org.eclipse.swt.widgets
Class Control

java.lang.Object
  |
  +--org.eclipse.swt.widgets.Widget
        |
        +--org.eclipse.swt.widgets.Control

All Implemented Interfaces:

Drawable, Runnable

Direct Known Subclasses:

Button, Label, Scrollable

public class Control

extends Widget

implements Drawable

Field Summary

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

h, INCMD_DISPOSE, INCMD_EXTKEY, INCMD_KEY, INCMD_LDOWN, INCMD_LUP, INCMD_MENU, INCMD_POS, UPDATEITEM_ENABLED, UPDATEITEM_NAME, w, x, y

Constructor Summary

protected

Control() Prevents uninitialized instances from being created outside the package.

Method Summary

Point	computeSize(int wHint, int hHint) Returns the preferred size of the receiver.
Point	computeSize(int wHint, int hHint, boolean changed) Returns the preferred size of the receiver.
Object	getLayoutData() Returns layout data which is associated with the receiver.
boolean	isFocusControl() Returns true if the receiver has the user-interface focus, and false otherwise.
void	pack() Causes the receiver to be resized to its preferred size.
void	pack(boolean changed) Causes the receiver to be resized to its preferred size.
void	setBackground(Color color) Sets the receiver's background color to the color specified by the argument, or to the default system color for the control if the argument is null.
void	setBounds(Rectangle rect) Sets the receiver's size and location to the rectangular area specified by the argument.
boolean	setFocus() Set the input focus to the widget, and returns whether the focus change was successful.
void	setLayoutData(Object layoutData) Sets the layout data associated with the receiver to the argument.
void	setSize(int width, int height) Sets the receiver's size to the point specified by the arguments.
void	setSize(Point size) Sets the receiver's size to the point specified by the argument.
void	update() Forces all outstanding paint requests for the widget to be processed before this method returns.

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

addListener, dispose, focusState, getBorderWidth, getDisplayArea, getSelection, getStyle, getText, isDisposed, removeListener, setBounds, setCursor, stop

Methods inherited from class java.lang.Object

equals, getClass, hashCode, toString

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

drawLine, drawRect, drawText, setColor

Methods inherited from interface java.lang.Runnable

run

Constructor Detail

Control

protected Control()

Prevents uninitialized instances from being created outside the package.

Method Detail

computeSize

public Point computeSize(int wHint,
                         int hHint)

Returns the preferred size of the receiver.

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.

Parameters:

wHint - the width hint (can be SWT.DEFAULT)

hHint - the height hint (can be SWT.DEFAULT)

Returns:

the preferred size of the control

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:

Layout, Widget.getBorderWidth(), #getBounds, #getSize, pack(), "computeTrim, getClientArea for controls that implement them"

computeSize

public Point computeSize(int wHint,
                         int hHint,
                         boolean changed)

Returns the preferred size of the receiver.

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.

Overrides:

computeSize in class Widget

Parameters:

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

Returns:

the preferred size of the control.

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:

Layout, Widget.getBorderWidth(), #getBounds, #getSize, pack(), "computeTrim, getClientArea for controls that implement them"

getLayoutData

public Object getLayoutData()

Returns layout data which is associated with the receiver.

Returns:

the receiver's layout data

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

isFocusControl

public boolean isFocusControl()

Returns true if the receiver has the user-interface focus, and false otherwise.

Returns:

the receiver's focus state

pack

public void pack()

Causes the receiver to be resized to its preferred size. For a composite, this involves computing the preferred size from its layout, if there is one.

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:

computeSize(int, int)

pack

public void pack(boolean changed)

Causes the receiver to be resized to its preferred size. For a composite, this involves computing the preferred size from its layout, if there is one.

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.

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:

computeSize(int, int)

setBackground

public void setBackground(Color color)

Sets the receiver's background color to the color specified by the argument, or to the default system color for the control if the argument is null.

Parameters:

color - the new color (or null)

Throws:

IllegalArgumentException -

• ERROR_INVALID_ARGUMENT - if the argument 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

setBounds

public void setBounds(Rectangle rect)

Sets the receiver's size and location to the rectangular area specified by the argument. The x and y fields of the rectangle are relative to the receiver's parent (or its display if its parent is null).

Note: Attempting to set the width or height of the receiver to a negative number will cause that value to be set to zero instead.

Parameters:

rect - the new bounds for the receiver

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

setFocus

public boolean setFocus()

Set the input focus to the widget, and returns whether the focus change was successful.

Returns:

true if the input focus could be handed over to the receiver

setLayoutData

public void setLayoutData(Object layoutData)

Sets the layout data associated with the receiver to the argument.

Parameters:

layoutData - the new layout data for the receiver.

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

setSize

public void setSize(Point size)

Sets the receiver's size to the point specified by the argument.

Note: Attempting to set the width or height of the receiver to a negative number will cause them to be set to zero instead.

Parameters:

size - the new size for the receiver

Throws:

IllegalArgumentException -

• ERROR_NULL_ARGUMENT - if the point is null

SWTException -

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

setSize

public void setSize(int width,
                    int height)

Sets the receiver's size to the point specified by the arguments.

Note: Attempting to set the width or height of the receiver to a negative number will cause that value to be set to zero instead.

Parameters:

width - the new width for the receiver

height - the new height for the receiver

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

update

public void update()

Forces all outstanding paint requests for the widget to be processed before this method returns.

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