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java.lang.Objectorg.eclipse.swt.widgets.Widget
org.eclipse.swt.widgets.Control
org.eclipse.swt.widgets.Scrollable
org.eclipse.swt.widgets.Composite
public class Composite
Instances of this class are controls which are capable of containing other controls.
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, Motif), this may cause
the children of this composite to be obscured. The EMBEDDED
style
is for use by other widget toolkits and should normally never be used.
This class may be subclassed by custom control implementors who are building controls that are constructed from aggregates of other controls.
Canvas
,
Composite snippets,
Sample code and further informationField Summary | |
---|---|
long |
embeddedHandle
|
Fields inherited from class org.eclipse.swt.widgets.Widget |
---|
handle |
Constructor Summary | |
---|---|
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 | |
---|---|
void |
changed(Control[] changed)
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. |
protected void |
checkSubclass()
Checks that this class can be subclassed. |
Point |
computeSize(int wHint,
int hHint,
boolean changed)
Returns the preferred size of the receiver. |
int |
getBackgroundMode()
Returns the receiver's background drawing mode. |
Control[] |
getChildren()
Returns a (possibly empty) array containing the receiver's children. |
Rectangle |
getClientArea()
Returns a rectangle which describes the area of the receiver which is capable of displaying data (that is, not covered by the "trimmings"). |
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 |
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. |
Methods inherited from class org.eclipse.swt.widgets.Scrollable |
---|
computeTrim, getBorderWidth, getHorizontalBar, getVerticalBar |
Methods inherited from class org.eclipse.swt.widgets.Widget |
---|
addDisposeListener, addListener, checkWidget, dispose, getData, getData, getDisplay, getListeners, getStyle, isDisposed, isListening, notifyListeners, removeDisposeListener, removeListener, removeListener, setData, setData, toString |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
---|
public long embeddedHandle
Constructor Detail |
---|
public Composite(Composite parent, int style)
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.
parent
- a widget which will be the parent of the new instance (cannot be null)style
- the style of widget to construct
java.lang.IllegalArgumentException
- SWTException
- SWT.NO_BACKGROUND
,
SWT.NO_FOCUS
,
SWT.NO_MERGE_PAINTS
,
SWT.NO_REDRAW_RESIZE
,
SWT.NO_RADIO_GROUP
,
Widget.getStyle()
Method Detail |
---|
public void changed(Control[] changed)
changed
- an array of controls that changed state and require a recalculation of size
java.lang.IllegalArgumentException
- SWTException
- protected void checkSubclass()
Widget
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.
checkSubclass
in class Widget
public Point computeSize(int wHint, int hHint, boolean changed)
Control
The preferred size of a control is the size that it would
best be displayed at. The width hint and height hint arguments
allow the caller to ask a control questions such as "Given a particular
width, how high does the control need to be to show all of the contents?"
To indicate that the caller does not wish to constrain a particular
dimension, the constant SWT.DEFAULT
is passed for the hint.
If the changed flag is true
, it indicates that the receiver's
contents have changed, therefore any caches that a layout manager
containing the control may have been keeping need to be flushed. When the
control is resized, the changed flag will be false
, so layout
manager caches can be retained.
computeSize
in class Control
wHint
- the width hint (can be SWT.DEFAULT
)hHint
- the height hint (can be SWT.DEFAULT
)changed
- true
if the control's contents have changed, and false
otherwise
Layout
,
Control.getBorderWidth()
,
Control.getBounds()
,
Control.getSize()
,
Control.pack(boolean)
,
"computeTrim, getClientArea for controls that implement them"public int getBackgroundMode()
SWT
:
INHERIT_NONE
, INHERIT_DEFAULT
,
INHERTIT_FORCE
.
SWTException
- SWT
public Control[] getChildren()
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.
SWTException
- Control.moveAbove(org.eclipse.swt.widgets.Control)
,
Control.moveBelow(org.eclipse.swt.widgets.Control)
public Rectangle getClientArea()
Scrollable
getClientArea
in class Scrollable
Scrollable.computeTrim(int, int, int, int)
public Layout getLayout()
SWTException
- public boolean getLayoutDeferred()
true
if the receiver has deferred
the performing of layout, and false
otherwise.
SWTException
- setLayoutDeferred(boolean)
,
isLayoutDeferred()
public Control[] getTabList()
SWTException
- setTabList(org.eclipse.swt.widgets.Control[])
public boolean isLayoutDeferred()
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.
SWTException
- setLayoutDeferred(boolean)
,
getLayoutDeferred()
public void layout()
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.
SWTException
- public void layout(boolean changed)
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.
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.
changed
- true
if the layout must flush its caches, and false
otherwise
SWTException
- public void layout(boolean changed, boolean all)
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)
).
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.
changed
- true
if the layout must flush its caches, and false
otherwiseall
- true
if all children in the receiver's widget tree should be laid out, and false
otherwise
SWTException
- public void layout(Control[] changed)
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.
changed
- a control that has had a state change which requires a recalculation of its size
java.lang.IllegalArgumentException
- SWTException
- public void setBackgroundMode(int mode)
SWT
:
INHERIT_NONE
, INHERIT_DEFAULT
,
INHERIT_FORCE
.
mode
- the new background mode
SWTException
- SWT
public boolean setFocus()
Control
setFocus
in class Control
true
if the control got focus, and false
if it was unable to.Control.forceFocus()
public void setLayout(Layout layout)
layout
- the receiver's new layout or null
SWTException
- public void setLayoutDeferred(boolean defer)
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.
defer
- the new defer state
SWTException
- layout(boolean)
,
layout(Control[])
public void setTabList(Control[] tabList)
tabList
- the ordered list of controls representing the tab order or null
java.lang.IllegalArgumentException
- SWTException
-
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