Class ActiveLabel
- All Implemented Interfaces:
ImageObserver
,MenuContainer
,Serializable
,Accessible
,CSProcess
java.awt.Label
with a channel interface.
Process Diagram
Description
ActiveLabel is a process extension of java.awt.Label with channels for run-time configuration and event notification. The event channels should be connected to one or more application-specific server processes (instead of registering a passive object as a Listener to this component).All channels are optional. The configure channel is settable from a constructor. Event channels can be added to notify the occurrence of any type of Event the component generates (by calling the appropriate addXXXEventChannel method before the process is run). Messages can be sent down the configure channel at any time to configure the component. See the table below for details.
All channels are managed by independent internal handler processes. It is, therefore, safe for a serial application process both to service an event channel and configure the component -- no deadlock can occur.
IMPORTANT: it is essential that event channels from this process are always serviced -- otherwise the Java Event Thread will be blocked and the GUI will stop responding. A simple way to guarantee this is to use channels configured with overwriting buffers. For example:
final One2OneChannel myMouseEvent = Channel.one2one (new OverWriteOldestBuffer (n)); final ActiveLabel myLabel = new ActiveLabel ("Look at Me"); myContainer.addMouseEventChannel (myMouseEvent.out ());This will ensure that the Java Event Thread will never be blocked. Slow or inattentive readers may miss rapidly generated events, but the n most recent events will always be available.
Channel Protocols
Input Channels | ||
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configure | String | Change the label on the ActiveLabel to the value of the String |
Boolean |
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ActiveLabel.Configure | Invoke the user-defined Configure.configure method on the label. | |
Output Channels | ||
componentEvent | ComponentEvent | See the addComponentEventChannel method. |
focusEvent | FocusEvent | See the addFocusEventChannel method. |
keyEvent | KeyEvent | See the addKeyEventChannel method. |
mouseEvent | MouseEvent | See the addMouseEventChannel method. |
mouseMotionEvent | MouseEvent | See the addMouseMotionEventChannel method. |
Example
import java.awt.*; import org.jcsp.lang.*; import org.jcsp.util.*; import org.jcsp.awt.*; public class ActiveLabelExample { public static void main (String argv[]) { final Frame root = new Frame ("ActiveLabel Example"); final int nLabels = 8; final int countdown = 10; final One2OneChannel[] configureLabel = Channel.one2oneArray (nLabels); final ActiveLabel[] label = new ActiveLabel[nLabels]; for (int i = 0; i invalid input: '<' label.length; i++) { label[i] = new ActiveLabel (configureLabel[i].in (), "==> " + countdown + " invalid input: '<'=="); label[i].setAlignment (Label.CENTER); } final One2OneChannel configureButton = Channel.one2one (); final One2OneChannel event = Channel.one2one (new OverWriteOldestBuffer (10)); final ActiveButton button = new ActiveButton (configureButton.in (), event.out (), "Start"); root.setSize (300, 200); root.setLayout (new GridLayout (3, 3)); for (int i = 0; i invalid input: '<' nLabels + 1; i++) { if (i invalid input: '<' 4) { root.add (label[i]); } else if (i == 4) { root.add (button); } else if (i > 4) { root.add (label[i - 1]); } } root.setVisible (true); new Parallel ( new CSProcess[] { new Parallel (label), button, new CSProcess () { public void run () { final long second = 1000; CSTimer tim = new CSTimer (); Alternative alt = new Alternative (new Guard[] {event.in (), tim}); event.in ().read (); // wait for the start signal configureButton.out ().write ("Restart"); int count = countdown; long timeout = tim.read () + second; while (count > 0) { tim.setAlarm (timeout); switch (alt.priSelect ()) { case 0: // reset signal event.in ().read (); // clear the reset timeout = tim.read () + second; count = countdown; break; case 1: // timeout signal timeout += second; count--; break; } final String newLabel = "==> " + count + " invalid input: '<'=="; for (int i = 0; i invalid input: '<' nLabels; i++) { configureLabel[i].out ().write (newLabel); } } root.setVisible (false); System.exit (0); } } } ).run (); } }
- See Also:
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionstatic interface
This enables general configuration of this component.Nested classes/interfaces inherited from class java.awt.Label
Label.AccessibleAWTLabel
Nested classes/interfaces inherited from class java.awt.Component
Component.AccessibleAWTComponent, Component.BaselineResizeBehavior, Component.BltBufferStrategy, Component.FlipBufferStrategy
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate ChannelInput
The channel from which configuration messages arrive.private Vector
The Vector construct containing the handlers.Fields inherited from class java.awt.Component
accessibleContext, BOTTOM_ALIGNMENT, CENTER_ALIGNMENT, LEFT_ALIGNMENT, RIGHT_ALIGNMENT, TOP_ALIGNMENT
Fields inherited from interface java.awt.image.ImageObserver
ABORT, ALLBITS, ERROR, FRAMEBITS, HEIGHT, PROPERTIES, SOMEBITS, WIDTH
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Constructor Summary
ConstructorsConstructorDescriptionConstructs a new ActiveLabel with no label or configuration channel.Constructs a new ActiveLabel with no configuration channel.ActiveLabel
(ChannelInput configure) Constructs a new ActiveLabel with no initial label.ActiveLabel
(ChannelInput configure, String s) Constructs a new ActiveLabel. -
Method Summary
Modifier and TypeMethodDescriptionvoid
addComponentEventChannel
(ChannelOutput componentEvent) Add a new channel to this component that will be used to notify that a ComponentEvent has occurred.void
addFocusEventChannel
(ChannelOutput focusEvent) Add a new channel to this component that will be used to notify that a FocusEvent has occurred.void
addKeyEventChannel
(ChannelOutput keyEvent) Add a new channel to this component that will be used to notify that a KeyEvent has occurred.void
addMouseEventChannel
(ChannelOutput mouseEvent) Add a new channel to this component that will be used to notify that a MouseEvent has occurred.void
addMouseMotionEventChannel
(ChannelOutput mouseMotionEvent) Add a new channel to this component that will be used to notify that a MouseMotionEvent has occurred.void
run()
The main body of this process.void
setConfigureChannel
(ChannelInput configure) Sets the configuration channel for this ActiveLabel.Methods inherited from class java.awt.Label
addNotify, getAccessibleContext, getAlignment, getText, paramString, setAlignment, setText
Methods inherited from class java.awt.Component
action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addMouseWheelListener, addPropertyChangeListener, addPropertyChangeListener, applyComponentOrientation, areFocusTraversalKeysSet, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, createVolatileImage, createVolatileImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBaseline, getBaselineResizeBehavior, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentListeners, getComponentOrientation, getCursor, getDropTarget, getFocusCycleRootAncestor, getFocusListeners, getFocusTraversalKeys, getFocusTraversalKeysEnabled, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getHierarchyBoundsListeners, getHierarchyListeners, getIgnoreRepaint, getInputContext, getInputMethodListeners, getInputMethodRequests, getKeyListeners, getListeners, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getMouseListeners, getMouseMotionListeners, getMousePosition, getMouseWheelListeners, getName, getParent, getPeer, getPreferredSize, getPropertyChangeListeners, getPropertyChangeListeners, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isBackgroundSet, isCursorSet, isDisplayable, isDoubleBuffered, isEnabled, isFocusable, isFocusCycleRoot, isFocusOwner, isFocusTraversable, isFontSet, isForegroundSet, isLightweight, isMaximumSizeSet, isMinimumSizeSet, isOpaque, isPreferredSizeSet, isShowing, isValid, isVisible, keyDown, keyUp, layout, list, list, list, list, list, locate, location, lostFocus, minimumSize, mouseDown, mouseDrag, mouseEnter, mouseExit, mouseMove, mouseUp, move, nextFocus, paint, paintAll, postEvent, preferredSize, prepareImage, prepareImage, print, printAll, processComponentEvent, processEvent, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, processMouseWheelEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeMouseWheelListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, requestFocus, requestFocusInWindow, requestFocusInWindow, reshape, resize, resize, revalidate, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFocusable, setFocusTraversalKeys, setFocusTraversalKeysEnabled, setFont, setForeground, setIgnoreRepaint, setLocale, setLocation, setLocation, setMaximumSize, setMinimumSize, setName, setPreferredSize, setSize, setSize, setVisible, show, show, size, toString, transferFocus, transferFocusBackward, transferFocusUpCycle, update, validate
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Field Details
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vec
The Vector construct containing the handlers. -
configure
The channel from which configuration messages arrive.
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Constructor Details
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ActiveLabel
public ActiveLabel()Constructs a new ActiveLabel with no label or configuration channel. -
ActiveLabel
Constructs a new ActiveLabel with no configuration channel.- Parameters:
s
- the initial string displayed on the label.
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ActiveLabel
Constructs a new ActiveLabel with no initial label.- Parameters:
configure
- the channel for configuration events -- can be null if no configuration is required.
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ActiveLabel
Constructs a new ActiveLabel.- Parameters:
configure
- the channel for configuration events -- can be null if no configuration is required.s
- the initial string displayed on the label.
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Method Details
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setConfigureChannel
Sets the configuration channel for this ActiveLabel. This method overwrites any configuration channel set in the constructor.- Parameters:
configure
- the channel for configuration events -- can be null if no configuration is required.
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addComponentEventChannel
Add a new channel to this component that will be used to notify that a ComponentEvent has occurred. This should be used instead of registering a ComponentListener with the component. It is possible to add more than one channel by calling this method multiple times If the channel passed is null, no action will be taken.NOTE: This method must be called before this process is run.
- Parameters:
componentEvent
- the channel down which to send ComponentEvents.
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addFocusEventChannel
Add a new channel to this component that will be used to notify that a FocusEvent has occurred. This should be used instead of registering a FocusListener with the component. It is possible to add more than one channel by calling this method multiple times If the channel passed is null, no action will be taken.NOTE: This method must be called before this process is run.
- Parameters:
focusEvent
- the channel down which to send FocusEvents.
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addKeyEventChannel
Add a new channel to this component that will be used to notify that a KeyEvent has occurred. This should be used instead of registering a KeyListener with the component. It is possible to add more than one channel by calling this method multiple times If the channel passed is null, no action will be taken.NOTE: This method must be called before this process is run.
- Parameters:
keyEvent
- the channel down which to send KeyEvents.
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addMouseEventChannel
Add a new channel to this component that will be used to notify that a MouseEvent has occurred. This should be used instead of registering a MouseListener with the component. It is possible to add more than one channel by calling this method multiple times If the channel passed is null, no action will be taken.NOTE: This method must be called before this process is run.
- Parameters:
mouseEvent
- the channel down which to send MouseEvents.
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addMouseMotionEventChannel
Add a new channel to this component that will be used to notify that a MouseMotionEvent has occurred. This should be used instead of registering a MouseMotionListener with the component. It is possible to add more than one channel by calling this method multiple times If the channel passed is null, no action will be taken.NOTE: This method must be called before this process is run.
- Parameters:
mouseMotionEvent
- the channel down which to send MouseMotionEvents.
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run
public void run()The main body of this process.
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