This makes it possible for downstream packagers and other integrators of
libjpeg-turbo to include only specific directories from the
libjpeg-turbo installation (or to install specific directories under a
different prefix, etc.) The names of the components correspond to the
directories into which they will be installed.
Refer to libvips/libvips#3931, #265, #338Closes#756
With rare exceptions ...
- Always separate line continuation characters by one space from
preceding code.
- Always use two-space indentation. Never use tabs.
- Always use K&R-style conditional blocks.
- Always surround operators with spaces, except in raw assembly code.
- Always put a space after, but not before, a comma.
- Never put a space between type casts and variables/function calls.
- Never put a space between the function name and the argument list in
function declarations and prototypes.
- Always surround braces ('{' and '}') with spaces.
- Always surround statements (if, for, else, catch, while, do, switch)
with spaces.
- Always attach pointer symbols ('*' and '**') to the variable or
function name.
- Always precede pointer symbols ('*' and '**') by a space in type
casts.
- Use the MIN() macro from jpegint.h within the libjpeg and TurboJPEG
API libraries (using min() from tjutil.h is still necessary for
TJBench.)
- Where it makes sense (particularly in the TurboJPEG code), put a blank
line after variable declaration blocks.
- Always separate statements in one-liners by two spaces.
The purpose of this was to ease maintenance on my part and also to make
it easier for contributors to figure out how to format patch
submissions. This was admittedly confusing (even to me sometimes) when
we had 3 or 4 different style conventions in the same source tree. The
new convention is more consistent with the formatting of other OSS code
bases.
This commit corrects deviations from the chosen formatting style in the
libjpeg API code and reformats the TurboJPEG API code such that it
conforms to the same standard.
NOTES:
- Although it is no longer necessary for the function name in function
declarations to begin in Column 1 (this was historically necessary
because of the ansi2knr utility, which allowed libjpeg to be built
with non-ANSI compilers), we retain that formatting for the libjpeg
code because it improves readability when using libjpeg's function
attribute macros (GLOBAL(), etc.)
- This reformatting project was accomplished with the help of AStyle and
Uncrustify, although neither was completely up to the task, and thus
a great deal of manual tweaking was required. Note to developers of
code formatting utilities: the libjpeg-turbo code base is an
excellent test bed, because AFAICT, it breaks every single one of the
utilities that are currently available.
- The legacy (MMX, SSE, 3DNow!) assembly code for i386 has been
formatted to match the SSE2 code (refer to
ff5685d5344273df321eb63a005eaae19d2496e3.) I hadn't intended to
bother with this, but the Loongson MMI implementation demonstrated
that there is still academic value to the MMX implementation, as an
algorithmic model for other 64-bit vector implementations. Thus, it
is desirable to improve its readability in the same manner as that of
the SSE2 implementation.
These improvements enable build systems to use GNUInstallDirs to define
custom directory variables.
- The set_dir() macro was renamed to GNUInstallDirs_set_install_dir(),
in keeping with the module's established macro naming convention.
- Rather than detecting whether the prefix has changed, the new
GNUInstallDirs_set_install_dir() macro instead examines whether the
default for the variable in question has changed. This allows for
more flexibility, since build systems may decide to change the
defaults based on factors other than the prefix. It also enables the
macro to work properly outside of the module.
- The module now performs directory variable substitution within the
body of GNUInstallDirs_get_absolute_install_dir().
- The JAVADIR variable is no longer included in GNUInstallDirs. That
directory is not part of the GNU spec, and it turns out that various
operating systems use different conventions for the location of Java
classes. Instead, the variable is now implemented in our build
system as a demonstration of the aforementioned GNUInstallDirs
enhancements.
This builds upon the existing GNUInstallDirs module in CMake but adds
the following features to that module:
- The ability to override the defaults for each install directory
through a new set of variables (`CMAKE_INSTALL_DEFAULT_*DIR`).
Before operating system vendors began shipping libjpeg-turbo, it was
meant to be a run-time drop-in replacement for the system's
distribution of libjpeg, so it has traditionally installed itself
under /opt/libjpeg-turbo on Un*x systems by default. On Windows, it
has traditionally installed itself under %SystemDrive%\libjpeg-turbo*,
which is not uncommon behavior for open source libraries (open source
SDKs tend to install outside of the Program Files directory so as to
avoid spaces in the directory name.) At least in the case of Un*x,
the install directory behavior is based somewhat on the Solaris
standard, which requires all non-O/S packages to install their files
under /opt/{package_name}. I adopted that standard for VirtualGL and
TurboVNC while working at Sun, because it allowed those packages to be
located under the same directory on all platforms. I adopted it for
libjpeg-turbo because it ensured that our files would never conflict
with the system's version of libjpeg. Even though many Un*x
distributions ship libjpeg-turbo these days, not all of them ship the
TurboJPEG API library or the Java classes or even the latest version
of the libjpeg API library, so there are still many cases in which it
is desirable to install a separate version of libjpeg-turbo than the
one installed by the system. Furthermore, installing the files under
/opt mimics the directory structure of our official binary packages,
and it makes it very easy to uninstall libjpeg-turbo.
For these reasons, our build system needs to be able to use
non-GNU-compliant defaults for each install directory if
`CMAKE_INSTALL_PREFIX` is set to the default value.
- For each directory variable, the module now detects changes to
`CMAKE_INSTALL_PREFIX` and changes the directory variable accordingly,
if the variable has not been changed by the user.
This makes it easy to switch between our "official" directory
structure and the GNU-compliant directory structure "on the fly"
simply by changing `CMAKE_INSTALL_PREFIX`. Also, this new mechanism
eliminated the need for the crufty mechanism that previously did the
same thing just for the library directory variable.
How it should work:
- If a dir variable is unset, then the module will set an internal
property indicating that the dir variable was initialized to its
default value.
- If the dir variable ever diverges from its default value, then the
internal property is cleared, and it cannot be set again without
unsetting the dir variable.
- If the install prefix changes, and if the internal property
indicates that the dir variable is still set to its default value,
and if the dir variable's value is not being manually changed at the
same time that the install prefix is being changed, then the dir
variable's value is automatically changed to the new default value
for that variable (as determined by the new install prefix.)
- The directory variables are now always cached, regardless of whether
they were set on the command line or not. This ensures that they can
easily be examined and modified after being set, regardless of how they
were set.
This was made possible by the introduction of the aforementioned
`CMAKE_INSTALL_DEFAULT_*DIR` variables.
- Improved directory variable documentation (based on descriptions at
https://www.gnu.org/prep/standards/html_node/Directory-Variables.html)
- The module now allows "<DATAROOTDIR>" to be used as a placeholder in
relative directory variables.
It is replaced "on the fly" with the actual path of
`CMAKE_INSTALL_DATAROOTDIR`.
This should more closely mimic the behavior of the old autotools build
system while retaining our customizations to it, and it should retain
the behavior of the old CMake build system.
Closes#124
Use a new checked exception type (TJException) when passing through
errors from the underlying C library. This gives the application a
choice of catching all exceptions or just those from TurboJPEG.
Throw IllegalArgumentException at the JNI level when arguments to the
JNI function are incorrect, and when one of the TurboJPEG "utility"
functions returns an error (because, per the C API specification, those
functions will only return an error if one of their arguments is out of
range.)
Remove "throws Exception" from the signature of any methods that no
longer pass through an error from the TurboJPEG C library.
Credit Viktor for the new code
Code formatting tweaks
