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/* pngstruct.h - header file for PNG reference library
* Last changed in libpng 1.7.0 [(PENDING RELEASE)]
* Copyright (c) 1998-2002,2004,2006-2016 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.)
* This code is released under the libpng license.
* For conditions of distribution and use, see the disclaimer
* and license in png.h
/* The structure that holds the information to read and write PNG files.
* The only people who need to care about what is inside of this are the
* people who will be modifying the library for their own special needs.
* It should NOT be accessed directly by an application.
/* zlib.h defines the structure z_stream, an instance of which is included
* in this structure and is required for decompressing the LZ compressed
* data in PNG files.
#ifndef ZLIB_CONST
/* We must ensure that zlib uses 'const' in declarations. */
# define ZLIB_CONST
#endif /* !ZLIB_CONST */
#ifdef const
/* zlib.h sometimes #defines const to nothing, undo this. */
# undef const
#endif /* const */
/* zlib.h has mediocre z_const use before 1.2.6, this stuff is for compatibility
* with older builds.
#if ZLIB_VERNUM < 0x1260
# define PNGZ_MSG_CAST(s) png_constcast(char*,s)
# define PNGZ_INPUT_CAST(b) png_constcast(png_bytep,b)
#else /* ZLIB_VERNUM >= 0x1260 */
# define PNGZ_MSG_CAST(s) (s)
# define PNGZ_INPUT_CAST(b) (b)
#endif /* ZLIB_VERNUM >= 0x1260 */
/* zlib.h declares a magic type 'uInt' that limits the amount of data that zlib
* can handle at once. This type need be no larger than 16 bits (so maximum of
* 65535), this define allows us to discover how big it is, but limited by the
* maximum for size_t. The value can be overridden in a library build (pngusr.h,
* or set it in CPPFLAGS) and it works to set it to a considerably lower value
* (e.g. 255 works). A lower value may help memory usage (slightly) and may
* even improve performance on some systems (and degrade it on others.)
#ifndef ZLIB_IO_MAX
# ifdef __COVERITY__
# define ZLIB_IO_MAX ((uInt)255U) /* else COVERITY whines */
# else /* !COVERITY */
# define ZLIB_IO_MAX ((uInt)-1)
# endif /* !COVERITY */
#endif /* !ZLIB_IO_MAX */
/* The write compression control (allocated on demand).
* TODO: use this for the read state too.
typedef struct png_zlib_state *png_zlib_statep;
#endif /* WRITE */
/* Colorspace support; structures used in png_struct, png_info and in internal
* functions to hold and communicate information about the color space.
* PNG_COLORSPACE_SUPPORTED is only required if the application will perform
* colorspace corrections, otherwise all the colorspace information can be
* skipped and the size of libpng can be reduced (significantly) by compiling
* out the colorspace support.
/* The chromaticities of the red, green and blue colorants and the chromaticity
* of the corresponding white point (i.e. of rgb(1.0,1.0,1.0)).
typedef struct png_xy
png_fixed_point redx, redy;
png_fixed_point greenx, greeny;
png_fixed_point bluex, bluey;
png_fixed_point whitex, whitey;
} png_xy;
/* The same data as above but encoded as CIE XYZ values. When this data comes
* from chromaticities the sum of the Y values is assumed to be 1.0
typedef struct png_XYZ
png_fixed_point red_X, red_Y, red_Z;
png_fixed_point green_X, green_Y, green_Z;
png_fixed_point blue_X, blue_Y, blue_Z;
} png_XYZ;
#endif /* COLORSPACE */
/* A colorspace is all the above plus, potentially, profile information;
* however at present libpng does not use the profile internally so it is only
* stored in the png_info struct (if iCCP is supported.) The rendering intent
* is retained here and is checked.
* The file gamma encoding information is also stored here and gamma correction
* is done by libpng, whereas color correction must currently be done by the
* application.
typedef struct png_colorspace
png_fixed_point gamma; /* File gamma */
#endif /* GAMMA */
png_xy end_points_xy; /* End points as chromaticities */
png_XYZ end_points_XYZ; /* End points as CIE XYZ colorant values */
png_uint_16 rendering_intent; /* Rendering intent of a profile */
#endif /* COLORSPACE */
/* Flags are always defined to simplify the code. */
png_uint_16 flags; /* As defined below */
} png_colorspace, * PNG_RESTRICT png_colorspacerp;
typedef const png_colorspace * PNG_RESTRICT png_const_colorspacerp;
/* General flags for the 'flags' field */
#define PNG_COLORSPACE_MATCHES_sRGB 0x0080U /* exact match on profile */
#define PNG_COLORSPACE_RGB_TO_GRAY_SET 0x0100U /* user specified coeffs */
#define PNG_COLORSPACE_CANCEL(flags) (0xffffU - (flags))
#endif /* COLORSPACE || GAMMA */
/***************************** READ and WRITE TRANSFORMS ***********************
* These structures are used in pngrtran.c, pngwtran.c and pngtrans.c to hold
* information about transforms in progress. This mechanism was introduced in
* libpng 1.7.0 to ensure reliable transform code and to fix multiple bugs in
* the pre-1.7 transform handling.
* Prior to 1.7.0 the internal transform routines took a png_row_infop, like the
* user transform function, but without the png_ptr because it was never used.
* In 1.7.0 a separate internal structure is used in place of this to allow both
* future development to change the structure.
* The values in this structure will normally be changed by transformation
* implementations.
***************************** READ and WRITE TRANSFORMS **********************/
typedef struct
png_structp png_ptr; /* png_struct for error handling and some
* transform parameters. May be aliased.
png_const_voidp sp; /* Source; the input row. */
png_voidp dp; /* Output buffer for the transformed row,
* this may be the same as sp.
/* If the row is changed the tranform routine must write the result to
* dp[] and set sp to dp, otherwise it must not write to dp and must leave
* sp unchanged. dp[] and sp[] are both 'malloc' aligned; i.e. they have
* the system alignment, so the data can be read as any valid ANSI-C
* type.
png_uint_32 width; /* width of row */
png_fixed_point gamma; /* Current gamma of the row data */
/* When a row is being transformed this contains the current gamma of the
* data if known. During initialization the value is used to accumulate
* information for png_struct::row_gamma in the first step,
* PNG_TC_INIT_FORMAT, then used to insert the correct gamma transforms
* during PNG_TC_INIT_FINAL. The field is only used on read; write
* transforms do not modify the gamma of the data.
# endif /* READ_GAMMA */
unsigned int format; /* As pngstruct::row_format below */
unsigned int range; /* Count of range transforms */
# define PNG_TC_CHANNELS(tc) PNG_FORMAT_CHANNELS((tc).format)
unsigned int bit_depth; /* bit depth of row */
png_byte sBIT_R;
png_byte sBIT_G;
png_byte sBIT_B;
png_byte sBIT_A; /* Signnificant bits in the row channels. */
/* The above four values are initially set to the number of bits significant
* in the input PNG data, R/G/B are set to the same (gray) value for
* grayscale input. All values are set to the bit depth if there is no sBIT
* chunk, if there is no alpha channel sBIT_A is set to the bit depth.
* When any potentially spurious bits have been cleared PNG_INFO_sBIT will be
* set in invalid_info. From this point on the above values record the
* approximate number of bits of accuracy in the channels and the lower bits
* should be preserved; they potentially contain useful information.
# define PNG_TC_PIXEL_DEPTH(tc) (PNG_TC_CHANNELS(tc) * (tc).bit_depth)
unsigned int invalid_info; /* PNG_INFO_* for invalidated chunks */
unsigned int cost; /* Cache cost */
# define PNG_CACHE_COST_LIMIT 0x100U
/* This is a runtime structure, so size doesn't matter much, and it helps
* code reliability to use real member names here. Feel free to experiment
* with integer values rather than bitfields.
unsigned int init :2; /* 0 for processing, non zero for init: */
# define PNG_TC_INIT_FORMAT 0x01U /* Initialization step 1: just set 'format',
* 'bit_depth' and 'gamma' to the output
* values iff the transform corresponds to
* a user requested change to those values.
# define PNG_TC_INIT_FINAL 0x03U /* Initialization step 2; set the 'format'
* 'bit_depth' and 'gamma' to the values the
* transform will actually produce (which
* need not be the same as the above).
/* During initialization 'init' must be set and sp and dp may be NULL. If
* neither flag is set sp and dp must be non-NULL.
* When the transform runs it must update 'format', 'bit_depth' and 'gamma'
* to the values previously reported during PNG_TC_INIT_FINAL; not doing so
* may result in an affirm from a later transform.
unsigned int caching :1; /* The color values are being used to
* generate a cache of the transforms.
unsigned int palette :1; /* The values come from a PNG palette and
* the palette will not be expanded. The
* CACHE flag must be set too. A
* transform which causes the palette to
* be expanded must clear this flag.
#if 0 /* NYI */
unsigned int interchannel:1; /* Set by a transform that combines two or
* more channels together; for example
* alpha composition or RGB to gray.
#endif /* NYI */
unsigned int channel_add :1; /* A channel (alpha/filler) was added */
unsigned int strip_alpha :1; /* Set if the alpha channel will be
* stripped on read, this also prevents
* the tRNS chunk being expanded. Only
* some transforms check this, depending
* on the handling order and checks in
* pre-1.7 versions.
unsigned int expand_tRNS :1; /* Set if the tRNS chunk should be
* expanded (ignored if read_strip_alpha
* is set). If this is *not* set
* transforms which do not use alpha/tRNS
* but would invalidate it (such as
* simple gamma correction) will simply
* mark the tRNS info as invalid.
unsigned int transparent_alpha :1; /* Indicates that the alpha channel
* consists entirely of opaque (1.0 alpha)
* or completely transparent (0.0 alpha)
* pixels. Set when tRNS is expanded to
* alpha.
unsigned int optimized_alpha :1; /* Meaningful only when bit_depth is
* 16 and gamma is 1 or unknown (0).
* Indicates that pixels which are opaque
* (alpha 1.0) have not been expanded to
* 16-bit linear; instead these pixels
* are encoded in the final format in
* png_struct::row_bit_depth and
* png_struct::row_gamma. This will
* invariably match the file format.
} png_transform_control, *png_transform_controlp;
typedef const png_transform_control *png_const_transform_controlp;
typedef const png_row_info *png_const_row_infop;
typedef struct png_transform *png_transformp; /* Forward declaration */
typedef void (*png_transform_free_fn)(/* Function to free a transform */
png_const_structrp png_ptr,
png_transformp transform); /* pointer to this transform */
/* This function need not exist in a transform, it must free all the data
* allocated within the transform but not the transform itself. It is called
* from png_transform_free.
typedef void (*png_transform_fn)(/* Function to implement a transform */
png_transformp *transform, /* pointer to this transform */
png_transform_controlp control); /* row information */
/* The transform function has two modes of operation:
* 1) Initialization. The list of transforms is processed from the start to
* the end and each function is called with one of hte PNG_TC_INIT_ flags
* set in control->flags, control->dp and control->sp may be NULL.
* For read the control structure contains the input row format and bit
* depth, the transform function changes this to represent what the
* transform will produce when it runs.
* For write the control structure contains the *required* output format
* and bit depth. The transform function changes this to the values that
* it needs to produce the required values.
* In both cases the transform function may update the 'fn' function to a
* new function to perform the desired transform; this allows considerable
* optimization on multi-row images.
* In both cases the caller considers the pixel bit depth changes and
* records the maximum required so that it can allocate a suitably sized
* buffer.
* 2) Execution.
* In the read case the transforms are processed in the stored order and
* must transform the row data appropriately *and* update the bit depth
* and format as before.
* In the write case the transforms are called in the reverse order and
* the input bit depth and format should match the required values.
* It is valid during initialization for the transform function to push
* another transform into the list in either the read or the write case if
* the transform cannot handle (read) or produce (write) the required format. * The transform pushes another transform into the list ahead of itself (at
* *transform) and runs that initialization; when control is returned to the
* caller the caller will re-run the transform initialization.
* It is also valid (during initialization) to push new transforms onto the
* list, just so long as the order of the transform is greater than the
* current transform (so that the caller will still call the new transform
* initialization.)
* In the write case the user transform callback might still end up producing
* an unexpected format, but at present this is unavoidable; the libpng API
* is extremely inconsistent in how a user transform reports the changes it
* made.
* TODO: fix this, probably with an API change in 1.7.0
typedef struct png_transform /* Linked list of transform functions */
png_transformp next; /* Next transform in the list */
png_transform_fn fn; /* Function to implement the transform */
png_transform_free_fn free; /* Free allocated data, normally NULL */
unsigned int order; /* Order of the transform in the list. */
unsigned int size; /* Size of this structure (max 65535) */
png_uint_32 args; /* Optional transform arguments. */
} png_transform;
#endif /* TRANSFORM_MECH */
/* Action to take on CRC errors (four values) */
typedef enum
crc_error_quit = PNG_CRC_ERROR_QUIT-1,
crc_warn_discard = PNG_CRC_WARN_DISCARD-1,
crc_warn_use = PNG_CRC_WARN_USE-1,
crc_quiet_use = PNG_CRC_QUIET_USE-1
} png_crc_action;
struct png_struct_def
/* Rearranged in libpng 1.7 to attempt to lessen padding; in general
* (char), (short), (int) and pointer types are kept separate; however
* associated members under the control of the same #define are still
* together.
/* jmp_buf can have very high alignment requirements on some systems, so put
* it first (the other setjmp members are later as they are infrequently
* accessed.)
jmp_buf jmp_buf_local;
#endif /* SETJMP */
/* Next the frequently accessed fields. Many processors perform arithmetic
* in the address pipeline, but frequently the amount of addition or
* subtraction is limited. By putting these fields at the head of png_struct
* the hope is that such processors will generate code that is both smaller
* and faster.
png_colorp palette; /* palette from the input file */
#endif /* READ */
png_bytep trans_alpha; /* alpha values for paletted files */
#endif /* READ_tRNS */
png_uint_32 width; /* width of image in pixels */
png_uint_32 height; /* height of image in pixels */
png_uint_32 chunk_name; /* PNG_CHUNK() id of current chunk */
png_uint_32 chunk_length; /* Length (possibly remaining) in said chunk. */
#endif /* READ */
png_uint_32 crc; /* current chunk CRC value */
unsigned int mode :6; /* where we are in the PNG file */
unsigned int read_struct :1; /* this is a read (not write) struct */
unsigned int num_palette :9; /* number of color entries in palette */
unsigned int num_trans :9; /* number of transparency values */
unsigned int transparent_palette :1; /* if they are all 0 or 255 */
#endif /* READ_tRNS */
unsigned int palette_index_max :8; /* maximum palette index in IDAT */
unsigned int palette_index_check :2; /* one of the following: */
unsigned int palette_index_have_max :1; /* max is being set */
unsigned int palette_index_check_issued :1; /* error message output */
#endif /* PALETTE_MAX */
png_color_16 trans_color; /* transparent color for non-paletted files */
#endif /* READ_tRNS */
png_color_8 sig_bit; /* significant bits in each channel */
#endif /* READ_sBIT */
/* Single byte values, typically used either to save space or to hold 1-byte
* values from the PNG chunk specifications.
png_byte filter_method; /* file filter type (only non-0 with MNG) */
png_byte interlaced; /* PNG_INTERLACE_NONE, PNG_INTERLACE_ADAM7 */
png_byte color_type; /* color type of file */
png_byte bit_depth; /* bit depth of file */
png_byte sig_bytes; /* magic bytes read/written at start of file */
/* The png_struct colorspace structure is only required on read - on write it
* is in (just) the info_struct.
png_colorspace colorspace;
#endif /* COLORSPACE || GAMMA */
#endif /* READ */
/* Transform handling */
png_transformp transform_list; /* List of transformation to perform. */
#endif /* TRANSFORM_MECH */
* Members used for image row compression (write) or decompression (read).
* filter byte (which is in next_filter.) All fields are only used during
* IDAT processing and start of 0.
png_bytep row_buffer; /* primary row buffer */
png_bytep transformed_row; /* pointer to the transformed row, if
* required. May point to row_buffer.
png_alloc_size_t row_bytes_read; /* Total read in row */
#endif /* READ */
png_uint_32 row_number; /* current row in pass */
png_fixed_point row_gamma; /* Gamma of final output */
#if 0 /* NYI */
unsigned int gamma_accuracy;
/* LINEAR gamma cache table size (in bits) times 100; for non-linear
* tables the value used is gamma_accuracy/gamma where 'gamma' is the
* encoding value of the data (typically less than 1).
#endif /* NYI */
png_uint_16 gamma_threshold;
/* Gamma threshold value as a fixed-point value in the range 0..1; the
* threshold at or below which gamma correction is skipped. '0' forces
* gamma correction even when there is none because the input and output
* gammas are equal.
#endif /* READ_GAMMA */
unsigned int invalid_info; /* PNG_INFO_* for invalidated chunks */
unsigned int palette_updated:1; /* png_struct::palette changed */
#endif /* READ_TRANSFORMS */
unsigned int read_started :1; /* at least one call to png_read_row */
#endif /* SEQUENTIAL_READ */
/* The next field is just used by the read IDAT process functions to store
* the state of IDAT processing; they should not be altered or used by other
* functions.
unsigned int row_state :2; /* state of row parsing (internal) */
#endif /* READ */
unsigned int do_interlace :1; /* libpng handles the interlace */
# endif /* R/W INTERLACING */
unsigned int pass :3; /* current (interlace) pass (0 - 6) */
/* The following fields are set by png_row_init to the pixel depths of the
* pixels at various states. If transforms are not supported they will
* always be the same value:
* input: PNG From application
* output: To application PNG
* max: Largest in transform
unsigned int row_input_pixel_depth :8;
unsigned int row_output_pixel_depth :8;
unsigned int row_max_pixel_depth :8;
# define PNG_RF_BITS 9 /* Number of bits required for the row format (below) */
/* The following fields describe the format of the user row; the output on
* read or the input on write, and give the maximum pixel depth, which
* controls the row buffer allocation size (row_allocated_bytes) above.
unsigned int row_range :3; /* range error count */
unsigned int row_bit_depth :6; /* bits per channel (up to 32) */
unsigned int row_format:PNG_RF_BITS;/* format of output(R)/input(W) row: */
/* PNG_FORMAT_FLAG_ALPHA 0x01U format with an alpha channel
* PNG_FORMAT_FLAG_COLOR 0x02U color format: otherwise grayscale
* PNG_FORMAT_FLAG_LINEAR 0x04U NOT used (informational)
* PNG_FORMAT_FLAG_COLORMAP 0x08U image data is color-mapped
* PNG_FORMAT_FLAG_BGR 0x10U BGR colors, else order is RGB
* PNG_FORMAT_FLAG_AFIRST 0x20U alpha channel comes first *
* PNG_FORAMT_FLAG_AFILLER 0x40U The 'alpha' channel is a filler:
* PNG_FORMAT_FLAG_ALPHA is set however the value in the alpha channel
* is not an alpha value and (therefore) cannot be used for alpha
* computations, it is just a filler value. PNG_COLOR_TYPE_FROM_FORMAT
* will return a color type *without* PNG_COLOR_MASK_ALPHA, however
* PNG_FORMAT_CHANNELS will return the correct number, including the
* filler channel.
* PNG_FORMAT_FLAG_SWAPPED 0x80U bytes or bits swapped:
* When the bit depth is 16 this means that the bytes within the
* components have been swapped, when the bit depth is less than 8
* it means the pixels within the bytes have been swapped. It should
* not be set for 8-bit compononents (it is meaningless).
* PNG_FORMAT_FLAG_RANGE 0x100U component range not 0..bit-depth:
* Low-bit-depth grayscale components have been unpacked into bytes
* without scaling, or RGB[A] pixels have been shifted back to the
* significant-bit range from the sBIT chunk or channels (currently
* alpha or gray) have been inverted.
unsigned int info_format:PNG_RF_BITS;
/* This field is used to validate the png_info used to write the
* IHDR. This is a new check in 1.7.0; previously it was possible to pass
* a png_info from a png_read with the read tranform information in the
* format having manually removed the required transforms from the rows
* passed to png_write_row.
unsigned int write_invert_alpha :1;
/* This indicates the png_set_invert_alpha was called, it is used by the
* write code to implement the transform without needing to run the whole
* transform mechanism on the PNG palette data.
unsigned int rgb_to_gray_status :1;
/* If set an RGB pixel was encountered by the RGB to gray transform
* wherein !(r==g==b).
#endif /* RGB_TO_GRAY */
#endif /* TRANSFORM_MECH */
/* These, and IDAT_size below, control how much input and output (at most) is
* available to zlib during read decompression.
png_alloc_size_t read_buffer_size; /* current size of the buffer */
#endif /* READ */
png_uint_32 IDAT_size; /* limit on IDAT read and write IDAT size */
jmp_buf *jmp_buf_ptr; /* passed to longjmp_fn */
png_longjmp_ptr longjmp_fn; /* setjmp non-local goto function. */
size_t jmp_buf_size; /* size of *jmp_buf_ptr, if allocated */
#endif /* SETJMP */
/* Error/warning callbacks */
png_error_ptr error_fn; /* print an error message and abort */
png_error_ptr warning_fn; /* print a warning and continue */
#endif /* WARNINGS */
png_voidp error_ptr; /* user supplied data for the above */
png_malloc_ptr malloc_fn; /* allocate memory */
png_free_ptr free_fn; /* free memory */
png_voidp mem_ptr; /* user supplied data for the above */
#endif /* USER_MEM */
png_voidp io_ptr; /* user supplied data for IO callbacks */
png_rw_ptr rw_data_fn; /* read/write some bytes (must succeed) */
png_read_status_ptr read_row_fn; /* called after each row is decoded */
png_bytep read_buffer; /* buffer for reading chunk data */
/* During read the following array is set up to point to the appropriate
* un-filter function, this allows per-image and per-processor optimization.
void (*read_filter[PNG_FILTER_VALUE_LAST-1])(png_alloc_size_t row_bytes,
unsigned int bpp, png_bytep row, png_const_bytep prev_row,
png_const_bytep prev_pixels);
#endif /* READ */
png_write_status_ptr write_row_fn; /* called after each row is encoded */
png_flush_ptr output_flush_fn; /* Function for flushing output */
#endif /* WRITE_FLUSH */
#endif /* WRITE */
png_uint_32 user_width_max; /* Maximum width on read */
png_uint_32 user_height_max; /* Maximum height on read */
/* Total memory that a single zTXt, sPLT, iTXt, iCCP, or unknown chunk
* can occupy when decompressed. 0 means unlimited. This field is a counter
* - it is decremented as memory is allocated.
png_alloc_size_t user_chunk_malloc_max;
#endif /* SET_USER_LIMITS */
/* limit on total *number* of sPLT, text and unknown chunks that can be
* stored. 0 means unlimited. This field is a counter - it is decremented
* as chunks are encountered.
png_uint_32 user_chunk_cache_max;
#endif /* USER_LIMITS */
/* The progressive reader gets passed data and calls application handling
* functions when appropriate.
png_progressive_info_ptr info_fn; /* called after header data fully read */
png_progressive_row_ptr row_fn; /* called after a row is decoded */
png_progressive_end_ptr end_fn; /* called after image is complete */
/* Progressive read control data */
png_bytep save_buffer_ptr; /* current location in save_buffer */
png_bytep save_buffer; /* buffer for previously read data */
png_bytep current_buffer_ptr; /* current location in current_buffer */
size_t save_buffer_size; /* amount of data now in save_buffer */
size_t save_buffer_max; /* total size of save_buffer */
size_t current_buffer_size; /* amount of data now in current_buffer */
size_t buffer_size; /* total amount of available input data */
unsigned int process_mode :8;
/* This is one or two four bit codes describing the current state of the
* 'push' reader. Normally the low four bits are a state code, however in
* some cases this may be pushed to the top four bits and replaced by a
* different temporary state code. The value is, in effect, a two entry
* stack.
png_uint_32 io_state; /* tells the app read/write progress */
#endif /* IO_STATE */
/* TODO: this is excessively complicated, there are multiple ways of doing
* the same thing. It should be cleaned up, possibly by finding out which
* APIs applications really use.
/* General purpose pointer for all user/unknown chunk handling; points to
* application supplied data for use in the read_user_chunk_fn callback
* (currently there is no write side support - the write side must use the
* set_unknown_chunks interface.)
png_voidp user_chunk_ptr;
#endif /* USER_CHUNKS */
/* This is called back from the unknown chunk handling */
png_user_chunk_ptr read_user_chunk_fn; /* user read chunk handler */
#endif /* READ_USER_CHUNKS */
png_uint_32 known_unknown; /* Bit mask of known chunks to be treated as
* unknown in the read code.
png_uint_32 save_unknown; /* Whether to save or skip these chunks:
* 'save' is 'known & save', 'skip' is
* 'known & ~save'.
# define png_IDATs_skipped(pp) (((pp)->known_unknown & ~(pp)->save_unknown)&1U)
# define png_IDATs_skipped(pp) ((pp)->known_unknown & 1U)
#endif /* HANDLE_AS_UNKNOWN */
png_bytep chunk_list; /* List of png_byte[5]; the textual chunk name
* followed by a PNG_HANDLE_* byte */
unsigned int unknown_default :2; /* As PNG_HANDLE_* */
unsigned int num_chunk_list; /* Number of entries in the list */
* zlib expects a 'zstream' as the fundamental control structure, it allows
* all the parameters to be passed as one pointer.
png_uint_32 zowner; /* ID (chunk type) of zlib owner, 0 if none */
png_zlib_statep zlib_state; /* State of zlib compression */
# endif /* WRITE */
z_stream zstream; /* decompression structure */
unsigned int zstream_ended:1; /* no more zlib output available [read] */
unsigned int zstream_error:1; /* zlib error message has been output [read] */
# endif /* READ */
unsigned int zstream_eod :1; /* all the required uncompressed data has been
* received; set by the zstream using code for
* its own purposes. [progressive read] */
# endif /* PROGRESSIVE_READ */
unsigned int benign_error_action :2;
unsigned int app_warning_action :2;
unsigned int app_error_action :2;
unsigned int IDAT_error_action :2;
# endif /* READ */
# endif /* BENIGN_ERRORS */
/* CRC checking actions, one for critical chunks, one for ancillary
* chunks.
unsigned int critical_crc :2;
unsigned int ancillary_crc :2;
unsigned int current_crc :2; /* Cache of one or other of the above */
# endif
unsigned int maximum_inflate_window :1U;
# endif /* READ */
unsigned int skip_sRGB_profile_check :1U;
# endif /* SET_OPTION */
unsigned int mng_features_permitted :3;
#endif /* MNG_FEATURES */
/* SCRATCH buffers, used when control returns to the application or a read
* loop.
png_byte scratch[PNG_ROW_BUFFER_SIZE+16U];
# endif /* READ */
#endif /* PNGSTRUCT_H */