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org.eclipse.swt.graphics
Class Device
java.lang.Object
org.eclipse.swt.graphics.Device
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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.
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Method Summary
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protected void
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checkDevice
()
Throws an SWTException if the receiver can not
be accessed by the caller. |
protected void
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destroy
()
Destroys the device . |
void
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dispose
()
Disposes of the operating system resources associated with
the receiver. |
Rectangle
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getBounds
()
Returns a rectangle describing the receiver's size and location. |
Rectangle
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getClientArea
()
Returns a rectangle which describes the area of the receiver which is
capable of displaying data. |
Color
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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
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getSystemFont
()
Returns a reasonable font for applications to use. |
boolean
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isDisposed
()
Returns true if the device has been disposed,
and false otherwise. |
protected void
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release
()
Releases any internal resources . |
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Methods inherited from class java.lang.
Object
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clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
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Device
public Device()
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.
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Parameters:
-
id - the color constant
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Returns:
- the matching color
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Throws:
-
SWTException
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- ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
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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.
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Returns:
- a font
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Throws:
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SWTException
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- 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.
-
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Returns:
- the client area
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Throws:
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SWTException
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- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
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Since:
- 1.2
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See Also:
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getBounds()
getBounds
public
Rectangle getBounds()
- Returns a rectangle describing the receiver's size and location.
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Returns:
- the bounding rectangle
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Throws:
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SWTException
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- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
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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().
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See Also:
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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.
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Returns:
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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.
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See Also:
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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.
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See Also:
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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.
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Throws:
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SWTException
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- ERROR_WIDGET_DISPOSED - if the receiver has been disposed
Copyright (c) Innoopract Informationssysteme GmbH and others 2002, 2008. All rights reserved.
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