This document describes SWT, the Standard Widget Toolkit, which is one of the two main graphical sub-systems that make up the Eclipse platform user interface, along with JFace. SWT provides a platform-independent API that sits close to the underlying native widgets. This module explains how to use SWT in views and editors and how to manage different resources. It also provides information on basic SWT concepts like widgets, events, layouts and more.

1. SWT - The Standard Widget Toolkit
The graphical sub-system of the Eclipse platform is made up of two
components: SWT, the Standard Widget Toolkit; and JFace, an
architecture independent modeling layer. This module describes how to
use SWT in views and editors and how different resources must be
managed.
Redistribution and other use of this material requires written permission from The RCP Company.
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2. Eclipse User Interface Layers
Eclipse RCP
Preferences
Commands
Four Layers:
Registry
Workbench
Jobs
ICU
 The Eclipse Workbench JFace
SWT

Overall look-n-feel
OSGi/Run-time
 JFace

Architecture-independent models
 SWT

Platform independent API yet rather close to the metal
 Native widgets

Platform dependent: Windows, Linux, Mac, Unix
The “Eclipse User Interface Guidelines” govern the look-n-feel of the
workbench and JFace
 Consequently (nearly) all Eclipse RCP based applications look the same!
Use the SWT Bible “The Definitive Guide to SWT and JFace” by Robert Harris
and Rob Warner
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3. SWT and the Native Widgets
SWT is short for ”The Standard Widget Toolkit”
SWT is a sub-project of the Eclipse project
SWT has a common API on all target platforms – the implementation is
different
 Base plug-in org.eclipse.swt contains only MANIFEST.MF plus some
configuration files
 A set of platform specific fragments implements all of SWT–
org.eclipse.swt.win32.win32.x86 for 32-bit Windows on x86 (not Vista
look-n-feel)
SWT is a thin layer on top of the native widgets
 Windows, Mac, Motif, GTK and more
SWT can easily be used stand-alone
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4. SWT on Different Platforms
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5. Working with SWT
SWT API is not as regular as Swing
The SWT site contains a large repository of “SWT Snippets” that demonstrate
most of the abilities of SWT
To find leaks with graphical resources use sleak plug-in
It is possible to integrate SWT and Swing to a very large degree
 But expect problems with shortcuts and focus management
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6. SWT Widgets
Basic
 Button, Combo, Composite, Group, Label, Link, List, Menu, ProgressBar,
Shell, Slider, Scale, Spinner, TabFolder, Table, Text, ToolBar, and Tree
Advanced
 Browser, Canvas, CBanner, CCombo, CLabel, CoolBar, CTabFolder,
DateTime, ExpandBar, GLCanvas, Sash, SashForm, ScrolledComposite,
StyledText, SWT_AWT, TableCursor, and Tray
Other Sources – e.g. Nebula, Sourceforge.net
 FormattedText, Gallery, Grid, and many more
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7. SWT Widgets
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8. The Basic Widget Hierarchy
Widget
Item
Menu
Control MenuItem TableItem TabItem
Label Button List
Composite
Canvas Combo Form OleSiteClient Table
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9. The Basic Widget Hierarchy
Widget Control Composite
Top-level abstract Top-level abstract Control that can
super class for all super class for contain other controls
widgets controls
Support for layout
Support for Support for management
 arbitrary  foreground, A Composite must
associated data background have a layout
 general event  border manager, or the child
management  content menu widgets will not be
 disposal shown!
 focus
management management
 layout
management –
layout, location
and size
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10. Using SWT Widgets
Common constructor form – e.g. new Text(parent, SWT.PASSWORD)
 The parent
 The style argument specifies the basic sub-function of the widget
Use Text controls for data values event when read-only, as this makes it
possible to select and copy the value
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11. Using SWT Styles
Second argument of all widget constructions – e.g. new Text(parent,
SWT.PASSWORD)
The most used styles are
 SWT.NONE – no style needed
 SWT.LEAD, SWT.CENTER, and SWT.TRAIL - the alignment of text in
labels, menus and buttons
 SWT.ARROW, SWT.CHECK, SWT.PUSH, SWT.RADIO, and SWT.TOGGLE -
the sub-type of a button
 SWT.PASSWORD - Text is used for password entry
 SWT.V_SCROLL, SWT.H_SCROLL, and SWT.NO_SCROLL – Table or Tree
has vertical, horizontal or no scroll bar (3.4 and later)
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12. Using SWT Styles
Some special considerations regarding styles
 Some style arguments cannot be changed once specified in the
constructor (e.g. SWT.CHECK for a Button), whereas others can (e.g.
SWT.LEAD for Label)
 Some style arguments have different meaning for different widgets –
e.g. SWT.MULTI for Table and Text
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13. Managing Composites (Composite)
Children are added to a composite during the construction of the children
 new Text(composite, SWT.BORDER)
Children are retrieved using
 comp.getChildren()
Children are removed using
 child.dispose()
Children can be moved in the parent using
 child.moveAbove(otherChild)
 child.moveBelow(otherChild)
When a composite is changed, remember to re-layout
 comp.layout()
Setting the background of children of a composite:
 comp.setBackgroundMode(SWT.INHERIT_DEFAULT)
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14. SWT Layout Managers
The positioning and sizing of controls in a Composite (and subclasses) is
performed using layout managers
SWT includes a rather complete set of standard layout managers
 FillLayout and RowLayout: layout is a single row or column
 GridLayout: layout in a grid with size constraints
 FormLayout: layout in canvas with size and edge-to-edge constraints
 Most GUI designer can handle these
A new layout manager can be created fairly easily
 computeSize: computes the “natural” size of the Composite
 layout: lays out the controls of the Composite
public abstract class Layout {
protected abstract Point computeSize(Composite composite, int wHint, int hHint, boolean flushCache);
protected abstract void layout(Composite composite, boolean flushCache);
}
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15. Using the Grid Layout (GridLayout)
Grid Layout is the most used layout manager in Eclipse
It works by adding the child widgets to the cells in a grid
 Widgets are added in sequence
When using a Grid Layout, the parent uses the GridLayout and all children
use GridData final Composite composite = new Composite(parent, SWT.NONE);
final GridLayout gridLayout = new GridLayout(3, false);
composite.setLayout(gridLayout);
...
label = new Label(composite, SWT.NONE);
label.setText("Label");
text = new Text(composite, SWT.BORDER);
text.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false, 2, 1));
// …
Label Text
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16. Using the Grid Layout (GridLayout)
The GridLayout class has two arguments
 numColumns – the number of columns in the grid (defaults to 1)
 makeColumnsEqualWidth – whether all columns in the grid have equal
width (defaults to false)
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17. Using the Grid Data (GridData)
GridData specifies how a child widget is laid out in the parent grid
A GridData holds the following primary information
 Grab Excess Space (horizontal and vertical) – describes whether the grid
column or row should expand to grab any excess space (defaults to no
grab)
 Span (horizontal and vertical) – describes the number of cells the
widget should span (defaults to 1,1)
 Alignment (horizontal and vertical) – placement of widget within the
cells – one of SWT.BEGINNING, SWT.CENTER, SWT.END or SWT.FILL
(defaults to BEGINNING, BEGINNING)
 A GridData also contains information about indentation, minimum size
and size hints
Don’t use the two-argument constructor!
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18. Using the Grid Data (GridData)
Grab Excess Space (horizontal and vertical)
 describes whether the grid column or row should expand to grab any
excess space (defaults to no grab)
Outer
Composite
Control to be
positioned
GridLayout with 3
columns and 3 rows
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19. Using the Grid Data (GridData)
Span (horizontal and vertical)
 describes the number of cells the widget should span (defaults to 1,1)
1,1 2,1
2,2
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20. Using the Grid Data (GridData)
Alignment (horizontal and vertical)
 placement of widget within the cells – one of SWT.BEGINNING,
SWT.CENTER, SWT.END or SWT.FILL (defaults to BEGINNING, BEGINNING)
C,C F,C
E,E
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21. Layout Managers for Tables and Trees
Tables and Trees have a layout how columns are sized
 TableLayout

Will only resize the columns the first time!

Applied to the Table or Tree
 TableColumnLayout

Applied to the Composite of the Table or Tree
 Column constraints saved as layout.setColumnData(column, constraint)
Both layout managers are based on the same column constraint objects:
 ColumnPixelData – makes a column a specific width in pixels
 ColumnWeightData – makes a column a specific percentage of the
summed width
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22. SWT Events
SWT events and listeners exist in two versions:
 A simple very light-weight version

One event format and listener interface
 A type-safe version

Multiple event formats and listener interfaces tailored to the specific
use
The difference is illustrated in the following example
filter.addListener(SWT.KeyDown, new Listener() {
public void handleEvent(Event event) {
if (event.type == SWT.KeyDown) {
//...
}
}
});
filter.addKeyListener(new KeyAdapter() {
@Override
public void keyPressed(KeyEvent e) {
//...
}
});
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23. SWT Events
Key Tree and Table
 KeyDown, KeyUp, HardKeyDown,  Expand, Collapse, EraseItem,
HardKeyUp MeasureItem, PaintItem
Mouse Shell
 MouseDown, MouseUp,  Iconify, Deiconify, Close,
MouseMove, MouseEnter, Activate, Deactivate
MouseExit, MouseDoubleClick,
MouseHover, MouseWheel Menu
 Show, Hide, Arm, MenuDetect
Control
 Paint, Move, Resize, Dispose Basic Controls
 Modify, Verify, SetData, Settings
Selection
 Selection, DefaultSelection Drag-n-Drop
 DragDetect
Focus
 FocusIn, FocusOut Misc
 Help
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24. Lab Exercise
Create a view with the following look using simple SWT controls
 GridLayout, GridData
 Label, Text, Button
 …addSelectionListener(…)
Label
Text - FILL aligned + grab
Button - spans two columns, RIGHT
aligned. SelectionListener that prints
current text of Text control
public class View extends ViewPart {
public void createPartControl(Composite parent) {
Composite top = new Composite(parent, SWT.NONE);
Composite with GridLayout // Add something here…
with 2 columns }
public void setFocus() {
}
}
Another extra lab for the fast ones:
 add “stuff” to the lab to only allow “a” and “b” in the text field
 and to only allow more “a” than “b”!
 Use a Verify listener
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25. Forms UI
A newer addition of the look-n-feel of the
Eclipse workbench is the Forms UI in
org.eclipse.ui.forms.
 Provide a Web browser like look-n-feel to
forms
 PDE is a good example of the increasing
use of this new technology
Have some of the same problems as seen in
ordinary Web applications: extensive use of the
mouse! Normally not welcome in office
applications
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26. More Information
“Eclipse User Interface Guidelines: Version 2.1”
 http://www.eclipse.org/resources/resource.php?id=162

The Look-n-Feel guidelines for Eclipse – heavily influenced by the corresponding
Microsoft Windows Look-n-Feel guidelines
SWT home
 http://www.eclipse.org/swt/
SWT versus Swing
 http://www.developer.com/java/other/article.php/2179061
“Using SwingRCP (instead of SWT) in RCP”
 http://www.eclipsezone.com/eclipse/forums/t104467.rhtml

A discussion of different ways to integrate Eclipse RCP and Swing
“The Definitive Guide to SWT and JFace” by Robert Harris and Rob Warner (ISBN:
978-1590593257)
 As it says – “The Definitive Guide…” – and needed due to the pure javadoc of SWT
“SWT Snippet” Repository
 http://www.eclipse.org/swt/snippets/

A large repository of sample code for most uses of SWT!
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27. More Information
“Plug a Swing-based development tool into Eclipse”
 http://www-128.ibm.com/developerworks/opensource/library/osswing/
“Eclipse Forms: Rich UI for the Rich Client”
 http://www.eclipse.org/resources/resource.php?id=140
“Custom Drawing Table and Tree Items”
 http://www.eclipse.org/resources/resource.php?id=122
“Using Images in the Eclipse UI”
 http://www.eclipse.org/resources/resource.php?id=236
“Rich clients with the SWT and JFace”
 http://www.javaworld.com/javaworld/jw-04-2004/jw-0426- swtjface.html?page=2
“SWT: The Standard Widget Toolkit”
 http://www.eclipse.org/resources/resource.php?id=241
“Understanding Layouts in SWT”
 http://www.eclipse.org/resources/resource.php?id=242

A good overview of the different basic layouts in Eclipse.
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28. More Information
“Drag and Drop in the Eclipse UI”
 http://www.eclipse.org/resources/resource.php?id=202
“Adding Drag and Drop to an SWT Application”
 http://www.eclipse.org/resources/resource.php?id=200
“Eclipse Data Binding Test Drive” (webinar)
 http://www.eclipse.org/resources/resource.php?id=299
“Swing/SWT Integration”
 http://www.eclipse.org/resources/resource.php?id=381
“Eclipse Forms: Rich UI for the Rich Client”
 http://www.eclipse.org/articles/Article-Forms/article.html

The Forms UI explained with some good examples
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