/* 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, 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 any case, the order of the parameters in png_info_struct should NOT * be changed for as long as possible to keep compatibility with applications * that use the old direct-access method with png_info_struct. * * 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. */ typedef struct png_info_struct { /* the following are necessary for every PNG file */ png_uint_32 width PNG_DEPSTRUCT; /* width of image in pixels (from IHDR) */ png_uint_32 height PNG_DEPSTRUCT; /* height of image in pixels (from IHDR) */ png_uint_32 valid PNG_DEPSTRUCT; /* valid chunk data (see PNG_INFO_ below) */ png_size_t rowbytes PNG_DEPSTRUCT; /* bytes needed to hold an untransformed row */ png_colorp palette PNG_DEPSTRUCT; /* array of color values (valid & PNG_INFO_PLTE) */ png_uint_16 num_palette PNG_DEPSTRUCT; /* number of color entries in "palette" (PLTE) */ png_uint_16 num_trans PNG_DEPSTRUCT; /* number of transparent palette color (tRNS) */ png_byte bit_depth PNG_DEPSTRUCT; /* 1, 2, 4, 8, or 16 bits/channel (from IHDR) */ png_byte color_type PNG_DEPSTRUCT; /* see PNG_COLOR_TYPE_ below (from IHDR) */ /* The following three should have been named *_method not *_type */ png_byte compression_type PNG_DEPSTRUCT; /* must be PNG_COMPRESSION_TYPE_BASE (IHDR) */ png_byte filter_type PNG_DEPSTRUCT; /* must be PNG_FILTER_TYPE_BASE (from IHDR) */ png_byte interlace_type PNG_DEPSTRUCT; /* One of PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */ /* The following is informational only on read, and not used on writes. */ png_byte channels PNG_DEPSTRUCT; /* number of data channels per pixel (1, 2, 3, 4) */ png_byte pixel_depth PNG_DEPSTRUCT; /* number of bits per pixel */ png_byte spare_byte PNG_DEPSTRUCT; /* to align the data, and for future use */ png_byte signature[8] PNG_DEPSTRUCT; /* 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. */ #if defined(PNG_gAMA_SUPPORTED) && defined(PNG_FLOATING_POINT_SUPPORTED) /* The gAMA chunk describes the gamma characteristics of the system * on which the image was created, normally in the range [1.0, 2.5]. * Data is valid if (valid & PNG_INFO_gAMA) is non-zero. */ float gamma PNG_DEPSTRUCT; /* gamma value of image, if (valid & PNG_INFO_gAMA) */ #endif #ifdef PNG_sRGB_SUPPORTED /* GR-P, 0.96a */ /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */ png_byte srgb_intent PNG_DEPSTRUCT; /* sRGB rendering intent [0, 1, 2, or 3] */ #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 PNG_DEPSTRUCT; /* number of comments read/to write */ int max_text PNG_DEPSTRUCT; /* current size of text array */ png_textp text PNG_DEPSTRUCT; /* array of comments read/to write */ #endif /* PNG_TEXT_SUPPORTED */ #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 PNG_DEPSTRUCT; #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 PNG_DEPSTRUCT; /* 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 PNG_DEPSTRUCT; /* alpha values for paletted image */ png_color_16 trans_color PNG_DEPSTRUCT; /* 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 PNG_DEPSTRUCT; #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 PNG_DEPSTRUCT; /* x offset on page */ png_int_32 y_offset PNG_DEPSTRUCT; /* y offset on page */ png_byte offset_unit_type PNG_DEPSTRUCT; /* 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 PNG_DEPSTRUCT; /* horizontal pixel density */ png_uint_32 y_pixels_per_unit PNG_DEPSTRUCT; /* vertical pixel density */ png_byte phys_unit_type PNG_DEPSTRUCT; /* resolution type (see PNG_RESOLUTION_ below) */ #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 PNG_DEPSTRUCT; #endif #ifdef PNG_cHRM_SUPPORTED /* The cHRM chunk describes the CIE color characteristics of the monitor * on which the PNG was created. This data allows the viewer to do gamut * mapping of the input image to ensure that the viewer sees the same * colors in the image as the creator. Values are in the range * [0.0, 0.8]. Data valid if (valid & PNG_INFO_cHRM) non-zero. */ #ifdef PNG_FLOATING_POINT_SUPPORTED float x_white PNG_DEPSTRUCT; float y_white PNG_DEPSTRUCT; float x_red PNG_DEPSTRUCT; float y_red PNG_DEPSTRUCT; float x_green PNG_DEPSTRUCT; float y_green PNG_DEPSTRUCT; float x_blue PNG_DEPSTRUCT; float y_blue PNG_DEPSTRUCT; #endif #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 PNG_DEPSTRUCT; /* pCAL chunk description string */ png_int_32 pcal_X0 PNG_DEPSTRUCT; /* minimum value */ png_int_32 pcal_X1 PNG_DEPSTRUCT; /* maximum value */ png_charp pcal_units PNG_DEPSTRUCT; /* Latin-1 string giving physical units */ png_charpp pcal_params PNG_DEPSTRUCT; /* ASCII strings containing parameter values */ png_byte pcal_type PNG_DEPSTRUCT; /* equation type (see PNG_EQUATION_ below) */ png_byte pcal_nparams PNG_DEPSTRUCT; /* number of parameters given in pcal_params */ #endif /* New members added in libpng-1.0.6 */ png_uint_32 free_me PNG_DEPSTRUCT; /* flags items libpng is responsible for freeing */ #if defined(PNG_UNKNOWN_CHUNKS_SUPPORTED) || \ defined(PNG_HANDLE_AS_UNKNOWN_SUPPORTED) /* Storage for unknown chunks that the library doesn't recognize. */ png_unknown_chunkp unknown_chunks PNG_DEPSTRUCT; png_size_t unknown_chunks_num PNG_DEPSTRUCT; #endif #ifdef PNG_iCCP_SUPPORTED /* iCCP chunk data. */ png_charp iccp_name PNG_DEPSTRUCT; /* profile name */ png_charp iccp_profile PNG_DEPSTRUCT; /* International Color Consortium profile data */ /* Note to maintainer: should be png_bytep */ png_uint_32 iccp_proflen PNG_DEPSTRUCT; /* ICC profile data length */ png_byte iccp_compression PNG_DEPSTRUCT; /* Always zero */ #endif #ifdef PNG_sPLT_SUPPORTED /* Data on sPLT chunks (there may be more than one). */ png_sPLT_tp splt_palettes PNG_DEPSTRUCT; png_uint_32 splt_palettes_num PNG_DEPSTRUCT; #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 corresponsing to one pixel * in the image. This external representation is converted to double * here. Data values are valid if (valid & PNG_INFO_sCAL) is non-zero. */ png_byte scal_unit PNG_DEPSTRUCT; /* unit of physical scale */ #ifdef PNG_FLOATING_POINT_SUPPORTED double scal_pixel_width PNG_DEPSTRUCT; /* width of one pixel */ double scal_pixel_height PNG_DEPSTRUCT; /* height of one pixel */ #endif #ifdef PNG_FIXED_POINT_SUPPORTED png_charp scal_s_width PNG_DEPSTRUCT; /* string containing height */ png_charp scal_s_height PNG_DEPSTRUCT; /* string containing width */ #endif #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 PNG_DEPSTRUCT; /* the image bits */ #endif #if defined(PNG_FIXED_POINT_SUPPORTED) && defined(PNG_gAMA_SUPPORTED) png_fixed_point int_gamma PNG_DEPSTRUCT; /* gamma of image, if (valid & PNG_INFO_gAMA) */ #endif #if defined(PNG_cHRM_SUPPORTED) && defined(PNG_FIXED_POINT_SUPPORTED) png_fixed_point int_x_white PNG_DEPSTRUCT; png_fixed_point int_y_white PNG_DEPSTRUCT; png_fixed_point int_x_red PNG_DEPSTRUCT; png_fixed_point int_y_red PNG_DEPSTRUCT; png_fixed_point int_x_green PNG_DEPSTRUCT; png_fixed_point int_y_green PNG_DEPSTRUCT; png_fixed_point int_x_blue PNG_DEPSTRUCT; png_fixed_point int_y_blue PNG_DEPSTRUCT; #endif } png_info;