Eclipse Plug-in Developer Guide (Galileo) - Display (Eclipse Platform API Specification)

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Eclipse Platform
Release 3.5

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org.eclipse.swt.widgets
Class Display


java.lang.Object
  

org.eclipse.swt.graphics.Device
      
org.eclipse.swt.widgets.Display

All Implemented Interfaces:: Drawable

public class Display
extends Device
extends Device

Instances of this class are responsible for managing the connection between SWT and the underlying operating system. Their most important function is to implement the SWT event loop in terms of the platform event model. They also provide various methods for accessing information about the operating system, and have overall control over the operating system resources which SWT allocates.

Applications which are built with SWT will almost always require only a single display. In particular, some platforms which SWT supports will not allow more than one active display. In other words, some platforms do not support creating a new display if one already exists that has not been sent the dispose() message.

In SWT, the thread which creates a Display instance is distinguished as the user-interface thread for that display.

The user-interface thread for a particular display has the following special attributes:

The event loop for that display must be run from the thread.
Some SWT API methods (notably, most of the public methods in Widget and its subclasses), may only be called from the thread. (To support multi-threaded user-interface applications, class Display provides inter-thread communication methods which allow threads other than the user-interface thread to request that it perform operations on their behalf.)
The thread is not allowed to construct other Displays until that display has been disposed. (Note that, this is in addition to the restriction mentioned above concerning platform support for multiple displays. Thus, the only way to have multiple simultaneously active displays, even on platforms which support it, is to have multiple threads.)

Enforcing these attributes allows SWT to be implemented directly on the underlying operating system's event model. This has numerous benefits including smaller footprint, better use of resources, safer memory management, clearer program logic, better performance, and fewer overall operating system threads required. The down side however, is that care must be taken (only) when constructing multi-threaded applications to use the inter-thread communication mechanisms which this class provides when required.

All SWT API methods which may only be called from the user-interface thread are distinguished in their documentation by indicating that they throw the "ERROR_THREAD_INVALID_ACCESS" SWT exception.

Styles:: (none)
Events:: Close, Dispose, Settings

IMPORTANT: This class is not intended to be subclassed.

See Also:: syncExec(java.lang.Runnable), asyncExec(java.lang.Runnable), wake(), readAndDispatch(), sleep(), Device.dispose(), Display snippets, Sample code and further information
Restriction:: This class is not intended to be subclassed by clients.

Field Summary

org.eclipse.swt.internal.win32.MSG msg
          the handle to the OS message queue (Warning: This field is platform dependent) IMPORTANT: This field is not part of the SWT public API.

Fields inherited from class org.eclipse.swt.graphics. Device

CurrentDevice, DEBUG, DeviceFinder, hPalette

Constructor Summary

Display ()
          Constructs a new instance of this class.

Display ( DeviceData data)
          Constructs a new instance of this class using the parameter.

Method Summary

void addFilter (int eventType, Listener listener)
          Adds the listener to the collection of listeners who will be notified when an event of the given type occurs anywhere in a widget.

void addListener (int eventType, Listener listener)
          Adds the listener to the collection of listeners who will be notified when an event of the given type occurs.

void asyncExec ( Runnable runnable)
          Causes the run() method of the runnable to be invoked by the user-interface thread at the next reasonable opportunity.

void beep ()
          Causes the system hardware to emit a short sound (if it supports this capability).

protected void checkDevice ()
          Throws an SWTException if the receiver can not be accessed by the caller.

protected void checkSubclass ()
          Checks that this class can be subclassed.

void close ()
          Requests that the connection between SWT and the underlying operating system be closed.

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 disposeExec ( Runnable runnable)
          Causes the run() method of the runnable to be invoked by the user-interface thread just before the receiver is disposed.

static Display findDisplay ( Thread thread)
          Returns the display which the given thread is the user-interface thread for, or null if the given thread is not a user-interface thread for any display.

Widget findWidget (int handle)
          Given the operating system handle for a widget, returns the instance of the Widget subclass which represents it in the currently running application, if such exists, or null if no matching widget can be found.

Widget findWidget (int handle, int id)
          Given the operating system handle for a widget, and widget-specific id, returns the instance of the Widget subclass which represents the handle/id pair in the currently running application, if such exists, or null if no matching widget can be found.

Widget findWidget ( Widget widget, int id)
          Given a widget and a widget-specific id, returns the instance of the Widget subclass which represents the widget/id pair in the currently running application, if such exists, or null if no matching widget can be found.

Shell getActiveShell ()
          Returns the currently active Shell, or null if no shell belonging to the currently running application is active.

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.

static Display getCurrent ()
          Returns the display which the currently running thread is the user-interface thread for, or null if the currently running thread is not a user-interface thread for any display.

Control getCursorControl ()
          Returns the control which the on-screen pointer is currently over top of, or null if it is not currently over one of the controls built by the currently running application.

Point getCursorLocation ()
          Returns the location of the on-screen pointer relative to the top left corner of the screen.

Point[] getCursorSizes ()
          Returns an array containing the recommended cursor sizes.

Object getData ()
          Returns the application defined, display specific data associated with the receiver, or null if it has not been set.

Object getData ( String key)
          Returns the application defined property of the receiver with the specified name, or null if it has not been set.

static Display getDefault ()
          Returns the default display.

int getDismissalAlignment ()
          Returns the button dismissal alignment, one of LEFT or RIGHT.

int getDoubleClickTime ()
          Returns the longest duration, in milliseconds, between two mouse button clicks that will be considered a double click by the underlying operating system.

Control getFocusControl ()
          Returns the control which currently has keyboard focus, or null if keyboard events are not currently going to any of the controls built by the currently running application.

boolean getHighContrast ()
          Returns true when the high contrast mode is enabled.

int getIconDepth ()
          Returns the maximum allowed depth of icons on this display, in bits per pixel.

Point[] getIconSizes ()
          Returns an array containing the recommended icon sizes.

Monitor[] getMonitors ()
          Returns an array of monitors attached to the device.

Monitor getPrimaryMonitor ()
          Returns the primary monitor for that device.

Shell[] getShells ()
          Returns a (possibly empty) array containing all shells which have not been disposed and have the receiver as their display.

Synchronizer getSynchronizer ()
          Gets the synchronizer used by the display.

Thread getSyncThread ()
          Returns the thread that has invoked syncExec or null if no such runnable is currently being invoked by the user-interface thread.

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.

Cursor getSystemCursor (int id)
          Returns the matching standard platform cursor for the given constant, which should be one of the cursor constants specified in class SWT.

Font getSystemFont ()
          Returns a reasonable font for applications to use.

Image getSystemImage (int id)
          Returns the matching standard platform image for the given constant, which should be one of the icon constants specified in class SWT.

Tray getSystemTray ()
          Returns the single instance of the system tray or null when there is no system tray available for the platform.

Thread getThread ()
          Returns the user-interface thread for the receiver.

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

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

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

Point map ( Control from, Control to, int x, int y)
          Maps a point from one coordinate system to another.

Rectangle map ( Control from, Control to, int x, int y, int width, int height)
          Maps a point from one coordinate system to another.

Point map ( Control from, Control to, Point point)
          Maps a point from one coordinate system to another.

Rectangle map ( Control from, Control to, Rectangle rectangle)
          Maps a point from one coordinate system to another.

boolean post ( Event event)
          Generate a low level system event.

boolean readAndDispatch ()
          Reads an event from the operating system's event queue, dispatches it appropriately, and returns true if there is potentially more work to do, or false if the caller can sleep until another event is placed on the event queue.

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

void removeFilter (int eventType, Listener listener)
          Removes the listener from the collection of listeners who will be notified when an event of the given type occurs anywhere in a widget.

void removeListener (int eventType, Listener listener)
          Removes the listener from the collection of listeners who will be notified when an event of the given type occurs.

static void setAppName ( String name)
          On platforms which support it, sets the application name to be the argument.

void setCursorLocation (int x, int y)
          Sets the location of the on-screen pointer relative to the top left corner of the screen.

void setCursorLocation ( Point point)
          Sets the location of the on-screen pointer relative to the top left corner of the screen.

void setData ( Object data)
          Sets the application defined, display specific data associated with the receiver, to the argument.

void setData ( String key, Object value)
          Sets the application defined property of the receiver with the specified name to the given argument.

void setSynchronizer ( Synchronizer synchronizer)
          Sets the synchronizer used by the display to be the argument, which can not be null.

boolean sleep ()
          Causes the user-interface thread to sleep (that is, to be put in a state where it does not consume CPU cycles) until an event is received or it is otherwise awakened.

void syncExec ( Runnable runnable)
          Causes the run() method of the runnable to be invoked by the user-interface thread at the next reasonable opportunity.

void timerExec (int milliseconds, Runnable runnable)
          Causes the run() method of the runnable to be invoked by the user-interface thread after the specified number of milliseconds have elapsed.

void update ()
          Forces all outstanding paint requests for the display to be processed before this method returns.

void wake ()
          If the receiver's user-interface thread was sleeping, causes it to be awakened and start running again.

Methods inherited from class org.eclipse.swt.graphics. Device

dispose, getDepth, getDeviceData, getDPI, getFontList, getWarnings, isDisposed, loadFont, setWarnings

Methods inherited from class java.lang. Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

msg

public org.eclipse.swt.internal.win32.MSG msg

the handle to the OS message queue (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.

Constructor Detail

Display

public Display()

Constructs a new instance of this class.

Note: The resulting display is marked as the current display. If this is the first display which has been constructed since the application started, it is also marked as the default display.

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if called from a thread that already created an existing display
ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass

Display

public Display(
DeviceData data)

Constructs a new instance of this class using the parameter.

Parameters:: data - the device data

Method Detail

addFilter

public void addFilter(int eventType,
                      
Listener listener)

Adds the listener to the collection of listeners who will be notified when an event of the given type occurs anywhere in a widget. The event type is one of the event constants defined in class SWT. When the event does occur, the listener is notified by sending it the handleEvent() message.

Setting the type of an event to SWT.None from within the handleEvent() method can be used to change the event type and stop subsequent Java listeners from running. Because event filters run before other listeners, event filters can both block other listeners and set arbitrary fields within an event. For this reason, event filters are both powerful and dangerous. They should generally be avoided for performance, debugging and code maintenance reasons.

Parameters:

eventType - the type of event to listen for

listener - the listener which should be notified when the event occurs

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the listener is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

addListener

public void addListener(int eventType,
                        
Listener listener)

Adds the listener to the collection of listeners who will be notified when an event of the given type occurs. The event type is one of the event constants defined in class SWT. When the event does occur in the display, the listener is notified by sending it the handleEvent() message.

Parameters:

eventType - the type of event to listen for

listener - the listener which should be notified when the event occurs

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the listener is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.0

asyncExec

public void asyncExec(
Runnable runnable)

Causes the run() method of the runnable to be invoked by the user-interface thread at the next reasonable opportunity. The caller of this method continues to run in parallel, and is not notified when the runnable has completed. Specifying null as the runnable simply wakes the user-interface thread when run.

Note that at the time the runnable is invoked, widgets that have the receiver as their display may have been disposed. Therefore, it is necessary to check for this case inside the runnable before accessing the widget.

Parameters:

runnable - code to run on the user-interface thread or null

Throws:


SWTException

ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

syncExec(java.lang.Runnable)

beep

public void beep()

Causes the system hardware to emit a short sound (if it supports this capability).

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

checkSubclass

protected void checkSubclass()

Checks that this class can be subclassed.

IMPORTANT: See the comment in Widget.checkSubclass().

Throws:


SWTException

ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass

See Also:

Widget.checkSubclass()

checkDevice

protected void checkDevice()

Description copied from class: Device

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.

Overrides:: checkDevice in class Device

close

public void close()

Requests that the connection between SWT and the underlying operating system be closed.

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.0

See Also:

Device.dispose()

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.

Overrides:: create in class Device

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.

Overrides:: destroy in class Device

See Also:: Device.dispose(), release()

disposeExec

public void disposeExec(
Runnable runnable)

Causes the run() method of the runnable to be invoked by the user-interface thread just before the receiver is disposed. Specifying a null runnable is ignored.

Parameters:

runnable - code to run at dispose time.

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

findWidget

public 
Widget findWidget(int handle)

Given the operating system handle for a widget, returns the instance of the Widget subclass which represents it in the currently running application, if such exists, or null if no matching widget can be found.

IMPORTANT: This method should not be called from application code. The arguments are platform-specific.

Parameters:

handle - the handle for the widget

Returns:

the SWT widget that the handle represents

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

findWidget

public 
Widget findWidget(int handle,
                         int id)

Given the operating system handle for a widget, and widget-specific id, returns the instance of the Widget subclass which represents the handle/id pair in the currently running application, if such exists, or null if no matching widget can be found.

IMPORTANT: This method should not be called from application code. The arguments are platform-specific.

Parameters:

handle - the handle for the widget

id - the id for the subwidget (usually an item)

Returns:

the SWT widget that the handle/id pair represents

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.1

findWidget

public 
Widget findWidget(
Widget widget,
                         int id)

Given a widget and a widget-specific id, returns the instance of the Widget subclass which represents the widget/id pair in the currently running application, if such exists, or null if no matching widget can be found.

Parameters:

widget - the widget

id - the id for the subwidget (usually an item)

Returns:

the SWT subwidget (usually an item) that the widget/id pair represents

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.3

findDisplay

public static 
Display findDisplay(
Thread thread)

Returns the display which the given thread is the user-interface thread for, or null if the given thread is not a user-interface thread for any display. Specifying null as the thread will return null for the display.

Parameters:: thread - the user-interface thread
Returns:: the display for the given thread

getActiveShell

public 
Shell getActiveShell()

Returns the currently active Shell, or null if no shell belonging to the currently running application is active.

Returns:

the active shell or null

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getBounds

public 
Rectangle getBounds()

Returns a rectangle describing the receiver's size and location. Note that on multi-monitor systems the origin can be negative.

Overrides:: getBounds in class Device

Returns:

the bounding rectangle

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getCurrent

public static 
Display getCurrent()

Returns the display which the currently running thread is the user-interface thread for, or null if the currently running thread is not a user-interface thread for any display.

Returns:: the current display

getClientArea

public 
Rectangle getClientArea()

Returns a rectangle which describes the area of the receiver which is capable of displaying data.

Overrides:: getClientArea in class Device

Returns:

the client area

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

getBounds()

getCursorControl

public 
Control getCursorControl()

Returns the control which the on-screen pointer is currently over top of, or null if it is not currently over one of the controls built by the currently running application.

Returns:

the control under the cursor

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getCursorLocation

public 
Point getCursorLocation()

Returns the location of the on-screen pointer relative to the top left corner of the screen.

Returns:

the cursor location

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getCursorSizes

public 
Point[] getCursorSizes()

Returns an array containing the recommended cursor sizes.

Returns:

the array of cursor sizes

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

getDefault

public static 
Display getDefault()

Returns the default display. One is created (making the thread that invokes this method its user-interface thread) if it did not already exist.

Returns:: the default display

getData

public 
Object getData(
String key)

Returns the application defined property of the receiver with the specified name, or null if it has not been set.

Applications may have associated arbitrary objects with the receiver in this fashion. If the objects stored in the properties need to be notified when the display is disposed of, it is the application's responsibility to provide a disposeExec() handler which does so.

Parameters:

key - the name of the property

Returns:

the value of the property or null if it has not been set

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the key is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getData

public 
Object getData()

Returns the application defined, display specific data associated with the receiver, or null if it has not been set. The display specific data is a single, unnamed field that is stored with every display.

Applications may put arbitrary objects in this field. If the object stored in the display specific data needs to be notified when the display is disposed of, it is the application's responsibility to provide a disposeExec() handler which does so.

Returns:

the display specific data

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getDismissalAlignment

public int getDismissalAlignment()

Returns the button dismissal alignment, one of LEFT or RIGHT. The button dismissal alignment is the ordering that should be used when positioning the default dismissal button for a dialog. For example, in a dialog that contains an OK and CANCEL button, on platforms where the button dismissal alignment is LEFT, the button ordering should be OK/CANCEL. When button dismissal alignment is RIGHT, the button ordering should be CANCEL/OK.

Returns:

the button dismissal order

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.1

getDoubleClickTime

public int getDoubleClickTime()

Returns the longest duration, in milliseconds, between two mouse button clicks that will be considered a double click by the underlying operating system.

Returns:

the double click time

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getFocusControl

public 
Control getFocusControl()

Returns the control which currently has keyboard focus, or null if keyboard events are not currently going to any of the controls built by the currently running application.

Returns:

the control under the cursor

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getHighContrast

public boolean getHighContrast()

Returns true when the high contrast mode is enabled. Otherwise, false is returned.

Note: This operation is a hint and is not supported on platforms that do not have this concept.

Returns:

the high contrast mode

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

getIconDepth

public int getIconDepth()

Returns the maximum allowed depth of icons on this display, in bits per pixel. On some platforms, this may be different than the actual depth of the display.

Returns:

the maximum icon depth

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

Device.getDepth()

getIconSizes

public 
Point[] getIconSizes()

Returns an array containing the recommended icon sizes.

Returns:

the array of icon sizes

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

See Also:

Decorations.setImages(Image[])

getMonitors

public 
Monitor[] getMonitors()

Returns an array of monitors attached to the device.

Returns:: the array of monitors
Since:: 3.0

getPrimaryMonitor

public 
Monitor getPrimaryMonitor()

Returns the primary monitor for that device.

Returns:: the primary monitor
Since:: 3.0

getShells

public 
Shell[] getShells()

Returns a (possibly empty) array containing all shells which have not been disposed and have the receiver as their display.

Returns:

the receiver's shells

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getSynchronizer

public 
Synchronizer getSynchronizer()

Gets the synchronizer used by the display.

Returns:

the receiver's synchronizer

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.4

getSyncThread

public 
Thread getSyncThread()

Returns the thread that has invoked syncExec or null if no such runnable is currently being invoked by the user-interface thread.

Note: If a runnable invoked by asyncExec is currently running, this method will return null.

Returns:

the receiver's sync-interface thread

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 free'd because it was allocated by the system, not the application.

Overrides:: getSystemColor in class Device

Parameters:

id - the color constant

Returns:

the matching color

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

SWT

getSystemCursor

public 
Cursor getSystemCursor(int id)

Returns the matching standard platform cursor for the given constant, which should be one of the cursor constants specified in class SWT. This cursor should not be free'd because it was allocated by the system, not the application. A value of null will be returned if the supplied constant is not an SWT cursor constant.

Parameters:

id - the SWT cursor constant

Returns:

the corresponding cursor or null

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

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.

Overrides:: getSystemFont in class Device

Returns:

a font

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

getSystemImage

public 
Image getSystemImage(int id)

Returns the matching standard platform image for the given constant, which should be one of the icon constants specified in class SWT. This image should not be free'd because it was allocated by the system, not the application. A value of null will be returned either if the supplied constant is not an SWT icon constant or if the platform does not define an image that corresponds to the constant.

Parameters:

id - the SWT icon constant

Returns:

the corresponding image or null

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

getSystemTray

public 
Tray getSystemTray()

Returns the single instance of the system tray or null when there is no system tray available for the platform.

Returns:

the system tray or null

Throws:


SWTException

ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

getThread

public 
Thread getThread()

Returns the user-interface thread for the receiver.

Returns:

the receiver's user-interface thread

Throws:


SWTException

ERROR_DEVICE_DISPOSED - if the receiver has been disposed

internal_new_GC

public 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 Display. 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
Specified by:: internal_new_GC in class Device

Parameters:

data - the platform specific GC data

Returns:

the platform specific GC handle

Throws:


SWTException

ERROR_DEVICE_DISPOSED - if the receiver has been disposed


SWTError

ERROR_NO_HANDLES if a handle could not be obtained for gc creation

init

protected void init()

Initializes any internal resources needed by the device.

This method is called after create.

Overrides:: init in class Device

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

internal_dispose_GC

public void internal_dispose_GC(int hDC,
                                
GCData data)

Invokes platform specific functionality to dispose a GC handle.

Specified by:: internal_dispose_GC in interface Drawable
Specified by:: internal_dispose_GC in class Device

Parameters:: hDC - the platform specific GC handle; data - the platform specific GC data

map

public 
Point map(
Control from,
                 
Control to,
                 
Point point)

Maps a point from one coordinate system to another. When the control is null, coordinates are mapped to the display.

NOTE: On right-to-left platforms where the coordinate systems are mirrored, special care needs to be taken when mapping coordinates from one control to another to ensure the result is correctly mirrored. Mapping a point that is the origin of a rectangle and then adding the width and height is not equivalent to mapping the rectangle. When one control is mirrored and the other is not, adding the width and height to a point that was mapped causes the rectangle to extend in the wrong direction. Mapping the entire rectangle instead of just one point causes both the origin and the corner of the rectangle to be mapped.

Parameters:

from - the source Control or null

to - the destination Control or null

point - to be mapped

Returns:

point with mapped coordinates

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the point is null
ERROR_INVALID_ARGUMENT - if the Control from or the Control to have been disposed


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.1.2

map

public 
Point map(
Control from,
                 
Control to,
                 int x,
                 int y)

Maps a point from one coordinate system to another. When the control is null, coordinates are mapped to the display.

Parameters:

from - the source Control or null

to - the destination Control or null

x - coordinates to be mapped

y - coordinates to be mapped

Returns:

point with mapped coordinates

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the Control from or the Control to have been disposed


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.1.2

map

public 
Rectangle map(
Control from,
                     
Control to,
                     
Rectangle rectangle)

Maps a point from one coordinate system to another. When the control is null, coordinates are mapped to the display.

Parameters:

from - the source Control or null

to - the destination Control or null

rectangle - to be mapped

Returns:

rectangle with mapped coordinates

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the rectangle is null
ERROR_INVALID_ARGUMENT - if the Control from or the Control to have been disposed


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.1.2

map

public 
Rectangle map(
Control from,
                     
Control to,
                     int x,
                     int y,
                     int width,
                     int height)

Maps a point from one coordinate system to another. When the control is null, coordinates are mapped to the display.

Parameters:

from - the source Control or null

to - the destination Control or null

x - coordinates to be mapped

y - coordinates to be mapped

width - coordinates to be mapped

height - coordinates to be mapped

Returns:

rectangle with mapped coordinates

Throws:


IllegalArgumentException

ERROR_INVALID_ARGUMENT - if the Control from or the Control to have been disposed


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.1.2

post

public boolean post(
Event event)

Generate a low level system event. post is used to generate low level keyboard and mouse events. The intent is to enable automated UI testing by simulating the input from the user. Most SWT applications should never need to call this method.

Note that this operation can fail when the operating system fails to generate the event for any reason. For example, this can happen when there is no such key or mouse button or when the system event queue is full.

Event Types:

KeyDown, KeyUp

The following fields in the Event apply:

(in) type KeyDown or KeyUp

Either one of:

(in) character a character that corresponds to a keyboard key
(in) keyCode the key code of the key that was typed, as defined by the key code constants in class SWT

MouseDown, MouseUp

The following fields in the Event apply:

(in) type MouseDown or MouseUp
(in) button the button that is pressed or released

MouseMove

The following fields in the Event apply:

(in) type MouseMove
(in) x the x coordinate to move the mouse pointer to in screen coordinates
(in) y the y coordinate to move the mouse pointer to in screen coordinates

MouseWheel

The following fields in the Event apply:

(in) type MouseWheel
(in) detail either SWT.SCROLL_LINE or SWT.SCROLL_PAGE
(in) count the number of lines or pages to scroll

Parameters:

event - the event to be generated

Returns:

true if the event was generated or false otherwise

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the event is null


SWTException

ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

3.0

readAndDispatch

public boolean readAndDispatch()

Reads an event from the operating system's event queue, dispatches it appropriately, and returns true if there is potentially more work to do, or false if the caller can sleep until another event is placed on the event queue.

In addition to checking the system event queue, this method also checks if any inter-thread messages (created by syncExec() or asyncExec()) are waiting to be processed, and if so handles them before returning.

Returns:

false if the caller can sleep upon return from this method

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed
ERROR_FAILED_EXEC - if an exception occurred while running an inter-thread message

See Also:

sleep(), wake()

release

protected void release()

Releases any internal resources back to the operating system and clears all fields except the device handle.

Disposes all shells which are currently open on the display. After this method has been invoked, all related related shells will answer true when sent the message isDisposed().

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.

Overrides:: release in class Device

See Also:: Device.dispose(), destroy()

removeFilter

public void removeFilter(int eventType,
                         
Listener listener)

Removes the listener from the collection of listeners who will be notified when an event of the given type occurs anywhere in a widget. The event type is one of the event constants defined in class SWT.

Parameters:

eventType - the type of event to listen for

listener - the listener which should no longer be notified when the event occurs

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the listener is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver

Since:

3.0

removeListener

public void removeListener(int eventType,
                           
Listener listener)

Removes the listener from the collection of listeners who will be notified when an event of the given type occurs. The event type is one of the event constants defined in class SWT.

Parameters:

eventType - the type of event to listen for

listener - the listener which should no longer be notified

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the listener is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.0

setCursorLocation

public void setCursorLocation(int x,
                              int y)

Sets the location of the on-screen pointer relative to the top left corner of the screen. Note: It is typically considered bad practice for a program to move the on-screen pointer location.

Parameters:

x - the new x coordinate for the cursor

y - the new y coordinate for the cursor

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.1

setCursorLocation

public void setCursorLocation(
Point point)

Sets the location of the on-screen pointer relative to the top left corner of the screen. Note: It is typically considered bad practice for a program to move the on-screen pointer location.

Parameters:

point - new position

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_NULL_ARGUMENT - if the point is null
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

Since:

2.0

setData

public void setData(
String key,
                    
Object value)

Sets the application defined property of the receiver with the specified name to the given argument.

Parameters:

key - the name of the property

value - the new value for the property

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the key is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

setData

public void setData(
Object data)

Sets the application defined, display specific data associated with the receiver, to the argument. The display specific data is a single, unnamed field that is stored with every display.

Parameters:

data - the new display specific data

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

getData(), disposeExec(Runnable)

setAppName

public static void setAppName(
String name)

On platforms which support it, sets the application name to be the argument. On Motif, for example, this can be used to set the name used for resource lookup. Specifying null for the name clears it.

Parameters:: name - the new app name or null

setSynchronizer

public void setSynchronizer(
Synchronizer synchronizer)

Sets the synchronizer used by the display to be the argument, which can not be null.

Parameters:

synchronizer - the new synchronizer for the display (must not be null)

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the synchronizer is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed
ERROR_FAILED_EXEC - if an exception occurred while running an inter-thread message

sleep

public boolean sleep()

Causes the user-interface thread to sleep (that is, to be put in a state where it does not consume CPU cycles) until an event is received or it is otherwise awakened.

Returns:

true if an event requiring dispatching was placed on the queue.

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

wake()

syncExec

public void syncExec(
Runnable runnable)

Causes the run() method of the runnable to be invoked by the user-interface thread at the next reasonable opportunity. The thread which calls this method is suspended until the runnable completes. Specifying null as the runnable simply wakes the user-interface thread.

Parameters:

runnable - code to run on the user-interface thread or null

Throws:


SWTException

ERROR_FAILED_EXEC - if an exception occurred when executing the runnable
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

asyncExec(java.lang.Runnable)

timerExec

public void timerExec(int milliseconds,
                      
Runnable runnable)

Causes the run() method of the runnable to be invoked by the user-interface thread after the specified number of milliseconds have elapsed. If milliseconds is less than zero, the runnable is not executed.

Parameters:

milliseconds - the delay before running the runnable

runnable - code to run on the user-interface thread

Throws:


IllegalArgumentException

ERROR_NULL_ARGUMENT - if the runnable is null


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

asyncExec(java.lang.Runnable)

update

public void update()

Forces all outstanding paint requests for the display to be processed before this method returns.

Throws:


SWTException

ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

Control.update()

wake

public void wake()

If the receiver's user-interface thread was sleeping, causes it to be awakened and start running again. Note that this method may be called from any thread.

Throws:


SWTException

ERROR_DEVICE_DISPOSED - if the receiver has been disposed

See Also:

sleep()

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org.eclipse.swt.widgets Class Display

msg

Display

Display

addFilter

addListener

asyncExec

beep

checkSubclass

checkDevice

close

create

destroy

disposeExec

findWidget

findWidget

findWidget

findDisplay

getActiveShell

getBounds

getCurrent

getClientArea

getCursorControl

getCursorLocation

getCursorSizes

getDefault

getData

getData

getDismissalAlignment

getDoubleClickTime

getFocusControl

getHighContrast

getIconDepth

getIconSizes

getMonitors

getPrimaryMonitor

getShells

getSynchronizer

getSyncThread

getSystemColor

getSystemCursor

getSystemFont

getSystemImage

getSystemTray

getThread

internal_new_GC

init

internal_dispose_GC

map

map

map

map

post

readAndDispatch

release

removeFilter

removeListener

setCursorLocation

setCursorLocation

setData

setData

setAppName

setSynchronizer

sleep

syncExec

timerExec

update

wake

org.eclipse.swt.widgets
Class Display