
		Tcl/Tk Image formats (TkImg)
		(Version 1.4 / September 2010)

		Jan Nijtmans, Andreas Kupries, Paul Obermeier

This file contains a collection of format handlers for the Tk photo
image type, and a new image type, pixmaps.  It can be used in
combination with Tcl/Tk 8.3 or later but 8.5.9 (or 8.6, when
available) are highly recommended.

Included in this distribution are the most recent versions (as of
sept 2010) of the libz, libpng, libjpeg, and libtiff libraries.
These are not required, unless you need support for the PNG, JPEG,
or TIFF format. Note that you have to build these libraries to
support the named formats, even if your system already has shared
libraries for these formats. This is because the libraries here are
built such that they can be loaded as packages by the Tcl/Tk core,
making the handling of the various dependencies much easier. An
earlier version, 1.2.4, used a modified copy of Tcl's functions for
loading of shared libraries to load the support libraries at runtime.
These have been abandoned in favor of the new approach.

BACKGROUND TO BUILDING

The TkImg sources have been heavily refactored. Instead of building
one big package there are several small packages most of which are
independent of each other.

All packages employ a TEA 2 based build system (configure/Make) for
easy configuration and building. This means that 99% of the options
to configure are the same for all the packages.

All packages save for the supporting ones (see below) have names
starting with 'img'. For compatibility with older scripts the
package index file of the utility package 'img::base' declares
pseudo-packages 'img' and 'Img' which load all packages provided
by this extension.

BUILDING - The convenient way

The toplevel directory of tkImg contains a configure and Makefile for
convenient configuration and building of all packages in the
extension.

Run this configure script in a build directory of your choice to
configure all packages, then run

	make all
	make install

in the build directory. The most important options for configure are
--prefix and --exec-prefix which tell the build system where to find
Tcl and Tk, and also where to install the results of the builds
(header, shared libraries, ...).

This convenient build installs all shared libraries in a single
directory 'Img<VERSION>, together with a union package index for all
packages.

If the builder requires only a subset of the packages he can use

	make all

to build all packages, but must not use 'make install' in the top
build directory. Instead run

	make install

in the sub directories of the build directory which contain the
requested packages, and their dependencies !

Note, that target install also builds the documentation based on 
Tcl script dtplite. To build and install without documentation, use

	make install-libraries

PACKAGES AND THEIR DEPENDENCIES

This section is for people who want to bypass the master
configure/Makefile.

At the bottom of the hierarchy of dependencies are the 'support
packages'. They encapsulate the support libraries for ZIP, TIFF, PNG
and JPEG in packages directly loadable by Tcl. They provide the
functionality of their underlying libraries via stub-tables. The names
of these packages are:

	Name		Directory		    Dependency
	-------------------------------------------------
	zlibtcl		tkimg/compat/libz
	pngtcl		tkimg/compat/libpng	  zlibtcl
	jpegtcl		tkimg/compat/libjpeg
	tifftcl		tkimg/compat/libtiff
	-------------------------------------------------

The package 'pngtcl' depends on 'zlibtcl' and has to be built after
it. Beyond that the order of building is free. Their TEA build systems
can be found in the directories listed above.

The configure/Makefile's in the directories

	tkimg/compat/libz, tkimg/compat/libpng, tkimg/compat/libjpeg, tkimg/compat/libtiff

must _not_ be used directly under any circumstances.


At the next level is the package 'tkimg'. It provides utility
functions used by all format handlers, and therefore has to be built
before any of them. Its TEA build system can be found in the directory

	Name		Directory		Dependency
	-------------------------------------------------
	img::base	tkimg/base
	-------------------------------------------------

Beyond that are the packages providing the various format
handlers. They can be built in any order. Some of them depend on
supporting packages, as noted below. Their names and directories are

	Name		Directory	Dependency
	-------------------------------------------------
	img::bmp	tkimg/bmp
	img::dted	tkimg/dted
	img::gif	tkimg/gif
	img::ico	tkimg/ico
	img::jpeg	tkimg/jpeg	jpegtcl
	img::pcx	tkimg/pcx
	img::pixmap	tkimg/pixmap
	img::png	tkimg/png	pngtcl, zlibtcl
	img::ppm	tkimg/ppm
	img::ps		tkimg/ps
	img::raw	tkimg/raw
	img::sgi	tkimg/sgi
	img::sun	tkimg/sun
	img::tga	tkimg/tga
	img::tiff	tkimg/tiff	tifftcl, zlibtcl, jpegtcl
	img::window	tkimg/window
	img::xbm	tkimg/xbm
	img::xpm	tkimg/xpm
	-------------------------------------------------

CONFIGURE

The source distributions have "configure", which  has the following
possibilities:
	configure ?options?

Some possible options:
	--prefix=<dir>		Install headers in <dir>/include.
				Default: "/usr/local"
	--exec-prefix=<dir>	Install libraries in <dir>/lib.
				Default: "${prefix}"
	--with-tcl=<dir>	Find Tcl libraries in <dir> and include files in
				<dir>/../include or <dir>/../generic.
				Default: "${exec-prefix}/lib" or a sibling directory
				of the Img build directory.
	--with-tk=<dir>		Find Tk libraries in <dir> and include files in
				<dir>/../include or <dir>/../generic.
				Default: the same values as given by --with-tcl
				or a sibling directory of the Img build directory.

	Packages dependent on one or more of the support packages have
	appropriate options to locate their libraries and headers, if
	they cannot be found via --prefix and --exec-prefix

	Use configure --help to query each configure for the full set
	of options available to it.


MAKE & INSTALL

	'make', or 'make all' will build any package.

	'make install' will install its headers and libraries in the
	directories specified via --prefix/include and --exec-prefix/lib.

USE

If you want to use one or more of new image formats to be available in
your own scripts, add a line like the following somewhere in your
script:

	package require img::FORMAT

where FORMAT stands for the name of the format requested. See the list
in section 'PACKAGES AND THEIR DEPENDENCIES' for the available
formats. Each format will automatically load all of the packages it is
dependent on.

The line
	package require Img

is still legal and will load all format handlers provided by this
extension except dted and raw.

As an example, have a look at the file "demo.tcl"

For further options see the manpages.


DOCUMENTATION

The documentation coming with the distribution is written in the
doctools format (see tcllib).

	NOTE:
		The Img documentation makes use of features (include
		files and variables) which are not part of an official
		tcllib release yet. A cvs snapshot of tcllib is
		required.



PLATFORMS
	tested:
		Linux 2.0.30	(gcc, egcs)
		IRIX 6.2	(cc, 32 bits only)
		ULTRIX 4.1	(cc, gcc, egcs)
		ULTRIX 4.4	(cc 3.0)
		HP-UX-9		(cc, gcc, egcs)
		HP-UX-10.2	(gcc, egcs)
		SunOS-4.1.2     (cc)
		Solaris 2.5	(gcc, egcs)
		FreeBSD	2.2	(gcc, egcs)
		Windows	95/98/NT(gcc-2.95/MS Visual C++ 4.2/5.0/6.0)

	Not done yet:
		Mac		) someone interested
		VMS		) to try??????

	Other machines and OS's should work too. 

Feedback about other OS's and compilers is appreciated. Please
help me in making this package better.

--
		Jan Nijtmans
		email: nijtmans@users.sourceforge.net
		url:   http://purl.oclc.org/net/nijtmans/

		Andreas Kupries, ActiveState Corp
		email:	andreas_kupries@users.sourceforge.net	(private)
			akupries@shaw.ca			(private)
			andreask@activestate.com		(work)
		url:	http://www.purl.org/NET/akupries/
