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[libpng16] Committed wrong version of INSTALL.

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Glenn Randers-Pehrson 2014-03-21 13:26:43 -05:00
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INSTALL
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@ -1,6 +1,27 @@
Installing libpng
Contents
I. Simple installation
II. Rebuilding the configure scripts
III. Using scripts/makefile*
IV. Using cmake
V. Directory structure
VI. Building with project files
VII. Building with makefiles
VIII. Configuring libpng for 16-bit platforms
IX. Configuring for DOS
X. Configuring for Medium Model
XI. Prepending a prefix to exported symbols
XII. Configuring for compiler xxx:
XIII. Removing unwanted object code
XIV. Changes to the build and configuration of libpng in libpng-1.5.x
XV. Configuring libpng for multiprocessing
XVI. Other sources of information about libpng:
I. Simple installation
On Unix/Linux and similar systems, you can simply type
./configure [--prefix=/path]
@ -9,6 +30,8 @@ On Unix/Linux and similar systems, you can simply type
and ignore the rest of this document.
II. Rebuilding the configure scripts
If configure does not work on your system, or if you have a need to
change configure.ac or Makefile.am, and you have a reasonably
up-to-date set of tools, running ./autogen.sh in a git clone before
@ -24,9 +47,12 @@ aren't using any of the included pre-built scripts, you can do this:
make install
make check
III. Using scripts/makefile*
Instead, you can use one of the custom-built makefiles in the
"scripts" directory
cp scripts/pnglibconf.h.prebuilt pnglibconf.h
cp scripts/makefile.system makefile
make test
make install
@ -41,19 +67,37 @@ is not already on your system. zlib can usually be found
wherever you got libpng. zlib can be placed in another directory,
at the same level as libpng.
If your system already has a preinstalled zlib you will still need
to have access to the zlib.h and zconf.h include files that
correspond to the version of zlib that's installed.
If you wish to test with a particular zlib that is not first in the
standard library search path, put ZLIBLIB, ZLIBINC, CPPFLAGS, LDFLAGS,
and LD_LIBRARY_PATH in your environment before running "make test"
or "make distcheck":
ZLIBLIB=/path/to/lib export ZLIBLIB
ZLIBINC=/path/to/include export ZLIBINC
CPPFLAGS="-I$ZLIBINC" export CPPFLAGS
LDFLAGS="-L$ZLIBLIB" export LDFLAGS
LD_LIBRARY_PATH="$ZLIBLIB:$LD_LIBRARY_PATH" export LD_LIBRARY_PATH
If you are using one of the makefile scripts, put ZLIBLIB and ZLIBINC
in your environment and type "make ZLIBLIB=$ZLIBLIB ZLIBINC=$ZLIBINC test".
IV. Using cmake
If you want to use "cmake" (see www.cmake.org), type
cmake . -DCMAKE_INSTALL_PREFIX=/path
make
make install
If your system already has a preinstalled zlib you will still need
to have access to the zlib.h and zconf.h include files that
correspond to the version of zlib that's installed.
V. Directory structure
You can rename the directories that you downloaded (they
might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.5"
or "zlib125") so that you have directories called "zlib" and "libpng".
might be called "libpng-x.y.z" or "libpngNN" and "zlib-1.2.8"
or "zlib128") so that you have directories called "zlib" and "libpng".
Your directory structure should look like this:
@ -71,6 +115,7 @@ Your directory structure should look like this:
depcomp, install-sh, mkinstalldirs, test-pngtest.sh
contrib
gregbook
libtests
pngminim
pngminus
pngsuite
@ -95,6 +140,8 @@ If the line endings in the files look funny, you may wish to get the other
distribution of libpng. It is available in both tar.gz (UNIX style line
endings) and zip (DOS style line endings) formats.
VI. Building with project files
If you are building libpng with MSVC, you can enter the
libpng projects\visualc6 or visualc71 directory and follow the instructions
in README.txt.
@ -103,11 +150,15 @@ Otherwise enter the zlib directory and follow the instructions in zlib/README,
then come back here and run "configure" or choose the appropriate
makefile.sys in the scripts directory.
VII. Building with makefiles
Copy the file (or files) that you need from the
scripts directory into this directory, for example
MSDOS example: copy scripts\makefile.msc makefile
copy scripts\pnglibconf.h.prebuilt pnglibconf.h
UNIX example: cp scripts/makefile.std makefile
cp scripts/pnglibconf.h.prebuilt pnglibconf.h
Read the makefile to see if you need to change any source or
target directories to match your preferences.
@ -130,6 +181,189 @@ do that, run "make install" in the zlib directory first if necessary).
Some also allow you to run "make test-installed" after you have
run "make install".
VIII. Configuring libpng for 16-bit platforms
You will want to look into zconf.h to tell zlib (and thus libpng) that
it cannot allocate more then 64K at a time. Even if you can, the memory
won't be accessible. So limit zlib and libpng to 64K by defining MAXSEG_64K.
IX. Configuring for DOS
For DOS users who only have access to the lower 640K, you will
have to limit zlib's memory usage via a png_set_compression_mem_level()
call. See zlib.h or zconf.h in the zlib library for more information.
X. Configuring for Medium Model
Libpng's support for medium model has been tested on most of the popular
compilers. Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
defined, and FAR gets defined to far in pngconf.h, and you should be
all set. Everything in the library (except for zlib's structure) is
expecting far data. You must use the typedefs with the p or pp on
the end for pointers (or at least look at them and be careful). Make
note that the rows of data are defined as png_bytepp, which is
an "unsigned char far * far *".
XI. Prepending a prefix to exported symbols
Starting with libpng-1.6.0, you can configure libpng (when using the
"configure" script) to prefix all exported symbols by means of the
configuration option "--with-libpng-prefix=FOO_", where FOO_ can be any
string beginning with a letter and containing only uppercase
and lowercase letters, digits, and the underscore (i.e., a C language
identifier). This creates a set of macros in pnglibconf.h, so this is
transparent to applications; their function calls get transformed by
the macros to use the modified names.
XII. Configuring for compiler xxx:
All includes for libpng are in pngconf.h. If you need to add, change
or delete an include, this is the place to do it.
The includes that are not needed outside libpng are placed in pngpriv.h,
which is only used by the routines inside libpng itself.
The files in libpng proper only include pngpriv.h and png.h, which
in turn includes pngconf.h and, as of libpng-1.5.0, pnglibconf.h.
As of libpng-1.5.0, pngpriv.h also includes three other private header
files, pngstruct.h, pnginfo.h, and pngdebug.h, which contain material
that previously appeared in the public headers.
XIII. Removing unwanted object code
There are a bunch of #define's in pngconf.h that control what parts of
libpng are compiled. All the defines end in _SUPPORTED. If you are
never going to use a capability, you can change the #define to #undef
before recompiling libpng and save yourself code and data space, or
you can turn off individual capabilities with defines that begin with
PNG_NO_.
In libpng-1.5.0 and later, the #define's are in pnglibconf.h instead.
You can also turn all of the transforms and ancillary chunk capabilities
off en masse with compiler directives that define
PNG_NO_READ[or WRITE]_TRANSFORMS, or PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS,
or all four, along with directives to turn on any of the capabilities that
you do want. The PNG_NO_READ[or WRITE]_TRANSFORMS directives disable the
extra transformations but still leave the library fully capable of reading
and writing PNG files with all known public chunks. Use of the
PNG_NO_READ[or WRITE]_ANCILLARY_CHUNKS directive produces a library
that is incapable of reading or writing ancillary chunks. If you are
not using the progressive reading capability, you can turn that off
with PNG_NO_PROGRESSIVE_READ (don't confuse this with the INTERLACING
capability, which you'll still have).
All the reading and writing specific code are in separate files, so the
linker should only grab the files it needs. However, if you want to
make sure, or if you are building a stand alone library, all the
reading files start with "pngr" and all the writing files start with "pngw".
The files that don't match either (like png.c, pngtrans.c, etc.)
are used for both reading and writing, and always need to be included.
The progressive reader is in pngpread.c
If you are creating or distributing a dynamically linked library (a .so
or DLL file), you should not remove or disable any parts of the library,
as this will cause applications linked with different versions of the
library to fail if they call functions not available in your library.
The size of the library itself should not be an issue, because only
those sections that are actually used will be loaded into memory.
XIV. Changes to the build and configuration of libpng in libpng-1.5.x
Details of internal changes to the library code can be found in the CHANGES
file and in the GIT repository logs. These will be of no concern to the vast
majority of library users or builders; however, the few who configure libpng
to a non-default feature set may need to change how this is done.
There should be no need for library builders to alter build scripts if
these use the distributed build support - configure or the makefiles -
however, users of the makefiles may care to update their build scripts
to build pnglibconf.h where the corresponding makefile does not do so.
Building libpng with a non-default configuration has changed completely.
The old method using pngusr.h should still work correctly even though the
way pngusr.h is used in the build has been changed; however, library
builders will probably want to examine the changes to take advantage of
new capabilities and to simplify their build system.
A. Specific changes to library configuration capabilities
The exact mechanism used to control attributes of API functions has
changed. A single set of operating system independent macro definitions
is used and operating system specific directives are defined in
pnglibconf.h
As part of this the mechanism used to choose procedure call standards on
those systems that allow a choice has been changed. At present this only
affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
running on Intel processors. As before, PNGAPI is defined where required
to control the exported API functions; however, two new macros, PNGCBAPI
and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
(PNGCAPI) for functions that must match a C library prototype (currently
only png_longjmp_ptr, which must match the C longjmp function.) The new
approach is documented in pngconf.h
Despite these changes, libpng 1.5.0 only supports the native C function
calling standard on those platforms tested so far (__cdecl on Microsoft
Windows). This is because the support requirements for alternative
calling conventions seem to no longer exist. Developers who find it
necessary to set PNG_API_RULE to 1 should advise the mailing list
(png-mng-implement) of this and library builders who use Openwatcom and
therefore set PNG_API_RULE to 2 should also contact the mailing list.
B. Changes to the configuration mechanism
Prior to libpng-1.5.0 library builders who needed to configure libpng
had either to modify the exported pngconf.h header file to add system
specific configuration or had to write feature selection macros into
pngusr.h and cause this to be included into pngconf.h by defining
PNG_USER_CONFIG. The latter mechanism had the disadvantage that an
application built without PNG_USER_CONFIG defined would see the
unmodified, default, libpng API and thus would probably fail to link.
These mechanisms still work in the configure build and in any makefile
build that builds pnglibconf.h, although the feature selection macros
have changed somewhat as described above. In 1.5.0, however, pngusr.h is
processed only once, when the exported header file pnglibconf.h is built.
pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the
build of pnglibconf.h and it is never included in an application build.
The rarely used alternative of adding a list of feature macros to the
CPPFLAGS setting in the build also still works; however, the macros will be
copied to pnglibconf.h and this may produce macro redefinition warnings
when the individual C files are compiled.
All configuration now only works if pnglibconf.h is built from
scripts/pnglibconf.dfa. This requires the program awk. Brian Kernighan
(the original author of awk) maintains C source code of that awk and this
and all known later implementations (often called by subtly different
names - nawk and gawk for example) are adequate to build pnglibconf.h.
The Sun Microsystems (now Oracle) program 'awk' is an earlier version
and does not work; this may also apply to other systems that have a
functioning awk called 'nawk'.
Configuration options are now documented in scripts/pnglibconf.dfa. This
file also includes dependency information that ensures a configuration is
consistent; that is, if a feature is switched off dependent features are
also removed. As a recommended alternative to using feature macros in
pngusr.h a system builder may also define equivalent options in pngusr.dfa
(or, indeed, any file) and add that to the configuration by setting
DFA_XTRA to the file name. The makefiles in contrib/pngminim illustrate
how to do this, and a case where pngusr.h is still required.
XV. Configuring libpng for multiprocessing
Libpng uses setjmp()/longjmp() for error handling. Unfortunately setjmp()
is known to be not thread-safe on some platforms and we don't know of
any platform where it is guaranteed to be thread-safe. Therefore, if
your application is going to be using multiple threads, you should
configure libpng with PNG_NO_SETJMP in your pngusr.dfa file, with
-DPNG_NO_SETJMP on your compile line, or with
#undef PNG_SETJMP_SUPPORTED
in your pnglibconf.h or pngusr.h.
XVI. Other sources of information about libpng:
Further information can be found in the README and libpng-manual.txt
files, in the individual makefiles, in png.h, and the manual pages
libpng.3 and png.5.