_ RU.UNIX (2:5077/15.22) _____________________________________________ RU.UNIX _
From : Boris Tobotras 2:5020/510 05 Mar 98 22:19:06
Subj : GUI toolkits : из Sun World Online
________________________________________________________________________________
[SunWorld]
March 1998
GUI toolkits: What are your options? [Next story]
An overview of today's best-bet GUI toolkits [Table of Contents]
By Cameron Laird and Kathryn Soraiz [Search]
[Sun's Site]
------------------------------------------------------------------------
Abstract
This article provides an overview of the various toolkits (or
programming interfaces) available for Solaris. Among these, we
selected only the most portable, commercially applicable, and
modestly priced packages. The toolkits described here are best for
office automation projects, graphical information system (GIS)
jobs, GUIfication of legacy programs, system administration
utilities that are easy to run, and so on.
We cover the following toolkits: OLIT, XView, TNT, Motif, Java,
OpenStep, Tk, MFC, MacOS toolkit, Amulet, GTK, MetaCard, and Qt.
You can see how these toolkits compare by checking out our
sidebar, Toolkit roundup. (3,000 words)
------------------------------------------------------------------------
ave you had your GUI toolkit in for its annual checkup?
No? Well, now is a good time to do it. As the wired
world moves away from Motif, and toward Java and scripting
technologies, you might be better off with a new toolkit.
Let's walk through your options together.
What's a toolkit?
Most applications built today fit the windows-icon- menu-pointer (WIMP)
model of operations. That is, in our daily work we program things that users
point-and-click. The vernacular word for the application programming
interfaces (APIs) that manage graphical user interfaces (GUIs) is "toolkit."
While most Unix professionals probably know of only one or two toolkits
there are dozens of useful alternatives available. This article will help
you learn which of them will best meet your needs. We'll leave the
discussion of specialized toolkits designed for three-dimensional or virtual
reality displays for another article.
The difficulty in understanding GUI toolkits lies in the number of subtly
different concepts involved. When people speak of "Motif," for example, they
may have in mind any one of a number of different things:
* The licensed product that bundles several pieces
* The specification for a style of GUI interfaces
* The windowing manager included with a Motif license
* The toolkit that implements a Motif specification
* A completely different (and mistaken) notion, i.e., the X bitmap model
that underlies Motif
------------------------------------------------------------------------
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X: The base for Unix GUIs
First, you'll need to understand the foundation on which most of these
toolkits rest. "The X Window System provides the base technology for
developing [Unix-oriented] graphical user interfaces," according to a
statement from its current custodian, the Open Group. X is a
freely-available windowing package, first released as X10.4 in 1986. It
provides a consistent API for graphical operations across all Unixes. X has
spread in recent years to OpenVMS, Windows, MacOS, and other operating
systems. It defines a particular client/server model of operation that
segments applications into a display portion and a computational portion.
One of the charms of X is that these two portions can run on different
machines. This makes it possible to run a weather simulation on the largest
supercomputer in the world, yet manage and observe its results from a
low-end screen located across the country.
X is not a toolkit, though, at least not for the purpose of this article. X
is low level. Most developers insulate themselves from its tedium by using
one of the toolkits described below. The important thing to understand about
X is where the responsibility for different features lies. For instance,
almost all toolkits share font management and screen redirection
functionality because they rely on X for these chores. How a menu posts,
though, is specific to a particular toolkit.
Most of the toolkits profiled below are APIs layered on top of X. At the
same time, several have been implemented over alternative low-level display
protocols. Tk programmers write the same scripts whether working on a
Macintosh or a SPARCstation. Underneath, the Solaris version of Tk calls X
routines, and the Mac Tk invokes MacOS system calls. OpenWin exemplifies
another instance of this distinction: It was originally an environment for
users and programmers built above Sun's Network Windows System (NeWS). With
version 3.3, though, it was rebuilt on top of X.
OpenWindows, SunView, NeWS
In a few Sun-oriented shops around the world, OpenWindows, SunView, or NeWS
are the canonical GUIs. OpenWindows -- sometimes called xnews or openwin --
is a windowing environment Sun has distributed as part of its standard
bundle since July 1990. Several of the pieces appeared in earlier Sun
products as early as 1985. OpenWindows implements Open Look. Open Look is a
specification for GUIs that Sun and AT&T published.
SunView was an earlier, proprietary windowing environment, as was Network
Window System (NeWS). Sun continues to support SunView and NeWS in ways too
complex to unravel here.
Sun bundled the Open Look Intrinsics Toolkit (OLIT) with OpenWindows. Sun
also bundled The NeWS Toolkit (TNT) with most releases of OpenWindows.
XView is Sun's toolkit for X11. Its API is similar to the SunView programmer
interface. XView and its sources are free.
The elegance and visual appeal of NeWS and SunView are widely admired. There
is no future for them, though. Sun made a strategic decision to keep them
proprietary, and they lost to X and Motif. While programmers continue to
maintain and occasionally even write Open Look applications, the numbers
decline every year.
Motif: The default choice
The single most widely used toolkit in the Unix world is Motif. Motif is the
child of a committee. Other Unix vendors feared success for Open Look would
benefit Sun disproportionately. Their response was to create the Open
Software Foundation (OSF). OSF produced Motif in 1989.
Motif is so ubiquitous that many Unix users confuse it with GUI operations
or window managers, or other pieces of technology, and speak as if Motif is
the only GUI foundation or toolkit.
Now, the Open Group maintains both X and Motif. With Motif, unlike X, users
must pay for their licenses. Most Unix customers don't realize this because
such vendors as Sun, Hewlett-Packard, and Silicon Graphics, along with many
others, bundle a Motif version with their Unix operating systems. The Motif
license fee is simply part of the purchase price for the operating system.
Motif remains logically distinct from the OS, though, and third parties sell
more recent or otherwise enhanced Motifs for most platforms.
Motif is the market leader among Unix GUI toolkits. As it nears its 10th
birthday, it enjoys both the advantages and disadvantages of maturity. It
has the most advanced support for text from languages other than English, a
wealth of third-party tools support it, and hundreds of books and online
documents explain it. It's also mediocre in performance, difficult to
program, and a poor fit for modern object-oriented styles.
Why use Motif?
* As an educational exercise. It's widely available, and the other
toolkits we describe reuse most of Motif's user interface concepts. If
you learn Motif, you'll pick up the others quickly. The online FAQs
maintained by independent consultant Kenton Lee and others are
enormously helpful.
Readers running Linux, FreeBSD, or similar freeware might be reluctant
to pay the few hundred dollars necessary for a Motif license. There's
now a freeware work-alike for Motif called LessTif. This is
particularly attractive for those teaching themselves Motif programming
and unwilling to pay an out-of-pocket charge to do so.
* To support legacy applications. Tens of thousands of Motif programs are
in place, and most are due for maintenance.
* To exploit a third-party toolkit built on top of Motif. GUI builders,
widget sets, test harnesses, and much more are available for Motif.
Many of these are commercial products with hefty prices. If you're
building a high-end computer-human interface (CHI), though, they're
worth the cost.
Portability is beginning to have a whole new meaning in Motif programming.
Traditionally, one of the attractions of the high-end toolkits from such
vendors as Neuron Data and Visual Edge has been that they managed the
complexity of working with Motif on different platforms, and sometimes even
targeted other low-level toolkits than Motif.
What all these vendors are doing now is targeting Java as an alternative
platform to Motif. Customers clamor for this, and it's the correct strategy
for the vendors to take. There's a danger in it, though. If customers
continue to rely on proprietary power widgets from the vendors, the latter
will prosper. Their fear is that customers are using the Java capabilities
just as a way to migrate legacy applications away. It will be interesting to
see which Motif tool-makers survive the transition to a world that Java
dominates.
Java
Sun's default answer to almost all questions these days seems to involve
Java in one way or another. This applies in particular to the search for a
GUI toolkit, where Sun hopes to see more and more use of the Java APIs.
Writing in Java holds the promise of unparalleled portability. Java
applications run not just under Unix, but also Windows, MacOS, and much
more. At least, that's the dream. As of spring 1998, it remains more dream
than reality. Java should be a big winner as we enter the 21st century. It's
likely that the current difficulties in porting are transient. Certainly
Java has the features -- re-entrancy, thread safety, and a strong
object-oriented model -- that modern techniques require. But Java's toolkits
simply aren't mature yet, and they are unavailable or incompatible for
several platforms. WIMP appearance varies between Win95 and Solaris, and
JavaSoft frequently releases toolkit versions for such popular Unixes as
HP-UX and Digital Unix long after the ones for Solaris and Windows NT.
Java supports a family of GUI toolkits. First was the Abstract Windowing
Toolkit (AWT). We discourage programming in AWT. AWT is difficult. Although
Sun Educational Services and the Sun Java Certification Program emphasize
AWT, we find it is simply not a useful toolkit for most programming teams.
The one salient advantage of AWT is that third parties sell interesting and
useful tools such as JBuilder for AWT programming. If you do pursue AWT,
bookstore shelves are heavy with explanations of it.
More useful for day-to-day programming tasks are the Java Foundation Classes
(JFC). A key element of Sun's February 1998 1.1 release is the new
high-level components, nicknamed Swing or Swing set. These are quite heavy;
Sun recommends 32 megabytes of RAM for developers working with Swing. What
that weight buys is a rich widget set, accessibility support for the blind
or those with other disabilities, drag-and-drop functionality, and a
pluggable look and feel. Sun's JavaSoft division also promises that JFC will
be the framework for such planned enhancements as multimedia controls and a
two-dimensional graphics API.
One interesting twist to all of this is the fact that Eugene O'Neil, a
student in Boston, has written a freeware X implementation in Java he calls
the X Tool Collection (XTC). His aim is to replace the existing C source
code for X. This will yield what O'Neil advertises as a "small, simple,
object-oriented, and multithreaded" base for Motif and other toolkit
programmers. The irony of this must be particularly poignant for chief Java
engineer James Gosling. As mentioned above, NeWS lost out to X a decade ago.
Gosling designed NeWS.
OpenStep
One more echo from the '80s deserves mention. NextStep was the development
environment for the NeXT cubes. NextStep was renamed OpenStep for its
release under HP-UX, Solaris, Windows NT, and other OSs. It inspires wild
enthusiasm in its programmers for its power and aesthetics. As with Open
Look, its market penetration has disappointed its owners. Now it appears to
be in the ascendant again, as part of Apple's latest OS, Rhapsody.
Tk: Scripting GUIs
The toolkit we use most in our consultancy is Tk. Tk is a GUI extension to
the Tcl scripting language. It's freely available for MacOS, OpenVMS, OS/2,
Unix, Windows, and other OSs.
Thousands of successful applications are written in Tk. Many are quite
sophisticated; Tk has firmly established itself in niches of GSI and
electronic design automation (EDA). Perhaps an even greater testimony to Tk
is the number of other packages that have embedded it, despite religious
objections. Popular toolkits give Tk bindings for other languages, including
Perl, Python, C, and Scheme. Sunscript, the development team responsible for
Tcl and Tk, has one FAQ that begins, "I hate Tcl, but I think Tk is cool."
Perhaps Tk's greatest virtue is its ease of use. It takes only a couple of
lines to make a primitive GUI application.
Tk isn't perfect. While it's the most portable toolkit we've encountered, it
feels a bit old-fashioned in its poor support for multiple document
interfaces (MDI), tabbed folders, and other widgets that end users have come
to expect.
Related extensions of Tcl provide toolkits that extend form-based GUIs to
character-only terminals.
Qt: Faster and more extensible than Motif
Qt is a shareware toolkit perhaps best known for its role in the K Desktop
Environment (KDE). KDE is a freeware project destined to produce a fast and
coherent desktop environment for the X Window System.
Even apart from KDE, though, Qt has a lot to offer. It is fundamentally an
object-oriented improvement on Motif. It is a multiplatform (Unix X, Win95,
and WinNT) C++ GUI applicationframework that's fully object-oriented, easily
extensible, and much faster than Motif for important operations. Its
architecture is cleaner than Motif's. Qt is exceptionally well documented
and several commercial products already rely on it.
Qt's developer, Troll Tech, explains "Qt provides a signals/slots concept
that is a type-safe alternative to callbacks and at the same time allows
objects to cooperate without any knowledge of each other. This makes Qt very
suitable for true component programming." Another important innovation in
Qt's architecture is its abstraction of the display destinations of widget,
pixmap, picture, and printer. This simplifies a variety of programming
tasks, including animation and printing.
Python and the benefits of scripting
Python is a scripting language, like Tcl or Perl. Python's official release
includes the Tkinter toolkit, which binds Tk to Python. Extensions to a
dozen other toolkits are also available. Python's clean object-oriented
design has facilitated toolkits which provide for scripting MFC, Amulet, Qt,
Motif, GTK, AWT, and more. Python is remarkably portable. It's an excellent
vehicle with which to learn, prototype, and, in many case, deliver finished
applications.
Most other scripting languages support at least one or two of these
toolkits. "Scripting" involves a number of technologies and ideas. Most
important for GUI programmers is the swiftness with which it's possible to
develop applications in scripting languages. Motif and MFC programmers are
familiar with the edit-compile-link-debug cycle, where the linking phase
alone (of a simple change to adjust a single widget position) can take five
minutes. With scripting languages, there's an immediate response to such
edits.
MFC: Bringing the Microsoft world to Unix
The next two families of toolkits are of no intrinsic interest to Unix
programmers. They offer no advantages over the other toolkits cataloged --
except that they're compatible with existing work on other platforms for
which you might be responsible.
Microsoft Foundation Classes (MFC) is the dominant toolkit in the Windows
world, followed most closely by Borland's Object Windows Library (OWL).
MainWin is one commercial implementation of MFC for Unix. The section on
Python, below, also points to an MFC alternative.
Latitude makes Solaris look like a Mac
Metrowerks sells almost all of the MacOS API for Solaris, IRIX, and Rhapsody
under the product name, Latitude. We haven't used Latitude. Many readers
will be familiar with Metrowerks' acclaimed CodeWarrior, though. Just as the
MFC ports most interest those who need to move existing Windows programs to
Unix, Latitude most interests developers who reproduce MacOS functionality
on Unix desktops.
Amulet animates
"Amulet is an entirely free, public domain user interface development
environment in C++. Code written using Amulet will work with little or no
changes on all platforms." So says Amulet's FAQ. Amulet has particularly
strong support for such operations as undo, gestural recognition, tool tips,
and animation. Amulet enables constraint-based programming and an innovative
input model it calls "interactors." Amulet descends from a late 1980s LISP
project called Garnet.
GTK: GNU project power
GIMP is a freely-available image manipulation utility that duplicates much
of PhotoShop's functionality. GIMP ToolKit (GTK) is the small, efficient
toolkit used to construct GIMP. GTK is also at the heart of GNOME, a
freeware desktop manager for Unix. GTK, in the tradition of other Free
Software Foundation projects, has little documentation and a bit of a bias
toward Linux. In principal it's portable to Windows and MacOS, but no one
has yet done the work to make it so. It's generally more powerful and faster
than Motif. Bindings exist for C, C++, Perl, Guile, and Python.
MetaCard is HyperCard for the '90s
MetaCard is a multimedia authoring tool and GUI development environment for
Unix/X11 workstations and Microsoft Windows 95 and NT. It inherits much from
the HyperCard Apple developed for the Macintosh in the '80s, including a
strong position in development of computer-based training applications.
MetaCard benefits include its ease of use and portability. A port to MacOS
is "our top priority at this point," according to president Scott Raney.
Although Raney says that MetaCard hasn't announced a release date for this,
the new version is nearly through a complete cycle of alpha-level tests.
Conclusion
Make your toolkit work for you. If you're not a GUI programmer now, know
there are plenty of resources to help you start. If you're already working
with a toolkit, and it's too expensive, slow, cumbersome, or otherwise
limiting, make a change. Try out freeware. Use one of the new
high-performance toolkits. Buy a third-party product, or get help through
classes or a support contract. (Be sure to see our sidebar, "Toolkit
roundup," below.)
Nowadays most of the technologies we've discussed are more or less
compatible. You might sit at a Macintosh screen, developing a Windows-style
MFC application hosted on a Unix workstation, built with a scripting
language. If you know what you need, in 1998 there's a fair chance someone
has created it already, or at least enough pieces that you can put it
together yourself.
If you've only programmed through an edit-compile-link-debug cycle, you
particularly owe it to yourself to experiment with one of the scripting
languages that can create small applications in less time than a single
compilation sometimes takes. Have fun with your GUI programming! [Image]
------------------------------------------------------------------------
Resources
Toolkit resources
* The GUI Toolkit Framework Page -- a reference for all kinds of GUI
toolkits http://www.geocities.com/SiliconValley/Vista/7184/guitool.html
* Amulet Project home page
http://www.cs.cmu.edu/afs/cs/project/amulet/www/amulet-home.html
* Free Software Foundation http://www.fsf.org
* The GIMP ToolKit [GTK] http://www.gimp.org/gtk/
* KDE FAQ http://www.kde.org/kdp/kde_faq.html
* Latitude home page http://www.metrowerks.com/desktop/latitude/
* LessTif
http://starbase.neosoft.com/~claird/comp.windows.x.motif/lesstif.html
* MainWin http://www.mainsoft.com/map.htm#mainwin
* MetaCard http://www.metacard.com
* Motif
http://starbase.neosoft.com/~claird/comp.windows.x.motif/motif.html
* Open Group Desktop Technologies -- X Window System
http://www.camb.opengroup.org/tech/desktop/x/
* OPENSTEP home page http://software.apple.com/openstep/
* Python http://www.python.org/
* Qt product information http://www.troll.no/qtinfo.html
* XTC, the X Tool Collection http://www.cs.umb.edu/~eugene/XTC/
More resources
* "Choosing a scripting language," October 1997 feature story in SunWorld
http://www.sun.com/sunworldonline/swol-10-1997/swol-10-scripting.html
* "Does Sun want to become the next Microsoft?" a SunWorld update on
Sun's OpenStep applications group
http://www.sun.com/sunworldonline/swol-02-1998/swol-02-lighthouse.html
* "Getting started with Python," February 1998 feature story in SunWorld
http://www.sun.com/sunworldonline/swol-02-1998/swol-02-python.html
* "Writing common code for Unix and NT," April 1997 feature story in
SunWorld
http://www.sun.com/sunworldonline/swol-04-1997/swol-04-porting.html
* Updates and amplifications of this article
http://starbase.neosoft.com/~claird/comp.windows.misc/toolkits.html
------------------------------------------------------------------------
About the author
Cameron Laird and Kathryn Soraiz manage their own software consultancy,
Network Engineered Solutions, from just outside Houston, Texas. They invite
you to e-mail them for notice of upcoming articles. Reach Cameron at
[email protected].
URL: http://www.sun.com/sunworldonline/swol-03-1998/swol-03-gui.html
Last modified: Wednesday, March 04, 1998
[Sidebar] [Back to story]
Toolkit roundup
Portable
Toolkit Market Market License Technical Technical beyond
Scriptable?
presence momentum fee advantages disadvantages
Unix?
Amulet tiny unclear free animation unusual yes
yes
GTK tiny unclear free speed of no docs no
yes
performance
Java medium exploding free Java juvenile yes
yes
MacOS medium static $399 Mac difficult yes
no
toolkit compatible
MetaCard tiny growing $995 ease-of-use, small yes
yes
computer developer
based community
training
MFC dominant static $0-1000 Win complex yes
yes
compatible
Motif dominant static $0-1000 maturity difficult barely
yes
OLIT, medium steep bundled legacy old no
no
XView, decline compatible,
TNT pretty
OpenStep niche unclear ~$1000 power, inconsistent yes
no
beauty platform
support
Qt tiny growing $0-1470 quality long yes
yes
maintenance
cycle
Tk medium growing free ease-of-use, few built-in yes
yes
portable widgets
[Sidebar] [Back to story]
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