| /* 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 | |
| */ | |
| /* 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 < 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. | |
| */ | |
| struct png_info_def | |
| { | |
| /* The following are necessary for every PNG file */ | |
| png_uint_32 width; /* width of image in pixels (from IHDR) */ | |
| png_uint_32 height; /* height of image in pixels (from IHDR) */ | |
| png_uint_32 valid; /* valid chunk data (see PNG_INFO_ below) */ | |
| png_size_t rowbytes; /* bytes needed to hold an untransformed row */ | |
| png_colorp palette; /* array of color values (valid & PNG_INFO_PLTE) */ | |
| png_uint_16 num_palette; /* number of color entries in "palette" (PLTE) */ | |
| png_uint_16 num_trans; /* number of transparent palette color (tRNS) */ | |
| png_byte bit_depth; /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */ | |
| png_byte color_type; /* see PNG_COLOR_TYPE_ below (from IHDR) */ | |
| /* The following three should have been named *_method not *_type */ | |
| png_byte compression_type; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */ | |
| png_byte filter_type; /* must be PNG_FILTER_TYPE_BASE (from IHDR) */ | |
| png_byte interlace_type; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */ | |
| /* The following are set by png_set_IHDR, called from the application on | |
| * write, but the are never actually used by the write code. | |
| */ | |
| png_byte channels; /* number of data channels per pixel (1, 2, 3, 4) */ | |
| png_byte pixel_depth; /* number of bits per pixel */ | |
| png_byte spare_byte; /* to align the data, and for future use */ | |
| /* This is never set during write */ | |
| png_byte signature[8]; /* magic bytes read by libpng from start of file */ | |
| /* 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. | |
| */ | |
| /* 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!) | |
| */ | |
| png_colorspace colorspace; | |
| /* iCCP chunk data. */ | |
| png_charp iccp_name; /* profile name */ | |
| png_bytep iccp_profile; /* International Color Consortium profile data */ | |
| png_uint_32 iccp_proflen; /* ICC profile data length */ | |
| /* 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. | |
| */ | |
| int num_text; /* number of comments read or comments to write */ | |
| int max_text; /* current size of text array */ | |
| png_textp text; /* array of comments read or comments to write */ | |
| /* The tIME chunk holds the last time the displayed image data was | |
| * modified. See the png_time struct for the contents of this struct. | |
| */ | |
| png_time mod_time; | |
| /* 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 & PNG_INFO_sBIT) is non-zero. | |
| */ | |
| png_color_8 sig_bit; /* significant bits in color channels */ | |
| /* 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 & PNG_INFO_tRNS) is non-zero. | |
| */ | |
| png_bytep trans_alpha; /* alpha values for paletted image */ | |
| png_color_16 trans_color; /* transparent color for non-palette image */ | |
| /* 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 & PNG_INFO_bKGD) is non-zero. | |
| */ | |
| png_color_16 background; | |
| /* 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 & PNG_INFO_oFFs) non-zero. | |
| */ | |
| png_int_32 x_offset; /* x offset on page */ | |
| png_int_32 y_offset; /* y offset on page */ | |
| png_byte offset_unit_type; /* offset units type */ | |
| /* 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 & PNG_INFO_pHYs) is non-zero. | |
| */ | |
| png_uint_32 x_pixels_per_unit; /* horizontal pixel density */ | |
| png_uint_32 y_pixels_per_unit; /* vertical pixel density */ | |
| png_byte phys_unit_type; /* resolution type (see PNG_RESOLUTION_ below) */ | |
| /* 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 & PNG_INFO_hIST) | |
| * is non-zero. | |
| */ | |
| png_uint_16p hist; | |
| /* 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 & PNG_INFO_pCAL) non-zero. | |
| */ | |
| png_charp pcal_purpose; /* pCAL chunk description string */ | |
| png_int_32 pcal_X0; /* minimum value */ | |
| png_int_32 pcal_X1; /* maximum value */ | |
| png_charp pcal_units; /* Latin-1 string giving physical units */ | |
| png_charpp pcal_params; /* ASCII strings containing parameter values */ | |
| png_byte pcal_type; /* equation type (see PNG_EQUATION_ below) */ | |
| png_byte pcal_nparams; /* number of parameters given in pcal_params */ | |
| /* New members added in libpng-1.0.6 */ | |
| png_uint_32 free_me; /* flags items libpng is responsible for freeing */ | |
| /* Storage for unknown chunks that the library doesn't recognize. */ | |
| png_unknown_chunkp unknown_chunks; | |
| /* The type of this field is limited by the type of | |
| * png_struct::user_chunk_cache_max, else overflow can occur. | |
| */ | |
| int unknown_chunks_num; | |
| /* Data on sPLT chunks (there may be more than one). */ | |
| png_sPLT_tp splt_palettes; | |
| int splt_palettes_num; /* Match type returned by png_get API */ | |
| /* 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 & PNG_INFO_sCAL) is | |
| * non-zero. | |
| */ | |
| png_byte scal_unit; /* unit of physical scale */ | |
| png_charp scal_s_width; /* string containing height */ | |
| png_charp scal_s_height; /* string containing width */ | |
| /* Memory has been allocated if (valid & PNG_ALLOCATED_INFO_ROWS) | |
| non-zero */ | |
| /* Data valid if (valid & PNG_INFO_IDAT) non-zero */ | |
| png_bytepp row_pointers; /* the image bits */ | |
| }; | |