libpng/scripts/pnglibconf.dfa

# scripts/pnglibconf.dfa - library build configuration control
#
@/*- pnglibconf.dfn intermediate file
@ *  generated from scripts/pnglibconf.dfa
@ */
#
com pnglibconf.h - library build configuration
com
com libpng version PNGLIB_VERSION - last changed on August 11, 2010
com
com Copyright (c) 1998-2010 Glenn Randers-Pehrson
com
com This code is released under the libpng license.
com For conditions of distribution and use, see the disclaimer
com and license in png.h
com
file pnglibconf.h scripts/pnglibconf.dfa PNGLCONF_H

# This file is preprocessed by scripts/options.awk and the
# C compiler to generate 'pnglibconf.h' - a list of all the
# configuration options.  The file lists the various options
# that can *only* be specified during the libpng build;
# pnglibconf.h freezes the definitons selected for the specific
# build.
#
# The syntax is detailed in scripts/options.awk, this is a summary
# only:
#
# setting <name> [requires ...] [default]
#    #define PNG_<name> <value>  /* value comes from current setting */
# option <name> [requires ...] [if ...] [enables ...] [disabled]
#    #define PNG_<name>_SUPPORTED if the requirements are met and
#    enable the other options listed
# chunk <name> [requires ...] [disabled]
#    Enable chunk processing for the given ancillary chunk
#
# Note that the 'on' and 'off' keywords, while valid on both option
# and chunk, should not be used in this file because they force the
# relevant options on or off.

#----------------------------------------------------------------------

# The following setting, option and chunk values can all be changed
# while building libpng:
# 
# setting: change 'setting' lines to fine tune library performance,
#   changes to the settings don't affect the libpng API functionally
#
# option: change 'option' lines to remove or add capabilities from
#   or to the library; options change the library API
#
# chunk: change 'chunk' lines to remove capabilities to process
#   optional ('ancillary') chunks.  This does not prevent PNG
#   decoding but does change the libpng API because some chunks
#   will be ignored.
#
# There are three ways of disabling features, in no particular order:
#
# 1) Create 'pngusr.h', enter the required private build information
# detailed below and #define PNG_NO_<option> for each option you
# don't want in that file in that file.  You can also turn on options
# using PNG_<option>_SUPPORTED.  When you have finished rerun
# configure and rebuild pnglibconf.h file with -DPNG_USER_CONFIG:
# 
#  make clean
#  CPPFLAGS='-DPNG_USER_CONFIG' ./configure
#  make pnglibconf.h
#
# pngusr.h is only used during the creation of pnglibconf.h, but it
# is safer to ensure that -DPNG_USER_CONFIG is specified throughout
# the build by changing the CPPFLAGS passed to the initial ./configure
#
# This process will result in a very annoying build fail if you
# forget to define both 'PNG_USER_PRIVATEBUILD' and
# 'PNG_USER_DLLFNAME_POSTFIX' in pngusr.h - this is deliberate.
#
# 2) Add definitions of the settings you want to change to
# CPPFLAGS; for example:
# 
#   -DPNG_DEFAULT_READ_MACROS=0
#
# (This would change the default to *not* use read macros.)  Be
# very careful to change only settings that don't alter the API
# because this approach bypasses the private build checking.  You
# can also change settings from pngpriv.h (read pngpriv.h) safely
# without API changes.  Do that in the same way.
#
# 3) Write a new '.dfa' file (say 'pngusr.dfa') and in this file
# provide override values for setting entries and turn option or
# chunk values explicitly 'on' or 'off':
#
#    setting FOO default VALUE
#    option BAR [on|off]
#
# Then add this file to the options.awk command line (the *first*
# one) after this file.  The make macro DFA_XTRA is provided to make
# this easier (set it like CPPFLAGS prior to running ./configure).
# Look at the builds below contrib/pngminim for some extreme examples
# of how this can be used.
#
# Don't edit this file unless you are contributing a patch to
# libpng and need new or modified options/settings.
#----------------------------------------------------------------------

# The following causes commented out #undef lines to be written to
# pnglibconf.h; this can be stopped by logunsupported=0 in a later
# file or on the command line (after pnglibconf.dfa)
logunsupported = 1

# PNG_USER_CONFIG has to be defined on the compiler command line
# to cause pngusr.h to be read while constructing pnglibconf.h
#
# If this is set during the build 'pnglibconf.h' will define
# PNG_USER_PRIVATEBUILD to the value that *must* be set by pngusr.h
# and contain other definitions as below.
#
# If you create a private DLL you need to define the following
# macros in the file 'pngusr.h' and set -DPNG_USER_CONFIG for
# compilation (i.e. in CFLAGS.)
# #define PNG_USER_PRIVATEBUILD \
#     <Describes by whom and why this version of the DLL was built>
#  e.g. #define PNG_USER_PRIVATEBUILD "Build by MyCompany for xyz reasons."
# #define PNG_USER_DLLFNAME_POSTFIX <two-letter postfix that serve to
#        distinguish your DLL from those of the official release. These
#        correspond to the trailing letters that come after the version
#        number and must match your private DLL name>
#  e.g. // private DLL "libpng13gx.dll"
#       #define PNG_USER_DLLFNAME_POSTFIX "gx"
#
# The following macros are also at your disposal if you want to complete the
# DLL VERSIONINFO structure.
# - PNG_USER_VERSIONINFO_COMMENTS
# - PNG_USER_VERSIONINFO_COMPANYNAME
# - PNG_USER_VERSIONINFO_LEGALTRADEMARKS

@#ifdef PNG_USER_CONFIG
@#  include "pngusr.h"
@#endif

# This is a special fixup for the Watcom C compiler on Windows, which has
# multiple procedure call standards.  Unless PNG_API_RULE is set explicitly
# (i.e. if it is not defined at this point) it will be forced to '2' here when
# using Watcom.  This indicates to the other header files that Watcom behaviour
# is required where appropriate.
@#ifdef __WATCOMC__
@#  ifndef PNG_API_RULE
@#     define PNG_API_RULE 2 /* Use Watcom calling conventions */
@#  endif
@#endif

# Note that PNG_USR_CONFIG only has an effect when building
# pnglibconf.h
setting USER_CONFIG requires USER_PRIVATEBUILD USER_DLLFNAME_POSTFIX
setting USER_PRIVATEBUILD
setting USER_DLLFNAME_POSTFIX
setting USER_VERSIONINFO_COMMENTS
setting USER_VERSIONINFO_COMPANYNAME
setting USER_VERSIONINFO_LEGALTRADEMARKS

# Record the 'API rule' used to select calling conventions on
# those systems that support such things (see all the comments in
# pngconf.h)
# Changing this setting has a fundamental affect on the PNG ABI,
# do not release shared libraries with this changed.
setting API_RULE default 0

# Default to using the read macros
setting DEFAULT_READ_MACROS default 1

# The alternative is to call functions to read PNG values, if
# the functions are turned *off* the read macros must always
# be enabled, so turning this off will actually force the
# USE_READ_MACROS option on (see pngconf.h)
option READ_INT_FUNCTIONS requires READ

# The same for write, but these can only be switched off if
# no writing is required at all - hence the use of an 'enables'
# not a 'requires' below:
option WRITE_INT_FUNCTIONS disabled
option WRITE enables WRITE_INT_FUNCTIONS

# Generic options - affect both read and write.
option WARNINGS
option BENIGN_ERRORS
option MNG_FEATURES

# Arithmetic options, the first is the big switch that chooses between internal
# floating and fixed point arithmetic implementations - it does not affect any
# APIs.  The second two (the _POINT settings) switch off individual APIs.
option FLOATING_ARITHMETIC
option FLOATING_POINT enables ok_math
option FIXED_POINT enables ok_math

# Added at libpng version 1.4.0 
option ERROR_TEXT

# The following is always on (defined empty) 
setting CALLOC_SUPPORTED default

# This protects us against compilers that run on a windowing system
# and thus don't have or would rather us not use the stdio types:
# stdin, stdout, and stderr.  The only one currently used is stderr
# in png_error() and png_warning().  #defining PNG_NO_CONSOLE_IO will
# prevent these from being compiled and used. #defining PNG_NO_STDIO
# will also prevent these, plus will prevent the entire set of stdio
# macros and functions (FILE *, printf, etc.) from being compiled and used,
# unless (PNG_DEBUG > 0) has been #defined.
option STDIO
option CONSOLE_IO requires STDIO

# Note: prior to 1.5.0 this option could not be disabled if STDIO
# was enabled.
option TIME_RFC1123 requires STDIO

# PNG_SETJMP_NOT_SUPPORTED is an old equivalent for NO_SETJMP
option SETJMP
= NO_SETJMP SETJMP_NOT_SUPPORTED

# For the moment this is disabled (no code support):
option ERROR_NUMBERS disabled

# If this is disabled it is not possible for apps to get the
# values from the 'info' structure, this effectively removes
# quite a lot of the READ API.
option EASY_ACCESS

# Added at libpng-1.2.0
option USER_MEM

# Added at libpng-1.4.0
option IO_STATE

# This is only for PowerPC big-endian and 680x0 systems
# some testing, not enabled by default.
# NO LONGER USED
#option READ_BIG_ENDIAN disabled

# Allow users to control limits on what the READ code will
# read:

# Added at libpng-1.2.43; adds limit fields to png_struct,
# allows some usages of these fields
option USER_LIMITS

# Added at libpng-1.2.6; adds setting APIs, allows additional
# usage of this field (UTSL)
option SET_USER_LIMITS requires USER_LIMITS

# Feature added at libpng-1.4.0, this flag added at 1.4.1
option SET_USER_LIMITS enables SET_CHUNK_CACHE_LIMIT
# Feature added at libpng-1.4.1, this flag added at 1.4.1
option SET_USER_LIMITS enables SET_CHUNK_MALLOC_LIMIT

# Added at libpng-1.0.16 and 1.2.6.  To accept all valid PNGs no matter
# how large, set these two limits to 0x7fffffffL
setting USER_WIDTH_MAX default 1000000L
setting USER_HEIGHT_MAX default 1000000L

# Added at libpng-1.2.43.  To accept all valid PNGs no matter
# how large, set these two limits to 0.
setting USER_CHUNK_CACHE_MAX default 0

# Added at libpng-1.2.43
setting USER_CHUNK_MALLOC_MAX default 0

# All of the following options relate to code capabilities for
# processing image data before creating a PNG or after reading one.
# You can remove these capabilities safely and still be PNG
# conformant, however the library that results is still non-standard.
# See the comments above about how to change options and settings.

# READ options
option READ enables READ_INTERLACING
option READ_QUANTIZE requires READ

option READ_TRANSFORMS requires READ
= NO_READ_TRANSFORMS PNG_READ_TRANSFORMS_NOT_SUPPORTED

option READ_EXPAND requires READ_TRANSFORMS
option READ_SHIFT requires READ_TRANSFORMS
option READ_PACK requires READ_TRANSFORMS
option READ_BGR requires READ_TRANSFORMS
option READ_SWAP requires READ_TRANSFORMS
option READ_PACKSWAP requires READ_TRANSFORMS
option READ_INVERT requires READ_TRANSFORMS
option READ_BACKGROUND requires READ_TRANSFORMS
option READ_16_TO_8 requires READ_TRANSFORMS
option READ_FILLER requires READ_TRANSFORMS
option READ_GAMMA requires READ_TRANSFORMS enables READ_gAMA
option READ_GRAY_TO_RGB requires READ_TRANSFORMS
option READ_SWAP_ALPHA requires READ_TRANSFORMS
option READ_INVERT_ALPHA requires READ_TRANSFORMS
option READ_STRIP_ALPHA requires READ_TRANSFORMS
option READ_USER_TRANSFORM requires READ_TRANSFORMS
option READ_RGB_TO_GRAY requires READ_TRANSFORMS

option PROGRESSIVE_READ requires READ
option SEQUENTIAL_READ requires READ

# You can define PNG_NO_PROGRESSIVE_READ if you don't do progressive reading.
# This is not talking about interlacing capability!  You'll still have
# interlacing unless you turn off the following which is required
# for PNG-compliant decoders.  (In other words, do not do this - in
# fact it can't be disabled from the command line!)
#option READ_INTERLACING requires READ

option READ_COMPOSITE_NODIV requires READ
= NO_READ_COMPOSITE_NODIV PNG_NO_READ_COMPOSITED_NODIV

# Inch conversions
option INCH_CONVERSIONS
= INCH_CONVERSIONS PNG_INCH_CONVERSIONS

# IN DEVELOPMENT
# These are currently experimental features, define them if you want

# Very little testing, not enabled by default.
option READ_16_TO_8_ACCURATE_SCALE requires READ disabled

# WRITE options
option WRITE

option WRITE_TRANSFORMS requires WRITE
= NO_WRITE_TRANSFORMS PNG_WRITE_TRANSFORMS_NOT_SUPPORTED

#  ifdef PNG_WRITE_TRANSFORMS_SUPPORTED
option WRITE_SHIFT requires WRITE_TRANSFORMS
option WRITE_PACK requires WRITE_TRANSFORMS
option WRITE_BGR requires WRITE_TRANSFORMS
option WRITE_SWAP requires WRITE_TRANSFORMS
option WRITE_PACKSWAP requires WRITE_TRANSFORMS
option WRITE_INVERT requires WRITE_TRANSFORMS
option WRITE_FILLER requires WRITE_TRANSFORMS
option WRITE_SWAP_ALPHA requires WRITE_TRANSFORMS
option WRITE_INVERT_ALPHA requires WRITE_TRANSFORMS
option WRITE_USER_TRANSFORM requires WRITE_TRANSFORMS

# This is not required for PNG-compliant encoders, but can cause
# trouble if left undefined
option WRITE_INTERLACING requires WRITE

# The following depends, internally, on WEIGHT_SHIFT and COST_SHIFT
# where are set below.
option WRITE_WEIGHTED_FILTER requires WRITE

option WRITE_FLUSH requires WRITE

# Note: this can be turned off explicitly, is this correcct?
option USER_TRANSFORM_PTR if READ_USER_TRANSFORM WRITE_USER_TRANSFORM

# Any chunks you are not interested in, you can undef here.  The
# ones that allocate memory may be expecially important (hIST,
# tEXt, zTXt, tRNS, pCAL).  Others will just save time and make png_info
# a bit smaller.

# The size of the png_text structure changed in libpng-1.0.6 when
# iTXt support was added.  iTXt support was turned off by default through
# libpng-1.2.x, to support old apps that malloc the png_text structure
# instead of calling png_set_text() and letting libpng malloc it.  It
# was turned on by default in libpng-1.4.0.

option READ_ANCILLARY_CHUNKS requires READ
# PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED is deprecated.
= NO_READ_ANCILLARY_CHUNKS READ_ANCILLARY_CHUNKS_NOT_SUPPORTED

option WRITE_ANCILLARY_CHUNKS requires WRITE
# PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED is deprecated.
= NO_WRITE_ANCILLARY_CHUNKS WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED

# These options disable *all* the text chunks if turned off
option READ_TEXT requires READ_ANCILLARY_CHUNKS enables TEXT
option WRITE_TEXT requires WRITE_ANCILLARY_CHUNKS enables TEXT

# Moved to pnglibconf.h at libpng-1.5.0
# Feature support: in 1.4 this was in pngconf.h, but the following
# features have no affect on the libpng API.  Add library
# only features to the end of this list.  Add features that
# affect the API above.  (Note: the list of chunks follows
# the library-only settings.)
#
# BUILD TIME ONLY OPTIONS
#   These options do not affect the API but rather alter how the
#   API is implemented, they get recorded in pnglibconf.h, but
#   can't be changed by the application.

# Check the correctness of cHRM chunks
option CHECK_cHRM requires cHRM
#
# Artificially align memory - the code typically aligns to 8 byte
# boundaries if this is switched on, it's a small waste of space
# but can help (in theory) on some architectures.  Only affects
# internal structures.  Added at libpng 1.4.0
option ALIGN_MEMORY

# Buggy compilers (e.g., gcc 2.7.2.2) need PNG_NO_POINTER_INDEXING
# See png[wr]util.c, normally this should always be *on*
option POINTER_INDEXING

# Other defines for things like memory and the like can go here.

# BUILD TIME SETTINGS
# Like build time options these do not affect the API, but they
# may be useful to applications because they record details of
# how the API will behave particularly with regard to overall
# accuracy.

# This controls how fine the quantizing gets.  As this allocates
# a largish chunk of memory (32K), those who are not as concerned
# with quantizing quality can decrease some or all of these.
setting QUANTIZE_RED_BITS default 5
setting QUANTIZE_GREEN_BITS default 5
setting QUANTIZE_BLUE_BITS default 5

# This controls how fine the gamma correction becomes when you
# are only interested in 8 bits anyway.  Increasing this value
# results in more memory being used, and more pow() functions
# being called to fill in the gamma tables.  Don't set this value
# less then 8, and even that may not work (I haven't tested it).
setting MAX_GAMMA_8 default 11

# This controls how much a difference in gamma we can tolerate before
# we actually start doing gamma conversion, it's a fixed point value,
# so the default below is 0.05, meaning libpng ignores corrections in
# the range 0.95 to 1.05
setting GAMMA_THRESHOLD_FIXED default 5000

# Scaling factor for filter heuristic weighting calculations
setting WEIGHT_SHIFT default 8
setting COST_SHIFT default 3

# Precision to use when converting a floating point value to a PNG
# extension format string in an sCAL chunk (only relevant if the
# floating point API is enabled)
setting sCAL_PRECISION default 5

# This is the size of the compression buffer, and thus the size of
# an IDAT chunk.  Make this whatever size you feel is best for your
# machine.  One of these will be allocated per png_struct.  When this
# is full, it writes the data to the disk, and does some other
# calculations.  Making this an extremely small size may slow
# the library down, but you may want to experiment to determine
# where it becomes significant, if you are concerned with memory
# usage.  Note that zlib allocates at least 32Kb also.  For readers,
# this describes the size of the buffer available to read the data in.
# Unless this gets smaller than the size of a row (compressed),
# it should not make much difference how big this is.
setting ZBUF_SIZE default 8192

# Ancillary chunks
chunk bKGD
chunk cHRM
chunk gAMA
chunk hIST
chunk iCCP
chunk iTXt requires TEXT
chunk oFFs
chunk pCAL
chunk sCAL
chunk pHYs
chunk sBIT
chunk sPLT
chunk sRGB
chunk tEXt requires TEXT
chunk tIME
chunk tRNS
chunk zTXt requires TEXT

# This only affects support of the optional PLTE chunk in RGB and RGBA
# images.  Notice that READ_ANCILLARY_CHUNKS therefore disables part
# of the regular chunk reading too.
option READ_OPT_PLTE requires READ_ANCILLARY_CHUNKS

option READ_UNKNOWN_CHUNKS requires READ
option READ_UNKNOWN_CHUNKS enables UNKNOWN_CHUNKS READ_USER_CHUNKS
option READ_USER_CHUNKS requires READ enables USER_CHUNKS

option CONVERT_tIME requires WRITE_ANCILLARY_CHUNKS
# The "tm" structure is not supported on WindowsCE
@#ifdef _WIN32_WCE
@#   define PNG_NO_CONVERT_tIME
@#endif

option WRITE_FILTER requires WRITE

option WRITE_UNKNOWN_CHUNKS requires WRITE

option HANDLE_AS_UNKNOWN

option SAVE_INT_32 requires WRITE
# png_save_int_32 is required by the ancillary chunks oFFs and pCAL
option WRITE_oFFs enables SAVE_INT_32
option WRITE_pCAL enables SAVE_INT_32

# Turn this off to disable png_read_png() and png_write_png() and
# leave the row_pointers member out of the info structure.
option INFO_IMAGE