README
1 ===========================
2 PNG: The Definitive Guide
3 ===========================
4
5 Source Code
6
7Chapters 13, 14 and 15 of "PNG: The Definitive Guide" discuss three free,
8cross-platform demo programs that show how to use the libpng reference
9library: rpng, rpng2 and wpng. rpng and rpng2 are viewers; the first is
10a very simple example that that shows how a standard file-viewer might use
11libpng, while the second is designed to process streaming data and shows
12how a web browser might be written. wpng is a simple command-line program
13that reads binary PGM and PPM files (the ``raw'' grayscale and RGB subsets
14of PBMPLUS/NetPBM) and converts them to PNG.
15
16The source code for all three demo programs currently compiles under
17Unix, OpenVMS, and 32-bit Windows. (Special thanks to Martin Zinser,
18zinser at decus.de, for making the necessary changes for OpenVMS and for
19providing an appropriate build script.) Build instructions can be found
20below.
21
22Files:
23
24 README this file
25 LICENSE terms of distribution and reuse (BSD-like or GNU GPL)
26 COPYING GNU General Public License (GPL)
27
28 Makefile.unx Unix makefile
29 Makefile.w32 Windows (MSVC) makefile
30 makevms.com OpenVMS build script
31
32 rpng-win.c Windows front end for the basic viewer
33 rpng-x.c X Window System (Unix, OpenVMS) front end
34 readpng.c generic back end for the basic viewer
35 readpng.h header file for the basic viewer
36
37 rpng2-win.c Windows front end for the progressive viewer
38 rpng2-x.c X front end for the progressive viewer
39 readpng2.c generic back end for the progressive viewer
40 readpng2.h header file for the progressive viewer
41
42 wpng.c generic (text) front end for the converter
43 writepng.c generic back end for the converter
44 writepng.h header file for the converter
45
46 toucan.png transparent PNG for testing (by Stefan Schneider)
47
48Note that, although the programs are designed to be functional, their
49primary purpose is to illustrate how to use libpng to add PNG support to
50other programs. As such, their user interfaces are crude and definitely
51are not intended for everyday use.
52
53Please see http://www.libpng.org/pub/png/pngbook.html for further infor-
54mation and links to the latest version of the source code, and Chapters
5513-15 of the book for detailed discussion of the three programs.
56
57Greg Roelofs
58https://pobox.com/~newt/greg_contact.html
5916 March 2008
60
61
62BUILD INSTRUCTIONS
63
64 - Prerequisites (in order of compilation):
65
66 - zlib https://zlib.net/
67 - libpng http://www.libpng.org/pub/png/libpng.html
68 - pngbook http://www.libpng.org/pub/png/book/sources.html
69
70 The pngbook demo programs are explicitly designed to demonstrate proper
71 coding techniques for using the libpng reference library. As a result,
72 you need to download and build both zlib (on which libpng depends) and
73 libpng. A common build setup is to place the zlib, libpng and pngbook
74 subdirectory trees ("folders") in the same parent directory. Then the
75 libpng build can refer to files in ../zlib (or ..\zlib or [-.zlib]),
76 and similarly for the pngbook build.
77
78 Note that all three packages are designed to be built from a command
79 line by default; those who wish to use a graphical or other integrated
80 development environments are on their own.
81
82
83 - Unix:
84
85 Unpack the latest pngbook sources (which should correspond to this
86 README file) into a directory and change into that directory.
87
88 Copy Makefile.unx to Makefile and edit the PNG* and Z* variables
89 appropriately (possibly also the X* variables if necessary).
90
91 make
92
93 There is no "install" target, so copy the three executables somewhere
94 in your path or run them from the current directory. All three will
95 print a basic usage screen when run without any command-line arguments;
96 see the book for more details.
97
98
99 - Windows:
100
101 Unpack the latest pngbook sources (which should correspond to this
102 README file) into a folder, open a "DOS shell" or "command prompt"
103 or equivalent command-line window, and cd into the folder where you
104 unpacked the source code.
105
106 For MSVC, set up the necessary environment variables by invoking
107
108 %devstudio%\vc\bin\vcvars32.bat
109
110 where where %devstudio% is the installation directory for MSVC /
111 DevStudio. If you get "environment out of space" errors under 95/98,
112 create a desktop shortcut with "c:\windows\command.com /e:4096" as
113 the program command line and set the working directory to the pngbook
114 directory. Then double-click to open the new DOS-prompt window with
115 a bigger environment and retry the commands above.
116
117 Copy Makefile.w32 to Makefile and edit the PNGPATH and ZPATH variables
118 appropriately (possibly also the "INC" and "LIB" variables if needed).
119 Note that the names of the dynamic and static libpng and zlib libraries
120 used in the makefile may change in later releases of the libraries.
121 Also note that, as of libpng version 1.0.5, MSVC DLL builds do not work.
122 This makefile therefore builds statically linked executables, but if
123 the DLL problems ever get fixed, uncommenting the appropriate PNGLIB
124 and ZLIB lines will build dynamically linked executables instead.
125
126 Do the build by typing
127
128 nmake
129
130 The result should be three executables: rpng-win.exe, rpng2-win.exe,
131 and wpng.exe. Copy them somewhere in your PATH or run them from the
132 current folder. Like the Unix versions, the two windowed programs
133 (rpng and rpng2) now display a usage screen in a console window when
134 invoked without command-line arguments; this is new behavior as of
135 the June 2001 release. Note that the programs use the Unix-style "-"
136 character to specify options, instead of the more common DOS/Windows
137 "/" character. (For example: "rpng2-win -bgpat 4 foo.png", not
138 "rpng2-win /bgpat 4 foo.png")
139
140
141 - OpenVMS:
142
143 Unpack the pngbook sources into a subdirectory and change into that
144 subdirectory.
145
146 Edit makevms.com appropriately, specifically the zpath and pngpath
147 variables.
148
149 @makevms
150
151 To run the programs, they probably first need to be set up as "foreign
152 symbols," with "disk" and "dir" set appropriately:
153
154 $ rpng == "$disk:[dir]rpng-x.exe"
155 $ rpng2 == "$disk:[dir]rpng2-x.exe"
156 $ wpng == "$disk:[dir]wpng.exe"
157
158 All three will print a basic usage screen when run without any command-
159 line arguments; see the book for more details. Note that the options
160 style is Unix-like, i.e., preceded by "-" rather than "/".
161
162
163RUNNING THE PROGRAMS: (VERY) BRIEF INTRO
164
165 rpng is a simple PNG viewer that can display transparent PNGs with a
166 specified background color; for example,
167
168 rpng -bgcolor \#ff0000 toucan.png
169
170 would display the image with a red background. rpng2 is a progressive
171 viewer that simulates a web browser in some respects; it can display
172 images against either a background color or a dynamically generated
173 background image. For example:
174
175 rpng2 -bgpat 16 toucan.png
176
177 wpng is a purely command-line image converter from binary PBMPLUS/NetPBM
178 format (.pgm or .ppm) to PNG; for example,
179
180 wpng -time < toucan-notrans.ppm > toucan-notrans.png
181
182 would convert the specified PPM file (using redirection) to PNG, auto-
183 matically setting the PNG modification-time chunk.
184
185 All options can be abbreviated to the shortest unique value; for example,
186 "-bgc" for -bgcolor (versus "-bgp" for -bgpat), or "-g" for -gamma.
187
