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Eclipse Platform
Release 3.5

org.eclipse.swt.graphics
Class Device

java.lang.Object
  extended by 
org.eclipse.swt.graphics.Device
All Implemented Interfaces:
Drawable
Direct Known Subclasses:
Display, Printer

public abstract class Device
extends Object
implements Drawable

This class is the abstract superclass of all device objects, such as the Display device and the Printer device. Devices can have a graphics context (GC) created for them, and they can be drawn on by sending messages to the associated GC.

See Also:
Sample code and further information

Field Summary
protected static  Device CurrentDevice
           
static boolean DEBUG
           
protected static  Runnable DeviceFinder
           
 int hPalette
          Palette (Warning: This field is platform dependent) IMPORTANT: This field is not part of the SWT public API.
 
Constructor Summary
Device ()
          Constructs a new instance of this class.
Device ( DeviceData data)
          Constructs a new instance of this class.
 
Method Summary
protected  void checkDevice ()
          Throws an SWTException if the receiver can not be accessed by the caller.
protected  void create ( DeviceData data)
          Creates the device in the operating system.
protected  void destroy ()
          Destroys the device in the operating system and releases the device's handle.
 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.
 int getDepth ()
          Returns the bit depth of the screen, which is the number of bits it takes to represent the number of unique colors that the screen is currently capable of displaying.
  DeviceData getDeviceData ()
          Returns a DeviceData based on the receiver.
  Point getDPI ()
          Returns a point whose x coordinate is the horizontal dots per inch of the display, and whose y coordinate is the vertical dots per inch of the display.
  FontData[] getFontList ( String faceName, boolean scalable)
          Returns FontData objects which describe the fonts that match the given arguments.
  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 getWarnings ()
          Returns true if the underlying window system prints out warning messages on the console, and setWarnings had previously been called with true.
protected  void init ()
          Initializes any internal resources needed by the device.
abstract  void internal_dispose_GC (int hDC, GCData data)
          Invokes platform specific functionality to dispose a GC handle.
abstract  int internal_new_GC ( GCData data)
          Invokes platform specific functionality to allocate a new GC handle.
 boolean isDisposed ()
          Returns true if the device has been disposed, and false otherwise.
 boolean loadFont ( String path)
          Loads the font specified by a file.
protected  void release ()
          Releases any internal resources back to the operating system and clears all fields except the device handle.
 void setWarnings (boolean warnings)
          If the underlying window system supports printing warning messages to the console, setting warnings to false prevents these messages from being printed.
 
Methods inherited from class java.lang. Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEBUG

public static boolean DEBUG

hPalette

public int hPalette
Palette (Warning: This field is platform dependent)

IMPORTANT: This field is not part of the SWT public API. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms and should never be accessed from application code.


CurrentDevice

protected static 
Device CurrentDevice

DeviceFinder

protected static 
Runnable DeviceFinder
Constructor Detail

Device

public Device()
Constructs a new instance of this class.

You must dispose the device when it is no longer required.

Since:
3.1
See Also:
create(org.eclipse.swt.graphics.DeviceData), init()

Device

public Device(
DeviceData data)
Constructs a new instance of this class.

You must dispose the device when it is no longer required.

Parameters:
data - the DeviceData which describes the receiver
See Also:
create(org.eclipse.swt.graphics.DeviceData), init(), DeviceData
Method Detail

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

create

protected void create(
DeviceData data)
Creates the device in the operating system. If the device does not have a handle, this method may do nothing depending on the device.

This method is called before init.

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

Parameters:
data - the DeviceData which describes the receiver
See Also:
init()

destroy

protected void destroy()
Destroys the device in the operating system and releases the device's handle. 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()

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()

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

getDeviceData

public 
DeviceData getDeviceData()
Returns a DeviceData based on the receiver. Modifications made to this DeviceData will not affect the receiver.

Returns:
a DeviceData containing the device's data and attributes
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed
See Also:
DeviceData

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
See Also:
getBounds()

getDepth

public int getDepth()
Returns the bit depth of the screen, which is the number of bits it takes to represent the number of unique colors that the screen is currently capable of displaying. This number will typically be one of 1, 8, 15, 16, 24 or 32.

Returns:
the depth of the screen
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getDPI

public 
Point getDPI()
Returns a point whose x coordinate is the horizontal dots per inch of the display, and whose y coordinate is the vertical dots per inch of the display.

Returns:
the horizontal and vertical DPI
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getFontList

public 
FontData[] getFontList(
String faceName,
                              boolean scalable)
Returns FontData objects which describe the fonts that match the given arguments. If the faceName is null, all fonts will be returned.

Parameters:
faceName - the name of the font to look for, or null
scalable - if true only scalable fonts are returned, otherwise only non-scalable fonts are returned.
Returns:
the matching font data
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed

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 freed because it was allocated by the system, not the application.

Parameters:
id - the color constant
Returns:
the matching color
Throws:
SWTException -
  • 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 freed 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_DEVICE_DISPOSED - if the receiver has been disposed

getWarnings

public boolean getWarnings()
Returns true if the underlying window system prints out warning messages on the console, and setWarnings had previously been called with true.

Returns:
trueif warnings are being handled, and false otherwise
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed

init

protected void init()
Initializes any internal resources needed by the device.

This method is called after create.

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

See Also:
create(org.eclipse.swt.graphics.DeviceData)

internal_new_GC

public abstract int internal_new_GC(
GCData data)
Invokes platform specific functionality to allocate a new GC handle.

IMPORTANT: This method is not part of the public API for Device. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code.

Specified by:
internal_new_GC in interface Drawable
Parameters:
data - the platform specific GC data
Returns:
the platform specific GC handle

internal_dispose_GC

public abstract void internal_dispose_GC(int hDC,
                                         
GCData data)
Invokes platform specific functionality to dispose a GC handle.

IMPORTANT: This method is not part of the public API for Device. It is marked public only so that it can be shared within the packages provided by SWT. It is not available on all platforms, and should never be called from application code.

Specified by:
internal_dispose_GC in interface Drawable
Parameters:
hDC - the platform specific GC handle
data - the platform specific GC data

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

loadFont

public boolean loadFont(
String path)
Loads the font specified by a file. The font will be present in the list of fonts available to the application.

Parameters:
path - the font file path
Returns:
whether the font was successfully loaded
Throws:
SWTException -
  • ERROR_NULL_ARGUMENT - if path is null
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed
Since:
3.3
See Also:
Font

release

protected void release()
Releases any internal resources back to the operating system and clears all fields except the device handle.

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()

setWarnings

public void setWarnings(boolean warnings)
If the underlying window system supports printing warning messages to the console, setting warnings to false prevents these messages from being printed. If the argument is true then message printing is not blocked.

Parameters:
warnings - trueif warnings should be printed, and false otherwise
Throws:
SWTException -
  • ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Eclipse Platform
Release 3.5

Guidelines for using Eclipse APIs.

Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.


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