edu.hws.jcm.awt
Class VariableSlider

java.lang.Object
  |
  +--java.awt.Component
        |
        +--java.awt.Scrollbar
              |
              +--edu.hws.jcm.awt.VariableSlider

All Implemented Interfaces:

javax.accessibility.Accessible, java.awt.Adjustable, java.awt.image.ImageObserver, InputObject, java.awt.MenuContainer, java.io.Serializable, Tieable, Value

public class VariableSlider

extends java.awt.Scrollbar

implements InputObject, Tieable, Value

A VariableSlider is a slider (implemented as a Scrollbar) whose position represents the value of an associated variable. The range of values represented by the slider is given by a pair of Value objects. They can be specified in the constructor or later with the setMin and setMax methods. A VariableSlider has an associated variable that represents the value of the slider. Note that the value of the variable can change only when the setInput() or checkInput() method is called. If you want the value of the variable to track the position of the slider as it is is manipulated by the user, add the slider to a Controller and set the Controller as the Slider's "onUserAction" property. This allows other objects that depend on the values of the slider to be recomputed by the controller when the value changes, as long as they are also registered with the Controller.

Some points to note: 1) setVal() can set a value outside the range from min to max, which will persist until the next time checkInput() or setVal() is called again. 2) If the value of min or max changes, the value of this variable will not change EXCEPT that it is clamped to the range between min and max. 3) Min does not have to be less than max. 4) The checkInput() routine only sets the needValueCheck flag to true. (The setVal() and getVal() routines both set this flag to false.) This "lazy evaluation" is used because checkInput() can't compute the new value itself. (The max and min might depend on Values that are themselves about to change when some other object's checkInput() mehtod is called.) 5) getVal() returns the current value, as stored in the variable, UNLESS needValueCheck is true. In that case, it recomputes the value first. getSerialNumber() works similarly. 6) A VariableSlider never throws JCMErrors. If an error occurs when min or max is evaluated, the value of the variable associated with this VariableSlider becomes undefined. (The point is, it doesn't generate any errors of its own. The error would be caused by other InputObjects which should throw their own errors when their checkInput() methods are called.)

See Also:

Serialized Form

Inner classes inherited from class java.awt.Scrollbar

java.awt.Scrollbar.AccessibleAWTScrollBar

Inner classes inherited from class java.awt.Component

java.awt.Component.AccessibleAWTComponent

Field Summary

protected boolean	integerValued If this is true, then the value of the variable associated with this slider is an integer.
protected int	intervals The number of possible value of the scrollbar (Unless integerValued is true.)
protected Value	max The Values that specify the range of values represented by the slider.
protected double	maxVal The values found for min and max the last time checkInput() was called.
protected Value	min The Values that specify the range of values represented by the slider.
protected double	minVal The values found for min and max the last time checkInput() was called.
protected boolean	needsValueCheck This is set to true when checkInput() is called to indicate that the min and max values must be checked the next time getVal() is called.
protected int	oldPosition This is the position of the scrollbar the last time getVal() or setVal() was called.
protected long	serialNumber This increases every time the value of the variable changes.
protected edu.hws.jcm.awt.VariableSlider.VS	variable The variable associated with this VariableSlider.

Fields inherited from class java.awt.Scrollbar

HORIZONTAL, VERTICAL

Fields inherited from class java.awt.Component

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

Constructor Summary

VariableSlider()
Create a horizontal variable slider with no name and with a default value range of -5 to 5.

VariableSlider(java.lang.String name, Value min, Value max, Parser p)
Create a horizontal variable slider with the given name and range of values, and register it with the given parser (but only if both name and p are non-null).

VariableSlider(java.lang.String name, Value min, Value max, Parser p, int intervals, int orientation)
Create a variable slider with the given name and range of values, and register it with the given parser (but only if both name and p are non-null).

VariableSlider(Value min, Value max)
Create a horizontal variable slider with no name and with the specified range of values.

Method Summary

void	addTo(Parser p) A convenience method that registers this VariableSlider's variable with p (but only if both p and the name of the variable are non-null).
void	checkInput() From the InputObject interface.
boolean	getIntegerValued() Return a boolean which is true if the VariableSlider restricts ranges of values to integers, false otherwise.
Value	getMax() Get the Value object that gives the value of the variable when the slider is at the right (or top) of the scrollbar.
Value	getMin() Get the Value object that gives the value of the variable when the slider is at the left (or bottom) of the scrollbar.
Controller	getOnUserAction() Return the Controller, if any, that is notified when the user adjusts the position of the scroll bar.
java.awt.Dimension	getPreferredSize() Modify getPreferredSize to return a width of 200, if the scrollbar is horzontal, or a height of 200, if it is vertical.
long	getSerialNumber() Return this object's serial number, which is increased every time the value changes.
double	getVal() Get the value of this VariableSlider.
Variable	getVariable() Return the variable associated with this VariableSlider.
void	notifyControllerOnChange(Controller c) Method required by InputObject interface; in this class, it simply calls setOnUserAction(c).
void	processAdjustmentEvent(java.awt.event.AdjustmentEvent evt) Overridden to call onUserAction.compute() if onUserAction is non-null.
void	setIntegerValued(boolean b) If set to true, restrict the values of the variable associated with this slider to be integers.
void	setMax(Value v) Set the value that the variable has when the slider is at the right (or top) of the scrollbar.
void	setMin(Value v) Set the value that the variable has when the slider is at the left (or bottom) of the scrollbar.
void	setName(java.lang.String name) Set the name of the associated variable.
void	setOnUserAction(Controller c) If the Controller, c, is non-null, then its compute method will be called whenever the user adjusts the position of the scroll bar.
void	setVal(double x) Set the value of the variable to x.
void	sync(Tie tie, Tieable newest) Change the value and serial number of this object to match those of newest.

Methods inherited from class java.awt.Scrollbar

addAdjustmentListener, addNotify, getAccessibleContext, getBlockIncrement, getLineIncrement, getListeners, getMaximum, getMinimum, getOrientation, getPageIncrement, getUnitIncrement, getValue, getVisible, getVisibleAmount, paramString, processEvent, removeAdjustmentListener, setBlockIncrement, setLineIncrement, setMaximum, setMinimum, setOrientation, setPageIncrement, setUnitIncrement, setValue, setValues, setVisibleAmount

Methods inherited from class java.awt.Component

action, add, addComponentListener, addFocusListener, addHierarchyBoundsListener, addHierarchyListener, addInputMethodListener, addKeyListener, addMouseListener, addMouseMotionListener, addPropertyChangeListener, addPropertyChangeListener, bounds, checkImage, checkImage, coalesceEvents, contains, contains, createImage, createImage, deliverEvent, disable, disableEvents, dispatchEvent, doLayout, enable, enable, enableEvents, enableInputMethods, firePropertyChange, getAlignmentX, getAlignmentY, getBackground, getBounds, getBounds, getColorModel, getComponentAt, getComponentAt, getComponentOrientation, getCursor, getDropTarget, getFont, getFontMetrics, getForeground, getGraphics, getGraphicsConfiguration, getHeight, getInputContext, getInputMethodRequests, getLocale, getLocation, getLocation, getLocationOnScreen, getMaximumSize, getMinimumSize, getName, getParent, getPeer, getSize, getSize, getToolkit, getTreeLock, getWidth, getX, getY, gotFocus, handleEvent, hasFocus, hide, imageUpdate, inside, invalidate, isDisplayable, isDoubleBuffered, isEnabled, isFocusTraversable, isLightweight, isOpaque, 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, processFocusEvent, processHierarchyBoundsEvent, processHierarchyEvent, processInputMethodEvent, processKeyEvent, processMouseEvent, processMouseMotionEvent, remove, removeComponentListener, removeFocusListener, removeHierarchyBoundsListener, removeHierarchyListener, removeInputMethodListener, removeKeyListener, removeMouseListener, removeMouseMotionListener, removeNotify, removePropertyChangeListener, removePropertyChangeListener, repaint, repaint, repaint, repaint, requestFocus, reshape, resize, resize, setBackground, setBounds, setBounds, setComponentOrientation, setCursor, setDropTarget, setEnabled, setFont, setForeground, setLocale, setLocation, setLocation, setSize, setSize, setVisible, show, show, size, toString, transferFocus, update, validate

Methods inherited from class java.lang.Object

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

Field Detail

variable

protected edu.hws.jcm.awt.VariableSlider.VS variable

The variable associated with this VariableSlider. VS is a nested private class, defined below.

min

protected Value min

The Values that specify the range of values represented by the slider. min does not have to be less than max.

max

protected Value max

The Values that specify the range of values represented by the slider. min does not have to be less than max.

integerValued

protected boolean integerValued

If this is true, then the value of the variable associated with this slider is an integer. Furthermore, the number of intervals on the slider is set to be the same as the range of possible values (unless this range is too big).

intervals

protected int intervals

The number of possible value of the scrollbar (Unless integerValued is true.)

serialNumber

protected long serialNumber

This increases every time the value of the variable changes.

needsValueCheck

protected boolean needsValueCheck

This is set to true when checkInput() is called to indicate that the min and max values must be checked the next time getVal() is called.

oldPosition

protected int oldPosition

This is the position of the scrollbar the last time getVal() or setVal() was called. It is used to check whether the user has repositioned the slider.

minVal

protected double minVal

The values found for min and max the last time checkInput() was called.

maxVal

protected double maxVal

The values found for min and max the last time checkInput() was called.

Constructor Detail

VariableSlider

public VariableSlider()

Create a horizontal variable slider with no name and with a default value range of -5 to 5.

VariableSlider

public VariableSlider(Value min,
                      Value max)

Create a horizontal variable slider with no name and with the specified range of values. If min is null, a default value -5 is used. If max is null, a default value 5 is used.

VariableSlider

public VariableSlider(java.lang.String name,
                      Value min,
                      Value max,
                      Parser p)

Create a horizontal variable slider with the given name and range of values, and register it with the given parser (but only if both name and p are non-null). If min is null, a default value -5 is used. If max is null, a default value 5 is used.

VariableSlider

public VariableSlider(java.lang.String name,
                      Value min,
                      Value max,
                      Parser p,
                      int intervals,
                      int orientation)

Create a variable slider with the given name and range of values, and register it with the given parser (but only if both name and p are non-null). The "intervals" parameter specifes how many different positions there are on the slider. (The value of the scrollbar ranges from 0 to intervals.) If intervals is <= 0, it will be set to 1000. If it is between 1 and 9, it will be set to 10. The orientation must be either Scrollbar.HORIZONTAL or Scrollbar.VERTICAL. It specifies whether this is a horizontal or vertical scrollbar. If min is null, a default value -5 is used. If max is null, a default value 5 is used.

Parameters:

name - name for this VariableSlider.

min - minimum value for slider.

max - maximum value for slider.

p - register VariableSlider with this Parser.

intervals - discrete positions on slider.

orientation - Scrollbar.HORIZONTAL or Scrollbar.VERTICAL.

Method Detail

setName

public void setName(java.lang.String name)

Set the name of the associated variable. You shouldn't do this if it has been added to a parser. If name is non-null, then the name of this Component is also set to the specified name.

Overrides:

setName in class java.awt.Component

addTo

public void addTo(Parser p)

A convenience method that registers this VariableSlider's variable with p (but only if both p and the name of the variable are non-null).

getVariable

public Variable getVariable()

Return the variable associated with this VariableSlider.

setIntegerValued

public void setIntegerValued(boolean b)

If set to true, restrict the values of the variable associated with this slider to be integers. Furthermore, the number of intervals on the scrollbar will be set to be the same as the size of the range from min to max (unless this range is too big). The setVal() method can still set the value of the variable to be a non-integer.

getIntegerValued

public boolean getIntegerValued()

Return a boolean which is true if the VariableSlider restricts ranges of values to integers, false otherwise.

setMin

public void setMin(Value v)

Set the value that the variable has when the slider is at the left (or bottom) of the scrollbar. If v is null, -5 is used as the default value.

setMax

public void setMax(Value v)

Set the value that the variable has when the slider is at the right (or top) of the scrollbar. If v is null, 5 is used as the default value.

getMin

public Value getMin()

Get the Value object that gives the value of the variable when the slider is at the left (or bottom) of the scrollbar. The Value is always non-null.

getMax

public Value getMax()

Get the Value object that gives the value of the variable when the slider is at the right (or top) of the scrollbar. The Value is always non-null.

setOnUserAction

public void setOnUserAction(Controller c)

If the Controller, c, is non-null, then its compute method will be called whenever the user adjusts the position of the scroll bar.

notifyControllerOnChange

public void notifyControllerOnChange(Controller c)

Method required by InputObject interface; in this class, it simply calls setOnUserAction(c). This is meant to be called by JCMPanel.gatherInputs().

Specified by:

notifyControllerOnChange in interface InputObject

getOnUserAction

public Controller getOnUserAction()

Return the Controller, if any, that is notified when the user adjusts the position of the scroll bar.

getSerialNumber

public long getSerialNumber()

Return this object's serial number, which is increased every time the value changes.

Specified by:

getSerialNumber in interface Tieable

sync

public void sync(Tie tie,
                 Tieable newest)

Change the value and serial number of this object to match those of newest. See the Tie class for more information. This is not meant to be called directly

Specified by:

sync in interface Tieable

getVal

public double getVal()

Get the value of this VariableSlider. (If needsValueCheck is true, then the value is recomputed. Otherwise, the current value is returned.)

Specified by:

getVal in interface Value

setVal

public void setVal(double x)

Set the value of the variable to x. If possible, set the value on the scroll bar to match.

checkInput

public void checkInput()

From the InputObject interface. This will force the slider to recompute its max and min values, and possibly clamp its value between these two extremes) the next time the value or serial number is checked. This is ordinarily called by a Controller.

Specified by:

checkInput in interface InputObject

getPreferredSize

public java.awt.Dimension getPreferredSize()

Modify getPreferredSize to return a width of 200, if the scrollbar is horzontal, or a height of 200, if it is vertical. This is not meant to be called directly.

Overrides:

getPreferredSize in class java.awt.Component

processAdjustmentEvent

public void processAdjustmentEvent(java.awt.event.AdjustmentEvent evt)

Overridden to call onUserAction.compute() if onUserAction is non-null. This is not meant to be called directly.

Overrides:

processAdjustmentEvent in class java.awt.Scrollbar