So we can have 2 kind of builds with the Zip/Deflate codec:
- zlib only
- zlib + libdeflate
Speed improvements in the 35%-50% range can be expected when libdeflate is used.
Compression level up to 12 is now supported (capped to 9 when zlib is used).
Still requires zlib for situations where libdeflate cannot be used (that
is for scanline access, since libdeflate has no streaming mode)
Pseudo-tag TIFFTAG_DEFLATE_SUBCODEC=DEFLATE_SUBCODEC_ZLIB/DEFLATE_SUBCODEC_LIBDEFLATE
is added to control which subcodec (zlib or libdeflate) should be used (it defaults
of course to libdeflate, when it is available).
This is mostly aimed at being used on the writing side, to be able to reproduce
output of previous libtiff versions at a binary level, in situations where this would
be really needed. Or as a safety belt in case there would be unforeseen issues
with using libdeflate.
It can be used to know when libdeflate is available at runtime (DEFLATE_SUBCODEC_LIBDEFLATE
will be the default value in that situation).
Of course, deflate codestreams produced by libdeflate can be read by zlib, and vice-versa.
According to http://bugzilla.maptools.org/show_bug.cgi?id=2125#c6
callers are not allowed to modify pointer or array values returned from
TIFFGetField or the like. So, make this explicit in the documentation
by specifying these things as const. Note that this is not an ABI
change, since C does not encode const in libraries. Also, this is
not really an API change, since the varargs call strips away all
the types anyway. So it really is more of a documentation change.
fixes#11
... and add per-strile offset/bytecount loading capabilities.
Part of this commit makes the behaviour that was previously met when
libtiff was compiled with -DDEFER_STRILE_LOAD available for default builds
when specifying the new 'D' (Deferred) TIFFOpen() flag. In that mode, the [Tile/Strip][ByteCounts/Offsets]
arrays are only loaded when first accessed. This can speed-up the opening
of files stored on the network when just metadata retrieval is needed.
This mode has been used for years by the GDAL library when compiled with
its embeded libtiff copy.
To avoid potential out-of-tree code (typically codecs) that would use
the td_stripbytecount and td_stripoffset array inconditionnaly assuming they
have been loaded, those have been suffixed with _p (for protected). The
use of the new functions mentionned below is then recommended.
Another addition of this commit is the capability of loading only the
values of the offset/bytecount of the strile of interest instead of the
whole array. This is enabled with the new 'O' (Ondemand) flag of TIFFOpen()
(which implies 'D'). That behaviour has also been used by GDAL, which hacked
into the td_stripoffset/td_stripbytecount arrays directly. The new code
added in the _TIFFFetchStrileValue() and _TIFFPartialReadStripArray() internal
functions is mostly a port of what was in GDAL GTiff driver previously.
Related to that, the public TIFFGetStrileOffset[WithErr]() and TIFFGetStrileByteCount[WithErr]()
functions have been added to API. They are of particular interest when
using sparse files (with offset == bytecount == 0) and you want to detect
if a strile is present or not without decompressing the data, or updating
an existing sparse file.
They will also be used to enable a future enhancement where client code can entirely
skip bytecount loading in some situtations
A new test/defer_strile_loading.c test has been added to test the above
capabilities.
ras2tiff, sgi2tiff, sgisv, and ycbcr are completely removed from
the distribution. The libtiff tools rgb2ycbcr and thumbnail are
only built in the build tree for testing. Old files are put in
new 'archive' subdirectory of the source repository, but not in
distribution archives. These changes are made in order to lessen
the maintenance burden.
Roger Leigh (via tiff mailing list on 2015-09-01) to fix issue
with BSD make and to make use of cmake in 'distcheck' target
conditional on if cmake is available.
libtiff mailing list on Mon, 22 Jun 2015 21:21:01 +0100. Several
corrections to ensure that the autotools build still works were
added by me. I have not yet tested the build using 'cmake' or
MSVC with 'nmake'.
some TIFF/FX support in libtiff. Add the tag definitions to
tiff.h. Add the related TIFF field definitions to tif_dirinfo.c,
and also fixes an error in a comment. Adds the photometric values
to tif_print.c, and fixes a bug. These changes are by Steve
Underwood.
* libtiff/tif_write.c: Fix bug rewriting image tiles in a
the run-time target whereas target is used to specify the final
output target if the package is a build tool (like a compiler),
which libtiff is not. Resolves libtiff bug 2307 "Use
AC_CANONICAL_HOST macro".
