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/* pngpriv.h - private declarations for use inside libpng
* 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 symbols declared in this file (including the functions declared
* as extern) are PRIVATE. They are not part of the libpng public
* interface, and are not recommended for use by regular applications.
* Some of them may become public in the future; others may stay private,
* change in an incompatible way, or even disappear.
* Although the libpng users are not forbidden to include this header,
* they should be well aware of the issues that may arise from doing so.
#ifndef PNGPRIV_H
#define PNGPRIV_H
/* Feature Test Macros. The following are defined here to ensure that correctly
* implemented libraries reveal the APIs libpng needs to build and hide those
* that are not needed and potentially damaging to the compilation.
* Feature Test Macros must be defined before any system header is included (see
* POSIX 1003.1 2.8.2 "POSIX Symbols."
* These macros only have an effect if the operating system supports either
* POSIX 1003.1 or C99, or both. On other operating systems (particularly
* Windows/Visual Studio) there is no effect; the OS specific tests below are
* still required (as of 2011-05-02.)
#define _POSIX_SOURCE 1 /* Just the POSIX 1003.1 and C89 APIs */
/* Keep standard libraries at the top of this file */
/* Standard library headers not required by png.h: */
# include <stdlib.h>
# include <string.h>
/* For headers only required with some build configurations see the lines after
* pnglibconf.h is included!
#endif /* VERSION_INFO_ONLY */
#define PNGLIB_BUILD /*libpng is being built, not used*/
/* If HAVE_CONFIG_H is defined during the build then the build system must
* provide an appropriate "config.h" file on the include path. The header file
* must provide definitions as required below (search for "HAVE_CONFIG_H");
* see for more details of the requirements. The macro
* "PNG_NO_CONFIG_H" is provided for maintainers to test for dependencies on
* 'configure'; define this macro to prevent the configure build including the
* configure generated config.h. Libpng is expected to compile without *any*
* special build system support on a reasonably ANSI-C compliant system.
#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H)
# include <config.h>
/* Pick up the definition of 'restrict' from config.h if it was read: */
# define PNG_RESTRICT restrict
/* To support symbol prefixing it is necessary to know *before* including png.h
* whether the fixed point (and maybe other) APIs are exported, because if they
* are not internal definitions may be required. This is handled below just
* before png.h is included, but load the configuration now if it is available.
#ifndef PNGLCONF_H
# include "pnglibconf.h"
/* Local renames may change non-exported API functions from png.h */
#if defined(PNG_PREFIX) && !defined(PNGPREFIX_H)
# include "pngprefix.h"
# include "pngusr.h"
/* These should have been defined in pngusr.h */
# define PNG_USER_PRIVATEBUILD "Custom libpng build"
# endif
# endif
/* Additional standard libaries required in certain cases, put only standard
* ANSI-C89 headers here. If not available, or non-functional, the problem
* should be fixed by writing a wrapper for the header and the file on your
* include path.
/* png.c requires the following ANSI-C constants if the conversion of
* floating point to ASCII is implemented therein:
* DBL_MIN_10_EXP Minimum negative integer such that 10^integer is a
* normalized (double) value.
* DBL_DIG Maximum number of decimal digits (can be set to any constant)
* DBL_MIN Smallest normalized fp number (can be set to an arbitrary value)
* DBL_MAX Maximum floating point number (can be set to an arbitrary value)
# include <float.h>
#endif /* sCAL && FLOATING_POINT */
/* ANSI-C90 math functions are required. Full compliance with the standard
* is probably not a requirement, but the functions must exist and be
* declared in <math.h>
# include <math.h>
#endif /* VERSION_INFO_ONLY */
/* Is this a build of a DLL where compilation of the object modules requires
* different preprocessor settings to those required for a simple library? If
* so PNG_BUILD_DLL must be set.
* If libpng is used inside a DLL but that DLL does not export the libpng APIs
* PNG_BUILD_DLL must not be set. To avoid the code below kicking in build a
* static library of libpng then link the DLL against that.
# ifdef DLL_EXPORT
/* This is set by libtool when files are compiled for a DLL; libtool
* always compiles twice, even on systems where it isn't necessary. Set
* PNG_BUILD_DLL in case it is necessary:
# define PNG_BUILD_DLL
# else
# ifdef _WINDLL
/* This is set by the Microsoft Visual Studio IDE in projects that
* build a DLL. It can't easily be removed from those projects (it
* isn't visible in the Visual Studio UI) so it is a fairly reliable
* indication that PNG_IMPEXP needs to be set to the DLL export
* attributes.
# define PNG_BUILD_DLL
# else
# ifdef __DLL__
/* This is set by the Borland C system when compiling for a DLL
* (as above.)
# define PNG_BUILD_DLL
# else
/* Add additional compiler cases here. */
# endif
# endif
# endif
#endif /* Setting PNG_BUILD_DLL if required */
/* See pngconf.h for more details: the builder of the library may set this on
* the command line to the right thing for the specific compilation system or it
* may be automagically set above (at present we know of no system where it does
* need to be set on the command line.)
* PNG_IMPEXP must be set here when building the library to prevent pngconf.h
* setting it to the "import" setting for a DLL build.
#ifndef PNG_IMPEXP
# else
/* Not building a DLL, or the DLL doesn't require specific export
* definitions.
# define PNG_IMPEXP
# endif
/* No warnings for private or deprecated functions in the build: */
# define PNG_PRIVATE
/* Symbol preprocessing support.
* To enable listing global, but internal, symbols the following macros should
* always be used to declare an extern data or function object in this file.
# define PNG_INTERNAL_DATA(type, name, array) extern type name array
# define PNG_INTERNAL_FUNCTION(type, name, args, attributes)\
extern PNG_FUNCTION(type, name, args, PNG_EMPTY attributes)
# define PNG_INTERNAL_CALLBACK(type, name, args, attributes)\
extern PNG_FUNCTION(type, (PNGCBAPI name), args, PNG_EMPTY attributes)
/* If floating or fixed point APIs are disabled they may still be compiled
* internally. To handle this make sure they are declared as the appropriate
* internal extern function (otherwise the symbol prefixing stuff won't work and
* the functions will be used without definitions.)
* NOTE: although all the API functions are declared here they are not all
* actually built! Because the declarations are still made it is necessary to
* fake out types that they depend on.
# define PNG_FP_EXPORT(ordinal, type, name, args)\
typedef struct png_incomplete png_double;
typedef png_double* png_doublep;
typedef const png_double* png_const_doublep;
typedef png_double** png_doublepp;
# endif
# endif
# define PNG_FIXED_EXPORT(ordinal, type, name, args)\
# endif
/* Include png.h here to get the version info and other macros, pngstruct.h and
* pnginfo.h are included later under the protection of !PNG_VERSION_INFO_ONLY
#include "png.h"
/* pngconf.h does not set PNG_DLL_EXPORT unless it is required, so: */
/* This is a global switch to set the compilation for an installed system
* (a release build). It can be set for testing debug builds to ensure that
* they will compile when the build type is switched to RC or STABLE, the
* default is just to use PNG_LIBPNG_BUILD_BASE_TYPE. Set this in CPPFLAGS
* with either:
* -DPNG_RELEASE_BUILD Turns on the release compile path
* -DPNG_RELEASE_BUILD=0 Turns it off
* or in your pngusr.h with
* #define PNG_RELEASE_BUILD=1 Turns on the release compile path
* #define PNG_RELEASE_BUILD=0 Turns it off
/* General purpose macros avoid the need to put #if PNG_RELEASE_BUILD
* macro blocks around function declarations and definitions when the
* parameter number varies. Using these results in slightly cleaner code.
# define only_rel(text) text
# define only_deb(text)
# define param_rel(param) param,
# define param_deb(param)
# define only_rel(text)
# define only_deb(text) text
# define param_rel(param)
# define param_deb(param) param,
/* The affirm mechanism results in a minimal png_error() in released versions
* ('STABLE' versions) and a more descriptive PNG_ABORT in all other cases,
* when the "condition" is false (zero). If "condition" is true (nonzero),
* then the affirm mechanism does nothing.
* The PNG_RELEASE_BUILD macro, defined above, controls the behavior of
* 'affirm': if set to 1 affirm will call png_error (or png_err) rather than
* abort. The png_error text is the minimal (file location) text in this case,
* if it is produced. This flag indicates a STABLE (or RC) build.
* The macros rely on the naming convention throughout this code - png_ptr
* exists and is of type png_const_structrp or a compatible type - and the
* presence in each file of a uniquely defined macro PNG_SRC_FILE; a number
* indicating which file this is (this is to save space in released versions).
* 'affirm' is intended to look like the ANSI-C <assert.h> macro; note that
* this macro can coexist with the assert macro if <assert.h> is
* included.
* PNG_SRC_LINE is the position of the affirm macro. There are currently 15
* main source files (4 bits) and the biggest (pngrtran.c) has more than 4095
* lines (12 bits). However, to ensure the number will fit into 16-bits in the
* future and to allow hardware files to use affirm, the encoding is a bit-wise
* encoding based on the current number of lines.
* 'debug' is a version of 'affirm' that is completely removed from RELEASE
* builds. This is used when either an unexpected condition is completely
* handled or when it can't be handled even by png_error, for example after a
* memory overwrite.
* UNTESTED is used to mark code that has not been tested; it causes an assert
* if the code is executed and (therefore) tested. UNTESTED should not remain
* in release candidate code.
* PNG_AFFIRM_TEXT is set to 1 if affirm text should be produced, either
* the minimal text or, if PNG_RELEASE_BUILD is 0, the more verbose text
* including the 'condition' string. This value depends on whether the
* build supports an appropriate way of outputting the message.
* Note that PNG_AFFIRM_TEXT is not configurable but is worked out here: this
* is just the affirm code; there's no reason to allow configuration of this
* option.
# define PNG_AFFIRM_TEXT 1
# define PNG_AFFIRM_TEXT 0
#endif /* PNG_AFFIRM_TEXT definition */
/* png_affirmpp and png_impossiblepp are macros to make the correct call to the
* png_affirm function; these macros do not assume that the png_structp is
* called png_ptr.
# define png_affirmpp(pp, cond)\
if (!(cond)) png_affirm(pp, PNG_SRC_LINE);\
while (0)
# define png_affirmexp(pp, cond)\
((cond) ? (void)0 : png_affirm(pp, PNG_SRC_LINE))
# define png_handled(pp, m) ((void)0)
# define png_impossiblepp(pp, reason) png_affirm(pp, PNG_SRC_LINE)
# define debug(cond) do {} while (0)
# define debug_handled(cond) do {} while (0)
/* Make sure there are no 'UNTESTED' macros in released code: */
# define UNTESTED libpng untested code
# endif
# define NOT_REACHED do {} while (0)
# define png_affirmpp(pp, cond)\
if (!(cond)) png_affirm(pp, #cond, PNG_SRC_LINE);\
while (0)
# define png_affirmexp(pp, cond)\
((cond) ? (void)0 : png_affirm(pp, #cond, PNG_SRC_LINE))
# define png_handled(pp, m) (png_handled_affirm((pp), (m), PNG_SRC_LINE))
# define png_impossiblepp(pp, reason) png_affirm(pp, reason, PNG_SRC_LINE)
# define debug(cond) png_affirmpp(png_ptr, cond)
# define debug_handled(cond)\
if (!(cond)) png_handled(png_ptr, #cond);\
while (0)
# define UNTESTED png_affirm(png_ptr, "untested code", PNG_SRC_LINE);
# define NOT_REACHED png_affirm(png_ptr, "NOT REACHED", PNG_SRC_LINE)
#define affirm(cond) png_affirmpp(png_ptr, cond)
#define affirmexp(cond) png_affirmexp(png_ptr, cond)
#define handled(m) png_handled(png_ptr, (m))
#define impossible(cond) png_impossiblepp(png_ptr, cond)
#define implies(a, b) debug(!(a) || (b))
/* The defines for PNG_SRC_FILE: */
#define PNG_SRC_FILE_(f,lines) PNG_SRC_FILE_ ## f + lines
#define PNG_SRC_FILE_png 0
#define PNG_SRC_FILE_pngerror (PNG_SRC_FILE_png +8192)
#define PNG_SRC_FILE_pngget (PNG_SRC_FILE_pngerror +2048)
#define PNG_SRC_FILE_pngmem (PNG_SRC_FILE_pngget +2048)
#define PNG_SRC_FILE_pngpread (PNG_SRC_FILE_pngmem +1024)
#define PNG_SRC_FILE_pngread (PNG_SRC_FILE_pngpread +2048)
#define PNG_SRC_FILE_pngrio (PNG_SRC_FILE_pngread +8192)
#define PNG_SRC_FILE_pngrtran (PNG_SRC_FILE_pngrio +1024)
#define PNG_SRC_FILE_pngrutil (PNG_SRC_FILE_pngrtran +8192)
#define PNG_SRC_FILE_pngset (PNG_SRC_FILE_pngrutil +8192)
#define PNG_SRC_FILE_pngtrans (PNG_SRC_FILE_pngset +2048)
#define PNG_SRC_FILE_pngwio (PNG_SRC_FILE_pngtrans +4096)
#define PNG_SRC_FILE_pngwrite (PNG_SRC_FILE_pngwio +1024)
#define PNG_SRC_FILE_pngwtran (PNG_SRC_FILE_pngwrite +4096)
#define PNG_SRC_FILE_pngwutil (PNG_SRC_FILE_pngwtran +1024)
#define PNG_SRC_FILE_arm_arm_init (PNG_SRC_FILE_pngwutil +8192)
#define PNG_SRC_FILE_arm_filter_neon_intrinsics\
(PNG_SRC_FILE_arm_arm_init +1024)
/* Add new files by changing the following line: */
#define PNG_SRC_FILE_LAST (PNG_SRC_FILE_arm_filter_neon_intrinsics +1024)
/* The following #define must list the files in exactly the same order as
* the above.
#define PNG_FILES\
* libpng is built with support for internal limits on image dimensions and
* memory usage. These are documented in scripts/pnglibconf.dfa of the
* source and recorded in the machine generated header file pnglibconf.h.
/* If you are running on a machine where you cannot allocate more
* than 64K of memory at once, uncomment this. While libpng will not
* normally need that much memory in a chunk (unless you load up a very
* large file), zlib needs to know how big of a chunk it can use, and
* libpng thus makes sure to check any memory allocation to verify it
* will fit into memory.
* zlib provides 'MAXSEG_64K' which, if defined, indicates the
* same limit and pngconf.h (already included) sets the limit
* if certain operating systems are detected.
#if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
# define PNG_MAX_MALLOC_64K
#ifndef PNG_UNUSED
/* Unused formal parameter warnings are silenced using the following macro
* which is expected to have no bad effects on performance (optimizing
* compilers will probably remove it entirely). Note that if you replace
* it with something other than whitespace, you must include the terminating
* semicolon.
# define PNG_UNUSED(param) (void)param;
/* This is a convenience for parameters which are not used in release
* builds.
#define PNG_UNUSEDRC(param) only_rel(PNG_UNUSED(param))
/* Just a little check that someone hasn't tried to define something
* contradictory.
#if (PNG_ZBUF_SIZE > 32768) && defined(PNG_MAX_MALLOC_64K)
# define PNG_ZBUF_SIZE 32768
/* If warnings or errors are turned off the code is disabled or redirected here.
* From 1.5.4 functions have been added to allow very limited formatting of
* error and warning messages - this code will also be disabled here.
# define PNG_WARNING_PARAMETERS(p) png_warning_parameters p;
# define png_warning_parameter(p,number,string) ((void)0)
# define png_warning_parameter_unsigned(p,number,format,value) ((void)0)
# define png_warning_parameter_signed(p,number,format,value) ((void)0)
# define png_formatted_warning(pp,p,message) ((void)(pp))
# define png_fixed_error(s1,s2) png_err(s1)
/* C allows up-casts from (void*) to any pointer and (const void*) to any
* pointer to a const object. C++ regards this as a type error and requires an
* explicit, static, cast and provides the static_cast<> rune to ensure that
* const is not cast away.
#ifdef __cplusplus
# define png_voidcast(type, value) static_cast<type>(value)
# define png_upcast(type, value) static_cast<type>(value)
# define png_constcast(type, value) const_cast<type>(value)
# define png_aligncast(type, value) \
# define png_aligncastconst(type, value) \
static_cast<type>(static_cast<const void*>(value))
# define png_voidcast(type, value) (value)
# define png_upcast(type, value) ((type)(value))
# define png_constcast(type, value) ((type)(value))
# define png_aligncast(type, value) ((void*)(value))
# define png_aligncastconst(type, value) ((const void*)(value))
#endif /* __cplusplus */
/* Some fixed point APIs are still required even if not exported because
* they get used by the corresponding floating point APIs. This magic
* deals with this:
# define PNGFAPI /* PRIVATE */
/* These macros may need to be architecture dependent. */
#define PNG_ALIGN_NONE 0 /* do not use data alignment */
#define PNG_ALIGN_ALWAYS 1 /* assume unaligned accesses are OK */
#ifdef offsetof
# define PNG_ALIGN_OFFSET 2 /* use offsetof to determine alignment */
# define PNG_ALIGN_OFFSET -1 /* prevent the use of this */
#define PNG_ALIGN_SIZE 3 /* use sizeof to determine alignment */
/* Default to using aligned access optimizations and requiring alignment to a
* multiple of the data type size. Override in a compiler specific fashion
* if necessary by inserting tests here:
/* This is used because in some compiler implementations non-aligned
* structure members are supported, so the offsetof approach below fails.
* Set PNG_ALIGN_SIZE=0 for compiler combinations where unaligned access
* is good for performance. Do not do this unless you have tested the result
* and understand it.
# define png_alignof(type) (sizeof (type))
# define png_alignof(type) offsetof(struct{char c; type t;}, t)
# else
# define png_alignof(type) (1)
# endif
/* Else leave png_alignof undefined to prevent use thereof */
# endif
/* This implicitly assumes alignment is always to a power of 2. */
#ifdef png_alignof
# define png_isaligned(ptr, type)\
((((const char*)ptr-(const char*)0) & (png_alignof(type)-1)) == 0)
# define png_isaligned(ptr, type) 0
/* Buffer alignment control. These #defines control how the buffers used during
* read are aligned and how big they are.
/* The absolute minimum alignment for a row buffer is that required for
* png_uint_32 direct access. The #define is of a legal C type that can be
* used as the type in the definition of the first member of a C union; give
* a typedef name if in doubt.
# define PNG_ROW_BUFFER_ALIGN_TYPE png_uint_32
/* This is the minimum size in bytes of the buffer used while processing
* parts of row. Except at the end of the row pixels will always be
* processed in blocks such that the block size is a multiple of this number
((unsigned int)/*SAFE*/(sizeof (PNG_ROW_BUFFER_ALIGN_TYPE)))
# define PNG_MAX_PIXEL_BYTES 16U /* 4x32-bit channels */
# define PNG_MAX_PIXEL_BYTES 8U /* 4x16-bit channels */
/* PNG_ROW_BUFFER_SIZE is a compile time constant for the size of the row
* buffer. The minimum size of 2048 bytes is intended to allow the buffer to
* hold a complete 256 entry color map of 64-bit (8-byte) pixels. This is a
* requirement at some points of the colormap handling code.
* The maximum size is intended to allow (unsigned int) indexing of the buffer,
* it only affects systems with a 16-bit unsigned value where it limits the
* maximum to 4096 bytes.
#endif /* ROW_BUFFER_SIZE */
/* End of memory model/platform independent support */
/* End of 1.5.0beta36 move from pngconf.h */
* These are used internally by libpng and not exposed in the API
/* Various modes of operation. Note that after an init, mode is set to
* zero automatically when the structure is created. Three of these
* are defined in png.h because they need to be visible to applications
* that call png_set_unknown_chunk().
/* #define PNG_HAVE_IHDR 0x01 (defined as (int) in png.h) */
/* #define PNG_HAVE_PLTE 0x02 (defined as (int) in png.h) */
#define PNG_HAVE_IDAT 0x04U
/* #define PNG_AFTER_IDAT 0x08 (defined as (int) in png.h) */
#define PNG_HAVE_IEND 0x10U
/* See below for the definitions of the tables used in these macros */
#define PNG_sRGB_FROM_LINEAR(pp, linear) png_check_byte(pp,\
(png_sRGB_base[(linear)>>15] +\
((((linear)&0x7fffU)*png_sRGB_delta[(linear)>>15])>>12)) >> 8)
/* Given a value 'linear' in the range 0..255*65535 calculate the 8-bit sRGB
* encoded value with maximum error 0.646365. Note that the input is not a
* 16-bit value; it has been multiplied by 255! */
/* Added to libpng-1.6.0: scale a 16-bit value in the range 0..65535 to 0..255
* by dividing by 257 *with rounding*. This macro is exact for the given range.
* See the discourse in pngrtran.c png_do_scale_16_to_8. The values in the
* macro were established by experiment (modifying the added value). The macro
* has a second variant that takes a value already scaled by 255 and divides by
* 65535 - this has a maximum error of .502. Over the range 0..65535*65535 it
* only gives off-by-one errors and only for 0.5% (1 in 200) of the values.
#define PNG_DIV65535(v24) (((v24) + 32895U) >> 16)
#define PNG_DIV257(v16) PNG_DIV65535((png_uint_32)(v16) * 255U)
/* Added to libpng-1.2.6 JB
* Modified in libpng-1.7.0 to avoid the intermediate calculation overflow
* when:
* pixel_bits == 4: any width over 0x3FFFFFFEU overflows
* pixel_bits == 2: any width over 0x7FFFFFFCU overflows
* In both these cases any width results in a rowbytes that fits in 32 bits.
* The problem arose in previous versions because the calculation used was
* simply ((width x pixel-bit-depth)+7)/8. At the cost of more calculations
* on pixel_depth this avoids the problem.
#define PNG_SHIFTOF(pixel_bits/*<8*/) \
( (pixel_bits) == 1 ? 3 : \
( (pixel_bits) == 2 ? 2 : \
( (pixel_bits) == 4 ? 1 : \
0/*force bytes*/ ) ) )
#define PNG_ADDOF(pixel_bits/*<8*/) ((1U<<PNG_SHIFTOF(pixel_bits))-1)
#define PNG_ROWBYTES(pixel_bits, width) \
((pixel_bits) >= 8 ? \
((png_alloc_size_t)(width) * ((pixel_bits) >> 3)) : \
(((png_alloc_size_t)(width) + PNG_ADDOF(pixel_bits)) >> \
PNG_SHIFTOF(pixel_bits)) )
/* This macros, added in 1.7.0, makes it easy to deduce the number of channels
* and therefore the pixel depth from the color type. The PNG specification
* numbers are used in preference to the png.h constants to make it more clear
* why the macro works.
1U : 1U+((ct) & 2U/*COLOR*/)+(((ct)>>2)&1U/*ALPHA*/))
#define PNG_CHANNELS(ps) PNG_COLOR_TYPE_CHANNELS((ps).color_type)
#define PNG_PIXEL_DEPTH(ps) (PNG_CHANNELS(ps) * (ps).bit_depth)
/* PNG_OUT_OF_RANGE returns true if value is outside the range
* ideal-delta..ideal+delta. Each argument is evaluated twice.
* "ideal" and "delta" should be constants, normally simple
* integers, "value" a variable. Added to libpng-1.2.6 JB
#define PNG_OUT_OF_RANGE(value, ideal, delta) \
( (value) < (ideal)-(delta) || (value) > (ideal)+(delta) )
/* Handling of bit-field masks. Because the expression:
* bit_field & ~mask
* has implementation defined behavior in ANSI C-90 for many (int) values of
* 'mask' and because some of these are defined in png.h and passed in (int)
* parameters use of '~' has been expunged in libpng 1.7 and replaced by this
* macro, which is well defined in ANSI C-90 (there is a similar, 16-bit,
* version in pngstruct.h for the colorspace flags.)
#define PNG_BIC_MASK(flags) (0xFFFFFFFFU - (flags))
/* Conversions between fixed and floating point, only defined if
* required (to make sure the code doesn't accidentally use float
* when it is supposedly disabled.)
/* The floating point conversion can't overflow, though it can and
* does lose accuracy relative to the original fixed point value.
* In practice this doesn't matter because png_fixed_point only
* stores numbers with very low precision. The png_ptr and s
* arguments are unused by default but are there in case error
* checking becomes a requirement.
#define png_float(png_ptr, fixed, s) (.00001 * (fixed))
/* The fixed point conversion performs range checking and evaluates
* its argument multiple times, so must be used with care. The
* range checking uses the PNG specification values for a signed
* 32 bit fixed point value except that the values are deliberately
* rounded-to-zero to an integral value - 21474 (21474.83 is roughly
* (2^31-1) * 100000). 's' is a string that describes the value being
* converted.
* NOTE: this macro will raise a png_error if the range check fails,
* therefore it is normally only appropriate to use this on values
* that come from API calls or other sources where an out of range
* error indicates a programming error, not a data error!
* NOTE: by default this is off - the macro is not used - because the
* function call saves a lot of code.
#define png_fixed(png_ptr, fp, s) ((fp) <= 21474 && (fp) >= -21474 ?\
((png_fixed_point)(100000 * (fp))) : (png_fixed_error(png_ptr, s),0))
/* else the corresponding function is defined below, inside the scope of the
* cplusplus test.
/* Gamma values (new at libpng-1.5.4): */
#define PNG_GAMMA_MAC_OLD 151724 /* Assume '1.8' is really 2.2/1.45! */
#define PNG_GAMMA_sRGB_INVERSE 45455
/* Almost everything below is C specific; the #defines above can be used in
* non-C code (so long as it is C-preprocessed) the rest of this stuff cannot.
#include "pngstruct.h"
#include "pnginfo.h"
/* Validate the include paths - the include path used to generate pnglibconf.h
* must match that used in the build, or we must be using pnglibconf.h.prebuilt:
"-I (include path) error: see the notes in pngpriv.h"
/* This means that when pnglibconf.h was built the copy of zlib.h that it
* used is not the same as the one being used here. Because the build of
* libpng makes decisions to use inflateInit2 and inflateReset2 based on the
* zlib version number and because this affects handling of certain broken
* PNG files the -I directives must match.
* The most likely explanation is that you passed a -I in CFLAGS. This will
* not work; all the preprocessor directories and in particular all the -I
* directives must be in CPPFLAGS.
/* This is used for 16 bit gamma tables -- only the top level pointers are
* const; this could be changed:
typedef const png_uint_16p * png_const_uint_16pp;
/* Added to libpng-1.5.7: sRGB conversion tables */
PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_table, [256]);
/* Convert from an sRGB encoded value 0..255 to a 16-bit linear value,
* 0..65535. This table gives the closest 16-bit answers (no errors).
PNG_INTERNAL_DATA(const png_uint_16, png_sRGB_base, [512]);
PNG_INTERNAL_DATA(const png_byte, png_sRGB_delta, [512]);
/* Inhibit C++ name-mangling for libpng functions but not for system calls. */
#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */
/* Internal functions; these are not exported from a DLL however because they
* are used within several of the C source files they have to be C extern.
* All of these functions must be declared with PNG_INTERNAL_FUNCTION.
/* Affirm handling */
PNG_INTERNAL_FUNCTION(void, png_affirm,(png_const_structrp png_ptr,
param_deb(png_const_charp condition) unsigned int position), PNG_NORETURN);
PNG_INTERNAL_FUNCTION(void, png_handled_affirm,(png_const_structrp png_ptr,
png_const_charp message, unsigned int position), PNG_EMPTY);
/* This is not marked PNG_NORETURN because in PNG_RELEASE_BUILD it will
* disappear and control will pass through it.
#endif /* !RELEASE_BUILD */
/* Character/byte range checking. */
/* GCC complains about assignments of an (int) expression to a (char) even when
* it can readily determine that the value is in range. This makes arithmetic
* on (char) or (png_byte) values tedious. The warning is not issued by
* default, but libpng coding rules require no warnings leading to excessive,
* ridiculous and dangerous expressions of the form:
* <char> = (char)(expression & 0xff)
* They are dangerous because they hide the warning, which might actually be
* valid, and therefore merely enable introduction of undetected overflows when
* code is modified.
* The following macros exist to reliably detect any overflow in non-release
* builds. The theory here is that we really want to know about overflows, not
* merely hide a basically flawed compiler warning by throwing unnecessary casts
* into the code. The warnings disappear in RC builds so that the released
* (STABLE) version just assigns the value (with, possibly, a warning if someone
* turns on the -Wconversion GCC warning.)
* Doing it this way ensures that the code meets two very important aims:
* 1) Overflows are detected in pre-release tests; previously versions of libpng
* have been released that really did have overflows in the RGB calculations.
* 2) In release builds GCC specific operations, which may reduce the ability
* of other compilers and even GCC to optimize the code, are avoided.
* There is one important extra consequence for pre-release code; it is
* performing a lot of checks in pixel arithmetic that the release code won't
* perform. As a consequence a build time option, RANGE_CHECK, is provided
* to allow the checks to be turned off in pre-release when building for
* performance testing. This is a standard "_SUPPORTED" option except that it
* cannot be set in the system configuration (pnglibconf.h, pnglibconf.dfa).
* A separate macro PNG_BYTE() is provided to safely convert an unsigned value
* to the PNG byte range 0..255. This handles the fact that, technically,
* an ANSI-C (unsigned char), hence a (png_byte), may be able to store values
* outside this range. Note that if you are building on a system where this is
* true libpng is almost certainly going to produce errors; it has never been
* tested on such a system. For the moment pngconf.h ensures that this will
* not happen.
* PNG_UINT_16 does the same thing for a 16-bit value passed in an (int) or
* (png_uint_32) (where checking is not expected.)
# ifndef PNG_NO_RANGE_CHECK /* Turn off even in pre-release */
# endif
PNG_INTERNAL_FUNCTION(unsigned int, png_bit_affirm,(png_const_structrp png_ptr,
unsigned int position, unsigned int u, unsigned int bits), PNG_EMPTY);
PNG_INTERNAL_FUNCTION(char, png_char_affirm,(png_const_structrp png_ptr,
unsigned int position, int c), PNG_EMPTY);
PNG_INTERNAL_FUNCTION(png_byte, png_byte_affirm,(png_const_structrp png_ptr,
unsigned int position, int b), PNG_EMPTY);
#if INT_MAX >= 65535
PNG_INTERNAL_FUNCTION(png_uint_16, png_u16_affirm,(png_const_structrp png_ptr,
unsigned int position, int u), PNG_EMPTY);
# define png_check_u16(pp, u) (png_u16_affirm((pp), PNG_SRC_LINE, (u)))
/* (int) cannot hold a (png_uint_16) so the above function just won't
* compile correctly, for the moment just do this:
# define png_check_u16(pp, u) (u)
# define png_check_bits(pp, u, bits)\
(((1U<<(bits))-1) & png_bit_affirm((pp), PNG_SRC_LINE, (u), (bits)))
# define png_check_char(pp, c) (png_char_affirm((pp), PNG_SRC_LINE, (c)))
# define png_check_byte(pp, b) (png_byte_affirm((pp), PNG_SRC_LINE, (b)))
# define PNG_BYTE(b) ((png_byte)((b) & 0xFFU))
# define PNG_UINT_16(u) ((png_uint_16)((u) & 0xFFFFU))
#elif !(defined PNG_REMOVE_CASTS) /* && !RANGE_CHECK */
# define png_check_bits(pp, u, bits) (((1U<<(bits))-1U) & (u))
# define png_check_char(pp, c) ((char)(c))
# define png_check_byte(pp, b) ((png_byte)(b))
# define png_check_u16(pp, u) ((png_uint_16)(u))
# define PNG_BYTE(b) ((png_byte)((b) & 0xFFU))
# define PNG_UINT_16(u) ((png_uint_16)((u) & 0xFFFFU))
#else /* !RANGE_CHECK */
/* This is somewhat trust-me-it-works: if PNG_REMOVE_CASTS is defined then
* the casts, which might otherwise change the values, are completely
* removed. Use this to test your compiler to see if it makes *any*
* difference (code size or speed.) Currently NOT SUPPORTED.
* It also makes the PNG_BYTE and PNG_UINT_16 macros do nothing either
* NOTE: this seems safe at present but might lead to unexpected results
* if someone writes code to depend on the truncation.
# define png_check_bits(pp, u, bits) (u)
# define png_check_char(pp, c) (c)
# define png_check_byte(pp, b) (b)
# define png_check_u16(pp, u) (u)
# define PNG_BYTE(b) (b)
# define PNG_UINT_16(u) (u)
#endif /* RANGE_CHECK */
/* Safe calculation of a rowbytes value; does a png_error if the system limits
* are exceeded.
(png_const_structrp png_ptr, unsigned int pixel_depth,
png_uint_32 row_width),PNG_EMPTY);
/* Common code to calculate the maximum number of pixels to transform or filter
* at one time; controlled by PNG_ROW_BUFFER_SIZE above:
PNG_INTERNAL_FUNCTION(unsigned int,png_max_pixel_block,
(png_const_structrp png_ptr),PNG_EMPTY);
/* Copy the row in row_buffer; this is the non-interlaced copy used in both the
* read and write code. 'x_in_dest' specifies whether the 'x' applies to
* the destination (sp->dp[x], x_in_dest tru) or the source (sp[x]->dp,
* x_in_dest false).
PNG_INTERNAL_FUNCTION(void, png_copy_row,(png_const_structrp png_ptr,
png_bytep dp, png_const_bytep sp, png_uint_32 x/*in INPUT*/,
png_uint_32 width/*of INPUT*/, unsigned int pixel_depth,
int clear/*clear the final byte*/, int x_in_dest),PNG_EMPTY);
/* Zlib support */
PNG_INTERNAL_FUNCTION(void, png_zstream_error,(z_stream *zstream, int ret),
/* Used by the zlib handling functions to ensure that z_stream::msg is always
* set before they return.
(defined(PNG_gAMA_SUPPORTED) || defined(PNG_cHRM_SUPPORTED) || \
(defined(PNG_sCAL_SUPPORTED) && \
PNG_INTERNAL_FUNCTION(png_fixed_point,png_fixed,(png_const_structrp png_ptr,
double fp, png_const_charp text),PNG_EMPTY);
/* Internal base allocator - no messages, NULL on failure to allocate. This
* does, however, call the application provided allocator and that could call
* png_error (although that would be a bug in the application implementation.)
PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_base,(png_const_structrp png_ptr,
png_alloc_size_t size),PNG_ALLOCATED);
#if defined(PNG_TEXT_SUPPORTED) || defined(PNG_sPLT_SUPPORTED) ||\
/* Internal array allocator, outputs no error or warning messages on failure,
* just returns NULL.
PNG_INTERNAL_FUNCTION(png_voidp,png_malloc_array,(png_const_structrp png_ptr,
int nelements, size_t element_size),PNG_ALLOCATED);
/* The same but an existing array is extended by add_elements. This function
* also memsets the new elements to 0 and copies the old elements. The old
* array is not freed or altered.
PNG_INTERNAL_FUNCTION(png_voidp,png_realloc_array,(png_structrp png_ptr,
png_const_voidp array, int old_elements, int add_elements,
size_t element_size),PNG_ALLOCATED);
#endif /* text, sPLT or unknown chunks */
/* Magic to create a struct when there is no struct to call the user supplied
* memory allocators. Because error handling has not been set up the memory
* handlers can't safely call png_error, but this is an obscure and undocumented
* restriction so libpng has to assume that the 'free' handler, at least, might
* call png_error.
(png_const_charp user_png_ver, png_voidp error_ptr, png_error_ptr error_fn,
png_error_ptr warn_fn, png_voidp mem_ptr, png_malloc_ptr malloc_fn,
png_free_ptr free_fn),PNG_ALLOCATED);
/* Free memory from internal libpng struct */
PNG_INTERNAL_FUNCTION(void,png_destroy_png_struct,(png_structrp png_ptr),
/* Free an allocated jmp_buf (always succeeds) */
PNG_INTERNAL_FUNCTION(void,png_free_jmpbuf,(png_structrp png_ptr),PNG_EMPTY);
/* Function to allocate memory for zlib. PNGAPI is disallowed. */
PNG_INTERNAL_FUNCTION(voidpf,png_zalloc,(voidpf png_ptr, uInt items, uInt size),
/* Function to free memory for zlib. PNGAPI is disallowed. */
PNG_INTERNAL_FUNCTION(void,png_zfree,(voidpf png_ptr, voidpf ptr),PNG_EMPTY);
/* The next three functions are used by png_init_io to set the default
* implementations for reading or writing to a stdio (png_FILE_p) stream.
* They can't be static because in 1.7 png_init_io needs to reference them.
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_read_data,(png_structp png_ptr,
png_bytep data, png_size_t length),PNG_EMPTY);
# endif /* READ */
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_write_data,(png_structp png_ptr,
png_bytep data, png_size_t length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void PNGCBAPI,png_default_flush,(png_structp png_ptr),
# endif /* WRITE_FLUSH */
# endif /* WRITE */
#endif /* STDIO */
/* Reset the CRC variable. The CRC is initialized with the chunk tag (4 bytes).
* NOTE: at present png_struct::chunk_name MUST be set before this as well so
* that png_struct::current_crc is initialized correctly!
PNG_INTERNAL_FUNCTION(void,png_reset_crc,(png_structrp png_ptr,
png_const_bytep chunk_tag), PNG_EMPTY);
/* Write the "data" buffer to whatever output you are using */
PNG_INTERNAL_FUNCTION(void,png_write_data,(png_structrp png_ptr,
png_const_voidp data, png_size_t length),PNG_EMPTY);
/* Read and check the PNG file signature */
PNG_INTERNAL_FUNCTION(void,png_read_sig,(png_structrp png_ptr,
png_inforp info_ptr),PNG_EMPTY);
/* Read data from whatever input you are using into the "data" buffer */
PNG_INTERNAL_FUNCTION(void,png_read_data,(png_structrp png_ptr, png_voidp data,
png_size_t length),PNG_EMPTY);
/* Read bytes into buf, and update png_ptr->crc */
PNG_INTERNAL_FUNCTION(void,png_crc_read,(png_structrp png_ptr, png_voidp buf,
png_uint_32 length),PNG_EMPTY);
/* Read "skip" bytes, read the file crc, and (optionally) verify png_ptr->crc */
PNG_INTERNAL_FUNCTION(int,png_crc_finish,(png_structrp png_ptr,
png_uint_32 skip),PNG_EMPTY);
/* Calculate the CRC over a section of data. Note that we are only
* passing a maximum of 64K on systems that have this as a memory limit,
* since this is the maximum buffer size we can specify.
PNG_INTERNAL_FUNCTION(void,png_calculate_crc,(png_structrp png_ptr,
png_const_voidp ptr, png_size_t length),PNG_EMPTY);
/* Write various chunks */
/* Write the IHDR chunk, and update the png_struct with the necessary
* information.
PNG_INTERNAL_FUNCTION(void,png_write_IHDR,(png_structrp png_ptr,
png_uint_32 width, png_uint_32 height, int bit_depth, int color_type,
int compression_method, int filter_method, int interlace_method),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_PLTE,(png_structrp png_ptr,
png_const_colorp palette, unsigned int num_pal),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_IEND,(png_structrp png_ptr),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_gAMA_fixed,(png_structrp png_ptr,
png_fixed_point file_gamma),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_sBIT,(png_structrp png_ptr,
png_const_color_8p sbit, int color_type),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_cHRM_fixed,(png_structrp png_ptr,
const png_xy *xy), PNG_EMPTY);
/* The xy value must have been previously validated */
PNG_INTERNAL_FUNCTION(void,png_write_sRGB,(png_structrp png_ptr,
int intent),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_iCCP,(png_structrp png_ptr,
png_const_charp name, png_const_voidp profile), PNG_EMPTY);
/* The profile must have been previously validated for correctness, the
* length comes from the first four bytes. Only the base, deflate,
* compression is supported.
PNG_INTERNAL_FUNCTION(void,png_write_sPLT,(png_structrp png_ptr,
png_const_sPLT_tp palette),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_tRNS,(png_structrp png_ptr,
png_const_bytep trans, png_const_color_16p values, int number,
int color_type),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_bKGD,(png_structrp png_ptr,
png_const_color_16p values, int color_type),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_hIST,(png_structrp png_ptr,
png_const_uint_16p hist, int num_hist),PNG_EMPTY);
/* Chunks that have keywords */
PNG_INTERNAL_FUNCTION(void,png_write_tEXt,(png_structrp png_ptr,
png_const_charp key, png_const_charp text, png_size_t text_len),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_zTXt,(png_structrp png_ptr,
png_const_charp key, png_const_charp text, int compression),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_iTXt,(png_structrp png_ptr,
int compression, png_const_charp key, png_const_charp lang,
png_const_charp lang_key, png_const_charp text),PNG_EMPTY);
#ifdef PNG_TEXT_SUPPORTED /* Added at version 1.0.14 and 1.2.4 */
PNG_INTERNAL_FUNCTION(int,png_set_text_2,(png_structrp png_ptr,
png_inforp info_ptr, png_const_textp text_ptr, int num_text),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_oFFs,(png_structrp png_ptr,
png_int_32 x_offset, png_int_32 y_offset, int unit_type),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_pCAL,(png_structrp png_ptr,
png_charp purpose, png_int_32 X0, png_int_32 X1, int type, int nparams,
png_const_charp units, png_charpp params),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_pHYs,(png_structrp png_ptr,
png_uint_32 x_pixels_per_unit, png_uint_32 y_pixels_per_unit,
int unit_type),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_tIME,(png_structrp png_ptr,
png_const_timep mod_time),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_sCAL_s,(png_structrp png_ptr,
int unit, png_const_charp width, png_const_charp height),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_write_start_IDAT,(png_structrp png_ptr),
/* Do any required initialization before IDAT or row processing starts. */
/* Choose the best filter to use and filter the row data then write it out. If
* WRITE_FILTERING is not supported this just writes the data out with a zero
* (NONE) filter byte.
* This may be called multiple times per row, but calls must be in 'x' order;
* first a call with x 0 to mark the start of the row and, at the end, one with
* PNG_ROW_END set (this can be done in the same function call if the whole row
* is passed.) The following flags are used internally to control pass
* filtering and deflate:
png_pass_last =0x1U, /* This is the last pass in the image */
png_pass_last_row =0x2U, /* This is the last row in a pass */
png_pass_first_row =0x4U, /* This is the first row in a pass */
png_row_end =0x8U, /* This is the last block in the row */
png_no_row_info =0x0U /* Placeholder */
/* A useful macro; return true if this is the last block of the last row in
* the image.
# define PNG_IDAT_END(f) (((f) & ~png_pass_first_row) == \
PNG_INTERNAL_FUNCTION(void,png_write_png_data,(png_structrp png_ptr,
png_bytep prev_pixels, png_const_bytep unfiltered_row, png_uint_32 x,
unsigned int width/*pixels*/, unsigned int row_info_flags),
PNG_INTERNAL_FUNCTION(void,png_write_png_rows,(png_structrp png_ptr,
png_const_bytep *rows, png_uint_32 num_rows), PNG_EMPTY);
/* As above but rows[num_rows] of correctly (PNG) formated but unfiltered
* data are passed in. For an interlaced image the rows will be interlaced
* rows and therefore may be narrower than the image width.
* This function advances png_structp::pass and png_structp::row_number as
* required.
/* Release memory used by the deflate mechanism */
PNG_INTERNAL_FUNCTION(void, png_deflate_destroy, (png_structp png_ptr),
#endif /* WRITE */
PNG_INTERNAL_FUNCTION(void,png_transform_free,(png_const_structrp png_ptr,
png_transformp *list),PNG_EMPTY);
/* Free the entire transform list, from the given point on. the argument is
* set to NULL.
png_transform_controlp out, png_structp png_ptr),PNG_EMPTY);
/* Initialize a transform control for running the transform list forward (the
* read case, and write initialization, but the write case is called within
* pngtrans.c by the above function.)
PNG_INTERNAL_FUNCTION(unsigned int,png_run_this_transform_list_forwards,
(png_transform_controlp tc, png_transformp *start, png_transformp end),
/* Used by the transform cache code to run a sub-list, from *start to the
* transform end.
#endif /* READ_TRANSFORMS */
PNG_INTERNAL_FUNCTION(unsigned int,png_run_transform_list_forwards,
(png_structp png_ptr, png_transform_controlp tc),PNG_EMPTY);
/* Run the transform list in the forwards direction (from PNG format to
* memory format). The transform control must be initialized completely by
* the caller. This function takes account of transforms which delete
* themselves during the run; it must be used.
#endif /* READ */
(png_structp png_ptr, png_transform_controlp tc),PNG_EMPTY);
/* Run the transform list in the backwards direction (from memory format to
* PNG format). The transform control must be initialized completely by
* the caller. This function takes account of transforms which delete
* themselves during the run; it must be used.
#endif /* WRITE */
PNG_INTERNAL_FUNCTION(png_transformp,png_add_transform,(png_structrp png_ptr,
size_t size, png_transform_fn fn, unsigned int order),PNG_EMPTY);
/* Add a transform, using the information in 'order' to control the position
* of the transform in the list, returning a pointer to the transform. The
* top 8 bits of 'order' control the position in the list. If a transform
* does not already exist in the list with the given value a new transform
* will be created and 'fn' and 'order' set. If there is a transform with
* that value 'fn' must match and 'order' will be updated by combining the
* new value in with a bitwise or (|). It is up to the function (fn) or the
* caller of png_add_transform to determine whether the combination is valid.
* 'size' is used when creating a new transform, it may be larger than
* (sizeof png_transform) if required to accomodate extra data.
* Prior to 1.7.0 transforms were executed in an order hard-wired into the
* code that executed the transform functions. This was summarized in the
* read case by the following comment from pngrtran.c
* (png_init_read_transformations), note that this has been marked up to
* indicate which PNG formats the transforms in the list apply to:
* *: applies to most formats
* A: only formats with alpha
* L: only low-bit-depth (less than 8 bits per component/pixel)
* H: only high-bit-depth (16-bits per component)
> From the code of png_do_read_transformations the order is:
* GGRR For example column: . no action
* AGG r acts on read
* BB w acts on write
* A B acts on both read and write
> r.r. 1) PNG_EXPAND (including PNG_EXPAND_tRNS)
> .r.r 2) PNG_STRIP_ALPHA (if no compose)
> ..rr 3) PNG_RGB_TO_GRAY
> rrrr 5) PNG_COMPOSE
> rrrr 6) PNG_GAMMA
> .r.r 7) PNG_STRIP_ALPHA (if compose)
> rrrr 9) PNG_SCALE_16_TO_8
> rrrr 10) PNG_16_TO_8
> ..rr 11) PNG_QUANTIZE (converts to palette)
> rrrr 12) PNG_EXPAND_16
* Note that transforms from this point on are used in 1.7.0 on palette
* indices as well; a png_set_pack request (for example) packs the palette
* index values if the output will be palettized and the grayscale values
* if it will not be (if the output is low-bit-grayscale, not palette.)
> B... 17) PNG_PACK
> ..BB 18) PNG_BGR
> rwrw 20) PNG_FILLER (includes PNG_ADD_ALPHA)
> BBBB 23) PNG_USER_TRANSFORM [must be last]
* Finally, outside the set of transforms prior to 1.7.0, the libpng
* interlace handling required the pixels to be replicated to match the pixel
* spacing in the image row; the first part the pre-1.7.0 interlace support,
* this is still the case when reading, but for writing the interlace is now
* a transform:
> BBBB 24) png_do_{read,write}_interlace (interlaced images only).
* First transforms are grouped according to basic function using the top 3
* bits of the order code:
# define PNG_TR_START 0x0000U /* initial ops on the PNG data */
# define PNG_TR_ARITHMETIC 0x2000U /* arithmetic linear operations */
# define PNG_TR_CHANNEL 0x4000U /* PNG conformant format changes */
# define PNG_TR_QUANTIZE 0x6000U /* quantize and following operations */
# define PNG_TR_ENCODING 0x8000U /* Row encoding transforms */
# define PNG_TR_INTERLACE 0xA000U /* write interlace transform */
* In libpng 1.7.0 the check on palette index values is moved to the start
* (of read, end of write, which is where it was before) immediately after
* the MNG filter handling
/* Perform intra-pixel differencing (write) or un-differencing on read. */
/* Done before at the start on read, at the end on write to give a
* consistent postion:
* PNG_RWTR_CHECK_PALETTE PI W11: happens in pngwrite.c last
# define PNG_TR_START_CACHE (PNG_TR_START + 0x0300U)
/* Not used on a transform; this is just a marker for the point at which
* palette or low-bit-depth caching can start on read. (The previous
* operations cannot be cached).
# define PNG_TR_INIT_ALPHA (PNG_TR_START + 0x0400U)
/* This just handles alpha/tRNS initialization issues to resolve the
* inter-dependencies with tRNS expansion and background composition; it
* doesn't do anything itself, just sets flags and pushes transforms.
* Prior to 1.7 the arithmetic operations interleaved with the RGB-to-gray
* and alpha strip byte level ops. This was done to reduce the amount of
* data processed, i.e. it was an optimization not a requirement. These
* operations were preceded by the 'expand' operations, which is the
* opposite; it was done to simplify the code and actually slows things down
* in the low bit depth gray case. The full list of operations after expand,
* in the 1.6 order, is:
* PNG_TR_STRIP_ALPHA png_do_strip_channel (sometimes)
* PNG_TR_RGB_TO_GRAY png_do_rgb_to_gray
* PNG_TR_GRAY_TO_RGB png_do_gray_to_rgb (sometimes)
* PNG_TR_COMPOSE png_do_compose
* PNG_TR_GAMMA png_do_gamma (if no RGB_TO_GRAY)
* PNG_TR_STRIP_ALPHA png_do_strip_channel (other times)
* PNG_TR_ENCODE_ALPHA png_do_encode_alpha
* In 1.7 the operations are moved round somewhat, including moving alpha and
* 16-to-8 bit reduction later. This leaves the following operations:
* PNG_TR_RGB_TO_GRAY png_do_rgb_to_gray
* PNG_TR_COMPOSE png_do_compose
* PNG_TR_GAMMA png_do_gamma (if no RGB_TO_GRAY)
* PNG_TR_ENCODE_ALPHA png_do_encode_alpha
* Prior to 1.7 some combinations of transforms would do gamma correction
* twice, the actual implementation in 1.7 is to use the following order and
* rely on the cache code to optimize gray 1,2,4,8 and (of course) palette.
/* Handle background composition. This may need to push a gray-to-rgb
* transform if the background is RGB for gray input. This precedes RGB
* to gray convertion so that it can handle tRNS appropriately when the
* background is in the PNG encoding however, typically, the processing
* happens at PNG_TR_COMPOSE_ALPHA below.
* NOTE: this must be the first arithmetic transform because the code in
* png_init_background relies on png_transform_control::gamma being the
* original PNG gamma.
# define PNG_TR_RGB_TO_GRAY (PNG_TR_ARITHMETIC + 0x0200U) /* to gray */
/* Convert any RGB input (8/16 bit depth, RGB, RGBA) to linear gray
* 16-bit. This happens first because it cannot be cached; the input data
* has 24 or 48 bits of uncorrelated data so the transform has to happen
* pixel-by-pixel. Internally the transform may maintain an 8 or 16-bit
* gamma correction table (to 16-bit linear) to speed things up.
* NOTE: this transform must follow PNG_TR_COMPOSE with no intervening
* transforms; see the code in png_init_background (pngrtran.c) which
* relies on this during PNG_TC_INIT_FORMAT.
/* Compose alpha composition and tRNS handling when the background is a
* screen color. Pushed by PNG_TR_COMPOSE as required.
# define PNG_TR_GAMMA_ENCODE (PNG_TR_ARITHMETIC + 0x1F00U) /* last */
/* Gamma encode the input. This encodes the gray or RGB channels to the
* required bit depth and either scales the alpha channel or encodes it as
* well, depending on the requested alpha encoding.
* The 'expand' operations come after the arithmetic ones in libpng 1.7, this
* forces the arithmetic stuff to do the expand, but since arithmetic is (in
* 1.7) normally done in 16-bit linear this avoids spurious expands.
# define PNG_TR_EXPAND (PNG_TR_CHANNEL + 0x0100U)
/* Includes:
* PNG_TR_EXPAND_PALETTE palette images only, includes tRNS
* PNG_TR_EXPAND_LBP_GRAY grayscale low-bit depth only
* PNG_TR_EXPAND_tRNS non-palette images only
# define PNG_TR_SCALE_16_TO_8 (PNG_TR_CHANNEL + 0x0200U)
/* Comes after the expand and before the chop version; note that it works on
* the pixel values directly, so it is a linear transform on a non-linear
* value.
* To handle transforms that affect the palette entries, not the palette
* indices in the row data, libpng 1.7 reorders some of the post-quantize
* transformations to put all the "PC" transforms ahead of all the "PI"
* transforms. The "PC" transforms that came after png_do_quantize in libpng
* 1.6 cannot be ordered to be before so they are included in the
* PNG_TR_QUANTIZE section. The PI transforms are all in PNG_TR_ENCODING,
* PNG_GRAY_TO_RGB is moved before PNG_TR_QUANTIZE to avoid the unpredictable
* behavior of png_set_quantize that otherwise arises.
* The transforms in the PNG_TR_QUANTIZE section are:
* PNG_RWTR_INVERT_MONO !P W10: invert the gray channel
* PNG_RWTR_INVERT_ALPHA PC W8: invert the alpha channel
* PNG_RWTR_SHIFT PC W6: read: down, write: scale up
* PNG_RWTR_FILLER !P W2: add on R, remove on W
* The ones in PNG_TR_ENCODING are:
* PNG_RWTR_PACK PI W4: R: unpack bytes, W: pack
* PNG_RWTR_PIXEL_SWAP PI W3: Swap pixels in a byte
/* The channel swap transforms that must happen before PNG_TR_QUANTIZE:
/* The post-quantize channel swap transforms:
* PNG_RWTR_FILLER !P W2: (filler) add on R, remove on W
* The 'CHANNEL' operation sets the transform_control channel_add flag for
* use below.
# define PNG_TR_INVERT (PNG_TR_QUANTIZE + 0x0200U)
/* Invert MONO and ALPHA. If the channel_add flag is set in the transform
* control INVERT_ALPHA will not be done; the png_add_alpha/filler APIs
* happened after png_set_invert_alpha in earlier versions so the filler
* value had to include the invert.
* PNG_RWTR_INVERT_MONO !P W10: invert the gray channel
* PNG_RWTR_INVERT_ALPHA PC W8: invert the alpha channel
# define PNG_TR_SHIFT (PNG_TR_QUANTIZE + 0x0300U)
/* The channel shift, except that if the channel_add flag has been set the
* alpha channel is not shifted.
* PNG_RWTR_SHIFT PC W6: read: down, write: scale up
# define PNG_TR_PACK (PNG_TR_ENCODING + 0x0200U)
/* PNG_RWTR_PACK PI W4: R: unpack bytes, W: pack */
/* PNG_RWTR_PIXEL_SWAP PI W3: Swap pixels in a byte */
# define PNG_TR_USER (PNG_TR_ENCODING + 0x1F00U)
/* The user transform; must be last before the interlace handling because it
* does unpredictable things to the format.
PNG_INTERNAL_FUNCTION(png_transformp,png_push_transform,(png_structrp png_ptr,
size_t size, png_transform_fn fn, png_transformp *transform,
png_transform_controlp tc),PNG_EMPTY);
/* As png_add_transform except that the new transform is inserted ahead of
* the given transform (*transform). The new transform is returned, but it
* will also invariably be in *transform. If 'tc' is not NULL the transform
* callback will also be called; it needs to be called if this function is
* called while transforms are being run.
* 'fn' must not be NULL.
* The transform is inserted with the same 'order' as the passed in
* *transform, that transform and following transforms are moved up ('order'
* is incremented) as required to make space. Consequently, unlike with
* png_add_transform, the transform will always be new. To detect loops
* (*transform)->fn must not be the same as the passed in 'fn'.
(png_const_structp png_ptr, unsigned int src_line, png_transformp tr,
size_t size),PNG_EMPTY);
/* Given a pointer to a transform, 'tr' validate that the underlying derived
* class has size 'size' using the tr->size field and return the same
* pointer. If there is a size mismatch the function does an affirm using
* the given line number.
#define png_transform_cast(type, pointer) png_voidcast(type*,\
png_transform_cast_check(png_ptr, PNG_SRC_LINE, (pointer), sizeof (type)))
/* This takes a pointer to a transform and safely returns a pointer to a
* derived transform class (type); type must not have the pointer. It
* validates the 'size' field. Derived classes start with a png_transform
* as the first member called 'tr'.
/* Remove a transform from a list, moving the next transform down into
* *transform.
PNG_INTERNAL_FUNCTION(void,png_remove_transform,(png_const_structp png_ptr,
png_transformp *transform),PNG_EMPTY);
/* Initializer for read transforms that handles caching, palette update and
* palette expansion.
PNG_INTERNAL_FUNCTION(unsigned int,png_read_init_transform_mech,
(png_structp png_ptr, png_transform_control *tc),PNG_EMPTY);
/* Optional call to update the users info structure */
PNG_INTERNAL_FUNCTION(void,png_read_transform_info,(png_structrp png_ptr,
png_inforp info_ptr),PNG_EMPTY);
/* APIs which do a tranform on both read and write but where the implementation
* is separate for each; the read and write init functions are in pngrtran.c or
* pngwtran.c, the API is in pngtrans.c
PNG_INTERNAL_FUNCTION(void,png_init_read_pack,(png_transformp *transform,
png_transform_controlp tc),PNG_EMPTY);
#endif /* READ_PACK || READ_EXPAND */
PNG_INTERNAL_FUNCTION(void,png_init_write_pack,(png_transformp *transform,
png_transform_controlp tc),PNG_EMPTY);
#endif /* WRITE_PACK */
/* Shared transform functions, defined in pngtran.c */
png_transform_controlp row_info, png_bytep row, int at_start),PNG_EMPTY);
#endif /* FILLER */
PNG_INTERNAL_FUNCTION(void,png_do_invert,(png_transform_controlp row_info,
png_bytep row),PNG_EMPTY);
#endif /* INVERT */
PNG_INTERNAL_FUNCTION(void,png_do_invert_alpha,(png_transform_controlp row_info,
png_bytep row),PNG_EMPTY);
#endif /* INVERT_ALPHA */
PNG_INTERNAL_FUNCTION(void,png_add_rgb_to_gray_byte_ops,(png_structrp png_ptr,
png_transform_controlp tc, unsigned int index, unsigned int order),
/* This is an init-time utility to add appropriate byte ops to select a given
* channel from R/G/B.
#endif /* READ_RGB_TO_GRAY */
PNG_INTERNAL_FUNCTION(void,png_push_gray_to_rgb_byte_ops,(png_transformp *tr,
png_transform_controlp tc), PNG_EMPTY);
/* This is an init-time utility to push appropriate byte ops to expand a
* grayscale PNG data set to RGB. It calls the function callback so 'tc'
* must be non-NULL.
PNG_INTERNAL_FUNCTION(void,png_add_strip_alpha_byte_ops,(png_structrp png_ptr),
/* Called from pngrtran.c to add the relevant byte op. */
#endif /* READ_STRIP_ALPHA */
/* The following decodes the appropriate chunks, and does error correction,
* then calls the appropriate callback for the chunk if it is valid.
PNG_INTERNAL_FUNCTION(png_bytep,png_read_buffer,(png_structrp png_ptr,
png_alloc_size_t new_size, int warn),PNG_EMPTY);
/* Manage the dynamically allocated read buffer */
/* Shared READ IDAT handling: */
PNG_INTERNAL_FUNCTION(void,png_read_start_IDAT,(png_structrp png_ptr),
/* Initialize the row buffers, etc. */
typedef enum
/* more IDAT data needed for row */
/* png_struct::row_buffer contains a complete row */
/* row not in this pass, but the existing row may be used */
/* row not in pass and no appropriate data; skip this row */
} png_row_op;
PNG_INTERNAL_FUNCTION(png_row_op,png_read_process_IDAT,(png_structrp png_ptr,
png_bytep transformed_row, png_bytep display_row, int save_row),
/* Process a block of IDAT data; the routine returns early if it has
* obtained a row. It is valid to call this routine with no input data;
* it will return png_row_incomplete if it needs input.
* transformed_row: The transformed pixels of the input are written here.
* For interlaced images only the pixels in the pass will
* be written, the other pixels will not be touched.
* display_row: The transformed pixels but replicated to that the entire
* buffer will have been initialized. For passes after the
* first the pixels written are determined by the 'block'
* algorithm; only those *following* pixels which are
* written by *later* passes are written (with a copy of the
* pixel from the pass.)
* save_row: A boolean which indicates that the row (unexpanded)
* should be saved in png_struct::transformed_row. This can
* be used in a later call to png_combine_row.
* During reading the row is built up until png_row_process is returned. At
* this point png_struct::row_buffer contains the original PNG row from the
* file and, if save_row was set, png_struct::transformed_row contains the
* row after the selected row transforms have been performed. For interlaced
* images both are the width of the interlace pass.
* When png_row_repeat is returned the same is true, except that the buffers
* still contain the contents of the preceding row (the one where this
* funciton returned png_row_pricess).
* The row buffers should not be accessed if png_row_skip is returned; this
* row is not modified in the current pass.
PNG_INTERNAL_FUNCTION(void,png_read_free_row_buffers,(png_structrp png_ptr),
/* Free allocated row buffers; done as soon as possible to avoid carrying
* around all the memory for longer than necessary.
PNG_INTERNAL_FUNCTION(int,png_read_finish_IDAT,(png_structrp png_ptr),
/* Complete reading of the IDAT chunks. This returns 0 if more data is to
* be read, 1 if the zlib stream has terminated. Call this routine with
* zstream.avail_in greater than zero unless there is no more input data.
* When zstream_avail_in is 0 on entry and the stream does not terminate
* an "IDAT truncated" error will be output.
* ENTRY: png_ptr->zstream.{next,avail}_in points to more IDAT data, if
* available, otherwise avail_in should be 0.
* RET 0: the LZ stream is still active, more IDAT date is required, if
* available, the routine *must* be called again.
* RET 1: the LZ stream has been closed and an error may have been output;
* png_ptr->zstream_error says whether it has. If not and there
* is more IDAT data available the caller should output an
* appropriate (too much IDAT) error message.
PNG_INTERNAL_FUNCTION(void,png_cache_known_unknown,(png_structrp png_ptr,
png_const_bytep add, int keep),PNG_EMPTY);
/* Update the png_struct::known_unknown bit cache which stores whether each
* known chunk should be treated as unknown.
typedef enum
png_chunk_skip = 0, /* Skip this chunk */
png_chunk_unknown, /* Pass the chunk to png_handle_unknown */
png_chunk_process_all, /* Process the chunk all at once */
png_chunk_process_part /* Process the chunk in parts (for IDAT) */
} png_chunk_op;
PNG_INTERNAL_FUNCTION(png_chunk_op,png_find_chunk_op,(png_structrp png_ptr),
/* Given a chunk in png_struct::{chunk_name,chunk_length} validate the name
* and work out how it should be handled. This function checks the chunk
* location using png_struct::mode and will set the mode appropriately for
* the known critical chunks but otherwise makes no changes to the stream
* read state.
PNG_INTERNAL_FUNCTION(void,png_check_chunk_name,(png_const_structrp png_ptr,
const png_uint_32 chunk_name),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_check_chunk_length,(png_const_structrp png_ptr,
const png_uint_32 chunk_length),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_handle_unknown,(png_structrp png_ptr,
png_inforp info_ptr, png_bytep chunk_data),PNG_EMPTY);
/* Handle an unknown chunk that needs to be processed. It is only valid
* to call this after png_find_chunk_op returns png_chunk_unknown. The
* data argument points to the png_struct::chunk_length bytes of the chunk
* data.
PNG_INTERNAL_FUNCTION(void,png_handle_chunk,(png_structrp png_ptr,
png_inforp info_ptr),PNG_EMPTY);
/* The chunk to handle is in png_struct::chunk_name,chunk_length.
* NOTE: at present it is only valid to call this after png_find_chunk_op
* has returned png_chunk_process_all and all the data is available for
* png_handle_chunk (via the libpng read callback.)
#endif /* READ */
PNG_INTERNAL_FUNCTION(void,png_init_row_info,(png_structrp png_ptr),PNG_EMPTY);
/* Set the png_struct::row_ members from the PNG file information, running
* transforms if required.
/* Added at libpng version 1.6.0 */
PNG_INTERNAL_FUNCTION(void,png_colorspace_set_gamma,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_fixed_point gAMA), PNG_EMPTY);
/* Set the colorspace gamma with a value provided by the application or by
* the gAMA chunk on read. The value will override anything set by an ICC
* profile.
PNG_INTERNAL_FUNCTION(void,png_colorspace_sync_info,(png_const_structrp png_ptr,
png_inforp info_ptr), PNG_EMPTY);
/* Synchronize the info 'valid' flags with the colorspace */
PNG_INTERNAL_FUNCTION(void,png_colorspace_sync,(png_const_structrp png_ptr,
png_inforp info_ptr), PNG_EMPTY);
/* Copy the png_struct colorspace to the info_struct and call the above to
* synchronize the flags. Checks for NULL info_ptr and does nothing.
/* Added at libpng version 1.4.0 */
/* These internal functions are for maintaining the colorspace structure within
* a png_info or png_struct (or, indeed, both).
(png_const_structrp png_ptr, png_colorspacerp colorspace, const png_xy *xy,
int preferred), PNG_EMPTY);
(png_const_structrp png_ptr, png_colorspacerp colorspace, const png_XYZ *XYZ,
int preferred), PNG_EMPTY);
PNG_INTERNAL_FUNCTION(int,png_colorspace_set_sRGB,(png_const_structrp png_ptr,
png_colorspacerp colorspace, int intent), PNG_EMPTY);
/* This does set the colorspace gAMA and cHRM values too, but doesn't set the
* flags to write them, if it returns false there was a problem and an error
* message has already been output (but the colorspace may still need to be
* synced to record the invalid flag).
#endif /* sRGB */
PNG_INTERNAL_FUNCTION(int,png_colorspace_set_ICC,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_charp name,
png_uint_32 profile_length, png_const_bytep profile, int is_color),
/* The 'name' is used for information only */
/* Routines for checking parts of an ICC profile. */
PNG_INTERNAL_FUNCTION(int,png_icc_check_length,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_charp name,
png_uint_32 profile_length), PNG_EMPTY);
PNG_INTERNAL_FUNCTION(int,png_icc_check_header,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_charp name,
png_uint_32 profile_length,
png_const_bytep profile /* first 132 bytes only */, int is_color),
PNG_INTERNAL_FUNCTION(int,png_icc_check_tag_table,(png_const_structrp png_ptr,
png_colorspacerp colorspace, png_const_charp name,
png_uint_32 profile_length,
png_const_bytep profile /* header plus whole tag table */), PNG_EMPTY);
png_const_structrp png_ptr, png_colorspacerp colorspace,
png_const_bytep profile, uLong adler), PNG_EMPTY);
/* 'adler' is the Adler32 checksum of the uncompressed profile data. It may
* be zero to indicate that it is not available. It is used, if provided,
* as a fast check on the profile when checking to see if it is sRGB.
#endif /* sRGB */
#endif /* iCCP */
#endif /* COLORSPACE */
/* Added at libpng version 1.4.0 */
PNG_INTERNAL_FUNCTION(void,png_check_IHDR,(png_const_structrp png_ptr,
png_uint_32 width, png_uint_32 height, int bit_depth,
int color_type, int interlace_type, int compression_type,
int filter_type),PNG_EMPTY);
PNG_INTERNAL_FUNCTION(void,png_fixed_error,(png_const_structrp png_ptr,
png_const_charp name),PNG_NORETURN);
/* Puts 'string' into 'buffer' at buffer[pos], taking care never to overwrite
* the end. Always leaves the buffer nul terminated. Never errors out (and
* there is no error code.)
PNG_INTERNAL_FUNCTION(size_t,png_safecat,(png_charp buffer, size_t bufsize,
size_t pos, png_const_charp string),PNG_EMPTY);
/* Various internal functions to handle formatted warning messages, currently
* only implemented for warnings.
/* Utility to dump an unsigned value into a buffer, given a start pointer and
* and end pointer (which should point just *beyond* the end of the buffer!)
* Returns the pointer to the start of the formatted string. This utility only
* does unsigned values.
PNG_INTERNAL_FUNCTION(png_charp,png_format_number,(png_const_charp start,
png_charp end, int format, png_alloc_size_t number),PNG_EMPTY);
/* Convenience macro that takes an array: */
#define PNG_FORMAT_NUMBER(buffer,format,number) \
png_format_number(buffer, buffer + (sizeof buffer), format, number)
/* Suggested size for a number buffer (enough for 64 bits and a sign!) */
/* These are the integer formats currently supported, the name is formed from
* the standard printf(3) format string.
#define PNG_NUMBER_FORMAT_u 1 /* chose unsigned API! */
#define PNG_NUMBER_FORMAT_02u 2
#define PNG_NUMBER_FORMAT_d 1 /* chose signed API! */
#define PNG_NUMBER_FORMAT_02d 2
#define PNG_NUMBER_FORMAT_02x 4
#define PNG_NUMBER_FORMAT_fixed 5 /* choose the signed API */
/* New defines and members adding in libpng-1.5.4 */
# define PNG_WARNING_PARAMETER_COUNT 8 /* Maximum 9; see pngerror.c */
/* An l-value of this type has to be passed to the APIs below to cache the
* values of the parameters to a formatted warning message.
typedef char png_warning_parameters[PNG_WARNING_PARAMETER_COUNT][
PNG_INTERNAL_FUNCTION(void,png_warning_parameter,(png_warning_parameters p,
int number, png_const_charp string),PNG_EMPTY);
/* Parameters are limited in size to PNG_WARNING_PARAMETER_SIZE characters,
* including the trailing '\0'.
(png_warning_parameters p, int number, int format, png_alloc_size_t value),
/* Use png_alloc_size_t because it is an unsigned type as big as any we
* need to output. Use the following for a signed value.
(png_warning_parameters p, int number, int format, png_int_32 value),
PNG_INTERNAL_FUNCTION(void,png_formatted_warning,(png_const_structrp png_ptr,
png_warning_parameters p, png_const_charp message),PNG_EMPTY);
/* 'message' follows the X/Open approach of using @1, @2 to insert
* parameters previously supplied using the above functions. Errors in
* specifying the parameters will simply result in garbage substitutions.
/* Application errors (new in 1.6); use these functions (declared below) for
* errors in the parameters or order of API function calls on read. The
* 'warning' should be used for an error that can be handled completely; the
* 'error' for one which can be handled safely but which may lose application
* information or settings.
* By default these both result in a png_error call prior to release, while in a
* released version the 'warning' is just a warning. However if the application
* explicitly disables benign errors (explicitly permitting the code to lose
* information) they both turn into warnings.
* If benign errors aren't supported they end up as the corresponding base call
* (png_warning or png_error.)
PNG_INTERNAL_FUNCTION(void,png_app_warning,(png_const_structrp png_ptr,
png_const_charp message),PNG_EMPTY);
/* The application provided invalid parameters to an API function or called
* an API function at the wrong time, libpng can completely recover.
PNG_INTERNAL_FUNCTION(void,png_app_error,(png_const_structrp png_ptr,
png_const_charp message),PNG_EMPTY);
/* As above but libpng will ignore the call, or attempt some other partial
* recovery from the error.
# define png_app_warning(pp,s) png_warning(pp,s)
# define png_app_error(pp,s) png_error(pp,s)
PNG_INTERNAL_FUNCTION(void,png_chunk_report,(png_const_structrp png_ptr,
png_const_charp message, int error),PNG_EMPTY);
/* Report a recoverable issue in chunk data. On read this is used to report
* a problem found while reading a particular chunk and the
* png_chunk_benign_error or png_chunk_warning function is used as
* appropriate. On write this is used to report an error that comes from
* data set via an application call to a png_set_ API and png_app_error or
* png_app_warning is used as appropriate.
* With PNG_CHUNK_FATAL an error can be marked as unrecoverable, and the
* function will not return.
* The 'error' parameter must have one of the following values:
#define PNG_CHUNK_WARNING 0 /* never an error */
#define PNG_CHUNK_WRITE_ERROR 1 /* an error only on write */
#define PNG_CHUNK_ERROR 2 /* always an error */
#define PNG_CHUNK_FATAL 3 /* an unrecoverable error */
# define png_chunk_report(pp,e,v) png_chunk_report(pp,NULL,v)
/* ASCII to FP interfaces, currently only implemented if sCAL
* support is required.
#if defined(PNG_sCAL_SUPPORTED)
/* MAX_DIGITS is actually the maximum number of characters in an sCAL
* width or height, derived from the precision (number of significant
* digits - a build time settable option) and assumptions about the
* maximum ridiculous exponent.
#define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)
PNG_INTERNAL_FUNCTION(void,png_ascii_from_fp,(png_const_structrp png_ptr,
png_charp ascii, png_size_t size, double fp, unsigned int precision),
#endif /* FLOATING_POINT */
PNG_INTERNAL_FUNCTION(void,png_ascii_from_fixed,(png_const_structrp png_ptr,
png_charp ascii, png_size_t size, png_fixed_point fp),PNG_EMPTY);
#endif /* FIXED_POINT */
#endif /* sCAL */
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
/* An internal API to validate the format of a floating point number.
* The result is the index of the next character. If the number is
* not valid it will be the index of a character in the supposed number.
* The format of a number is defined in the PNG extensions specification
* and this API is strictly conformant to that spec, not anyone elses!
* The format as a regular expression is:
* [+-]?[0-9]+.?([Ee][+-]?[0-9]+)?
* or:
* [+-]?.[0-9]+(.[0-9]+)?([Ee][+-]?[0-9]+)?
* The complexity is that either integer or fraction must be present and the
* fraction is permitted to have no digits only if the integer is present.
* NOTE: The dangling E problem.
* There is a PNG valid floating point number in the following:
* PNG floating point numbers are not greedy.
* Working this out requires *TWO* character lookahead (because of the
* sign), the parser does not do this - it will fail at the 'r' - this
* doesn't matter for PNG sCAL chunk values, but it requires more care
* if the value were ever to be embedded in something more complex. Use
* ANSI-C strtod if you need the lookahead.
/* State table for the parser. */
#define PNG_FP_INTEGER 0 /* before or in integer */
#define PNG_FP_FRACTION 1 /* before or in fraction */
#define PNG_FP_EXPONENT 2 /* before or in exponent */
#define PNG_FP_STATE 3 /* mask for the above */
#define PNG_FP_SAW_SIGN 4 /* Saw +/- in current state */
#define PNG_FP_SAW_DIGIT 8 /* Saw a digit in current state */
#define PNG_FP_SAW_DOT 16 /* Saw a dot in current state */
#define PNG_FP_SAW_E 32 /* Saw an E (or e) in current state */
#define PNG_FP_SAW_ANY 60 /* Saw any of the above 4 */
/* These three values don't affect the parser. They are set but not used.
#define PNG_FP_WAS_VALID 64 /* Preceding substring is a valid fp number */
#define PNG_FP_NEGATIVE 128 /* A negative number, including "-0" */
#define PNG_FP_NONZERO 256 /* A non-zero value */
#define PNG_FP_STICKY 448 /* The above three flags */
/* This is available for the caller to store in 'state' if required. Do not
* call the parser after setting it (the parser sometimes clears it.)
#define PNG_FP_INVALID 512 /* Available for callers as a distinct value */
/* Result codes for the parser (boolean - true meants ok, false means
* not ok yet.)
#define PNG_FP_MAYBE 0 /* The number may be valid in the future */
#define PNG_FP_OK 1 /* The number is valid */
/* Tests on the sticky non-zero and negative flags. To pass these checks
* the state must also indicate that the whole number is valid - this is
* achieved by testing PNG_FP_SAW_DIGIT (see the implementation for why this
* is equivalent to PNG_FP_OK above.)
/* NZ_MASK: the string is valid and a non-zero negative value */
/* Z MASK: the string is valid and a non-zero value. */
/* PNG_FP_SAW_DIGIT: the string is valid. */
#define PNG_FP_IS_ZERO(state) (((state) & PNG_FP_Z_MASK) == PNG_FP_SAW_DIGIT)
#define PNG_FP_IS_POSITIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_Z_MASK)
#define PNG_FP_IS_NEGATIVE(state) (((state) & PNG_FP_NZ_MASK) == PNG_FP_NZ_MASK)
/* The actual parser. This can be called repeatedly. It updates
* the index into the string and the state variable (which must
* be initialized to 0). It returns a result code, as above. There
* is no point calling the parser any more if it fails to advance to
* the end of the string - it is stuck on an invalid character (or
* terminated by '\0').
* Note that the pointer will consume an E or even an E+ and then leave
* a 'maybe' state even though a preceding integer.fraction is valid.
* The PNG_FP_WAS_VALID flag indicates that a preceding substring was
* a valid number. It's possible to recover from this by calling
* the parser again (from the start, with state 0) but with a string
* that omits the last character (i.e. set the size to the index of
* the problem character.) This has not been tested within libpng.
PNG_INTERNAL_FUNCTION(int,png_check_fp_number,(png_const_charp string,
png_size_t size, int *statep, png_size_tp whereami),PNG_EMPTY);
/* This is the same but it checks a complete string and returns true
* only if it just contains a floating point number. As of 1.5.4 this
* function also returns the state at the end of parsing the number if
* it was valid (otherwise it returns 0.) This can be used for testing
* for negative or zero values using the sticky flag.
PNG_INTERNAL_FUNCTION(int,png_check_fp_string,(png_const_charp string,
png_size_t size),PNG_EMPTY);
#endif /* pCAL || sCAL */
#if defined(PNG_GAMMA_SUPPORTED) ||\
/* Added at libpng version 1.5.0 */
/* This is a utility to provide a*times/div (rounded) and indicate
* if there is an overflow. The result is a boolean - false (0)
* for overflow, true (1) if no overflow, in which case *res
* holds the result.
PNG_INTERNAL_FUNCTION(int,png_muldiv,(png_fixed_point_p res, png_fixed_point a,
png_int_32 multiplied_by, png_int_32 divided_by),PNG_EMPTY);
/* Internal fixed point gamma correction. These APIs are called as
* required to convert single values - they don't need to be fast,
* they are not used when processing image pixel values.
PNG_INTERNAL_FUNCTION(unsigned int,png_gamma_nxmbit_correct,
(unsigned int value, png_fixed_point gamma_val, unsigned int n/*input bits*/,
unsigned int m/*output bits */),PNG_EMPTY);
/* In this case the value must have 'n' bits and the output will have 'm'
* bits.
PNG_INTERNAL_FUNCTION(int,png_gamma_check,(png_const_structrp png_ptr,
png_const_transform_controlp tc),PNG_EMPTY);
/* Debugging only routine to repeat the test used above to determine if the
* gamma was insignificant.
#endif /* !RELEASE_BUILD */
#endif /* READ_GAMMA */
/* Internal check function to saw if the gamma of the PNG data is far enough
* from the given screen gamma to require gamma correction (only needed for a
* bug work-round in the simplified API).
* TODO: it should be possible to remove the bug work-round in 1.7
PNG_INTERNAL_FUNCTION(int,png_need_gamma_correction,(png_const_structrp png_ptr,
png_fixed_point gamma, int sRGB_output),PNG_EMPTY);
#endif /* SIMPLIFIED_READ */
/* This is a utility macro to say whether a gamma value is close enough to sRGB.
* The test is now hardwired:
* API CHANGE: prior to 1.7 this would depend on the build-time
* PNG_GAMMA_THRESHOLD_FIXED setting, which would cause inconsistent results
* when the setting was changed. Since this setting can now be changed at
* run-time it seems more sensible to have a single fixed definition of 'sRGB'.
* The test is approximately +/- 1%, it allows any decimal value from 0.45 (the
* two digit rounded version of 1/2.2) to just under 0.46).
#define PNG_GAMMA_IS_sRGB(g) ((g) >= 45000 && (g) < 46000)
/* The internal structure that png_image::opaque points to. */
typedef struct png_control
png_structp png_ptr;
png_infop info_ptr;
png_voidp error_buf; /* Always a jmp_buf at present. */
png_const_bytep memory; /* Memory buffer. */
png_size_t size; /* Size of the memory buffer. */
unsigned int for_write :1; /* Otherwise it is a read structure */
unsigned int owned_file :1; /* We own the file in io_ptr */
} png_control;
/* Return the pointer to the jmp_buf from a png_control: necessary because C
* does not reveal the type of the elements of jmp_buf.
#ifdef __cplusplus
# define png_control_jmp_buf(pc) (((jmp_buf*)((pc)->error_buf))[0])
# define png_control_jmp_buf(pc) ((pc)->error_buf)
/* Utility to safely execute a piece of libpng code catching and logging any
* errors that might occur. Returns true on success, false on failure (either
* of the function or as a result of a png_error.)
PNG_INTERNAL_CALLBACK(void,png_safe_error,(png_structp png_ptr,
png_const_charp error_message),PNG_NORETURN);
PNG_INTERNAL_CALLBACK(void,png_safe_warning,(png_structp png_ptr,
png_const_charp warning_message),PNG_EMPTY);
# define png_safe_warning 0/*dummy argument*/
PNG_INTERNAL_FUNCTION(int,png_safe_execute,(png_imagep image,
int (*function)(png_voidp), png_voidp arg),PNG_EMPTY);
/* Utility to log an error; this also cleans up the png_image; the function
* always returns 0 (false).
PNG_INTERNAL_FUNCTION(int,png_image_error,(png_imagep image,
png_const_charp error_message),PNG_EMPTY);
/* Safely initialize a stdio pointer - used by both the read and the write
* code.
PNG_INTERNAL_FUNCTION(int,png_image_init_io,(png_imagep image, png_FILE_p file),
#endif /* STDIO */
/* png_image_free is used by the write code but not exported */
PNG_INTERNAL_FUNCTION(void, png_image_free, (png_imagep image), PNG_EMPTY);
#endif /* !SIMPLIFIED_READ */
PNG_INTERNAL_FUNCTION(png_int_32, png_read_setting, (png_structrp png_ptr,
png_uint_32 setting, png_uint_32 parameter, png_int_32 value), PNG_EMPTY);
#endif /* READ */
PNG_INTERNAL_FUNCTION(png_int_32, png_write_setting, (png_structrp png_ptr,
png_uint_32 setting, png_uint_32 parameter, png_int_32 value), PNG_EMPTY);
/* Implementations of read and write settings, in pngrutil.c and pngwutil.c
* respectively.
#endif /* WRITE */
/* Maintainer: Put new private prototypes here ^ */
/* These are initialization functions for hardware specific PNG filter
* optimizations; list these here then select the appropriate one at compile
* time using the macro PNG_FILTER_OPTIMIZATIONS. If the macro is not defined
* the generic code is used.
unsigned int bpp), PNG_EMPTY);
/* Just declare the optimization that will be used */
/* List *all* the possible optimizations here - this branch is required if
* the builder of libpng passes the definition of PNG_FILTER_OPTIMIZATIONS in
* CFLAGS in place of CPPFLAGS *and* uses symbol prefixing.
PNG_INTERNAL_FUNCTION(void, png_init_filter_functions_neon,
(png_structp png_ptr, unsigned int bpp), PNG_EMPTY);
#include "pngdebug.h"
#ifdef __cplusplus
#endif /* PNGPRIV_H */