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1 | README for libpng version 1.5.1 - February 3, 2011 (shared library 15.0) |
1 | README for libpng version 1.6.5 - September 14, 2013 (shared library 16.0) |
2 | See the note about version numbers near the top of png.h |
2 | See the note about version numbers near the top of png.h |
3 | 3 | ||
4 | See INSTALL for instructions on how to install libpng. |
4 | See INSTALL for instructions on how to install libpng. |
5 | 5 | ||
6 | Libpng comes in several distribution formats. Get libpng-*.tar.gz, |
6 | Libpng comes in several distribution formats. Get libpng-*.tar.gz or |
7 | libpng-*.tar.xz or libpng-*.tar.bz2 if you want UNIX-style line endings |
7 | libpng-*.tar.xz or if you want UNIX-style line endings in the text files, |
8 | in the text files, or lpng*.zip if you want DOS-style line endings. |
8 | or lpng*.7z or lpng*.zip if you want DOS-style line endings. |
9 | 9 | ||
10 | Version 0.89 was the first official release of libpng. Don't let the |
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 |
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 |
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 |
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 |
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 |
15 | libraries with versions < 1.0. Version 1.0.0 was released in |
16 | March 1998. |
16 | March 1998. |
17 | 17 | ||
18 | **** |
18 | **** |
19 | Note that some of the changes to the png_info structure render this |
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 |
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 |
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 |
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 |
23 | png_uint_32, which will affect shared-library applications that use |
24 | this function. |
24 | this function. |
25 | 25 | ||
26 | To avoid problems with changes to the internals of png_info_struct, |
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 |
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_ |
28 | access to info_ptr. These functions are the png_set_ |
29 | png_get_ |
29 | png_get_ |
30 | accessing/storing the info_struct data, rather than manipulating it |
30 | accessing/storing the info_struct data, rather than manipulating it |
31 | directly, to avoid such problems in the future. |
31 | directly, to avoid such problems in the future. |
32 | 32 | ||
33 | It is important to note that the APIs do not make current programs |
33 | It is important to note that the APIs do not make current programs |
34 | that access the info struct directly incompatible with the new |
34 | that access the info struct directly incompatible with the new |
35 | library. However, it is strongly suggested that new programs use |
35 | library. However, it is strongly suggested that new programs use |
36 | the new APIs (as shown in example.c and pngtest.c), and older programs |
36 | the new APIs (as shown in example.c and pngtest.c), and older programs |
37 | be converted to the new format, to facilitate upgrades in the future. |
37 | be converted to the new format, to facilitate upgrades in the future. |
38 | **** |
38 | **** |
39 | 39 | ||
40 | Additions since 0.90 include the ability to compile libpng as a |
40 | Additions since 0.90 include the ability to compile libpng as a |
41 | Windows DLL, and new APIs for accessing data in the info struct. |
41 | Windows DLL, and new APIs for accessing data in the info struct. |
42 | Experimental functions include the ability to set weighting and cost |
42 | Experimental functions include the ability to set weighting and cost |
43 | factors for row filter selection, direct reads of integers from buffers |
43 | factors for row filter selection, direct reads of integers from buffers |
44 | on big-endian processors that support misaligned data access, faster |
44 | on big-endian processors that support misaligned data access, faster |
45 | methods of doing alpha composition, and more accurate 16->8 bit color |
45 | methods of doing alpha composition, and more accurate 16->8 bit color |
46 | conversion. |
46 | conversion. |
47 | 47 | ||
48 | The additions since 0.89 include the ability to read from a PNG stream |
48 | The additions since 0.89 include the ability to read from a PNG stream |
49 | which has had some (or all) of the signature bytes read by the calling |
49 | which has had some (or all) of the signature bytes read by the calling |
50 | application. This also allows the reading of embedded PNG streams that |
50 | application. This also allows the reading of embedded PNG streams that |
51 | do not have the PNG file signature. As well, it is now possible to set |
51 | do not have the PNG file signature. As well, it is now possible to set |
52 | the library action on the detection of chunk CRC errors. It is possible |
52 | the library action on the detection of chunk CRC errors. It is possible |
53 | to set different actions based on whether the CRC error occurred in a |
53 | to set different actions based on whether the CRC error occurred in a |
54 | critical or an ancillary chunk. |
54 | critical or an ancillary chunk. |
55 | 55 | ||
56 | The changes made to the library, and bugs fixed are based on discussions |
56 | The changes made to the library, and bugs fixed are based on discussions |
57 | on the PNG-implement mailing list and not on material submitted |
57 | on the PNG-implement mailing list and not on material submitted |
58 | privately to Guy, Andreas, or Glenn. They will forward any good |
58 | privately to Guy, Andreas, or Glenn. They will forward any good |
59 | suggestions to the list. |
59 | suggestions to the list. |
60 | 60 | ||
61 | For a detailed description on using libpng, read libpng-manual.txt. For |
61 | For a detailed description on using libpng, read libpng-manual.txt. For |
62 | examples of libpng in a program, see example.c and pngtest.c. For usage |
62 | examples of libpng in a program, see example.c and pngtest.c. For usage |
63 | information and restrictions (what little they are) on libpng, see |
63 | information and restrictions (what little they are) on libpng, see |
64 | png.h. For a description on using zlib (the compression library used by |
64 | png.h. For a description on using zlib (the compression library used by |
65 | libpng) and zlib's restrictions, see zlib.h |
65 | libpng) and zlib's restrictions, see zlib.h |
66 | 66 | ||
67 | I have included a general makefile, as well as several machine and |
67 | I have included a general makefile, as well as several machine and |
68 | compiler specific ones, but you may have to modify one for your own needs. |
68 | compiler specific ones, but you may have to modify one for your own needs. |
69 | 69 | ||
70 | You should use zlib 1.0.4 or later to run this, but it MAY work with |
70 | You should use zlib 1.0.4 or later to run this, but it MAY work with |
71 | versions as old as zlib 0.95. Even so, there are bugs in older zlib |
71 | versions as old as zlib 0.95. Even so, there are bugs in older zlib |
72 | versions which can cause the output of invalid compression streams for |
72 | versions which can cause the output of invalid compression streams for |
73 | some images. You will definitely need zlib 1.0.4 or later if you are |
73 | some images. You will definitely need zlib 1.0.4 or later if you are |
74 | taking advantage of the MS-DOS "far" structure allocation for the small |
74 | taking advantage of the MS-DOS "far" structure allocation for the small |
75 | and medium memory models. You should also note that zlib is a |
75 | and medium memory models. You should also note that zlib is a |
76 | compression library that is useful for more things than just PNG files. |
76 | compression library that is useful for more things than just PNG files. |
77 | You can use zlib as a drop-in replacement for fread() and fwrite() if |
77 | You can use zlib as a drop-in replacement for fread() and fwrite() if |
78 | you are so inclined. |
78 | you are so inclined. |
79 | 79 | ||
80 | zlib should be available at the same place that libpng is, or at. |
- | |
81 | ftp://ftp.info-zip.org/pub/infozip/zlib |
80 | zlib should be available at the same place that libpng is, or at zlib.net. |
82 | 81 | ||
83 | You may also want a copy of the PNG specification. It is available |
82 | You may also want a copy of the PNG specification. It is available |
84 | as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find |
83 | as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find |
85 | these at http://www.libpng.org/pub/png/documents/ |
84 | these at http://www.libpng.org/pub/png/documents/ |
86 | 85 | ||
87 | This code is currently being archived at libpng.sf.net in the |
86 | This code is currently being archived at libpng.sf.net in the |
88 | [DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT) |
87 | [DOWNLOAD] area, and at ftp://ftp.simplesystems.org. If you can't find it |
89 | at GO GRAPHSUP. If you can't find it in any of those places, |
- | |
90 | e-mail me, and I'll help you find it. |
88 | in any of those places, e-mail me, and I'll help you find it. |
91 | 89 | ||
92 | If you have any code changes, requests, problems, etc., please e-mail |
90 | If you have any code changes, requests, problems, etc., please e-mail |
93 | them to me. Also, I'd appreciate any make files or project files, |
91 | them to me. Also, I'd appreciate any make files or project files, |
94 | and any modifications you needed to make to get libpng to compile, |
92 | and any modifications you needed to make to get libpng to compile, |
95 | along with a #define variable to tell what compiler/system you are on. |
93 | along with a #define variable to tell what compiler/system you are on. |
96 | If you needed to add transformations to libpng, or wish libpng would |
94 | If you needed to add transformations to libpng, or wish libpng would |
97 | provide the image in a different way, drop me a note (and code, if |
95 | provide the image in a different way, drop me a note (and code, if |
98 | possible), so I can consider supporting the transformation. |
96 | possible), so I can consider supporting the transformation. |
99 | Finally, if you get any warning messages when compiling libpng |
97 | Finally, if you get any warning messages when compiling libpng |
100 | (note: not zlib), and they are easy to fix, I'd appreciate the |
98 | (note: not zlib), and they are easy to fix, I'd appreciate the |
101 | fix. Please mention "libpng" somewhere in the subject line. Thanks. |
99 | fix. Please mention "libpng" somewhere in the subject line. Thanks. |
102 | 100 | ||
103 | This release was created and will be supported by myself (of course |
101 | This release was created and will be supported by myself (of course |
104 | based in a large way on Guy's and Andreas' earlier work), and the PNG |
102 | based in a large way on Guy's and Andreas' earlier work), and the PNG |
105 | development group. |
103 | development group. |
106 | 104 | ||
107 | Send comments/corrections/commendations to png-mng-implement at |
105 | Send comments/corrections/commendations to png-mng-implement at |
108 | lists.sourceforge.net (subscription required; visit |
106 | lists.sourceforge.net (subscription required; visit |
109 | https://lists.sourceforge.net/lists/listinfo/png-mng-implement |
107 | https://lists.sourceforge.net/lists/listinfo/png-mng-implement |
110 | to subscribe) or to glennrp at users.sourceforge.net |
108 | to subscribe) or to glennrp at users.sourceforge.net |
111 | 109 | ||
112 | You can't reach Guy, the original libpng author, at the addresses |
110 | You can't reach Guy, the original libpng author, at the addresses |
113 | given in previous versions of this document. He and Andreas will |
111 | given in previous versions of this document. He and Andreas will |
114 | read mail addressed to the png-implement list, however. |
112 | read mail addressed to the png-implement list, however. |
115 | 113 | ||
116 | Please do not send general questions about PNG. Send them to |
114 | Please do not send general questions about PNG. Send them to |
117 | the (png-list at ccrc.wustl.edu, subscription required, write to |
115 | png-mng-misc at lists.sf.net (subscription required; visit |
118 | majordomo at ccrc.wustl.edu with "subscribe png-list" in your message). |
- | |
119 | On the other hand, |
- | |
120 | please do not send libpng questions to that address, send them to me |
116 | https://lists.sourceforge.net/lists/listinfo/png-mng-misc to |
121 | or to the png-implement list. I'll |
- | |
122 | get them in the end anyway. If you have a question about something |
117 | subscribe). If you have a question about something |
123 | in the PNG specification that is related to using libpng, send it |
118 | in the PNG specification that is related to using libpng, send it |
124 | to me. Send me any questions that start with "I was using libpng, |
119 | to me. Send me any questions that start with "I was using libpng, |
125 | and ...". If in doubt, send questions to me. I'll bounce them |
120 | and ...". If in doubt, send questions to me. I'll bounce them |
126 | to others, if necessary. |
121 | to others, if necessary. |
127 | 122 | ||
128 | Please do not send suggestions on how to change PNG. We have |
123 | Please do not send suggestions on how to change PNG. We have |
129 | been discussing PNG for nine years now, and it is official and |
124 | been discussing PNG for eighteen years now, and it is official and |
130 | finished. If you have suggestions for libpng, however, I'll |
125 | finished. If you have suggestions for libpng, however, I'll |
131 | gladly listen. Even if your suggestion is not used immediately, |
126 | gladly listen. Even if your suggestion is not used immediately, |
132 | it may be used later. |
127 | it may be used later. |
133 | 128 | ||
134 | Files in this distribution: |
129 | Files in this distribution: |
135 | 130 | ||
136 | ANNOUNCE => Announcement of this version, with recent changes |
131 | ANNOUNCE => Announcement of this version, with recent changes |
137 | CHANGES => Description of changes between libpng versions |
132 | CHANGES => Description of changes between libpng versions |
138 | KNOWNBUG => List of known bugs and deficiencies |
133 | KNOWNBUG => List of known bugs and deficiencies |
139 | LICENSE => License to use and redistribute libpng |
134 | LICENSE => License to use and redistribute libpng |
140 | README => This file |
135 | README => This file |
141 | TODO => Things not implemented in the current library |
136 | TODO => Things not implemented in the current library |
142 | Y2KINFO => Statement of Y2K compliance |
137 | Y2KINFO => Statement of Y2K compliance |
143 | example.c => Example code for using libpng functions |
138 | example.c => Example code for using libpng functions |
144 | libpng.3 => manual page for libpng (includes libpng-manual.txt) |
139 | libpng.3 => manual page for libpng (includes libpng-manual.txt) |
145 | libpng-manual.txt => Description of libpng and its functions |
140 | libpng-manual.txt => Description of libpng and its functions |
146 | libpngpf.3 => manual page for libpng's private functions |
141 | libpngpf.3 => manual page for libpng's private functions |
147 | png.5 => manual page for the PNG format |
142 | png.5 => manual page for the PNG format |
148 | png.c => Basic interface functions common to library |
143 | png.c => Basic interface functions common to library |
149 | png.h => Library function and interface declarations (public) |
144 | png.h => Library function and interface declarations (public) |
150 | pngpriv.h => Library function and interface declarations (private) |
145 | pngpriv.h => Library function and interface declarations (private) |
151 | pngconf.h => System specific library configuration (public) |
146 | pngconf.h => System specific library configuration (public) |
152 | pngstruct.h => png_struct declaration (private) |
147 | pngstruct.h => png_struct declaration (private) |
153 | pnginfo.h => png_info struct declaration (private) |
148 | pnginfo.h => png_info struct declaration (private) |
154 | pngdebug.h => debugging macros (private) |
149 | pngdebug.h => debugging macros (private) |
155 | pngerror.c => Error/warning message I/O functions |
150 | pngerror.c => Error/warning message I/O functions |
156 | pngget.c => Functions for retrieving info from struct |
151 | pngget.c => Functions for retrieving info from struct |
157 | pngmem.c => Memory handling functions |
152 | pngmem.c => Memory handling functions |
158 | pngbar.png => PNG logo, 88x31 |
153 | pngbar.png => PNG logo, 88x31 |
159 | pngnow.png => PNG logo, 98x31 |
154 | pngnow.png => PNG logo, 98x31 |
160 | pngpread.c => Progressive reading functions |
155 | pngpread.c => Progressive reading functions |
161 | pngread.c => Read data/helper high-level functions |
156 | pngread.c => Read data/helper high-level functions |
162 | pngrio.c => Lowest-level data read I/O functions |
157 | pngrio.c => Lowest-level data read I/O functions |
163 | pngrtran.c => Read data transformation functions |
158 | pngrtran.c => Read data transformation functions |
164 | pngrutil.c => Read data utility functions |
159 | pngrutil.c => Read data utility functions |
165 | pngset.c => Functions for storing data into the info_struct |
160 | pngset.c => Functions for storing data into the info_struct |
166 | pngtest.c => Library test program |
161 | pngtest.c => Library test program |
167 | pngtest.png => Library test sample image |
162 | pngtest.png => Library test sample image |
168 | pngtrans.c => Common data transformation functions |
163 | pngtrans.c => Common data transformation functions |
169 | pngwio.c => Lowest-level write I/O functions |
164 | pngwio.c => Lowest-level write I/O functions |
170 | pngwrite.c => High-level write functions |
165 | pngwrite.c => High-level write functions |
171 | pngwtran.c => Write data transformations |
166 | pngwtran.c => Write data transformations |
172 | pngwutil.c => Write utility functions |
167 | pngwutil.c => Write utility functions |
- | 168 | arm => Contains optimized code for the ARM platform |
|
173 | contrib => Contributions |
169 | contrib => Contributions |
- | 170 | examples => Example programs |
|
174 | gregbook => source code for PNG reading and writing, from |
171 | gregbook => source code for PNG reading and writing, from |
175 | Greg Roelofs' "PNG: The Definitive Guide", |
172 | Greg Roelofs' "PNG: The Definitive Guide", |
176 | O'Reilly, 1999 |
173 | O'Reilly, 1999 |
- | 174 | libtests => Test programs |
|
- | 175 | pngminim => Minimal decoder, encoder, and progressive decoder |
|
177 | msvctest => Builds and runs pngtest using a MSVC workspace |
176 | programs demonstrating use of pngusr.dfa |
178 | pngminus => Simple pnm2png and png2pnm programs |
177 | pngminus => Simple pnm2png and png2pnm programs |
179 | pngsuite => Test images |
178 | pngsuite => Test images |
- | 179 | tools => Various tools |
|
180 | visupng => Contains a MSVC workspace for VisualPng |
180 | visupng => Contains a MSVC workspace for VisualPng |
181 | projects => Contains project files and workspaces for |
181 | projects => Contains project files and workspaces for |
182 | building a DLL |
182 | building a DLL |
183 | cbuilder5 => Contains a Borland workspace for building |
183 | owatcom => Contains a WATCOM project for building libpng |
184 | libpng and zlib |
- | |
185 | visualc6 => Contains a Microsoft Visual C++ (MSVC) |
- | |
186 | workspace for building libpng and zlib |
- | |
187 | visualc71 => Contains a Microsoft Visual C++ (MSVC) |
184 | visualc71 => Contains a Microsoft Visual C++ (MSVC) |
188 | workspace for building libpng and zlib |
185 | workspace for building libpng and zlib |
189 | xcode => Contains an Apple xcode |
186 | vstudio => Contains a Microsoft Visual C++ (MSVC) |
190 | workspace for building libpng and zlib |
187 | workspace for building libpng and zlib |
191 | scripts => Directory containing scripts for building libpng: |
188 | scripts => Directory containing scripts for building libpng: |
192 | (see scripts/README.txt for the list of scripts) |
189 | (see scripts/README.txt for the list of scripts) |
193 | 190 | ||
194 | Good luck, and happy coding. |
191 | Good luck, and happy coding. |
195 | 192 | ||
196 | -Glenn Randers-Pehrson (current maintainer, since 1998) |
193 | -Glenn Randers-Pehrson (current maintainer, since 1998) |
197 | Internet: glennrp at users.sourceforge.net |
194 | Internet: glennrp at users.sourceforge.net |
198 | 195 | ||
199 | -Andreas Eric Dilger (former maintainer, 1996-1997) |
196 | -Andreas Eric Dilger (former maintainer, 1996-1997) |
200 | Internet: adilger at enel.ucalgary.ca |
197 | Internet: adilger at enel.ucalgary.ca |
201 | Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/ |
198 | Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/ |
202 | 199 | ||
203 | -Guy Eric Schalnat (original author and former maintainer, 1995-1996) |
200 | -Guy Eric Schalnat (original author and former maintainer, 1995-1996) |
204 | (formerly of Group 42, Inc) |
201 | (formerly of Group 42, Inc) |
205 | Internet: gschal at infinet.com> |
202 | Internet: gschal at infinet.com> |