| # scripts/pnglibconf.dfa - library build configuration control |
| # |
| @/*- pnglibconf.dfn intermediate file |
| @ * generated from scripts/pnglibconf.dfa |
| @ */ |
| # |
| com pnglibconf.h - library build configuration |
| com |
| version |
| com |
| com Copyright (c) 2018-2024 Cosmin Truta |
| com Copyright (c) 1998-2002,2004,2006-2018 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 definitions 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 ...] [enables ...] [disabled] |
| # Enable chunk processing for the given ancillary chunk; any |
| # 'requires something' expands to READ_something for read and |
| # WRITE_something for write, but the enables list members are |
| # used as given (e.g. enables GAMMA just expands to that on the |
| # correspond READ_name and WRITE_name lines.) |
| # |
| # "," may be used to separate options on an 'option' line and is ignored; it |
| # doesn't change the meaning of the line. (NOT setting, where "," becomes |
| # part of the setting!) A comma at the end of an option line causes a |
| # continuation (the next line is included in the option too.) |
| # |
| # 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. 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 |
| # |
| # 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 |
| |
| # The following allows the output from configure to modify the contents of |
| # pnglibconf.h |
| |
| @#ifdef HAVE_CONFIG_H |
| @# include "config.h" |
| @#endif |
| |
| # PNG_USER_CONFIG has to be defined on the compiler command line |
| # to cause pngusr.h to be read while constructing pnglibconf.h |
| # |
| # 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 CPPFLAGS.) |
| # #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 |
| |
| # It is necessary to include configures definitions here so that AC_DEFINE |
| # in configure.ac works in a comprehensible way |
| @#if defined(HAVE_CONFIG_H) && !defined(PNG_NO_CONFIG_H) |
| @# include "config.h" |
| @#endif |
| |
| @#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 |
| |
| # IN DEVELOPMENT |
| # These are currently experimental features; define them if you want (NOTE: |
| # experimental options must be disabled before they are defined in this file!) |
| |
| # NONE |
| |
| # Note that PNG_USER_CONFIG only has an effect when building |
| # pnglibconf.h |
| |
| setting USER_CONFIG |
| 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 |
| |
| # This allows a prefix to be added to the front of every API function name (and |
| # therefore every symbol) by redefining all the function names with the prefix |
| # at the end of pnglibconf.h. It also turns on similar internal symbol renaming |
| # by causing a similar build-time only file, pngprefix.h, to be generated. |
| |
| setting PREFIX |
| |
| # Implementation specific control of the optimizations, enabled by those |
| # hardware or software options that need it (typically when run-time choices |
| # must be made by the user) |
| option SET_OPTION disabled |
| |
| # These options are specific to the ARM NEON hardware optimizations. At present |
| # these optimizations depend on GCC specific pre-processing of an assembler (.S) |
| # file, so they probably won't work with other compilers. |
| # |
| # ARM_NEON_OPT: |
| # unset: check at compile time |
| # (__ARM_NEON__ must be predefined by the compiler, as a result of |
| # passing "-mfpu=neon" to the compiler options) |
| # 0: disable (even if the CPU has a NEON FPU) |
| # 1: check at run time (via ARM_NEON_{API,CHECK}) |
| # 2: switch on unconditionally |
| # (inadvisable - instead, pass "-mfpu=neon" to the compiler) |
| # NOTE: |
| # When building libpng, avoid using any setting other than '0'; |
| # '1' is set automatically when either 'API' or 'CHECK' are configured in; |
| # '2' should not be necessary, as "-mfpu=neon" will achieve the same effect |
| # as well as applying the NEON optimizations to the rest of libpng. |
| # NOTE: |
| # Any setting other than '0' requires ALIGNED_MEMORY. |
| # |
| # ARM_NEON_API: |
| # (PNG_ARM_NEON == 1) |
| # Allow the optimization to be switched on with png_set_option. |
| # |
| # ARM_NEON_CHECK: |
| # (PNG_ARM_NEON == 1) |
| # Compile a run-time check to see if Neon extensions are supported. |
| # This is poorly supported and deprecated - use the png_set_option API. |
| # |
| setting ARM_NEON_OPT |
| option ARM_NEON_API disabled requires ALIGNED_MEMORY enables SET_OPTION, |
| sets ARM_NEON_OPT 1 |
| option ARM_NEON_CHECK disabled requires ALIGNED_MEMORY, |
| sets ARM_NEON_OPT 1 |
| |
| # These options are specific to the PowerPC VSX hardware optimizations. |
| # |
| # POWERPC_VSX_OPT: |
| # unset: check at compile time |
| # (__PPC64__,__ALTIVEC__,__VSX__ must be predefined by the compiler, |
| # as a result of passing "-mvsx -maltivec" to the compiler options) |
| # 0: disable (even if the CPU supports VSX) |
| # 1: check at run time (via POWERPC_VSX_{API,CHECK}) |
| # 2: switch on unconditionally |
| # (inadvisable - instead, pass "-mvsx -maltivec" to the compiler) |
| # NOTE: |
| # When building libpng, avoid using any setting other than '0'; |
| # '1' is set automatically when either 'API' or 'CHECK' are configured in; |
| # '2' should not be necessary, as "-mvsx -maltivec" will achieve the same |
| # effect as well as applying the VSX optimizations to the rest of libpng. |
| # |
| # POWERPC_VSX_API: |
| # (PNG_POWERPC_VSX == 1) |
| # Allow the optimization to be switched on with png_set_option. |
| # |
| # POWERPC_VSX_CHECK: |
| # (PNG_POWERPC_VSX == 1) |
| # Compile a run-time check to see if VSX extensions are supported. |
| # This is not supported on all systems. See contrib/powerpc-vsx/README. |
| # |
| setting POWERPC_VSX_OPT |
| option POWERPC_VSX_API disabled enables SET_OPTION, |
| sets POWERPC_VSX_OPT 1 |
| option POWERPC_VSX_CHECK disabled, |
| sets POWERPC_VSX_OPT 1 |
| |
| # These options are specific to the MIPS MSA hardware optimizations. |
| # |
| # MIPS_MSA_OPT: |
| # unset: check at compile time |
| # (__mips_msa must be predefined by the compiler, as a result of |
| # passing "-mmsa -mfp64" to the compiler options) |
| # 0: disable (even if the CPU supports MSA) |
| # 1: check at run time (via MIPS_MSA_{API,CHECK}) |
| # 2: switch on unconditionally |
| # (inadvisable - instead, pass "-mmsa -mfp64" to the compiler) |
| # NOTE: |
| # When building libpng, avoid using any setting other than '0'; |
| # '1' is set automatically when either 'API' or 'CHECK' are configured in; |
| # '2' should not be necessary, as "-mmsa -mfp64" will achieve the same |
| # effect as well as applying the MSA optimizations to the rest of libpng. |
| # NOTE: |
| # Any setting other than '0' requires ALIGNED_MEMORY. |
| # |
| # MIPS_MSA_API: |
| # (PNG_MIPS_MSA == 1) |
| # Allow the optimization to be switched on with png_set_option. |
| # |
| # MIPS_MSA_CHECK: |
| # (PNG_MIPS_MSA == 1) |
| # Compile a run-time check to see if MSA extensions are supported. |
| # |
| setting MIPS_MSA_OPT |
| option MIPS_MSA_API disabled requires ALIGNED_MEMORY enables SET_OPTION, |
| sets MIPS_MSA_OPT 1 |
| option MIPS_MSA_CHECK disabled requires ALIGNED_MEMORY, |
| sets MIPS_MSA_OPT 1 |
| |
| # These options are specific to the MIPS MMI hardware optimizations. |
| # |
| # MIPS_MMI_OPT: |
| # unset: check at compile time |
| # (__mips_loongson_mmi must be defined by the compiler, as a result of |
| # passing "-mloongson-mmi -march=loongson3a" to the compiler options) |
| # 0: disable (even if the CPU supports MMI) |
| # 1: check at run time (via MIPS_MMI_{API,CHECK}) |
| # 2: switch on unconditionally |
| # (inadvisable - instead, pass "-mloongson-mmi -march=loongson3a" to the |
| # compiler) |
| # NOTE: |
| # When building libpng, avoid using any setting other than '0'; |
| # '1' is set automatically when either 'API' or 'CHECK' are configured in; |
| # '2' should not be necessary, as "-mloongson-mmi -march=loongson3a" will |
| # achieve the same effect as well as applying the MMI optimizations to the |
| # rest of libpng. |
| # |
| # MIPS_MMI_API: |
| # (PNG_MIPS_MMI == 1) |
| # Allow the optimization to be switched on with png_set_option. |
| # |
| # MIPS_MMI_CHECK: |
| # (PNG_MIPS_MMI == 1) |
| # Compile a run-time check to see if MMI extensions are supported. |
| # |
| setting MIPS_MMI_OPT |
| option MIPS_MMI_API disabled requires ALIGNED_MEMORY enables SET_OPTION, |
| sets MIPS_MMI_OPT 1 |
| option MIPS_MMI_CHECK disabled requires ALIGNED_MEMORY, |
| sets MIPS_MMI_OPT 1 |
| |
| |
| # These settings configure the default compression level (0-9) and 'strategy'; |
| # strategy is as defined by the implementors of zlib. It describes the input |
| # data and modifies the zlib parameters in an attempt to optimize the balance |
| # between search and huffman encoding in the zlib algorithms. The defaults are |
| # the zlib.h defaults - the apparently recursive definition does not arise |
| # because the name of the setting is prefixed by PNG_ |
| # |
| # The TEXT values are the defaults when writing compressed text (all forms) |
| |
| # Include the zlib header so that the defaults below are known |
| @# include <zlib.h> |
| |
| # The '@' here means to substitute the value when pnglibconf.h is built |
| setting Z_DEFAULT_COMPRESSION default @Z_DEFAULT_COMPRESSION |
| # TODO: why aren't these Z_RLE; zlib.h says that Z_RLE, specifically, is |
| # appropriate for PNG images, maybe it doesn't exist in all versions? |
| setting Z_DEFAULT_STRATEGY default @Z_FILTERED |
| setting Z_DEFAULT_NOFILTER_STRATEGY default @Z_DEFAULT_STRATEGY |
| setting ZLIB_VERNUM default @ZLIB_VERNUM |
| |
| # Linkage of: |
| # |
| # API: libpng API functions |
| # CALLBACK: internal non-file-local callbacks |
| # FUNCTION: internal non-file-local functions |
| # DATA: internal non-file-local (const) data |
| setting LINKAGE_API default extern |
| setting LINKAGE_CALLBACK default extern |
| setting LINKAGE_FUNCTION default extern |
| setting LINKAGE_DATA default extern |
| |
| setting TEXT_Z_DEFAULT_COMPRESSION default @Z_DEFAULT_COMPRESSION |
| setting TEXT_Z_DEFAULT_STRATEGY default @Z_DEFAULT_STRATEGY |
| |
| # 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 a 'disabled', not a 'requires'. |
| # If these are needed, they are enabled in the 'WRITE options' section |
| # below. |
| |
| option WRITE_INT_FUNCTIONS disabled |
| |
| # Error controls |
| # |
| # WARNINGS: normally on, if off no warnings are generated |
| # ERROR_TEXT: normally on, if off errors happen but there is no message |
| # ERROR_NUMBERS: unimplemented feature, therefore disabled |
| # BENIGN_ERRORS: support for just issuing warnings for recoverable errors |
| # |
| # BENIGN_READ_ERRORS: |
| # By default recoverable errors on read should just generate warnings, |
| # generally safe but PNG files that don't conform to the specification will |
| # be accepted if a meaningful result can be produced. |
| # |
| # BENIGN_WRITE_ERRORS: |
| # By default recoverable errors on write should just generate warnings, |
| # not generally safe because this allows the application to write invalid |
| # PNG files. Applications should enable this themselves; it's useful |
| # because it means that a failure to write an ancillary chunk can often be |
| # ignored. |
| |
| option WARNINGS |
| option ERROR_TEXT |
| option ERROR_NUMBERS disabled |
| |
| option BENIGN_ERRORS |
| option BENIGN_WRITE_ERRORS requires BENIGN_ERRORS disabled |
| option BENIGN_READ_ERRORS requires BENIGN_ERRORS |
| |
| # Adler32 checksum |
| # |
| # This option allows the check of the Adler32 checksum performed by zlib to |
| # be turned off for IDAT chunks (only). Unless this option is enabled and |
| # turned on (not the default even if enabled) a failed Adler32 at the end of the |
| # stream will result in a decompression (inflate) failure on read even though |
| # the entire image might have been read successfully. |
| # |
| # This option relies on an undocumented function 'inflateValidate' which is |
| # present in only some versions of zlib. If the function is not present in the |
| # zlib used with libpng code which uses -lpng is likely to fail to link or to |
| # launch in the case of a DLL. |
| # |
| # Therefore this option is currently disabled by default; it has to be turned on |
| # in pngusr.dfa and then the application program has to explicitly turn the |
| # functionality on by calling png_set_option. |
| # |
| # Furthermore the option is explicitly turned off here if the zlib version |
| # number is below that required - libpng wouldn't compile in that case if the |
| # option were turned on. |
| option DISABLE_ADLER32_CHECK requires READ enables SET_OPTION disabled |
| |
| # ZLIB_VERNUM must be used here, not PNG_ZLIB_VERNUM, because |
| # scripts/options.awk ends up putting this test adhead of the setting of |
| # PNG_ZLIB_VERNUM (apparently above, but not because of the two-pass processing) |
| @#if ZLIB_VERNUM < 0x1290 |
| @# define PNG_NO_DISABLE_ADLER32_CHECK |
| @#endif |
| |
| # Generic options - affect both read and write. |
| |
| 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. |
| # |
| # Prior to libpng 1.6.8 one of the API (_POINT) variants had to be selected. At |
| # 1.6.8 this restriction has been removed; the simplified API can be used |
| # without enabling any of the low level fixed/floating APIs. |
| |
| option FLOATING_ARITHMETIC |
| option FLOATING_POINT |
| option FIXED_POINT |
| |
| # 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. Prior to 1.5.3 this option required STDIO |
| |
| option TIME_RFC1123 |
| |
| # PNG_SETJMP_NOT_SUPPORTED is an old equivalent for NO_SETJMP |
| |
| option SETJMP |
| = NO_SETJMP SETJMP_NOT_SUPPORTED |
| |
| # 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 |
| |
| # Libpng limits: limit the size of images and data on read. |
| # |
| # If this option is disabled all the limit checking code will be disabled: |
| |
| option USER_LIMITS requires READ |
| |
| # The default settings given below for the limits mean that libpng will |
| # limit the size of images or the size of data in ancillary chunks to less |
| # than the specification or implementation limits. Settings have the |
| # following interpretations: |
| # |
| # USER_WIDTH_MAX: maximum width of an image that will be read |
| # USER_HEIGHT_MAX: maximum height |
| # USER_CHUNK_MALLOC_MAX: maximum in-memory (decompressed) size of a single chunk |
| # USER_CHUNK_CACHE_MAX: maximum number of chunks to be cached |
| # |
| # Only chunks that are variable in number are counted towards the |
| |
| # Use 0x7fffffff for unlimited |
| setting USER_WIDTH_MAX default 1000000 |
| setting USER_HEIGHT_MAX default 1000000 |
| |
| # Use 0 for unlimited |
| setting USER_CHUNK_CACHE_MAX default 1000 |
| setting USER_CHUNK_MALLOC_MAX default 8000000 |
| |
| # If this option is enabled APIs to set the above limits at run time are added; |
| # without this the hardwired (compile time) limits will be used. |
| option SET_USER_LIMITS requires USER_LIMITS |
| |
| # 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 |
| # |
| # WARNING: in libpng 1.5 maintained configuration compatibility with earlier |
| # versions. In some cases turning off an option turned off other options, in |
| # others it was ineffective unless dependent options were also turned off. |
| # Libpng 1.6 changes this: in general if you turn off an option that affects |
| # APIs it stays off and simply disables APIs that depend on it. |
| # |
| # As a result if you simply port the libpng 1.5 configuration to libpng 1.6 you |
| # will probably see build failures due to missing APIs. Fixing these failures |
| # requires some, perhaps considerable, knowledge of what your libpng using |
| # applications are doing, fortunately there is no great reason for you to move |
| # to libpng 1.6; the new interfaces in 1.6 will take several years to become |
| # popular. |
| |
| option READ enables READ_INTERLACING SET_OPTION |
| |
| # Disabling READ_16BIT does not disable reading 16-bit PNG files, but it |
| # forces them to be chopped down to 8-bit, and disables any 16-bit |
| # processing after that has happened. You need to be sure to enable |
| # READ_SCALE_16_TO_8 or READ_STRIP_16_TO_8 when you disable READ_16BIT for |
| # this to work properly. You should disable the other option if you need to |
| # ensure a particular conversion (otherwise the app can chose.) |
| |
| option READ_16BIT requires READ enables 16BIT |
| |
| option READ_QUANTIZE requires READ |
| |
| option READ_TRANSFORMS requires READ |
| = NO_READ_TRANSFORMS READ_TRANSFORMS_NOT_SUPPORTED |
| |
| # Read gamma handling. Gamma processing is a core part of libpng and many of |
| # the capabilities are dependent on libpng performing gamma correction. |
| # |
| # In libpng 1.6 disabling gamma processing (setting PNG_NO_READ_GAMMA) |
| # consistently disables those parts of the API that depend on it. Prior to |
| # 1.6.0 this was not true; the results were unpredictable and varied between |
| # releases. |
| # |
| # If you disable gamma processing and your program no longer compiles you need |
| # to ask whether you really need the APIs that are missing. If you do then you |
| # almost certainly need the gamma processing. |
| # |
| # If you handle gamma issues outside libpng then you do not need the libpng |
| # gamma processing; and it is an enormous waste of space. You just need to |
| # remove the use of libpng APIs that depend on it. |
| option READ_GAMMA requires READ_TRANSFORMS, READ_gAMA, READ_sRGB |
| |
| option READ_ALPHA_MODE requires READ_TRANSFORMS, READ_GAMMA |
| option READ_BACKGROUND requires READ_TRANSFORMS, READ_STRIP_ALPHA, READ_GAMMA |
| option READ_BGR requires READ_TRANSFORMS |
| option READ_EXPAND_16 requires READ_TRANSFORMS, READ_16BIT, READ_EXPAND |
| option READ_EXPAND requires READ_TRANSFORMS |
| option READ_FILLER requires READ_TRANSFORMS |
| option READ_GRAY_TO_RGB requires READ_TRANSFORMS |
| option READ_INVERT_ALPHA requires READ_TRANSFORMS |
| option READ_INVERT requires READ_TRANSFORMS |
| option READ_PACK requires READ_TRANSFORMS |
| option READ_PACKSWAP requires READ_TRANSFORMS |
| option READ_RGB_TO_GRAY requires READ_TRANSFORMS, READ_GAMMA enables COLORSPACE |
| option READ_SCALE_16_TO_8 requires READ_TRANSFORMS |
| option READ_SHIFT requires READ_TRANSFORMS |
| option READ_STRIP_16_TO_8 requires READ_TRANSFORMS |
| option READ_STRIP_ALPHA requires READ_TRANSFORMS |
| option READ_SWAP_ALPHA requires READ_TRANSFORMS |
| option READ_SWAP requires READ_TRANSFORMS, READ_16BIT |
| option READ_USER_TRANSFORM 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 NO_READ_COMPOSITED_NODIV |
| |
| # Inch conversions |
| |
| option INCH_CONVERSIONS |
| = INCH_CONVERSIONS INCH_CONVERSIONS |
| |
| # API to build a grayscale palette |
| # NOTE: this is not used internally by libpng at present. |
| |
| option BUILD_GRAYSCALE_PALETTE |
| |
| # WRITE options |
| |
| option WRITE enables WRITE_INT_FUNCTIONS |
| |
| # Disabling WRITE_16BIT prevents 16-bit PNG files from being |
| # generated. |
| option WRITE_16BIT requires WRITE enables 16BIT |
| |
| option WRITE_TRANSFORMS requires WRITE |
| = NO_WRITE_TRANSFORMS WRITE_TRANSFORMS_NOT_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, WRITE_16BIT |
| 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 |
| |
| # Deprecated, will be removed. |
| option WRITE_WEIGHTED_FILTER requires WRITE |
| |
| option WRITE_FLUSH requires WRITE |
| |
| # Note: these can be turned off explicitly if not required by the |
| # apps implementing the user transforms |
| option USER_TRANSFORM_PTR if READ_USER_TRANSFORM, WRITE_USER_TRANSFORM |
| option USER_TRANSFORM_INFO if READ_USER_TRANSFORM, WRITE_USER_TRANSFORM |
| |
| # This enables API to set compression parameters for compressing |
| # non-IDAT chunks (zTXt, iTXt, iCCP, and unknown chunks). This feature |
| # was added at libpng-1.5.3. |
| option WRITE_CUSTOMIZE_ZTXT_COMPRESSION requires WRITE |
| option WRITE_CUSTOMIZE_COMPRESSION requires WRITE |
| |
| # Any chunks you are not interested in, you can undef here. The |
| # ones that allocate memory may be especially 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 TEXT disabled |
| 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. |
| |
| # Colorspace support (enabled as required); just the support for colorant |
| # information. Gamma support, likewise, is just support for the gamma |
| # information, READ_GAMMA is required for gamma transformations (so it |
| # is possible to read PNG gamma without enabling all the libpng transform |
| # code - do this for applications that do their own gamma processing) |
| # |
| # As of 1.6.0 COLORSPACE is only useful if the application processes the |
| # information; this is because the library does not do any colorspace |
| # processing, it just validates the data in the PNG file. |
| |
| option GAMMA disabled |
| option COLORSPACE enables GAMMA disabled |
| |
| # When an ICC profile is read, or png_set, it will be checked for a match |
| # against known sRGB profiles if the sRGB handling is enabled. The |
| # PNG_sRGB_PROFILE_CHECKS setting controls how much work is done during the |
| # check: |
| # |
| # -1: Don't do any sRGB profile checking. |
| # |
| # 0: Just validate the profile MD5 signature if present, otherwise use |
| # the checks in option 1. |
| # |
| # 1: Additionally check the length, intent and adler32 checksum of the |
| # actual data. If enabled this will reject known profiles that have |
| # had the rendering intent in the header changed as well as other edits |
| # done without updating the checksum. See the discussion below. |
| # |
| # 2: Additionally checksum all the data using the ethernet CRC32 algorithm. |
| # This makes it more difficult to fake profiles and makes it less likely |
| # to get a false positive on profiles with no signature, but is probably |
| # just a waste of time since all currently approved ICC sRGB profiles have |
| # a secure MD5 signature. |
| # |
| # The rendering intent. An ICC profile stores an intended rendering intent, |
| # but does not include the value in the signature. The intent is documented |
| # as the intent that should be used when combining two profiles. The sRGB |
| # profile is intended, however, to be used with any of the four defined intents. |
| # For this reason the sRGB chunk includes an 'intent' to be used when displaying |
| # the image (intent is really a property of the image not the profile.) |
| # |
| # Unfortunately the iCCP chunk does not. It may therefore be that some |
| # applications modify the intent in profiles (including sRGB profiles) to work |
| # round this problem. Selecting an option other than option '0' will cause such |
| # modified profiles to be rejected. |
| # |
| # Security. The use of Adler32 and CRC32 checksums does not help significantly |
| # with any security issues. It is relatively easy to produce arbitrary profiles |
| # with the required checksums on current computer systems. Nevertheless |
| # security does not seem to be an issue because the only consequence of a false |
| # positive is a false assertion that the profile is an sRGB profile. This might |
| # be used to hide data from libpng using applications, but it doesn't seem |
| # possible to damage them. |
| |
| setting sRGB_PROFILE_CHECKS default 2 |
| |
| # 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 ALIGNED_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 than 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 |
| |
| # 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 |
| |
| # This is the size of the decompression buffer used when counting or checking |
| # the decompressed size of an LZ stream from a compressed ancillary chunk; the |
| # decompressed data is never used so a different size may be optimal. This size |
| # was determined using contrib/libtests/timepng.c with compressed zTXt data |
| # around 11MByte in size. Slight speed improvements (up to about 14% in |
| # timepng) can be achieved by very large increases (to 32kbyte) on regular data, |
| # but highly compressible data shows only around 2% improvement. The size is |
| # chosen to minimize the effects of DoS attacks based on using very large |
| # amounts of highly compressible data. |
| |
| setting INFLATE_BUF_SIZE default 1024 |
| |
| # This is the maximum amount of IDAT data that the sequential reader will |
| # process at one time. The setting does not affect the size of IDAT chunks |
| # read, just the amount read at once. Neither does it affect the progressive |
| # reader, which processes just the amount of data the application gives it. |
| # The sequential reader is currently unable to process more than one IDAT at |
| # once - it has to read and process each one in turn. There is no point setting |
| # this to a value larger than the IDAT chunks typically encountered (it would |
| # just waste memory) but there may be some point in reducing it below the value |
| # of ZBUF_SIZE (the size of IDAT chunks written by libpng.) |
| |
| setting IDAT_READ_SIZE default PNG_ZBUF_SIZE |
| |
| # Ancillary chunks |
| chunk bKGD |
| chunk cHRM enables COLORSPACE |
| chunk eXIf |
| chunk gAMA enables GAMMA |
| chunk hIST |
| chunk iCCP enables COLORSPACE, GAMMA |
| chunk iTXt enables TEXT |
| chunk oFFs |
| chunk pCAL |
| chunk pHYs |
| chunk sBIT |
| chunk sCAL |
| chunk sPLT |
| chunk sRGB enables COLORSPACE, GAMMA, SET_OPTION |
| chunk tEXt requires TEXT |
| chunk tIME |
| chunk tRNS |
| chunk zTXt enables 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 |
| |
| # Unknown chunk handling |
| # |
| # 'UNKNOWN_CHUNKS' is a global option to disable all unknown chunk handling on |
| # read or write; everything else below requires it (directly or indirectly). |
| option UNKNOWN_CHUNKS |
| |
| # There are three main options to control the ability to read and write unknown |
| # chunks. If either read option is turned on then unknown chunks will be read, |
| # otherwise they are skipped. If the write option is turned on unknown chunks |
| # set by png_set_unknown_chunks will be written otherwise it is an error to call |
| # that API on a write struct. |
| option WRITE_UNKNOWN_CHUNKS requires WRITE requires UNKNOWN_CHUNKS |
| option WRITE_UNKNOWN_CHUNKS enables STORE_UNKNOWN_CHUNKS |
| |
| # The first way to read user chunks is to have libpng save them for a later call |
| # to png_get_unknown_chunks, the application must call |
| # png_set_keep_unknown_chunks to cause this to actually happen (see png.h) |
| option SAVE_UNKNOWN_CHUNKS requires READ requires SET_UNKNOWN_CHUNKS |
| option SAVE_UNKNOWN_CHUNKS enables READ_UNKNOWN_CHUNKS, STORE_UNKNOWN_CHUNKS |
| |
| # The second approach is to use an application provided callback to process the |
| # chunks, the callback can either handle the chunk entirely itself or request |
| # that libpng store the chunk for later retrieval via png_get_unknown_chunks. |
| # |
| # NOTE: If STORE_UNKNOWN_CHUNKS is not enabled (which is the default if |
| # both SAVE_UNKNOWN_CHUNKS and WRITE_UNKNOWN_CHUNKS are disabled) then a |
| # 0 result from the callback will be ignored because no support for saving |
| # unknown chunks has been compiled in. The normal symptom is that your app |
| # fails to compile because png_get_unknown_chunks is no longer defined in png.h. |
| # If you encounter this issue simply enable STORE_UNKNOWN_CHUNKS in your build. |
| # |
| # Note that there is no 'WRITE_USER_CHUNKS' so the USER_CHUNKS option is always |
| # the same as READ_USER_CHUNKS at present |
| option READ_USER_CHUNKS requires READ, UNKNOWN_CHUNKS |
| option READ_USER_CHUNKS enables READ_UNKNOWN_CHUNKS, USER_CHUNKS |
| |
| # Two further options are provided to allow detailed control of the handling. |
| # The first enables png_set_keep_unknown_chunks; this allows the default to be |
| # changed from discarding unknown chunks and allows per-chunk control. This is |
| # required to use the SAVE_UNKNOWN_CHUNKS option. If enabled this option also |
| # applies to write (see png.h), otherwise the write API simply writes all the |
| # chunks it is given. |
| # |
| # The second option extends the unknown handling to allow known chunks to be |
| # handled as though they were unknown. This option doesn't change any APIs, it |
| # merely turns on the code to check known as well as unknown chunks. |
| # |
| # This option no longer affects the write code. It can be safely disabled and |
| # will prevent applications stopping libpng reading known chunks. |
| option SET_UNKNOWN_CHUNKS requires UNKNOWN_CHUNKS |
| option HANDLE_AS_UNKNOWN requires SET_UNKNOWN_CHUNKS |
| |
| # The following options are derived from the above and should not be turned on |
| # explicitly. |
| option READ_UNKNOWN_CHUNKS requires UNKNOWN_CHUNKS disabled |
| option STORE_UNKNOWN_CHUNKS requires UNKNOWN_CHUNKS disabled |
| |
| 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 SAVE_INT_32 disabled |
| # png_save_int_32 is required internally for writing the ancillary chunks oFFs |
| # and pCAL and for both reading and writing iCCP (for the generation/checking of |
| # the corresponding cHRM/gAMA chunks) if full ICC is supported. |
| |
| # added at libpng-1.5.4 |
| |
| option WRITE_OPTIMIZE_CMF requires WRITE |
| |
| option READ_COMPRESSED_TEXT disabled |
| option READ_iCCP enables READ_COMPRESSED_TEXT |
| option READ_iTXt enables READ_COMPRESSED_TEXT |
| option READ_zTXt enables READ_COMPRESSED_TEXT |
| |
| option WRITE_oFFs enables SAVE_INT_32 |
| option WRITE_pCAL enables SAVE_INT_32 |
| option WRITE_cHRM enables SAVE_INT_32 |
| |
| option WRITE_COMPRESSED_TEXT disabled |
| option WRITE_iCCP enables WRITE_COMPRESSED_TEXT |
| option WRITE_iTXt enables WRITE_COMPRESSED_TEXT |
| option WRITE_zTXt enables WRITE_COMPRESSED_TEXT |
| |
| # 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 |
| |
| # added at libpng-1.5.10 |
| # Turn this off to disable warning about invalid palette index and |
| # leave the num_palette_max member out of the png structure. |
| |
| option CHECK_FOR_INVALID_INDEX enables READ_CHECK_FOR_INVALID_INDEX |
| option CHECK_FOR_INVALID_INDEX enables WRITE_CHECK_FOR_INVALID_INDEX |
| option READ_CHECK_FOR_INVALID_INDEX requires READ, CHECK_FOR_INVALID_INDEX |
| option WRITE_CHECK_FOR_INVALID_INDEX requires WRITE, CHECK_FOR_INVALID_INDEX |
| |
| # added at libpng-1.5.15 |
| option GET_PALETTE_MAX enables READ_GET_PALETTE_MAX WRITE_GET_PALETTE_MAX |
| option READ_GET_PALETTE_MAX requires READ_CHECK_FOR_INVALID_INDEX disabled |
| option WRITE_GET_PALETTE_MAX requires WRITE_CHECK_FOR_INVALID_INDEX disabled |
| |
| # Simplified API options (added at libpng-1.6.0) |
| # In libpng 1.6.8 the handling of these options was changed to used 'requires' |
| # throughout, so that disabling some of the low level support always disables |
| # the base simplified read/write API. This much simplifies the handling and |
| # makes 'everything = off' work in a more intuitive way. It eliminates a |
| # previously reported feature that APIs previously enabled by the simplified |
| # API couldn't be turned off without explicitly turning off the simplified |
| # APIs. |
| # |
| # Read: |
| option SIMPLIFIED_READ, |
| requires SEQUENTIAL_READ, READ_TRANSFORMS, SETJMP, BENIGN_ERRORS, |
| READ_EXPAND, READ_16BIT, READ_EXPAND_16, READ_SCALE_16_TO_8, |
| READ_RGB_TO_GRAY, READ_ALPHA_MODE, READ_BACKGROUND, READ_STRIP_ALPHA, |
| READ_FILLER, READ_SWAP, READ_PACK, READ_GRAY_TO_RGB, READ_GAMMA, |
| READ_tRNS, READ_bKGD, READ_gAMA, READ_cHRM, READ_sRGB, READ_sBIT |
| |
| # AFIRST and BGR read options: |
| # Prior to libpng 1.6.8 these were disabled but switched on if the low level |
| # libpng routines that do the swaps were enabled. This worked but was |
| # confusing. In libpng 1.6.8 the options were changed to simple 'requires' |
| # and are enabled by default. This should work the same way in practice. |
| option SIMPLIFIED_READ_AFIRST enables FORMAT_AFIRST, |
| requires SIMPLIFIED_READ READ_SWAP_ALPHA |
| |
| option SIMPLIFIED_READ_BGR enables FORMAT_BGR, |
| requires SIMPLIFIED_READ READ_BGR |
| |
| # Write: |
| option SIMPLIFIED_WRITE, |
| requires WRITE, SETJMP, WRITE_SWAP, WRITE_PACK, |
| WRITE_tRNS, WRITE_gAMA, WRITE_sRGB, WRITE_cHRM |
| |
| # 1.6.22: allow simplified write without stdio support: |
| option SIMPLIFIED_WRITE_STDIO requires SIMPLIFIED_WRITE STDIO |
| |
| option SIMPLIFIED_WRITE_AFIRST enables FORMAT_AFIRST, |
| requires SIMPLIFIED_WRITE WRITE_SWAP_ALPHA |
| |
| option SIMPLIFIED_WRITE_BGR enables FORMAT_BGR, |
| requires SIMPLIFIED_WRITE WRITE_BGR |
| |
| # Formats: |
| option FORMAT_AFIRST disabled |
| option FORMAT_BGR disabled |