| |
| /* pnginfo.h - header file for PNG reference library |
| * |
| * Copyright (c) 2018 Cosmin Truta |
| * Copyright (c) 1998-2002,2004,2006-2013,2018 Glenn Randers-Pehrson |
| * Copyright (c) 1996-1997 Andreas Dilger |
| * Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc. |
| * |
| * 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. |
| */ |
| #ifndef PNGINFO_H |
| #define PNGINFO_H |
| |
| 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) */ |
| 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 */ |
| |
| #ifdef PNG_READ_SUPPORTED |
| /* This is never set during write */ |
| png_byte signature[8]; /* magic bytes read by libpng from start of file */ |
| #endif |
| |
| /* 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. |
| */ |
| |
| #if defined(PNG_COLORSPACE_SUPPORTED) || defined(PNG_GAMMA_SUPPORTED) |
| /* 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; |
| #endif |
| |
| #ifdef PNG_iCCP_SUPPORTED |
| /* 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 */ |
| #endif |
| |
| #ifdef PNG_TEXT_SUPPORTED |
| /* 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 */ |
| #endif /* TEXT */ |
| |
| #ifdef PNG_tIME_SUPPORTED |
| /* 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; |
| #endif |
| |
| #ifdef PNG_sBIT_SUPPORTED |
| /* 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 */ |
| #endif |
| |
| #if defined(PNG_tRNS_SUPPORTED) || defined(PNG_READ_EXPAND_SUPPORTED) || \ |
| defined(PNG_READ_BACKGROUND_SUPPORTED) |
| /* 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 */ |
| #endif |
| |
| #if defined(PNG_bKGD_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED) |
| /* 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; |
| #endif |
| |
| #ifdef PNG_oFFs_SUPPORTED |
| /* 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 */ |
| #endif |
| |
| #ifdef PNG_pHYs_SUPPORTED |
| /* 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) */ |
| #endif |
| |
| #ifdef PNG_eXIf_SUPPORTED |
| int num_exif; /* Added at libpng-1.6.31 */ |
| png_bytep exif; |
| # ifdef PNG_READ_eXIf_SUPPORTED |
| png_bytep eXIf_buf; /* Added at libpng-1.6.32 */ |
| # endif |
| #endif |
| |
| #ifdef PNG_hIST_SUPPORTED |
| /* 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; |
| #endif |
| |
| #ifdef PNG_pCAL_SUPPORTED |
| /* 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 */ |
| #endif |
| |
| /* New members added in libpng-1.0.6 */ |
| png_uint_32 free_me; /* flags items libpng is responsible for freeing */ |
| |
| #ifdef PNG_STORE_UNKNOWN_CHUNKS_SUPPORTED |
| /* 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; |
| #endif |
| |
| #ifdef PNG_sPLT_SUPPORTED |
| /* 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 */ |
| #endif |
| |
| #ifdef PNG_sCAL_SUPPORTED |
| /* 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 corresponding 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 */ |
| #endif |
| |
| #ifdef PNG_INFO_IMAGE_SUPPORTED |
| /* 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 */ |
| #endif |
| |
| }; |
| #endif /* PNGINFO_H */ |
