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918ace63
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2022-11-16T10:36:57
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example.c: Fix compiler warning
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b5a9ef64
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2022-11-13T13:00:26
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Don't allow 12-bit JPEG support to be disabled
In libjpeg-turbo 2.1.x and prior, the WITH_12BIT CMake variable was used
to enable 12-bit JPEG support at compile time, because the libjpeg API
library could not handle multiple JPEG data precisions at run time. The
initial approach to handling multiple JPEG data precisions at run time
(7fec5074f962b20ed00b4f5da4533e1e8d4ed8ac) created a whole new API,
library, and applications for 12-bit data precision, so it made sense to
repurpose WITH_12BIT to allow 12-bit data precision to be disabled.
e8b40f3c2ba187ba95c13c3e8ce21c8534256df7 made it so that the libjpeg API
library can handle multiple JPEG data precisions at run time via a
handful of straightforward API extensions. Referring to
6c2bc901e27b047440ed46920c4d3f0480b48268, it hasn't been possible to
build libjpeg-turbo with both forward and backward libjpeg API/ABI
compatibility since libjpeg-turbo 1.4.x. Thus, whereas we retain full
backward API/ABI compatibility with libjpeg v6b-v8, forward libjpeg
API/ABI compatibility ceased being realistic years ago, so it no longer
makes sense to provide compile-time options that give a false sense of
forward API/ABI compatibility by allowing some (but not all) of our
libjpeg API extensions to be disabled. Such options are difficult to
maintain and clutter the code with #ifdefs.
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e8b40f3c
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2022-11-01T21:45:39
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Vastly improve 12-bit JPEG integration
The Gordian knot that 7fec5074f962b20ed00b4f5da4533e1e8d4ed8ac attempted
to unravel was caused by the fact that there are several
data-precision-dependent (JSAMPLE-dependent) fields and methods in the
exposed libjpeg API structures, and if you change the exposed libjpeg
API structures, then you have to change the whole API. If you change
the whole API, then you have to provide a whole new library to support
the new API, and that makes it difficult to support multiple data
precisions in the same application. (It is not impossible, as example.c
demonstrated, but using data-precision-dependent libjpeg API structures
would have made the cjpeg, djpeg, and jpegtran source code hard to read,
so it made more sense to build, install, and package 12-bit-specific
versions of those applications.)
Unfortunately, the result of that initial integration effort was an
unreadable and unmaintainable mess, which is a problem for a library
that is an ISO/ITU-T reference implementation. Also, as I dug into the
problem of lossless JPEG support, I realized that 16-bit lossless JPEG
images are a thing, and supporting yet another version of the libjpeg
API just for those images is untenable.
In fact, however, the touch points for JSAMPLE in the exposed libjpeg
API structures are minimal:
- The colormap and sample_range_limit fields in jpeg_decompress_struct
- The alloc_sarray() and access_virt_sarray() methods in
jpeg_memory_mgr
- jpeg_write_scanlines() and jpeg_write_raw_data()
- jpeg_read_scanlines() and jpeg_read_raw_data()
- jpeg_skip_scanlines() and jpeg_crop_scanline()
(This is subtle, but both of those functions use JSAMPLE-dependent
opaque structures behind the scenes.)
It is much more readable and maintainable to provide 12-bit-specific
versions of those six top-level API functions and to document that the
aforementioned methods and fields must be type-cast when using 12-bit
samples. Since that eliminates the need to provide a 12-bit-specific
version of the exposed libjpeg API structures, we can:
- Compile only the precision-dependent libjpeg modules (the
coefficient buffer controllers, the colorspace converters, the
DCT/IDCT managers, the main buffer controllers, the preprocessing
and postprocessing controller, the downsampler and upsamplers, the
quantizers, the integer DCT methods, and the IDCT methods) for
multiple data precisions.
- Introduce 12-bit-specific methods into the various internal
structures defined in jpegint.h.
- Create precision-independent data type, macro, method, field, and
function names that are prefixed by an underscore, and use an
internal header to convert those into precision-dependent data
type, macro, method, field, and function names, based on the value
of BITS_IN_JSAMPLE, when compiling the precision-dependent libjpeg
modules.
- Expose precision-dependent jinit*() functions for each of the
precision-dependent libjpeg modules.
- Abstract the precision-dependent libjpeg modules by calling the
appropriate precision-dependent jinit*() function, based on the
value of cinfo->data_precision, from top-level libjpeg API
functions.
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8a3b0f70
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2022-06-24T15:21:51
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Implement 12-bit-specific error/warn/trace macros
The macros in jerror.h refer to j_common_ptr, so it is unfortunately
necessary to introduce a 12-bit-specific version of that header file
(j12error.h) with 12-bit specific ERREXIT*(), WARNMS*(), and
TRACEMS*() macros. (The message table is still shared between 8-bit and
12-bit implementations.)
Fixes #607
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cb715fe1
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2022-03-11T17:12:37
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example.c: Fix compiler warning with GCC 4.4.7
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a32038e3
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2022-03-10T23:10:12
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Fix formatting issues detected by checkstyle
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7fec5074
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2022-03-08T12:34:11
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Support 8-bit & 12-bit JPEGs using the same build
Partially implements #199
This commit also implements a request from #178 (the ability to compile
the libjpeg example as a standalone program.)
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8c40ac8a
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2017-11-16T18:46:01
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Add TurboJPEG C example and clean up Java example
Also rename example.c --> example.txt and add a disclaimer to that file
so people will stop trying to compile it.
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bd49803f
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2016-02-19T08:53:33
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Use consistent/modern code formatting for pointers
The convention used by libjpeg:
type * variable;
is not very common anymore, because it looks too much like
multiplication. Some (particularly C++ programmers) prefer to tuck the
pointer symbol against the type:
type* variable;
to emphasize that a pointer to a type is effectively a new type.
However, this can also be confusing, since defining multiple variables
on the same line would not work properly:
type* variable1, variable2; /* Only variable1 is actually a
pointer. */
This commit reformats the entirety of the libjpeg-turbo code base so
that it uses the same code formatting convention for pointers that the
TurboJPEG API code uses:
type *variable1, *variable2;
This seems to be the most common convention among C programmers, and
it is the convention used by other codec libraries, such as libpng and
libtiff.
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489583f5
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1996-02-07T00:00:00
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The Independent JPEG Group's JPEG software v6a
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bc79e068
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1995-08-02T00:00:00
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The Independent JPEG Group's JPEG software v6
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a8b67c4f
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1995-03-15T00:00:00
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The Independent JPEG Group's JPEG software v5b
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36a4cccc
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1994-09-24T00:00:00
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The Independent JPEG Group's JPEG software v5
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cc7150e2
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1993-02-18T00:00:00
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The Independent JPEG Group's JPEG software v4a
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88aeed42
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1992-12-10T00:00:00
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The Independent JPEG Group's JPEG software v4
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4a6b7303
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1992-03-17T00:00:00
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The Independent JPEG Group's JPEG software v3
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5996a25e
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2009-06-27T00:00:00
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The Independent JPEG Group's JPEG software v7
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b7753510
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2014-05-11T09:36:25
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Convert tabs to spaces in the libjpeg code and the SIMD code (TurboJPEG retains the use of tabs for historical reasons. They were annoying in the libjpeg code primarily because they were not consistently used and because they were used to format as well as indent the code. In the case of TurboJPEG, tabs are used just to indent the code, so even if the editor assumes a different tab width, the code will still be readable.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/branches/1.3.x@1285 632fc199-4ca6-4c93-a231-07263d6284db
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e5eaf374
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2014-05-09T18:00:32
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Convert tabs to spaces in the libjpeg code and the SIMD code (TurboJPEG retains the use of tabs for historical reasons. They were annoying in the libjpeg code primarily because they were not consistently used and because they were used to format as well as indent the code. In the case of TurboJPEG, tabs are used just to indent the code, so even if the editor assumes a different tab width, the code will still be readable.)
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1278 632fc199-4ca6-4c93-a231-07263d6284db
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c8753072
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2006-05-25T05:01:55
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Migrating to new directory structure adopted from the RealVNC's source tree. More changes will follow.
git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@1 632fc199-4ca6-4c93-a231-07263d6284db
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