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1 README for libpng version 1.2.32 - September 18, 2008 (shared library 12.0) |
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2 See the note about version numbers near the top of png.h |
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3 |
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4 See INSTALL for instructions on how to install libpng. |
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5 |
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6 Libpng comes in several distribution formats. Get libpng-*.tar.gz, |
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7 libpng-*.tar.lzma, or libpng-*.tar.bz2 if you want UNIX-style line |
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8 endings in the text files, or lpng*.7z or lpng*.zip if you want DOS-style |
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9 line endings. You can get UNIX-style line endings from the *.zip file |
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10 by using "unzip -a" but there seems to be no simple way to recover |
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11 UNIX-style line endings from the *.7z file. The *.tar.lzma file is |
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12 recommended for *NIX users instead. |
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13 |
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14 Version 0.89 was the first official release of libpng. Don't let the |
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15 fact that it's the first release fool you. The libpng library has been in |
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16 extensive use and testing since mid-1995. By late 1997 it had |
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17 finally gotten to the stage where there hadn't been significant |
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18 changes to the API in some time, and people have a bad feeling about |
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19 libraries with versions < 1.0. Version 1.0.0 was released in |
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20 March 1998. |
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21 |
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22 **** |
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23 Note that some of the changes to the png_info structure render this |
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24 version of the library binary incompatible with libpng-0.89 or |
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25 earlier versions if you are using a shared library. The type of the |
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26 "filler" parameter for png_set_filler() has changed from png_byte to |
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27 png_uint_32, which will affect shared-library applications that use |
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28 this function. |
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29 |
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30 To avoid problems with changes to the internals of png_info_struct, |
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31 new APIs have been made available in 0.95 to avoid direct application |
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32 access to info_ptr. These functions are the png_set_<chunk> and |
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33 png_get_<chunk> functions. These functions should be used when |
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34 accessing/storing the info_struct data, rather than manipulating it |
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35 directly, to avoid such problems in the future. |
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36 |
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37 It is important to note that the APIs do not make current programs |
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38 that access the info struct directly incompatible with the new |
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39 library. However, it is strongly suggested that new programs use |
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40 the new APIs (as shown in example.c and pngtest.c), and older programs |
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41 be converted to the new format, to facilitate upgrades in the future. |
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42 **** |
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43 |
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44 Additions since 0.90 include the ability to compile libpng as a |
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45 Windows DLL, and new APIs for accessing data in the info struct. |
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46 Experimental functions include the ability to set weighting and cost |
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47 factors for row filter selection, direct reads of integers from buffers |
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48 on big-endian processors that support misaligned data access, faster |
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49 methods of doing alpha composition, and more accurate 16->8 bit color |
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50 conversion. |
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51 |
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52 The additions since 0.89 include the ability to read from a PNG stream |
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53 which has had some (or all) of the signature bytes read by the calling |
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54 application. This also allows the reading of embedded PNG streams that |
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55 do not have the PNG file signature. As well, it is now possible to set |
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56 the library action on the detection of chunk CRC errors. It is possible |
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57 to set different actions based on whether the CRC error occurred in a |
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58 critical or an ancillary chunk. |
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59 |
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60 The changes made to the library, and bugs fixed are based on discussions |
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61 on the png-mng-implement mailing list |
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62 and not on material submitted privately to Guy, Andreas, or Glenn. They will |
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63 forward any good suggestions to the list. |
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64 |
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65 For a detailed description on using libpng, read libpng.txt. For |
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66 examples of libpng in a program, see example.c and pngtest.c. For usage |
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67 information and restrictions (what little they are) on libpng, see |
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68 png.h. For a description on using zlib (the compression library used by |
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69 libpng) and zlib's restrictions, see zlib.h |
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70 |
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71 I have included a general makefile, as well as several machine and |
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72 compiler specific ones, but you may have to modify one for your own needs. |
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73 |
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74 You should use zlib 1.0.4 or later to run this, but it MAY work with |
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75 versions as old as zlib 0.95. Even so, there are bugs in older zlib |
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76 versions which can cause the output of invalid compression streams for |
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77 some images. You will definitely need zlib 1.0.4 or later if you are |
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78 taking advantage of the MS-DOS "far" structure allocation for the small |
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79 and medium memory models. You should also note that zlib is a |
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80 compression library that is useful for more things than just PNG files. |
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81 You can use zlib as a drop-in replacement for fread() and fwrite() if |
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82 you are so inclined. |
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83 |
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84 zlib should be available at the same place that libpng is, or at |
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85 ftp://ftp.simplesystems.org/pub/png/src/ |
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86 |
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87 You may also want a copy of the PNG specification. It is available |
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88 as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find |
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89 these at http://www.libpng.org/pub/png/pngdocs.html |
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90 |
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91 This code is currently being archived at libpng.sf.net in the |
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92 [DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT) |
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93 at GO GRAPHSUP. If you can't find it in any of those places, |
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94 e-mail me, and I'll help you find it. |
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95 |
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96 If you have any code changes, requests, problems, etc., please e-mail |
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97 them to me. Also, I'd appreciate any make files or project files, |
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98 and any modifications you needed to make to get libpng to compile, |
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99 along with a #define variable to tell what compiler/system you are on. |
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100 If you needed to add transformations to libpng, or wish libpng would |
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101 provide the image in a different way, drop me a note (and code, if |
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102 possible), so I can consider supporting the transformation. |
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103 Finally, if you get any warning messages when compiling libpng |
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104 (note: not zlib), and they are easy to fix, I'd appreciate the |
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105 fix. Please mention "libpng" somewhere in the subject line. Thanks. |
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106 |
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107 This release was created and will be supported by myself (of course |
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108 based in a large way on Guy's and Andreas' earlier work), and the PNG group. |
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109 |
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110 Send comments/corrections/commendations to png-mng-implement at lists.sf.net |
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111 (subscription required; visit |
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112 https://lists.sourceforge.net/lists/listinfo/png-mng-implement |
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113 to subscribe) or to glennrp at users.sourceforge.net |
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114 |
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115 You can't reach Guy, the original libpng author, at the addresses |
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116 given in previous versions of this document. He and Andreas will read mail |
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117 addressed to the png-mng-implement list, however. |
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118 |
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119 Please do not send general questions about PNG. Send them to |
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120 the (png-mng-misc at lists.sourceforge.net, subscription required, visit |
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121 https://lists.sourceforge.net/lists/listinfo/png-mng-implement to subscribe) |
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122 On the other hand, |
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123 please do not send libpng questions to that address, send them to me |
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124 or to the png-mng-implement list. I'll |
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125 get them in the end anyway. If you have a question about something |
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126 in the PNG specification that is related to using libpng, send it |
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127 to me. Send me any questions that start with "I was using libpng, |
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128 and ...". If in doubt, send questions to me. I'll bounce them |
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129 to others, if necessary. |
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130 |
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131 Please do not send suggestions on how to change PNG. We have |
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132 been discussing PNG for twelve years now, and it is official and |
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133 finished. If you have suggestions for libpng, however, I'll |
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134 gladly listen. Even if your suggestion is not used immediately, |
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135 it may be used later. |
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136 |
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137 Files in this distribution: |
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138 |
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139 ANNOUNCE => Announcement of this version, with recent changes |
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140 CHANGES => Description of changes between libpng versions |
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141 KNOWNBUG => List of known bugs and deficiencies |
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142 LICENSE => License to use and redistribute libpng |
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143 README => This file |
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144 TODO => Things not implemented in the current library |
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145 Y2KINFO => Statement of Y2K compliance |
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146 example.c => Example code for using libpng functions |
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147 libpng-*-*-diff.txt => Diff from previous release |
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148 libpng.3 => manual page for libpng (includes libpng.txt) |
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149 libpng.txt => Description of libpng and its functions |
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150 libpngpf.3 => manual page for libpng's private functions |
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151 png.5 => manual page for the PNG format |
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152 png.c => Basic interface functions common to library |
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153 png.h => Library function and interface declarations |
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154 pngconf.h => System specific library configuration |
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155 pngerror.c => Error/warning message I/O functions |
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156 pngget.c => Functions for retrieving info from struct |
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157 pngmem.c => Memory handling functions |
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158 pngbar.png => PNG logo, 88x31 |
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159 pngnow.png => PNG logo, 98x31 |
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160 pngpread.c => Progressive reading functions |
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161 pngread.c => Read data/helper high-level functions |
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162 pngrio.c => Lowest-level data read I/O functions |
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163 pngrtran.c => Read data transformation functions |
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164 pngrutil.c => Read data utility functions |
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165 pngset.c => Functions for storing data into the info_struct |
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166 pngtest.c => Library test program |
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167 pngtest.png => Library test sample image |
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168 pngtrans.c => Common data transformation functions |
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169 pngwio.c => Lowest-level write I/O functions |
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170 pngwrite.c => High-level write functions |
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171 pngwtran.c => Write data transformations |
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172 pngwutil.c => Write utility functions |
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173 contrib => Contributions |
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174 gregbook => source code for PNG reading and writing, from |
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175 Greg Roelofs' "PNG: The Definitive Guide", |
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176 O'Reilly, 1999 |
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177 msvctest => Builds and runs pngtest using a MSVC workspace |
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178 pngminus => Simple pnm2png and png2pnm programs |
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179 pngsuite => Test images |
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180 visupng => Contains a MSVC workspace for VisualPng |
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181 projects => Contains project files and workspaces for building DLL |
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182 beos => Contains a Beos workspace for building libpng |
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183 c5builder => Contains a Borland workspace for building libpng |
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184 and zlib |
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185 visualc6 => Contains a Microsoft Visual C++ (MSVC) workspace |
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186 for building libpng and zlib |
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187 netware.txt => Contains instructions for downloading a set of |
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188 project files for building libpng and zlib on |
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189 Netware. |
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190 wince.txt => Contains instructions for downloading a Microsoft |
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191 Visual C++ (Windows CD Toolkit) workspace for |
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192 building libpng and zlib on WindowsCE |
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193 scripts => Directory containing scripts for building libpng: |
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194 descrip.mms => VMS makefile for MMS or MMK |
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195 makefile.std => Generic UNIX makefile (cc, creates static libpng.a) |
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196 makefile.elf => Linux/ELF makefile symbol versioning, |
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197 gcc, creates libpng12.so.0.1.2.32) |
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198 makefile.linux => Linux/ELF makefile |
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199 (gcc, creates libpng12.so.0.1.2.32) |
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200 makefile.gcmmx => Linux/ELF makefile |
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201 (gcc, creates libpng12.so.0.1.2.32, |
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202 uses assembler code tuned for Intel MMX platform) |
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203 makefile.gcc => Generic makefile (gcc, creates static libpng.a) |
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204 makefile.knr => Archaic UNIX Makefile that converts files with |
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205 ansi2knr (Requires ansi2knr.c from |
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206 ftp://ftp.cs.wisc.edu/ghost) |
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207 makefile.aix => AIX makefile |
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208 makefile.cygwin => Cygwin/gcc makefile |
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209 makefile.darwin => Darwin makefile |
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210 makefile.dec => DEC Alpha UNIX makefile |
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211 makefile.freebsd => FreeBSD makefile |
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212 makefile.hpgcc => HPUX makefile using gcc |
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213 makefile.hpux => HPUX (10.20 and 11.00) makefile |
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214 makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit |
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215 makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static) |
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216 makefile.intel => Intel C/C++ version 4.0 and later |
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217 libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later |
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218 makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so. |
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219 makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so |
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220 makefile.openbsd => OpenBSD makefile |
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221 makefile.sgi => Silicon Graphics IRIX (cc, creates static lib) |
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222 makefile.sggcc => Silicon Graphics |
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223 (gcc, creates libpng12.so.0.1.2.32) |
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224 makefile.sunos => Sun makefile |
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225 makefile.solaris => Solaris 2.X makefile |
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226 (gcc, creates libpng12.so.0.1.2.32) |
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227 makefile.so9 => Solaris 9 makefile |
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228 (gcc, creates libpng12.so.0.1.2.32) |
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229 makefile.32sunu => Sun Ultra 32-bit makefile |
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230 makefile.64sunu => Sun Ultra 64-bit makefile |
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231 makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc |
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232 makefile.mips => MIPS makefile |
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233 makefile.acorn => Acorn makefile |
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234 makefile.amiga => Amiga makefile |
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235 smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC |
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236 compiler (Requires SCOPTIONS, copied from |
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237 scripts/SCOPTIONS.ppc) |
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238 makefile.atari => Atari makefile |
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239 makefile.beos => BEOS makefile for X86 |
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240 makefile.bor => Borland makefile (uses bcc) |
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241 makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode) |
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242 makefile.tc3 => Turbo C 3.0 makefile |
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243 makefile.dj2 => DJGPP 2 makefile |
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244 makefile.msc => Microsoft C makefile |
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245 makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and |
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246 later (uses assembler code tuned for Intel MMX |
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247 platform) |
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248 makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and |
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249 later (does not use assembler code) |
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250 makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def) |
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251 pngos2.def => OS/2 module definition file used by makefile.os2 |
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252 makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model |
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253 makevms.com => VMS build script |
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254 SCOPTIONS.ppc => Used with smakefile.ppc |
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255 |
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256 Good luck, and happy coding. |
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257 |
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258 -Glenn Randers-Pehrson (current maintainer) |
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259 Internet: glennrp at users.sourceforge.net |
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260 |
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261 -Andreas Eric Dilger (former maintainer, 1996-1997) |
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262 Internet: adilger at enel.ucalgary.ca |
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263 Web: http://members.shaw.ca/adilger/ |
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264 |
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265 -Guy Eric Schalnat (original author and former maintainer, 1995-1996) |
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266 (formerly of Group 42, Inc) |
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267 Internet: gschal at infinet.com |