Developing GUIs With the Eclipse Visual Editor, SWT Edition presentation

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Title: Developing GUIs With the Eclipse Visual Editor, SWT Edition

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Developing GUIs With the Eclipse Visual Editor,
SWT Edition

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My books

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Presentation and source available at

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The Visual Editor is Eclipses long-awaited GUI
Builder for Swing/AWT and SWT
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Whats a GUI builder good for?

Coding graphical user interfaces is tedious and
requires verbose code
Visualizing the effects of code and code changes
isnt intuitive for most people
The flexible, powerful layouts that give
professional results can be especially difficult
to program
A GUI builder lets you use graphical design tools
in a WYSIWYG environment to design the GUI and
generates code for you

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The Eclipse Visual Editor

Its been a long time coming
Difficult to develop
Hard to make one that generates good code and
that doesnt require proprietary artifacts like
format files
Visual Age for Java had one of the few good ones
Little incentive for IBM to contribute this to
Eclipse?
The lack of a GUI build was one of the chief
complaints about Eclipse, vis-à-vis competitors

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Introducing the Eclipse Visual Editor

IBM eventually relented and contributed their
Visual Editor in Fall 2003
Initial version, 0.5, was Swing/AWT only
Version 1.0, released Fall 2004, introduced
limited support for SWTthe Standard Widget
toolkit
Version 1.1, released July 2005, adds more SWT
support and support for RCP views

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Why SWT?

IBM created SWT as a replacement for Swing/AWT
AWT controls were native, but took lowest-common
denominator approach to achieve cross-platform
compatability
Swing emulated controls dont always match
platform
Swing controls performed poorly relative to
native controls
SWT took a hybrid approach
Thin layer over native controls
Emulated controls where native controls for a
particular platform arent available
SWT applications have the look responsiveness
of native applications
SWT is relatively simple and easy to use

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Installing VE

VE is an independent component that plugs into
Eclipse JDT
Install using Eclipse Update feature. This will
install VE and the following dependencies
Graphical Editing Framework (GEF)
Eclipse Modeling Framework (EMF)
Versions of Eclipse, VE, GEF and EMF must be
compatibleUpdate will make sure that dependency
requirements are met

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Principal VE features

Wizard for creating Visual Classesclasses that
include an SWT Shell or Composite
Visual editor with palette of controls and two
views in usual editor location
Design view
Source view
Java Beans View
Properties View
Indicator and tool buttons for controlling
synchronization between views
No support for JFace

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Visual class wizard

SWT options
Composite
Shell
SWT controls are not intended to be subclassed
SWT favors re-use through composition rather than
inheritance.
The generated visual class, by default, only
subclasses Object.
VE generates the code for declaring and
instantiating the selected type

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SWT palette selections

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Working with controls

Drag and drop from palette to design view or Java
Beans view
Adjust size or position in design view (if layout
manager permits)
Modify properties in Properties View
Add event handlers in design view or Java Beans
view
Modify source directly
By default, changes in one view will be reflected
automatically in the rest
Synchronization can be turned off or on with
toolbutton indicator appears in status bar

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Working with layouts

There is no default layout manager for a SWT
containers. (Or to put it another way, the
default is the null layout manager.)
Null layout lets you modify controls sizes and
placement arbitrarily, but will not adjust
automatically well when window is re-sized or UI
is localized for different languages.
To select a layout manager, make sure the
container is selected in the design view or Java
Beans view, then change the layout manager in
Properties view

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VE supported SWT layouts

but offers no support for FormLayout
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VE layout customizers

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Adding listeners

To make a GUI work, you need to add listeners to
wire controls together
Listeners can be added by right-clicking on a
control in design view or Java Beans view and
selecting Events-gt
Handlers specific to a control can be selected
directly
Other events can be selected by selecting Add
Events
Dialog box will show applicable listeners and
adapters

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Listeners and adapters

SWT often offers a choice between a
listenerwhich is an interfaceand an adapter
which is a class
An interface requires that you implement all the
methods it defines
Most SWT interfaces have a corresponding
adaptera class that implements the interfaces
methods with stubs
You subclass the adapter and only need to
implement the methods you care about
The only disadvantage of adapters is that your
event handler cant subclass anything else
VE will create all the code needed in either
case, including method stubs for the listener
interface, so using a listener is not much of an
inconvenience

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Running an SWT application

Can run as a Java Bean in Eclipse environment
To run as a Java app requires a native library
(DLL on Windows). There are four options
Use a -Djava.library.path VM argument in the
launch configuration to tell the application
where the library is.
Put the library in the root directory of your
project.
Add the location of the library the path the OS
uses to locate libraries. On Windows, this is
PATH environment variable on Mac OS X and Linux,
this is LD_LIBRARY_PATH.
Move the library to a place that is already on
the path, such as the SystemRoot\SYSTEM32
directory on Windows, or /usr/local/lib on Linux
and Mac.

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Demo

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Planning the GridLayout

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