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Eclipse Rich Ajax Platform
Release 1.2

org.eclipse.swt.graphics
Class Device

java.lang.Object
  extended by
org.eclipse.swt.graphics.Device
Direct Known Subclasses:
Display

public abstract class Device
extends Object

This class is the abstract superclass of all device objects, such as Display.

This class is not intended to be directly used by clients.


Constructor Summary
Device ()
           
 
Method Summary
protected  void checkDevice ()
          Throws an SWTException if the receiver can not be accessed by the caller.
protected  void destroy ()
          Destroys the device .
 void dispose ()
          Disposes of the operating system resources associated with the receiver.
  Rectangle getBounds ()
          Returns a rectangle describing the receiver's size and location.
  Rectangle getClientArea ()
          Returns a rectangle which describes the area of the receiver which is capable of displaying data.
  Color getSystemColor (int id)
          Returns the matching standard color for the given constant, which should be one of the color constants specified in class SWT.
  Font getSystemFont ()
          Returns a reasonable font for applications to use.
 boolean isDisposed ()
          Returns true if the device has been disposed, and false otherwise.
protected  void release ()
          Releases any internal resources .
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

Device

public Device()
Method Detail

getSystemColor

public 
Color getSystemColor(int id)
Returns the matching standard color for the given constant, which should be one of the color constants specified in class SWT. Any value other than one of the SWT color constants which is passed in will result in the color black. This color should not be free'd because it was allocated by the system, not the application.

Parameters:
id - the color constant
Returns:
the matching color
Throws:
SWTException -
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed
See Also:
SWT

getSystemFont

public 
Font getSystemFont()
Returns a reasonable font for applications to use. On some platforms, this will match the "default font" or "system font" if such can be found. This font should not be free'd because it was allocated by the system, not the application.

Typically, applications which want the default look should simply not set the font on the widgets they create. Widgets are always created with the correct default font for the class of user-interface component they represent.

Returns:
a font
Throws:
SWTException -
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getClientArea

public 
Rectangle getClientArea()
Returns a rectangle which describes the area of the receiver which is capable of displaying data.

Returns:
the client area
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed
Since:
1.2
See Also:
getBounds()

getBounds

public 
Rectangle getBounds()
Returns a rectangle describing the receiver's size and location.

Returns:
the bounding rectangle
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed
Since:
1.2

dispose

public void dispose()
Disposes of the operating system resources associated with the receiver. After this method has been invoked, the receiver will answer true when sent the message isDisposed().

See Also:
release(), destroy(), checkDevice()

isDisposed

public boolean isDisposed()
Returns true if the device has been disposed, and false otherwise.

This method gets the dispose state for the device. When a device has been disposed, it is an error to invoke any other method using the device.

Returns:
true when the device is disposed and false otherwise

release

protected void release()
Releases any internal resources .

When a device is destroyed, resources that were acquired on behalf of the programmer need to be returned to the operating system. For example, if the device allocated a font to be used as the system font, this font would be freed in release. Also,to assist the garbage collector and minimize the amount of memory that is not reclaimed when the programmer keeps a reference to a disposed device, all fields except the handle are zero'd. The handle is needed by destroy.

This method is called before destroy.

If subclasses reimplement this method, they must call the super implementation.

See Also:
dispose(), destroy()

destroy

protected void destroy()
Destroys the device . If the device does not have a handle, this method may do nothing depending on the device.

This method is called after release.

Subclasses are supposed to reimplement this method and not call the super implementation.

See Also:
dispose(), release()

checkDevice

protected void checkDevice()
Throws an SWTException if the receiver can not be accessed by the caller. This may include both checks on the state of the receiver and more generally on the entire execution context. This method should be called by device implementors to enforce the standard SWT invariants.

Currently, it is an error to invoke any method (other than isDisposed() and dispose()) on a device that has had its dispose() method called.

In future releases of SWT, there may be more or fewer error checks and exceptions may be thrown for different reasons.

Throws:
SWTException -
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed

Eclipse Rich Ajax Platform
Release 1.2

Copyright (c) Innoopract Informationssysteme GmbH and others 2002, 2008. All rights reserved.


 
 
  Published under the terms of the Eclipse Public License Version 1.0 ("EPL") Design by Interspire