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 java.lang.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

Structure Diagram

Field Summary

Fields

Modifier and Type	Field and Description
(package private) int[]	colorRefCount
protected static Device	CurrentDevice
(package private) boolean	debug
static boolean	DEBUG
protected static java.lang.Runnable	DeviceFinder
(package private) boolean	disposed
(package private) java.lang.Error[]	errors
(package private) int	fontCollection
(package private) int[]	gdipToken
int	hPalette Palette (Warning: This field is platform dependent) IMPORTANT: This field is not part of the SWT public API.
(package private) java.lang.String[]	loadedFonts
(package private) LOGFONT[]	logFonts
(package private) TEXTMETRIC	metrics
(package private) int	nFonts
(package private) java.lang.Object[]	objects
(package private) int[]	pixels
(package private) int[]	scripts
(package private) Font	systemFont
(package private) boolean	tracking
(package private) java.lang.Object	trackingLock

Constructor Summary

Constructors

Constructor and Description
Device() Constructs a new instance of this class.
Device(DeviceData data) Constructs a new instance of this class.

Method Summary

Methods

Modifier and Type	Method and Description
(package private) void	addFont(java.lang.String font)
protected void	checkDevice() Throws an SWTException if the receiver can not be accessed by the caller.
(package private) void	checkGDIP()
(package private) int	computePixels(float height)
(package private) float	computePoints(LOGFONT logFont, int hFont)
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.
(package private) void	dispose_Object(java.lang.Object object)
void	dispose() Disposes of the operating system resources associated with the receiver.
(package private) int	EnumFontFamProc(int lpelfe, int lpntme, int FontType, int lParam)
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.
(package private) static Device	getDevice()
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(java.lang.String faceName, boolean scalable) Returns FontData objects which describe the fonts that match the given arguments.
(package private) java.lang.String	getLastError()
(package private) java.lang.String	getLastErrorText()
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(java.lang.String path) Loads the font specified by a file.
(package private) void	new_Object(java.lang.Object object)
(package private) void	printErrors()
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

debug

boolean debug

tracking

boolean tracking

errors

java.lang.Error[] errors

objects

java.lang.Object[] objects

trackingLock

java.lang.Object trackingLock

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.

colorRefCount

int[] colorRefCount

systemFont

Font systemFont

nFonts

int nFonts

logFonts

LOGFONT[] logFonts

metrics

TEXTMETRIC metrics

pixels

int[] pixels

scripts

int[] scripts

gdipToken

int[] gdipToken

fontCollection

int fontCollection

loadedFonts

java.lang.String[] loadedFonts

disposed

boolean disposed

CurrentDevice

protected static Device CurrentDevice

DeviceFinder

protected static java.lang.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

getDevice

static Device getDevice()

addFont

void addFont(java.lang.String font)

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

checkGDIP

void checkGDIP()

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()

computePixels

int computePixels(float height)

computePoints

float computePoints(LOGFONT logFont,
                  int hFont)

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()

dispose_Object

void dispose_Object(java.lang.Object object)

EnumFontFamProc

int EnumFontFamProc(int lpelfe,
                  int lpntme,
                  int FontType,
                  int lParam)

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(java.lang.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

getLastError

java.lang.String getLastError()

getLastErrorText

java.lang.String getLastErrorText()

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(java.lang.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

new_Object

void new_Object(java.lang.Object object)

printErrors

void printErrors()

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