Notes: Libpng

Installation

First one has to copy makevms.com from the [.scripts]-subdirectory to the root directory. Then just execute @makevms to build the library. This checks for available compilers as well as for MMS/MMK and uses them for the build if available. The build expects to find the Zlib library and headerfiles in [-.zlib]. In case you do have them in a different place just edit makevms.com and change the definiton of zlibsrc.

Together with the source for the library some small sample applications are delivered, which can be found in the [.contrib] directories. The most simple way to build these ist to execute @makevms contrib in the root directory, in case you are using the version from this server.

Package contents

The main result of the compilation is the object library libpng.olb, which other applications need to link against. Additionally five small executable programs are created in [.contrib.gregbook] and [.contrib.pngminus]:

RPNG-X
Simple PNG display program. This program decodes and displays PNG images, with gamma correction and optionally with a user-specified background color (in case the image has transparency). It is very nearly the most basic PNG viewer possible.
RPNG2-X
Progressive-model PNG display program. This program decodes and displays PNG files progressively, as if it were a web browser (though the front end is only set up to read from files). It supports gamma correction, user-specified background colors, and user-specified background patterns (for transparent images).
WPNG
Simple PNG-writing program. This program converts certain NetPBM binary files (grayscale and RGB, maxval = 255) to PNG. Non-interlaced PNGs are written progressively; interlaced PNGs are read and written in one memory-intensive blast.
PNG2PNM
Converts a PNG-file into the PNM format.
PNM2PNG
Converts a PNM-file into the PNG format.

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Comments to: Martin P.J. Zinser
Last modified: 20000822