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org.eclipse.swt.graphics
Class Device
java.lang.Object
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
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
|
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
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
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:
-
true if 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 - true if warnings should be printed, and false otherwise
-
Throws:
-
SWTException
-
- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
Guidelines for using Eclipse APIs.
Copyright (c) Eclipse contributors and others 2000, 2008. All rights reserved.
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