Package org.eclipse.swt.widgets

Class Event

java.lang.Object

org.eclipse.swt.widgets.Event

public class Event
extends Object

Instances of this class provide a description of a particular event which occurred within SWT. The SWT untyped listener API uses these instances for all event dispatching.

Note: For a given event, only the fields which are appropriate will be filled in. The contents of the fields which are not used by the event are unspecified.

See Also:

• Listener
• TypedEvent
• SWT Example: ControlExample, Listeners
• Sample code and further information

Field Summary

Fields

Modifier and Type	Field	Description
int	button	the button that was pressed or released; 1 for the first button, 2 for the second button, and 3 for the third button, etc.
char	character	depending on the event, the character represented by the key that was typed.
int	count	depending on the event type, the number of following paint events that are pending which may always be zero on some platforms, or the number of lines or pages to scroll using the mouse wheel, or the number of times the mouse has been clicked
Object	data	a field for application use
int	detail	the event specific detail field, as defined by the detail constants in class SWT
Display	display	the display where the event occurred
boolean	doit	depending on the event, a flag indicating whether the operation should be allowed.
int	end	depending on the event, the range of text being modified.
GC	gc	the graphics context to use when painting that is configured to use the colors, font and damaged region of the control.
int	height	the height of the bounding rectangle of the region that requires painting
int	index	the index of the item where the event occurred
Widget	item	the item that the event occurred in (can be null)
int	keyCode	character that is good for keyboard shortcut comparison.
int	keyLocation	depending on the event, the location of key specified by the keyCode or character.
double	magnification	The change in magnification.
double	rotation	The number of degrees rotated on the track pad.
int[]	segments	Bidi segment offsets
char[]	segmentsChars	Characters to be applied on the segment boundaries
int	start	depending on the event, the range of text being modified.
int	stateMask	depending on the event, the state of the keyboard modifier keys and mouse masks at the time the event was generated.
String	text	depending on the event, the new text that will be inserted.
int	time	the time that the event occurred.
Touch[]	touches	An array of the touch states for the current touch event.
int	type	the type of event, as defined by the event type constants in class SWT
Widget	widget	the widget that issued the event
int	width	the width of the bounding rectangle of the region that requires painting
int	x	depending on the event type, the x offset of the bounding rectangle of the region that requires painting or the widget-relative, x coordinate of the pointer at the time the mouse button was pressed or released
int	xDirection	If nonzero, a positive value indicates a swipe to the right, and a negative value indicates a swipe to the left.
int	y	depending on the event type, the y offset of the bounding rectangle of the region that requires painting or the widget-relative, y coordinate of the pointer at the time the mouse button was pressed or released
int	yDirection	If nonzero, a positive value indicates a swipe in the up direction, and a negative value indicates a swipe in the down direction.

Constructor Summary

Constructors

Constructor	Description
Event()

Method Summary

Modifier and Type	Method	Description
Rectangle	getBounds()	Gets the bounds.
void	setBounds(Rectangle rect)	Sets the bounds.
String	toString()	Returns a string containing a concise, human-readable description of the receiver.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

display

public Display display

the display where the event occurred

Since:

2.0

widget

public Widget widget

the widget that issued the event

type

public int type

the type of event, as defined by the event type constants in class SWT

See Also:

• SWT

detail

public int detail

the event specific detail field, as defined by the detail constants in class SWT

See Also:

• SWT

item

public Widget item

the item that the event occurred in (can be null)

index

public int index

the index of the item where the event occurred

Since:

3.2

gc

public GC gc

the graphics context to use when painting that is configured to use the colors, font and damaged region of the control. It is valid only during the paint and must not be disposed

x

public int x

depending on the event type, the x offset of the bounding rectangle of the region that requires painting or the widget-relative, x coordinate of the pointer at the time the mouse button was pressed or released

y

public int y

depending on the event type, the y offset of the bounding rectangle of the region that requires painting or the widget-relative, y coordinate of the pointer at the time the mouse button was pressed or released

width

public int width

the width of the bounding rectangle of the region that requires painting

height

public int height

the height of the bounding rectangle of the region that requires painting

count

public int count

depending on the event type, the number of following paint events that are pending which may always be zero on some platforms, or the number of lines or pages to scroll using the mouse wheel, or the number of times the mouse has been clicked

time

public int time

the time that the event occurred. NOTE: This field is an unsigned integer and should be AND'ed with 0xFFFFFFFFL so that it can be treated as a signed long.

button

public int button

the button that was pressed or released; 1 for the first button, 2 for the second button, and 3 for the third button, etc.

character

public char character

depending on the event, the character represented by the key that was typed. This is the final character that results after all modifiers have been applied. For example, when the user types Ctrl+A, the character value is 0x01 (ASCII SOH). It is important that applications do not attempt to modify the character value based on a stateMask (such as SWT.CTRL) or the resulting character will not be correct.

keyCode

public int keyCode

character that is good for keyboard shortcut comparison. Unlike character, this tries to ignore modifier keys and deal with non-latin keyboard layouts. Examples:

Layout	US key label	character	keyCode
Windows English US	C	'c'	'c'
Windows English US	Shift+C	'C'	'c'
Windows English US	Ctrl+C	0x03	'c'
Windows English Dvorak	I	'c'	'c'
Windows Bulgarian	Ъ	'ъ'	'c'
Windows French	2	'é'	'2'
Windows French	Shift+2	'2'	'2'

How it is done differs per platform, and on many platforms, SWT resorts to various magic. To understand the problem, consider the following questions about the well known Ctrl+C shortcut:

• Which key invokes Ctrl+C in English? Well, that's easy, key C does it.
• Dvorak is basically an English layout, but with keys shuffled around. Where English has C, Dvorak has J. Where English has I, Dvorak has C. Which key invokes Ctrl+C in English-Dvorak? Well, both answers are kind of correct. There's a heated debate on the internet which answer is better: some argue that they like English shortcuts they learned before they decided to try Dvorak. Others argue that key labels shall match invoked shortcuts. The usually preferred answer is that if a key types C in Dvorak, then it shall invoke Ctrl+C. That is, the key that is labeled I in English.
• Which key invokes Ctrl+C in non-latin keyboard layouts? That's where it gets hard. Consider Hebrew, Cyrillic, Japanese. These layouts simply don't have latin C anywhere!

Approaching all 3 questions at once is non-trivial, and each OS does it in a different way. In very simple words:

• Windows keyboard layouts have an additional invisible mapping of keys to keyboard shortcuts, completely independent from characters typed by these keys. Layouts also have the regular mapping of keys to produced characters. Both are edited in keyboard layout editors.
• macOS keyboard layouts have hidden Latin sub-layouts and switch to them when a modifier such as Cmd is pressed. This is easy to see in builtin on-screen keyboard. It's a lot more complicated with modifiers other than Cmd and Ctrl.
• Linux is worst. It lacks the information to map shortcuts on non-latin keyboards and resorts to inspecting other installed layouts to find something latin.

For detailed information, see Widget.setKeyState(org.eclipse.swt.widgets.Event, int, long, long) per platform.

See Also:

• SWT

keyLocation

public int keyLocation

depending on the event, the location of key specified by the keyCode or character. The possible values for this field are SWT.LEFT, SWT.RIGHT, SWT.KEYPAD, or SWT.NONE representing the main keyboard area.

The location field can be used to differentiate key events that have the same key code and character but are generated by different keys in the keyboard. For example, a key down event with the key code equals to SWT.SHIFT can be generated by the left and the right shift keys in the keyboard. The location field can only be used to determine the location of the key code or character in the current event. It does not include information about the location of modifiers in state mask.

Since:

3.6

See Also:

• SWT.LEFT
• SWT.RIGHT
• SWT.KEYPAD

stateMask

public int stateMask

depending on the event, the state of the keyboard modifier keys and mouse masks at the time the event was generated.

See Also:

• SWT.MODIFIER_MASK
• SWT.BUTTON_MASK

start

public int start

depending on the event, the range of text being modified. Setting these fields only has effect during ImeComposition events.

end

public int end

depending on the event, the range of text being modified. Setting these fields only has effect during ImeComposition events.

text

public String text

depending on the event, the new text that will be inserted. Setting this field will change the text that is about to be inserted or deleted.

segments

public int[] segments

Bidi segment offsets

Since:

3.8

segmentsChars

public char[] segmentsChars

Characters to be applied on the segment boundaries

Since:

3.8

doit

public boolean doit

depending on the event, a flag indicating whether the operation should be allowed. Setting this field to false will cancel the operation.

data

public Object data

a field for application use

touches

public Touch[] touches

An array of the touch states for the current touch event.

Since:

3.7

xDirection

public int xDirection

If nonzero, a positive value indicates a swipe to the right, and a negative value indicates a swipe to the left.

Since:

3.7

yDirection

public int yDirection

If nonzero, a positive value indicates a swipe in the up direction, and a negative value indicates a swipe in the down direction.

Since:

3.7

magnification

public double magnification

The change in magnification. This value should be added to the current scaling of an item to get the new scale factor.

Since:

3.7

rotation

public double rotation

The number of degrees rotated on the track pad.

Since:

3.7

Constructor Details

Event

public Event()

Method Details

getBounds

public Rectangle getBounds()

Gets the bounds.

Returns:

a rectangle that is the bounds.

setBounds

public void setBounds(Rectangle rect)

Sets the bounds.

Parameters:

rect - the new rectangle

toString

public String toString()

Returns a string containing a concise, human-readable description of the receiver.

Overrides:

toString in class Object

Returns:

a string representation of the event