1 README for libpng version 1.6.28 - January 5, 2017 (shared library 16.0)
2 See the note about version numbers near the top of png.h
3
4 See INSTALL for instructions on how to install libpng.
5
6 Libpng comes in several distribution formats. Get libpng-*.tar.gz or
7 libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
8 or lpng*.7z or lpng*.zip if you want DOS-style line endings.
9
10 Version 0.89 was the first official release of libpng. Don't let the
11 fact that it's the first release fool you. The libpng library has been in
12 extensive use and testing since mid-1995. By late 1997 it had
13 finally gotten to the stage where there hadn't been significant
14 changes to the API in some time, and people have a bad feeling about
15 libraries with versions < 1.0. Version 1.0.0 was released in
16 March 1998.
17
18 ****
19 Note that some of the changes to the png_info structure render this
20 version of the library binary incompatible with libpng-0.89 or
21 earlier versions if you are using a shared library. The type of the
22 "filler" parameter for png_set_filler() has changed from png_byte to
23 png_uint_32, which will affect shared-library applications that use
24 this function.
25
26 To avoid problems with changes to the internals of png info_struct,
27 new APIs have been made available in 0.95 to avoid direct application
28 access to info_ptr. These functions are the png_set_<chunk> and
29 png_get_<chunk> functions. These functions should be used when
30 accessing/storing the info_struct data, rather than manipulating it
31 directly, to avoid such problems in the future.
32
33 It is important to note that the APIs did not make current programs
34 that access the info struct directly incompatible with the new
35 library, through libpng-1.2.x. In libpng-1.4.x, which was meant to
36 be a transitional release, members of the png_struct and the
37 info_struct can still be accessed, but the compiler will issue a
38 warning about deprecated usage. Since libpng-1.5.0, direct access
39 to these structs is not allowed, and the definitions of the structs
40 reside in private pngstruct.h and pnginfo.h header files that are not
41 accessible to applications. It is strongly suggested that new
42 programs use the new APIs (as shown in example.c and pngtest.c), and
43 older programs be converted to the new format, to facilitate upgrades
44 in the future.
45 ****
46
71 png.h. For a description on using zlib (the compression library used by
72 libpng) and zlib's restrictions, see zlib.h
73
74 I have included a general makefile, as well as several machine and
75 compiler specific ones, but you may have to modify one for your own needs.
76
77 You should use zlib 1.0.4 or later to run this, but it MAY work with
78 versions as old as zlib 0.95. Even so, there are bugs in older zlib
79 versions which can cause the output of invalid compression streams for
80 some images. You will definitely need zlib 1.0.4 or later if you are
81 taking advantage of the MS-DOS "far" structure allocation for the small
82 and medium memory models. You should also note that zlib is a
83 compression library that is useful for more things than just PNG files.
84 You can use zlib as a drop-in replacement for fread() and fwrite() if
85 you are so inclined.
86
87 zlib should be available at the same place that libpng is, or at zlib.net.
88
89 You may also want a copy of the PNG specification. It is available
90 as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
91 these at http://www.libpng.org/pub/png/documents/
92
93 This code is currently being archived at libpng.sf.net in the
94 [DOWNLOAD] area, and at ftp://ftp.simplesystems.org. If you can't find it
95 in any of those places, e-mail me, and I'll help you find it.
96
97 I am not a lawyer, but I believe that the Export Control Classification
98 Number (ECCN) for libpng is EAR99, which means not subject to export
99 controls or International Traffic in Arms Regulations (ITAR) because it
100 is open source, publicly available software, that does not contain any
101 encryption software. See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
102
103 If you have any code changes, requests, problems, etc., please e-mail
104 them to me. Also, I'd appreciate any make files or project files,
105 and any modifications you needed to make to get libpng to compile,
106 along with a #define variable to tell what compiler/system you are on.
107 If you needed to add transformations to libpng, or wish libpng would
108 provide the image in a different way, drop me a note (and code, if
109 possible), so I can consider supporting the transformation.
110 Finally, if you get any warning messages when compiling libpng
111 (note: not zlib), and they are easy to fix, I'd appreciate the
112 fix. Please mention "libpng" somewhere in the subject line. Thanks.
113
114 This release was created and will be supported by myself (of course
115 based in a large way on Guy's and Andreas' earlier work), and the PNG
162 pngdebug.h => debugging macros (private)
163 pngerror.c => Error/warning message I/O functions
164 pngget.c => Functions for retrieving info from struct
165 pngmem.c => Memory handling functions
166 pngbar.png => PNG logo, 88x31
167 pngnow.png => PNG logo, 98x31
168 pngpread.c => Progressive reading functions
169 pngread.c => Read data/helper high-level functions
170 pngrio.c => Lowest-level data read I/O functions
171 pngrtran.c => Read data transformation functions
172 pngrutil.c => Read data utility functions
173 pngset.c => Functions for storing data into the info_struct
174 pngtest.c => Library test program
175 pngtest.png => Library test sample image
176 pngtrans.c => Common data transformation functions
177 pngwio.c => Lowest-level write I/O functions
178 pngwrite.c => High-level write functions
179 pngwtran.c => Write data transformations
180 pngwutil.c => Write utility functions
181 arm => Contains optimized code for the ARM platform
182 contrib => Contributions
183 arm-neon => Optimized code for ARM-NEON platform
184 examples => Example programs
185 gregbook => source code for PNG reading and writing, from
186 Greg Roelofs' "PNG: The Definitive Guide",
187 O'Reilly, 1999
188 intel => Optimized code for INTEL-SSE2 platform
189 libtests => Test programs
190 pngminim => Minimal decoder, encoder, and progressive decoder
191 programs demonstrating use of pngusr.dfa
192 pngminus => Simple pnm2png and png2pnm programs
193 pngsuite => Test images
194 testpngs
195 tools => Various tools
196 visupng => Contains a MSVC workspace for VisualPng
197 projects => Contains project files and workspaces for
198 building a DLL
199 owatcom => Contains a WATCOM project for building libpng
200 visualc71 => Contains a Microsoft Visual C++ (MSVC)
201 workspace for building libpng and zlib
202 vstudio => Contains a Microsoft Visual C++ (MSVC)
203 workspace for building libpng and zlib
204 scripts => Directory containing scripts for building libpng:
205 (see scripts/README.txt for the list of scripts)
206
207 Good luck, and happy coding.
208
209 -Glenn Randers-Pehrson (current maintainer, since 1998)
210 Internet: glennrp at users.sourceforge.net
211
212 -Andreas Eric Dilger (former maintainer, 1996-1997)
213 Internet: adilger at enel.ucalgary.ca
214 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
215
216 -Guy Eric Schalnat (original author and former maintainer, 1995-1996)
|
1 README for libpng version 1.6.34 - September 29, 2017 (shared library 16.0)
2 See the note about version numbers near the top of png.h
3
4 See INSTALL for instructions on how to install libpng.
5
6 Libpng comes in several distribution formats. Get libpng-*.tar.gz or
7 libpng-*.tar.xz or if you want UNIX-style line endings in the text files,
8 or lpng*.7z or lpng*.zip if you want DOS-style line endings.
9
10 Version 0.89 was the first official release of libpng. Don't let the
11 fact that it's the first release fool you. The libpng library has been in
12 extensive use and testing since mid-1995. By late 1997 it had
13 finally gotten to the stage where there hadn't been significant
14 changes to the API in some time, and people have a bad feeling about
15 libraries with versions < 1.0. Version 1.0.0 was released in
16 March 1998.
17
18 ****
19 Note that some of the changes to the png_info structure render this
20 version of the library binary incompatible with libpng-0.89 or
21 earlier versions if you are using a shared library. The type of the
22 "filler" parameter for png_set_filler() has changed from png_byte to
23 png_uint_32, which will affect shared-library applications that use
24 this function.
25
26 To avoid problems with changes to the internals of the png info_struct,
27 new APIs have been made available in 0.95 to avoid direct application
28 access to info_ptr. These functions are the png_set_<chunk> and
29 png_get_<chunk> functions. These functions should be used when
30 accessing/storing the info_struct data, rather than manipulating it
31 directly, to avoid such problems in the future.
32
33 It is important to note that the APIs did not make current programs
34 that access the info struct directly incompatible with the new
35 library, through libpng-1.2.x. In libpng-1.4.x, which was meant to
36 be a transitional release, members of the png_struct and the
37 info_struct can still be accessed, but the compiler will issue a
38 warning about deprecated usage. Since libpng-1.5.0, direct access
39 to these structs is not allowed, and the definitions of the structs
40 reside in private pngstruct.h and pnginfo.h header files that are not
41 accessible to applications. It is strongly suggested that new
42 programs use the new APIs (as shown in example.c and pngtest.c), and
43 older programs be converted to the new format, to facilitate upgrades
44 in the future.
45 ****
46
71 png.h. For a description on using zlib (the compression library used by
72 libpng) and zlib's restrictions, see zlib.h
73
74 I have included a general makefile, as well as several machine and
75 compiler specific ones, but you may have to modify one for your own needs.
76
77 You should use zlib 1.0.4 or later to run this, but it MAY work with
78 versions as old as zlib 0.95. Even so, there are bugs in older zlib
79 versions which can cause the output of invalid compression streams for
80 some images. You will definitely need zlib 1.0.4 or later if you are
81 taking advantage of the MS-DOS "far" structure allocation for the small
82 and medium memory models. You should also note that zlib is a
83 compression library that is useful for more things than just PNG files.
84 You can use zlib as a drop-in replacement for fread() and fwrite() if
85 you are so inclined.
86
87 zlib should be available at the same place that libpng is, or at zlib.net.
88
89 You may also want a copy of the PNG specification. It is available
90 as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
91 these at http://www.libpng.org/pub/png/pngdocs.html .
92
93 This code is currently being archived at libpng.sourceforge.io in the
94 [DOWNLOAD] area, and at http://libpng.download/src . If you
95 can't find it in any of those places, e-mail me, and I'll help you find it.
96
97 I am not a lawyer, but I believe that the Export Control Classification
98 Number (ECCN) for libpng is EAR99, which means not subject to export
99 controls or International Traffic in Arms Regulations (ITAR) because it
100 is open source, publicly available software, that does not contain any
101 encryption software. See the EAR, paragraphs 734.3(b)(3) and 734.7(b).
102
103 If you have any code changes, requests, problems, etc., please e-mail
104 them to me. Also, I'd appreciate any make files or project files,
105 and any modifications you needed to make to get libpng to compile,
106 along with a #define variable to tell what compiler/system you are on.
107 If you needed to add transformations to libpng, or wish libpng would
108 provide the image in a different way, drop me a note (and code, if
109 possible), so I can consider supporting the transformation.
110 Finally, if you get any warning messages when compiling libpng
111 (note: not zlib), and they are easy to fix, I'd appreciate the
112 fix. Please mention "libpng" somewhere in the subject line. Thanks.
113
114 This release was created and will be supported by myself (of course
115 based in a large way on Guy's and Andreas' earlier work), and the PNG
162 pngdebug.h => debugging macros (private)
163 pngerror.c => Error/warning message I/O functions
164 pngget.c => Functions for retrieving info from struct
165 pngmem.c => Memory handling functions
166 pngbar.png => PNG logo, 88x31
167 pngnow.png => PNG logo, 98x31
168 pngpread.c => Progressive reading functions
169 pngread.c => Read data/helper high-level functions
170 pngrio.c => Lowest-level data read I/O functions
171 pngrtran.c => Read data transformation functions
172 pngrutil.c => Read data utility functions
173 pngset.c => Functions for storing data into the info_struct
174 pngtest.c => Library test program
175 pngtest.png => Library test sample image
176 pngtrans.c => Common data transformation functions
177 pngwio.c => Lowest-level write I/O functions
178 pngwrite.c => High-level write functions
179 pngwtran.c => Write data transformations
180 pngwutil.c => Write utility functions
181 arm => Contains optimized code for the ARM platform
182 powerpc => Contains optimized code for the PowerPC platform
183 contrib => Contributions
184 arm-neon => Optimized code for ARM-NEON platform
185 powerpc-vsx => Optimized code for POWERPC-VSX platform
186 examples => Example programs
187 gregbook => source code for PNG reading and writing, from
188 Greg Roelofs' "PNG: The Definitive Guide",
189 O'Reilly, 1999
190 libtests => Test programs
191 mips-msa => Optimized code for MIPS-MSA platform
192 pngminim => Minimal decoder, encoder, and progressive decoder
193 programs demonstrating use of pngusr.dfa
194 pngminus => Simple pnm2png and png2pnm programs
195 pngsuite => Test images
196 testpngs
197 tools => Various tools
198 visupng => Contains a MSVC workspace for VisualPng
199 intel => Optimized code for INTEL-SSE2 platform
200 mips => Optimized code for MIPS platform
201 projects => Contains project files and workspaces for
202 building a DLL
203 owatcom => Contains a WATCOM project for building libpng
204 visualc71 => Contains a Microsoft Visual C++ (MSVC)
205 workspace for building libpng and zlib
206 vstudio => Contains a Microsoft Visual C++ (MSVC)
207 workspace for building libpng and zlib
208 scripts => Directory containing scripts for building libpng:
209 (see scripts/README.txt for the list of scripts)
210
211 Good luck, and happy coding.
212
213 -Glenn Randers-Pehrson (current maintainer, since 1998)
214 Internet: glennrp at users.sourceforge.net
215
216 -Andreas Eric Dilger (former maintainer, 1996-1997)
217 Internet: adilger at enel.ucalgary.ca
218 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
219
220 -Guy Eric Schalnat (original author and former maintainer, 1995-1996)
|