1 # scripts/pnglibconf.dfa - library build configuration control
3 @/*- pnglibconf.dfn intermediate file
4 @ * generated from scripts/pnglibconf.dfa
7 com pnglibconf.h - library build configuration
11 com Copyright (c) 1998-2011 Glenn Randers-Pehrson
13 com This code is released under the libpng license.
14 com For conditions of distribution and use, see the disclaimer
15 com and license in png.h
18 file pnglibconf.h scripts/pnglibconf.dfa PNGLCONF_H
20 # This file is preprocessed by scripts/options.awk and the
21 # C compiler to generate 'pnglibconf.h' - a list of all the
22 # configuration options. The file lists the various options
23 # that can *only* be specified during the libpng build;
24 # pnglibconf.h freezes the definitons selected for the specific
27 # The syntax is detailed in scripts/options.awk, this is a summary
30 # setting <name> [requires ...] [default]
31 # #define PNG_<name> <value> /* value comes from current setting */
32 # option <name> [requires ...] [if ...] [enables ...] [disabled]
33 # #define PNG_<name>_SUPPORTED if the requirements are met and
34 # enable the other options listed
35 # chunk <name> [requires ...] [disabled]
36 # Enable chunk processing for the given ancillary chunk
38 # Note that the 'on' and 'off' keywords, while valid on both option
39 # and chunk, should not be used in this file because they force the
40 # relevant options on or off.
42 #----------------------------------------------------------------------
44 # The following setting, option and chunk values can all be changed
45 # while building libpng:
47 # setting: change 'setting' lines to fine tune library performance,
48 # changes to the settings don't affect the libpng API functionally
50 # option: change 'option' lines to remove or add capabilities from
51 # or to the library; options change the library API
53 # chunk: change 'chunk' lines to remove capabilities to process
54 # optional ('ancillary') chunks. This does not prevent PNG
55 # decoding but does change the libpng API because some chunks
58 # There are three ways of disabling features, in no particular order:
60 # 1) Create 'pngusr.h', enter the required private build information
61 # detailed below and #define PNG_NO_<option> for each option you
62 # don't want in that file in that file. You can also turn on options
63 # using PNG_<option>_SUPPORTED. When you have finished rerun
64 # configure and rebuild pnglibconf.h file with -DPNG_USER_CONFIG:
67 # CPPFLAGS='-DPNG_USER_CONFIG' ./configure
70 # pngusr.h is only used during the creation of pnglibconf.h, but it
71 # is safer to ensure that -DPNG_USER_CONFIG is specified throughout
72 # the build by changing the CPPFLAGS passed to the initial ./configure
74 # 2) Add definitions of the settings you want to change to
75 # CPPFLAGS; for example:
77 # -DPNG_DEFAULT_READ_MACROS=0
79 # (This would change the default to *not* use read macros.) Be
80 # very careful to change only settings that don't alter the API
81 # because this approach bypasses the private build checking. You
82 # can also change settings from pngpriv.h (read pngpriv.h) safely
83 # without API changes. Do that in the same way.
85 # 3) Write a new '.dfa' file (say 'pngusr.dfa') and in this file
86 # provide override values for setting entries and turn option or
87 # chunk values explicitly 'on' or 'off':
89 # setting FOO default VALUE
92 # Then add this file to the options.awk command line (the *first*
93 # one) after this file. The make macro DFA_XTRA is provided to make
94 # this easier (set it like CPPFLAGS prior to running ./configure).
95 # Look at the builds below contrib/pngminim for some extreme examples
96 # of how this can be used.
98 # Don't edit this file unless you are contributing a patch to
99 # libpng and need new or modified options/settings.
100 #----------------------------------------------------------------------
102 # The following causes commented out #undef lines to be written to
103 # pnglibconf.h; this can be stopped by logunsupported=0 in a later
104 # file or on the command line (after pnglibconf.dfa)
108 # PNG_USER_CONFIG has to be defined on the compiler command line
109 # to cause pngusr.h to be read while constructing pnglibconf.h
111 # If you create a private DLL you need to define the following
112 # macros in the file 'pngusr.h' and set -DPNG_USER_CONFIG for
113 # compilation (i.e. in CFLAGS.)
114 # #define PNG_USER_PRIVATEBUILD \
115 # <Describes by whom and why this version of the DLL was built>
116 # e.g. #define PNG_USER_PRIVATEBUILD "Build by MyCompany for xyz reasons."
117 # #define PNG_USER_DLLFNAME_POSTFIX <two-letter postfix that serve to
118 # distinguish your DLL from those of the official release. These
119 # correspond to the trailing letters that come after the version
120 # number and must match your private DLL name>
121 # e.g. // private DLL "libpng13gx.dll"
122 # #define PNG_USER_DLLFNAME_POSTFIX "gx"
124 # The following macros are also at your disposal if you want to complete the
125 # DLL VERSIONINFO structure.
126 # - PNG_USER_VERSIONINFO_COMMENTS
127 # - PNG_USER_VERSIONINFO_COMPANYNAME
128 # - PNG_USER_VERSIONINFO_LEGALTRADEMARKS
130 @#ifdef PNG_USER_CONFIG
131 @# include "pngusr.h"
134 # This is a special fixup for the Watcom C compiler on Windows, which has
135 # multiple procedure call standards. Unless PNG_API_RULE is set explicitly
136 # (i.e. if it is not defined at this point) it will be forced to '2' here when
137 # using Watcom. This indicates to the other header files that Watcom behaviour
138 # is required where appropriate.
141 @# ifndef PNG_API_RULE
142 @# define PNG_API_RULE 2 /* Use Watcom calling conventions */
146 # Note that PNG_USR_CONFIG only has an effect when building
150 setting USER_PRIVATEBUILD
151 setting USER_DLLFNAME_POSTFIX
152 setting USER_VERSIONINFO_COMMENTS
153 setting USER_VERSIONINFO_COMPANYNAME
154 setting USER_VERSIONINFO_LEGALTRADEMARKS
156 # Record the 'API rule' used to select calling conventions on
157 # those systems that support such things (see all the comments in
159 # Changing this setting has a fundamental affect on the PNG ABI,
160 # do not release shared libraries with this changed.
162 setting API_RULE default 0
164 # Default to using the read macros
166 setting DEFAULT_READ_MACROS default 1
168 # The alternative is to call functions to read PNG values, if
169 # the functions are turned *off* the read macros must always
170 # be enabled, so turning this off will actually force the
171 # USE_READ_MACROS option on (see pngconf.h)
173 option READ_INT_FUNCTIONS requires READ
175 # The same for write, but these can only be switched off if
176 # no writing is required at all - hence the use of an 'enables'
177 # not a 'requires' below:
179 option WRITE_INT_FUNCTIONS disabled
180 option WRITE enables WRITE_INT_FUNCTIONS
182 # Generic options - affect both read and write.
188 # Arithmetic options, the first is the big switch that chooses between internal
189 # floating and fixed point arithmetic implementations - it does not affect any
190 # APIs. The second two (the _POINT settings) switch off individual APIs.
192 option FLOATING_ARITHMETIC
193 option FLOATING_POINT enables ok_math
194 option FIXED_POINT enables ok_math
196 # Added at libpng version 1.4.0
200 # The following is always on (defined empty)
202 setting CALLOC_SUPPORTED default
204 # This protects us against compilers that run on a windowing system
205 # and thus don't have or would rather us not use the stdio types:
206 # stdin, stdout, and stderr. The only one currently used is stderr
207 # in png_error() and png_warning(). #defining PNG_NO_CONSOLE_IO will
208 # prevent these from being compiled and used. #defining PNG_NO_STDIO
209 # will also prevent these, plus will prevent the entire set of stdio
210 # macros and functions (FILE *, printf, etc.) from being compiled and used,
211 # unless (PNG_DEBUG > 0) has been #defined.
214 option CONSOLE_IO requires STDIO
216 # Note: prior to 1.5.0 this option could not be disabled if STDIO
217 # was enabled. Prior to 1.5.3 this option required STDIO
221 # PNG_SETJMP_NOT_SUPPORTED is an old equivalent for NO_SETJMP
224 = NO_SETJMP SETJMP_NOT_SUPPORTED
226 # For the moment this is disabled (no code support):
228 option ERROR_NUMBERS disabled
230 # If this is disabled it is not possible for apps to get the
231 # values from the 'info' structure, this effectively removes
232 # quite a lot of the READ API.
236 # Added at libpng-1.2.0
240 # Added at libpng-1.4.0
244 # This is only for PowerPC big-endian and 680x0 systems
245 # some testing, not enabled by default.
248 #option READ_BIG_ENDIAN disabled
250 # Allow users to control limits on what the READ code will
253 # Added at libpng-1.2.43; adds limit fields to png_struct,
254 # allows some usages of these fields
258 # Added at libpng-1.2.6; adds setting APIs, allows additional
259 # usage of this field (UTSL)
261 option SET_USER_LIMITS requires USER_LIMITS
263 # Feature added at libpng-1.4.0, this flag added at 1.4.1
264 option SET_USER_LIMITS enables SET_CHUNK_CACHE_LIMIT
265 # Feature added at libpng-1.4.1, this flag added at 1.4.1
267 option SET_USER_LIMITS enables SET_CHUNK_MALLOC_LIMIT
269 # Added at libpng-1.0.16 and 1.2.6. To accept all valid PNGs no matter
270 # how large, set these two limits to 0x7fffffff
272 setting USER_WIDTH_MAX default 1000000
273 setting USER_HEIGHT_MAX default 1000000
275 # Added at libpng-1.2.43. To accept all valid PNGs no matter
276 # how large, set these two limits to 0.
278 setting USER_CHUNK_CACHE_MAX default 0
280 # Added at libpng-1.2.43
282 setting USER_CHUNK_MALLOC_MAX default 0
284 # All of the following options relate to code capabilities for
285 # processing image data before creating a PNG or after reading one.
286 # You can remove these capabilities safely and still be PNG
287 # conformant, however the library that results is still non-standard.
288 # See the comments above about how to change options and settings.
292 option READ enables READ_INTERLACING
294 # Disabling READ_16BIT does not disable reading 16-bit PNG files, but it
295 # forces them to be chopped down to 8-bit, and disables any 16-bit
296 # processing after that has happened. You need to be sure to enable
297 # READ_SCALE_16_TO_8 or READ_STRIP_16_TO_8 when you disable READ_16BIT for
298 # this to work properly. You should disable the other option if you need to
299 # ensure a particular conversion (otherwise the app can chose.)
301 option READ_16BIT requires READ enables 16BIT
303 option READ_QUANTIZE requires READ
305 option READ_TRANSFORMS requires READ
306 = NO_READ_TRANSFORMS READ_TRANSFORMS_NOT_SUPPORTED
308 option READ_EXPAND requires READ_TRANSFORMS
309 option READ_EXPAND_16 requires READ_TRANSFORMS READ_16BIT enables READ_EXPAND
310 option READ_SHIFT requires READ_TRANSFORMS
311 option READ_PACK requires READ_TRANSFORMS
312 option READ_BGR requires READ_TRANSFORMS
313 option READ_SWAP requires READ_TRANSFORMS READ_16BIT
314 option READ_PACKSWAP requires READ_TRANSFORMS
315 option READ_INVERT requires READ_TRANSFORMS
316 option READ_BACKGROUND requires READ_TRANSFORMS enables READ_STRIP_ALPHA
317 option READ_STRIP_16_TO_8 requires READ_TRANSFORMS
318 option READ_SCALE_16_TO_8 requires READ_TRANSFORMS
319 option READ_FILLER requires READ_TRANSFORMS
320 option READ_GAMMA requires READ_TRANSFORMS enables READ_gAMA
321 option READ_GRAY_TO_RGB requires READ_TRANSFORMS
323 option READ_ALPHA_MODE requires READ_TRANSFORMS enables READ_GAMMA
324 option READ_SWAP_ALPHA requires READ_TRANSFORMS
325 option READ_INVERT_ALPHA requires READ_TRANSFORMS
326 option READ_STRIP_ALPHA requires READ_TRANSFORMS
327 option READ_USER_TRANSFORM requires READ_TRANSFORMS
328 option READ_RGB_TO_GRAY requires READ_TRANSFORMS
330 option PROGRESSIVE_READ requires READ
331 option SEQUENTIAL_READ requires READ
333 # You can define PNG_NO_PROGRESSIVE_READ if you don't do progressive reading.
334 # This is not talking about interlacing capability! You'll still have
335 # interlacing unless you turn off the following which is required
336 # for PNG-compliant decoders. (In other words, do not do this - in
337 # fact it can't be disabled from the command line!)
338 #option READ_INTERLACING requires READ
340 option READ_COMPOSITE_NODIV requires READ
341 = NO_READ_COMPOSITE_NODIV NO_READ_COMPOSITED_NODIV
345 option INCH_CONVERSIONS
346 = INCH_CONVERSIONS INCH_CONVERSIONS
348 # API to build a grayscale palette
350 option BUILD_GRAYSCALE_PALETTE
353 # These are currently experimental features; define them if you want
361 # Disabling WRITE_16BIT prevents 16-bit PNG files from being
363 option WRITE_16BIT requires WRITE enables 16BIT
365 option WRITE_TRANSFORMS requires WRITE
366 = NO_WRITE_TRANSFORMS WRITE_TRANSFORMS_NOT_SUPPORTED
368 option WRITE_SHIFT requires WRITE_TRANSFORMS
369 option WRITE_PACK requires WRITE_TRANSFORMS
370 option WRITE_BGR requires WRITE_TRANSFORMS
371 option WRITE_SWAP requires WRITE_TRANSFORMS WRITE_16BIT
372 option WRITE_PACKSWAP requires WRITE_TRANSFORMS
373 option WRITE_INVERT requires WRITE_TRANSFORMS
374 option WRITE_FILLER requires WRITE_TRANSFORMS
375 option WRITE_SWAP_ALPHA requires WRITE_TRANSFORMS
376 option WRITE_INVERT_ALPHA requires WRITE_TRANSFORMS
377 option WRITE_USER_TRANSFORM requires WRITE_TRANSFORMS
379 # This is not required for PNG-compliant encoders, but can cause
380 # trouble if left undefined
382 option WRITE_INTERLACING requires WRITE
384 # The following depends, internally, on WEIGHT_SHIFT and COST_SHIFT
385 # where are set below.
387 option WRITE_WEIGHTED_FILTER requires WRITE
389 option WRITE_FLUSH requires WRITE
391 # Note: these can be turned off explicitly if not required by the
392 # apps implementing the user transforms
393 option USER_TRANSFORM_PTR if READ_USER_TRANSFORM WRITE_USER_TRANSFORM
394 option USER_TRANSFORM_INFO if READ_USER_TRANSFORM WRITE_USER_TRANSFORM
396 # This enables API to set compression parameters for compressing
397 # non-IDAT chunks (zTXt, iTXt, iCCP, and unknown chunks). This feature
398 # was added at libpng-1.5.3.
399 option WRITE_CUSTOMIZE_ZTXT_COMPRESSION requires WRITE
401 # Any chunks you are not interested in, you can undef here. The
402 # ones that allocate memory may be expecially important (hIST,
403 # tEXt, zTXt, tRNS, pCAL). Others will just save time and make png_info
406 # The size of the png_text structure changed in libpng-1.0.6 when
407 # iTXt support was added. iTXt support was turned off by default through
408 # libpng-1.2.x, to support old apps that malloc the png_text structure
409 # instead of calling png_set_text() and letting libpng malloc it. It
410 # was turned on by default in libpng-1.4.0.
412 option READ_ANCILLARY_CHUNKS requires READ
413 # PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED is deprecated.
414 = NO_READ_ANCILLARY_CHUNKS READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
416 option WRITE_ANCILLARY_CHUNKS requires WRITE
417 # PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED is deprecated.
418 = NO_WRITE_ANCILLARY_CHUNKS WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
420 # These options disable *all* the text chunks if turned off
422 option READ_TEXT requires READ_ANCILLARY_CHUNKS enables TEXT
423 option WRITE_TEXT requires WRITE_ANCILLARY_CHUNKS enables TEXT
425 # Moved to pnglibconf.h at libpng-1.5.0
426 # Feature support: in 1.4 this was in pngconf.h, but the following
427 # features have no affect on the libpng API. Add library
428 # only features to the end of this list. Add features that
429 # affect the API above. (Note: the list of chunks follows
430 # the library-only settings.)
432 # BUILD TIME ONLY OPTIONS
433 # These options do not affect the API but rather alter how the
434 # API is implemented, they get recorded in pnglibconf.h, but
435 # can't be changed by the application.
437 # Check the correctness of cHRM chunks
439 option CHECK_cHRM requires cHRM
442 # Artificially align memory - the code typically aligns to 8 byte
443 # boundaries if this is switched on, it's a small waste of space
444 # but can help (in theory) on some architectures. Only affects
445 # internal structures. Added at libpng 1.4.0
449 # Buggy compilers (e.g., gcc 2.7.2.2) need PNG_NO_POINTER_INDEXING
450 # See png[wr]util.c, normally this should always be *on*
452 option POINTER_INDEXING
454 # Other defines for things like memory and the like can go here.
456 # BUILD TIME SETTINGS
457 # Like build time options these do not affect the API, but they
458 # may be useful to applications because they record details of
459 # how the API will behave particularly with regard to overall
462 # This controls how fine the quantizing gets. As this allocates
463 # a largish chunk of memory (32K), those who are not as concerned
464 # with quantizing quality can decrease some or all of these.
466 setting QUANTIZE_RED_BITS default 5
467 setting QUANTIZE_GREEN_BITS default 5
468 setting QUANTIZE_BLUE_BITS default 5
470 # This controls how fine the gamma correction becomes when you
471 # are only interested in 8 bits anyway. Increasing this value
472 # results in more memory being used, and more pow() functions
473 # being called to fill in the gamma tables. Don't set this value
474 # less then 8, and even that may not work (I haven't tested it).
476 setting MAX_GAMMA_8 default 11
478 # This controls how much a difference in gamma we can tolerate before
479 # we actually start doing gamma conversion, it's a fixed point value,
480 # so the default below is 0.05, meaning libpng ignores corrections in
481 # the range 0.95 to 1.05
483 setting GAMMA_THRESHOLD_FIXED default 5000
485 # Scaling factor for filter heuristic weighting calculations
487 setting WEIGHT_SHIFT default 8
488 setting COST_SHIFT default 3
490 # Precision to use when converting a floating point value to a PNG
491 # extension format string in an sCAL chunk (only relevant if the
492 # floating point API is enabled)
494 setting sCAL_PRECISION default 5
496 # This is the size of the compression buffer, and thus the size of
497 # an IDAT chunk. Make this whatever size you feel is best for your
498 # machine. One of these will be allocated per png_struct. When this
499 # is full, it writes the data to the disk, and does some other
500 # calculations. Making this an extremely small size may slow
501 # the library down, but you may want to experiment to determine
502 # where it becomes significant, if you are concerned with memory
503 # usage. Note that zlib allocates at least 32Kb also. For readers,
504 # this describes the size of the buffer available to read the data in.
505 # Unless this gets smaller than the size of a row (compressed),
506 # it should not make much difference how big this is.
508 setting ZBUF_SIZE default 8192
524 chunk tEXt requires TEXT
529 # This only affects support of the optional PLTE chunk in RGB and RGBA
530 # images. Notice that READ_ANCILLARY_CHUNKS therefore disables part
531 # of the regular chunk reading too.
533 option READ_OPT_PLTE requires READ_ANCILLARY_CHUNKS
535 option READ_UNKNOWN_CHUNKS requires READ
536 option READ_UNKNOWN_CHUNKS enables UNKNOWN_CHUNKS READ_USER_CHUNKS
537 option READ_USER_CHUNKS requires READ enables USER_CHUNKS
539 option CONVERT_tIME requires WRITE_ANCILLARY_CHUNKS
540 # The "tm" structure is not supported on WindowsCE
543 @# define PNG_NO_CONVERT_tIME
546 option WRITE_FILTER requires WRITE
548 option WRITE_UNKNOWN_CHUNKS requires WRITE
550 option HANDLE_AS_UNKNOWN
552 option SAVE_INT_32 requires WRITE
554 # png_save_int_32 is required by the ancillary chunks oFFs and pCAL
556 # added at libpng-1.5.4
558 option WRITE_OPTIMIZE_CMF requires WRITE
560 option READ_COMPRESSED_TEXT disabled
561 option READ_iCCP enables READ_COMPRESSED_TEXT
562 option READ_iTXt enables READ_COMPRESSED_TEXT
563 option READ_zTXt enables READ_COMPRESSED_TEXT
564 option READ_COMPRESSED_TEXT enables READ_TEXT
566 option WRITE_oFFs enables SAVE_INT_32
567 option WRITE_pCAL enables SAVE_INT_32
569 option WRITE_COMPRESSED_TEXT disabled
570 option WRITE_iCCP enables WRITE_COMPRESSED_TEXT
571 option WRITE_iTXt enables WRITE_COMPRESSED_TEXT
572 option WRITE_zTXt enables WRITE_COMPRESSED_TEXT
573 option WRITE_COMPRESSED_TEXT enables WRITE_TEXT
575 # Turn this off to disable png_read_png() and png_write_png() and
576 # leave the row_pointers member out of the info structure.