Console'>)</font>
<font color='#009900'>/* The tRNS chunk supplies transparency data for paletted images and
* other image types that don't need a full alpha channel. There are
* "num_trans" transparency values for a paletted image, stored in the
* same order as the palette colors, starting from index 0. Values
* for the data are in the range [0, 255], ranging from fully transparent
* to fully opaque, respectively. For non-paletted images, there is a
* single color specified that should be treated as fully transparent.
* Data is valid if (valid &amp; PNG_INFO_tRNS) is non-zero.
*/</font>
png_bytep trans_alpha; <font color='#009900'>/* alpha values for paletted image */</font>
png_color_16 trans_color; <font color='#009900'>/* transparent color for non-palette image */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#if</font> defined<font face='Lucida Console'>(</font>PNG_bKGD_SUPPORTED<font face='Lucida Console'>)</font> <font color='#5555FF'>|</font><font color='#5555FF'>|</font> defined<font face='Lucida Console'>(</font>PNG_READ_BACKGROUND_SUPPORTED<font face='Lucida Console'>)</font>
<font color='#009900'>/* The bKGD chunk gives the suggested image background color if the
* display program does not have its own background color and the image
* is needs to composited onto a background before display. The colors
* in "background" are normally in the same color space/depth as the
* pixel data. Data is valid if (valid &amp; PNG_INFO_bKGD) is non-zero.
*/</font>
png_color_16 background;
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_oFFs_SUPPORTED
<font color='#009900'>/* The oFFs chunk gives the offset in "offset_unit_type" units rightwards
* and downwards from the top-left corner of the display, page, or other
* application-specific co-ordinate space. See the PNG_OFFSET_ defines
* below for the unit types. Valid if (valid &amp; PNG_INFO_oFFs) non-zero.
*/</font>
png_int_32 x_offset; <font color='#009900'>/* x offset on page */</font>
png_int_32 y_offset; <font color='#009900'>/* y offset on page */</font>
png_byte offset_unit_type; <font color='#009900'>/* offset units type */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_pHYs_SUPPORTED
<font color='#009900'>/* The pHYs chunk gives the physical pixel density of the image for
* display or printing in "phys_unit_type" units (see PNG_RESOLUTION_
* defines below). Data is valid if (valid &amp; PNG_INFO_pHYs) is non-zero.
*/</font>
png_uint_32 x_pixels_per_unit; <font color='#009900'>/* horizontal pixel density */</font>
png_uint_32 y_pixels_per_unit; <font color='#009900'>/* vertical pixel density */</font>
png_byte phys_unit_type; <font color='#009900'>/* resolution type (see PNG_RESOLUTION_ below) */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_hIST_SUPPORTED
<font color='#009900'>/* The hIST chunk contains the relative frequency or importance of the
* various palette entries, so that a viewer can intelligently select a
* reduced-color palette, if required. Data is an array of "num_palette"
* values in the range [0,65535]. Data valid if (valid &amp; PNG_INFO_hIST)
* is non-zero.
*/</font>
png_uint_16p hist;
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_pCAL_SUPPORTED
<font color='#009900'>/* The pCAL chunk describes a transformation between the stored pixel
* values and original physical data values used to create the image.
* The integer range [0, 2^bit_depth - 1] maps to the floating-point
* range given by [pcal_X0, pcal_X1], and are further transformed by a
* (possibly non-linear) transformation function given by "pcal_type"
* and "pcal_params" into "pcal_units". Please see the PNG_EQUATION_
* defines below, and the PNG-Group's PNG extensions document for a
* complete description of the transformations and how they should be
* implemented, and for a description of the ASCII parameter strings.
* Data values are valid if (valid &amp; PNG_INFO_pCAL) non-zero.
*/</font>
png_charp pcal_purpose; <font color='#009900'>/* pCAL chunk description string */</font>
png_int_32 pcal_X0; <font color='#009900'>/* minimum value */</font>
png_int_32 pcal_X1; <font color='#009900'>/* maximum value */</font>
png_charp pcal_units; <font color='#009900'>/* Latin-1 string giving physical units */</font>
png_charpp pcal_params; <font color='#009900'>/* ASCII strings containing parameter values */</font>
png_byte pcal_type; <font color='#009900'>/* equation type (see PNG_EQUATION_ below) */</font>
png_byte pcal_nparams; <font color='#009900'>/* number of parameters given in pcal_params */</font>
<font color='#0000FF'>#endif</font>
<font color='#009900'>/* New members added in libpng-1.0.6 */</font>
png_uint_32 free_me; <font color='#009900'>/* flags items libpng is responsible for freeing */</font>
<font color='#0000FF'>#ifdef</font> PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED
<font color='#009900'>/* Storage for unknown chunks that the library doesn't recognize. */</font>
png_unknown_chunkp unknown_chunks;
<font color='#009900'>/* The type of this field is limited by the type of
* png_struct::user_chunk_cache_max, else overflow can occur.
*/</font>
<font color='#0000FF'><u>int</u></font> unknown_chunks_num;
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_sPLT_SUPPORTED
<font color='#009900'>/* Data on sPLT chunks (there may be more than one). */</font>
png_sPLT_tp splt_palettes;
<font color='#0000FF'><u>int</u></font> splt_palettes_num; <font color='#009900'>/* Match type returned by png_get API */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_sCAL_SUPPORTED
<font color='#009900'>/* The sCAL chunk describes the actual physical dimensions of the
* subject matter of the graphic. The chunk contains a unit specification
* a byte value, and two ASCII strings representing floating-point
* values. The values are width and height corresponsing to one pixel
* in the image. Data values are valid if (valid &amp; PNG_INFO_sCAL) is
* non-zero.
*/</font>
png_byte scal_unit; <font color='#009900'>/* unit of physical scale */</font>
png_charp scal_s_width; <font color='#009900'>/* string containing height */</font>
png_charp scal_s_height; <font color='#009900'>/* string containing width */</font>
<font color='#0000FF'>#endif</font>
<font color='#0000FF'>#ifdef</font> PNG_INFO_IMAGE_SUPPORTED
<font color='#009900'>/* Memory has been allocated if (valid &amp; PNG_ALLOCATED_INFO_ROWS)
non-zero */</font>
<font color='#009900'>/* Data valid if (valid &amp; PNG_INFO_IDAT) non-zero */</font>
png_bytepp row_pointers; <font color='#009900'>/* the image bits */</font>
<font color='#0000FF'>#endif</font>
<b>}</b>;
<font color='#0000FF'>#endif</font> <font color='#009900'>/* PNGINFO_H */</font>
</pre></body></html>