Package org.eclipse.swt.widgets

Class Composite

java.lang.Object

org.eclipse.swt.widgets.Widget

org.eclipse.swt.widgets.Control

org.eclipse.swt.widgets.Scrollable

org.eclipse.swt.widgets.Composite

All Implemented Interfaces:

Drawable

Direct Known Subclasses:

Browser, Canvas, CBanner, CCombo, Combo, CoolBar, CTabFolder, DateTime, DrillDownComposite, ExpandBar, FilteredList, FilteredTree, Form, Group, OleClientSite, OleFrame, PageBook, ProgressIndicator, ProgressMonitorPart, SashForm, ScrolledComposite, Spinner, TabFolder, Table, ToolBar, Tree, ViewForm

public class Composite
extends Scrollable

Instances of this class are controls which are capable of containing other controls.

Styles:

NO_BACKGROUND, NO_FOCUS, NO_MERGE_PAINTS, NO_REDRAW_RESIZE, NO_RADIO_GROUP, EMBEDDED, DOUBLE_BUFFERED

Events:

(none)

Note: The NO_BACKGROUND, NO_FOCUS, NO_MERGE_PAINTS, and NO_REDRAW_RESIZE styles are intended for use with Canvas. They can be used with Composite if you are drawing your own, but their behavior is undefined if they are used with subclasses of Composite other than Canvas.

Note: The CENTER style, although undefined for composites, has the same value as EMBEDDED which is used to embed widgets from other widget toolkits into SWT. On some operating systems (GTK), this may cause the children of this composite to be obscured.

This class may be subclassed by custom control implementors who are building controls that are constructed from aggregates of other controls.

See Also:

• Canvas
• Composite snippets
• Sample code and further information

Field Summary

Fields inherited from class org.eclipse.swt.widgets.Control

handle

Constructor Summary

Constructors

Constructor	Description
Composite(Composite parent, int style)	Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

Method Summary

Modifier and Type	Method	Description
void	changed(Control[] changed)	Deprecated. use layout(Control[], int) instead
protected void	checkSubclass()	Checks that this class can be subclassed.
void	drawBackground(GC gc, int x, int y, int width, int height, int offsetX, int offsetY)	Fills the interior of the rectangle specified by the arguments, with the receiver's background.
int	getBackgroundMode()	Returns the receiver's background drawing mode.
Control[]	getChildren()	Returns a (possibly empty) array containing the receiver's children.
Layout	getLayout()	Returns layout which is associated with the receiver, or null if one has not been set.
boolean	getLayoutDeferred()	Returns true if the receiver has deferred the performing of layout, and false otherwise.
Control[]	getTabList()	Gets the (possibly empty) tabbing order for the control.
boolean	isLayoutDeferred()	Returns true if the receiver or any ancestor up to and including the receiver's nearest ancestor shell has deferred the performing of layouts.
void	layout()	If the receiver has a layout, asks the layout to lay out (that is, set the size and location of) the receiver's children.
void	layout(boolean changed)	If the receiver has a layout, asks the layout to lay out (that is, set the size and location of) the receiver's children.
void	layout(boolean changed, boolean all)	If the receiver has a layout, asks the layout to lay out (that is, set the size and location of) the receiver's children.
void	layout(Control[] changed)	Forces a lay out (that is, sets the size and location) of all widgets that are in the parent hierarchy of the changed control up to and including the receiver.
void	layout(Control[] changed, int flags)	Forces a lay out (that is, sets the size and location) of all widgets that are in the parent hierarchy of the changed control up to and including the receiver.
void	setBackgroundMode(int mode)	Sets the background drawing mode to the argument which should be one of the following constants defined in class SWT: INHERIT_NONE, INHERIT_DEFAULT, INHERIT_FORCE.
boolean	setFocus()	Causes the receiver to have the keyboard focus, such that all keyboard events will be delivered to it.
void	setLayout(Layout layout)	Sets the layout which is associated with the receiver to be the argument which may be null.
void	setLayoutDeferred(boolean defer)	If the argument is true, causes subsequent layout operations in the receiver or any of its children to be ignored.
void	setTabList(Control[] tabList)	Sets the tabbing order for the specified controls to match the order that they occur in the argument list.
String	toString()	Returns a string containing a concise, human-readable description of the receiver.

Methods inherited from class org.eclipse.swt.widgets.Scrollable

computeTrim, getClientArea, getHorizontalBar, getScrollbarsMode, getVerticalBar

Methods inherited from class org.eclipse.swt.widgets.Control

addControlListener, addDragDetectListener, addFocusListener, addGestureListener, addHelpListener, addKeyListener, addMenuDetectListener, addMouseListener, addMouseMoveListener, addMouseTrackListener, addMouseWheelListener, addPaintListener, addTouchListener, addTraverseListener, computeSize, computeSize, dragDetect, dragDetect, forceFocus, getAccessible, getBackground, getBackgroundImage, getBorderWidth, getBounds, getCursor, getDragDetect, getEnabled, getFont, getForeground, getLayoutData, getLocation, getMenu, getMonitor, getOrientation, getParent, getRegion, getShell, getSize, getTextDirection, getToolTipText, getTouchEnabled, getVisible, internal_dispose_GC, internal_new_GC, isEnabled, isFocusControl, isReparentable, isVisible, moveAbove, moveBelow, pack, pack, print, redraw, redraw, removeControlListener, removeDragDetectListener, removeFocusListener, removeGestureListener, removeHelpListener, removeKeyListener, removeMenuDetectListener, removeMouseListener, removeMouseMoveListener, removeMouseTrackListener, removeMouseWheelListener, removePaintListener, removeTouchListener, removeTraverseListener, requestLayout, setBackground, setBackgroundImage, setBounds, setBounds, setCapture, setCursor, setDragDetect, setEnabled, setFont, setForeground, setLayoutData, setLocation, setLocation, setMenu, setOrientation, setParent, setRedraw, setRegion, setSize, setSize, setTextDirection, setToolTipText, setTouchEnabled, setVisible, toControl, toControl, toDisplay, toDisplay, traverse, traverse, traverse, update

Methods inherited from class org.eclipse.swt.widgets.Widget

addDisposeListener, addListener, checkWidget, dispose, getData, getData, getDisplay, getListeners, getStyle, isAutoDirection, isDisposed, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, reskin, setData, setData

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.eclipse.swt.graphics.Drawable

isAutoScalable

Constructor Details

Composite

public Composite(Composite parent,
 int style)

Constructs a new instance of this class given its parent and a style value describing its behavior and appearance.

The style value is either one of the style constants defined in class SWT which is applicable to instances of this class, or must be built by bitwise OR'ing together (that is, using the int "|" operator) two or more of those SWT style constants. The class description lists the style constants that are applicable to the class. Style bits are also inherited from superclasses.

Parameters:

parent - a widget which will be the parent of the new instance (cannot be null)

style - the style of widget to construct

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the parent is null

SWTException -

• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent

See Also:

• SWT.NO_BACKGROUND
• SWT.NO_FOCUS
• SWT.NO_MERGE_PAINTS
• SWT.NO_REDRAW_RESIZE
• SWT.NO_RADIO_GROUP
• SWT.EMBEDDED
• SWT.DOUBLE_BUFFERED
• Widget.getStyle()

Method Details

changed

@Deprecated
public void changed(Control[] changed)

Deprecated.

use layout(Control[], int) instead

Clears any data that has been cached by a Layout for all widgets that are in the parent hierarchy of the changed control up to and including the receiver. If an ancestor does not have a layout, it is skipped.

Parameters:

changed - an array of controls that changed state and require a recalculation of size

Throws:

IllegalArgumentException -

• ERROR_INVALID_ARGUMENT - if the changed array is null any of its controls are null or have been disposed
• ERROR_INVALID_PARENT - if any control in changed is not in the widget tree of the receiver

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.1

checkSubclass

protected void checkSubclass()

Description copied from class: Widget

Checks that this class can be subclassed.

The SWT class library is intended to be subclassed only at specific, controlled points (most notably, Composite and Canvas when implementing new widgets). This method enforces this rule unless it is overridden.

IMPORTANT: By providing an implementation of this method that allows a subclass of a class which does not normally allow subclassing to be created, the implementer agrees to be fully responsible for the fact that any such subclass will likely fail between SWT releases and will be strongly platform specific. No support is provided for user-written classes which are implemented in this fashion.

The ability to subclass outside of the allowed SWT classes is intended purely to enable those not on the SWT development team to implement patches in order to get around specific limitations in advance of when those limitations can be addressed by the team. Subclassing should not be attempted without an intimate and detailed understanding of the hierarchy.

Overrides:

checkSubclass in class Widget

drawBackground

public void drawBackground(GC gc,
 int x,
 int y,
 int width,
 int height,
 int offsetX,
 int offsetY)

Fills the interior of the rectangle specified by the arguments, with the receiver's background.

The offsetX and offsetY are used to map from the gc origin to the origin of the parent image background. This is useful to ensure proper alignment of the image background.

Parameters:

gc - the gc where the rectangle is to be filled

x - the x coordinate of the rectangle to be filled

y - the y coordinate of the rectangle to be filled

width - the width of the rectangle to be filled

height - the height of the rectangle to be filled

offsetX - the image background x offset

offsetY - the image background y offset

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the gc is null
• ERROR_INVALID_ARGUMENT - if the gc has been disposed

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.6

getBackgroundMode

public int getBackgroundMode()

Returns the receiver's background drawing mode. This will be one of the following constants defined in class SWT: INHERIT_NONE, INHERIT_DEFAULT, INHERIT_FORCE.

Returns:

the background mode

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.2

See Also:

• SWT

getChildren

public Control[] getChildren()

Returns a (possibly empty) array containing the receiver's children. Children are returned in the order that they are drawn. The topmost control appears at the beginning of the array. Subsequent controls draw beneath this control and appear later in the array.

Note: This is not the actual structure used by the receiver to maintain its list of children, so modifying the array will not affect the receiver.

Returns:

an array of children

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

• Control.moveAbove(org.eclipse.swt.widgets.Control)
• Control.moveBelow(org.eclipse.swt.widgets.Control)

getLayout

public Layout getLayout()

Returns layout which is associated with the receiver, or null if one has not been set.

Returns:

the receiver's layout or null

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

getTabList

public Control[] getTabList()

Gets the (possibly empty) tabbing order for the control.

Returns:

tabList the ordered list of controls representing the tab order

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

See Also:

• setTabList(org.eclipse.swt.widgets.Control[])

getLayoutDeferred

public boolean getLayoutDeferred()

Returns true if the receiver has deferred the performing of layout, and false otherwise.

Returns:

the receiver's deferred layout state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.1

See Also:

• setLayoutDeferred(boolean)
• isLayoutDeferred()

isLayoutDeferred

public boolean isLayoutDeferred()

Returns true if the receiver or any ancestor up to and including the receiver's nearest ancestor shell has deferred the performing of layouts. Otherwise, false is returned.

Returns:

the receiver's deferred layout state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.1

See Also:

• setLayoutDeferred(boolean)
• getLayoutDeferred()

layout

public void layout()

If the receiver has a layout, asks the layout to lay out (that is, set the size and location of) the receiver's children. If the receiver does not have a layout, do nothing.

Use of this method is discouraged since it is the least-efficient way to trigger a layout. The use of layout(true) discards all cached layout information, even from controls which have not changed. It is much more efficient to invoke Control.requestLayout() on every control which has changed in the layout than it is to invoke this method on the layout itself.

This is equivalent to calling layout(true).

Note: Layout is different from painting. If a child is moved or resized such that an area in the parent is exposed, then the parent will paint. If no child is affected, the parent will not paint.

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

layout

public void layout(boolean changed)

If the receiver has a layout, asks the layout to lay out (that is, set the size and location of) the receiver's children. If the argument is true the layout must not rely on any information it has cached about the immediate children. If it is false the layout may (potentially) optimize the work it is doing by assuming that none of the receiver's children has changed state since the last layout. If the receiver does not have a layout, do nothing.

It is normally more efficient to invoke Control.requestLayout() on every control which has changed in the layout than it is to invoke this method on the layout itself. Clients are encouraged to use Control.requestLayout() where possible instead of calling this method.

If a child is resized as a result of a call to layout, the resize event will invoke the layout of the child. The layout will cascade down through all child widgets in the receiver's widget tree until a child is encountered that does not resize. Note that a layout due to a resize will not flush any cached information (same as layout(false)).

Note: Layout is different from painting. If a child is moved or resized such that an area in the parent is exposed, then the parent will paint. If no child is affected, the parent will not paint.

Parameters:

changed - true if the layout must flush its caches, and false otherwise

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

layout

public void layout(boolean changed,
 boolean all)

If the receiver has a layout, asks the layout to lay out (that is, set the size and location of) the receiver's children. If the changed argument is true the layout must not rely on any information it has cached about its children. If it is false the layout may (potentially) optimize the work it is doing by assuming that none of the receiver's children has changed state since the last layout. If the all argument is true the layout will cascade down through all child widgets in the receiver's widget tree, regardless of whether the child has changed size. The changed argument is applied to all layouts. If the all argument is false, the layout will not cascade down through all child widgets in the receiver's widget tree. However, if a child is resized as a result of a call to layout, the resize event will invoke the layout of the child. Note that a layout due to a resize will not flush any cached information (same as layout(false)).

It is normally more efficient to invoke Control.requestLayout() on every control which has changed in the layout than it is to invoke this method on the layout itself. Clients are encouraged to use Control.requestLayout() where possible instead of calling this method.

Note: Layout is different from painting. If a child is moved or resized such that an area in the parent is exposed, then the parent will paint. If no child is affected, the parent will not paint.

Parameters:

changed - true if the layout must flush its caches, and false otherwise

all - true if all children in the receiver's widget tree should be laid out, and false otherwise

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.1

layout

public void layout(Control[] changed)

Forces a lay out (that is, sets the size and location) of all widgets that are in the parent hierarchy of the changed control up to and including the receiver. The layouts in the hierarchy must not rely on any information cached about the changed control or any of its ancestors. The layout may (potentially) optimize the work it is doing by assuming that none of the peers of the changed control have changed state since the last layout. If an ancestor does not have a layout, skip it.

It is normally more efficient to invoke Control.requestLayout() on every control which has changed in the layout than it is to invoke this method on the layout itself. Clients are encouraged to use Control.requestLayout() where possible instead of calling this method.

Note: Layout is different from painting. If a child is moved or resized such that an area in the parent is exposed, then the parent will paint. If no child is affected, the parent will not paint.

Parameters:

changed - a control that has had a state change which requires a recalculation of its size

Throws:

IllegalArgumentException -

• ERROR_INVALID_ARGUMENT - if the changed array is null any of its controls are null or have been disposed
• ERROR_INVALID_PARENT - if any control in changed is not in the widget tree of the receiver

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.1

layout

public void layout(Control[] changed,
 int flags)

Forces a lay out (that is, sets the size and location) of all widgets that are in the parent hierarchy of the changed control up to and including the receiver.

The parameter flags may be a combination of:

SWT.ALL

all children in the receiver's widget tree should be laid out

SWT.CHANGED

the layout must flush its caches

SWT.DEFER

layout will be deferred

When the changed array is specified, the flags SWT.ALL and SWT.CHANGED have no effect. In this case, the layouts in the hierarchy must not rely on any information cached about the changed control or any of its ancestors. The layout may (potentially) optimize the work it is doing by assuming that none of the peers of the changed control have changed state since the last layout. If an ancestor does not have a layout, skip it.

When the changed array is not specified, the flag SWT.ALL indicates that the whole widget tree should be laid out. And the flag SWT.CHANGED indicates that the layouts should flush any cached information for all controls that are laid out.

The SWT.DEFER flag always causes the layout to be deferred by calling Composite.setLayoutDeferred(true) and scheduling a call to Composite.setLayoutDeferred(false), which will happen when appropriate (usually before the next event is handled). When this flag is set, the application should not call Composite.setLayoutDeferred(boolean).

Note: Layout is different from painting. If a child is moved or resized such that an area in the parent is exposed, then the parent will paint. If no child is affected, the parent will not paint.

Parameters:

changed - a control that has had a state change which requires a recalculation of its size

flags - the flags specifying how the layout should happen

Throws:

IllegalArgumentException -

• ERROR_INVALID_ARGUMENT - if any of the controls in changed is null or has been disposed
• ERROR_INVALID_PARENT - if any control in changed is not in the widget tree of the receiver

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.6

setBackgroundMode

public void setBackgroundMode(int mode)

Sets the background drawing mode to the argument which should be one of the following constants defined in class SWT: INHERIT_NONE, INHERIT_DEFAULT, INHERIT_FORCE.

Parameters:

mode - the new background mode

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.2

See Also:

• SWT

setFocus

public boolean setFocus()

Description copied from class: Control

Causes the receiver to have the keyboard focus, such that all keyboard events will be delivered to it. Focus reassignment will respect applicable platform constraints.

Overrides:

setFocus in class Control

Returns:

true if the control got focus, and false if it was unable to.

See Also:

• Control.forceFocus()

setLayout

public void setLayout(Layout layout)

Sets the layout which is associated with the receiver to be the argument which may be null.

Parameters:

layout - the receiver's new layout or null

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

setLayoutDeferred

public void setLayoutDeferred(boolean defer)

If the argument is true, causes subsequent layout operations in the receiver or any of its children to be ignored. No layout of any kind can occur in the receiver or any of its children until the flag is set to false. Layout operations that occurred while the flag was true are remembered and when the flag is set to false, the layout operations are performed in an optimized manner. Nested calls to this method are stacked.

Parameters:

defer - the new defer state

Throws:

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.1

See Also:

• layout(boolean)
• layout(Control[])

setTabList

public void setTabList(Control[] tabList)

Sets the tabbing order for the specified controls to match the order that they occur in the argument list.

Parameters:

tabList - the ordered list of controls representing the tab order or null

Throws:

IllegalArgumentException -

• ERROR_INVALID_ARGUMENT - if a widget in the tabList is null or has been disposed
• ERROR_INVALID_PARENT - if widget in the tabList is not in the same widget tree

SWTException -

• ERROR_WIDGET_DISPOSED - if the receiver has been disposed
• ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

toString

public String toString()

Description copied from class: Widget

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

Overrides:

toString in class Widget

Returns:

a string representation of the receiver