Class Device
- java.lang.Object
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- org.eclipse.swt.graphics.Device
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- All Implemented Interfaces:
Drawable
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
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Field Summary
Fields Modifier and Type Field Description protected static Device
CurrentDevice
static boolean
DEBUG
protected static Runnable
DeviceFinder
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Constructor Summary
Constructors Constructor Description Device()
Constructs a new instance of this class.Device(DeviceData data)
Constructs a new instance of this class.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description protected void
checkDevice()
Throws anSWTException
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 aDeviceData
based on the receiver.protected int
getDeviceZoom()
Gets the scaling factor from the device and calculates the zoom level.Point
getDPI()
Returns a point whose x coordinate is the logical horizontal dots per inch of the display, and whose y coordinate is the logical vertical dots per inch of the display.FontData[]
getFontList(String faceName, boolean scalable)
ReturnsFontData
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 classSWT
.Font
getSystemFont()
Returns a reasonable font for applications to use.boolean
getWarnings()
Returnstrue
if the underlying window system prints out warning messages on the console, andsetWarnings
had previously been called withtrue
.protected void
init()
Initializes any internal resources needed by the device.abstract void
internal_dispose_GC(long hDC, GCData data)
Invokes platform specific functionality to dispose a GC handle.abstract long
internal_new_GC(GCData data)
Invokes platform specific functionality to allocate a new GC handle.boolean
isDisposed()
Returnstrue
if the device has been disposed, andfalse
otherwise.boolean
isTracking()
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
setTracking(boolean tracking)
void
setWarnings(boolean warnings)
If the underlying window system supports printing warning messages to the console, setting warnings tofalse
prevents these messages from being printed.-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
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Methods inherited from interface org.eclipse.swt.graphics.Drawable
isAutoScalable
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Constructor Detail
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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()
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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
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Method Detail
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isTracking
public boolean isTracking()
- Throws:
SWTException
-- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
- Since:
- 3.115
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setTracking
public void setTracking(boolean tracking)
- Throws:
SWTException
-- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
- Since:
- 3.115
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checkDevice
protected void checkDevice()
Throws anSWTException
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()
anddispose()
) on a device that has had itsdispose()
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
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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()
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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.
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dispose
public void dispose()
Disposes of the operating system resources associated with the receiver. After this method has been invoked, the receiver will answertrue
when sent the messageisDisposed()
.- See Also:
release()
,destroy()
,checkDevice()
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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
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getDeviceData
public DeviceData getDeviceData()
Returns aDeviceData
based on the receiver. Modifications made to thisDeviceData
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
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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()
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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
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getDPI
public Point getDPI()
Returns a point whose x coordinate is the logical horizontal dots per inch of the display, and whose y coordinate is the logical vertical dots per inch of the display.- Returns:
- the horizontal and vertical DPI
- Throws:
SWTException
-- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
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getFontList
public FontData[] getFontList(String faceName, boolean scalable)
ReturnsFontData
objects which describe the fonts that match the given arguments. If thefaceName
is null, all fonts will be returned.- Parameters:
faceName
- the name of the font to look for, or nullscalable
- 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
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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 classSWT
. 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
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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
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getWarnings
public boolean getWarnings()
Returnstrue
if the underlying window system prints out warning messages on the console, andsetWarnings
had previously been called withtrue
.- Returns:
true
if warnings are being handled, andfalse
otherwise- Throws:
SWTException
-- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
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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.
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internal_new_GC
public abstract long 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 interfaceDrawable
- Parameters:
data
- the platform specific GC data- Returns:
- the platform specific GC handle
- Restriction:
- This method is not intended to be referenced by clients.
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internal_dispose_GC
public abstract void internal_dispose_GC(long 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 interfaceDrawable
- Parameters:
hDC
- the platform specific GC handledata
- the platform specific GC data- Restriction:
- This method is not intended to be referenced by clients.
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isDisposed
public boolean isDisposed()
Returnstrue
if the device has been disposed, andfalse
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 andfalse
otherwise
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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
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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
This method is called beforerelease
. 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 bydestroy
.destroy
.If subclasses reimplement this method, they must call the
super
implementation.
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setWarnings
public void setWarnings(boolean warnings)
If the underlying window system supports printing warning messages to the console, setting warnings tofalse
prevents these messages from being printed. If the argument istrue
then message printing is not blocked.- Parameters:
warnings
-true
if warnings should be printed, andfalse
otherwise- Throws:
SWTException
-- ERROR_DEVICE_DISPOSED - if the receiver has been disposed
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getDeviceZoom
protected int getDeviceZoom()
Gets the scaling factor from the device and calculates the zoom level.- Returns:
- zoom in percentage
- Since:
- 3.105
- Restriction:
- This method is not intended to be referenced by clients.
- Restriction:
- This method is not intended to be re-implemented or extended by clients.
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