Class ZoneView

java.lang.Object

javax.swing.text.View

javax.swing.text.CompositeView

javax.swing.text.BoxView

javax.swing.text.ZoneView

All Implemented Interfaces:

SwingConstants

public class ZoneView
extends BoxView

ZoneView is a View implementation that creates zones for which the child views are not created or stored until they are needed for display or model/view translations. This enables a substantial reduction in memory consumption for situations where the model being represented is very large, by building view objects only for the region being actively viewed/edited. The size of the children can be estimated in some way, or calculated asynchronously with only the result being saved.

ZoneView extends BoxView to provide a box that implements zones for its children. The zones are special View implementations (the children of an instance of this class) that represent only a portion of the model that an instance of ZoneView is responsible for. The zones don't create child views until an attempt is made to display them. A box shaped view is well suited to this because:

• Boxes are a heavily used view, and having a box that provides this behavior gives substantial opportunity to plug the behavior into a view hierarchy from the view factory.
• Boxes are tiled in one direction, so it is easy to divide them into zones in a reliable way.
• Boxes typically have a simple relationship to the model (i.e. they create child views that directly represent the child elements).
• Boxes are easier to estimate the size of than some other shapes.

The default behavior is controlled by two properties, maxZoneSize and maxZonesLoaded. Setting maxZoneSize to Integer.MAX_VALUE would have the effect of causing only one zone to be created. This would effectively turn the view into an implementation of the decorator pattern. Setting maxZonesLoaded to a value of Integer.MAX_VALUE would cause zones to never be unloaded. For simplicity, zones are created on boundaries represented by the child elements of the element the view is responsible for. The zones can be any View implementation, but the default implementation is based upon AsyncBoxView which supports fairly large zones efficiently.

Since:

1.3

See Also:

• View

Field Summary

Fields declared in class View

BadBreakWeight, ExcellentBreakWeight, ForcedBreakWeight, GoodBreakWeight, X_AXIS, Y_AXIS

Modifier and Type	Field	Description
static final int	BadBreakWeight	The weight to indicate a view is a bad break opportunity for the purpose of formatting.
static final int	ExcellentBreakWeight	The weight to indicate a view supports breaking, and this represents a very attractive place to break.
static final int	ForcedBreakWeight	The weight to indicate a view supports breaking, and must be broken to be represented properly when placed in a view that formats its children by breaking them.
static final int	GoodBreakWeight	The weight to indicate a view supports breaking, but better opportunities probably exist.
static final int	X_AXIS	Axis for format/break operations.
static final int	Y_AXIS	Axis for format/break operations.

Fields declared in interface SwingConstants

BOTTOM, CENTER, EAST, HORIZONTAL, LEADING, LEFT, NEXT, NORTH, NORTH_EAST, NORTH_WEST, PREVIOUS, RIGHT, SOUTH, SOUTH_EAST, SOUTH_WEST, TOP, TRAILING, VERTICAL, WEST

Modifier and Type	Field	Description
static final int	BOTTOM	Box-orientation constant used to specify the bottom of a box.
static final int	CENTER	The central position in an area.
static final int	EAST	Compass-direction east (right).
static final int	HORIZONTAL	Horizontal orientation.
static final int	LEADING	Identifies the leading edge of text for use with left-to-right and right-to-left languages.
static final int	LEFT	Box-orientation constant used to specify the left side of a box.
static final int	NEXT	Identifies the next direction in a sequence.
static final int	NORTH	Compass-direction North (up).
static final int	NORTH_EAST	Compass-direction north-east (upper right).
static final int	NORTH_WEST	Compass-direction north west (upper left).
static final int	PREVIOUS	Identifies the previous direction in a sequence.
static final int	RIGHT	Box-orientation constant used to specify the right side of a box.
static final int	SOUTH	Compass-direction south (down).
static final int	SOUTH_EAST	Compass-direction south-east (lower right).
static final int	SOUTH_WEST	Compass-direction south-west (lower left).
static final int	TOP	Box-orientation constant used to specify the top of a box.
static final int	TRAILING	Identifies the trailing edge of text for use with left-to-right and right-to-left languages.
static final int	VERTICAL	Vertical orientation.
static final int	WEST	Compass-direction west (left).

Constructor Summary

Constructors

Constructor	Description
ZoneView(Element elem, int axis)	Constructs a ZoneView.

Method Summary

Modifier and Type	Method	Description
protected View	createZone(int p0, int p1)	Create a view to represent a zone for the given range within the model (which should be within the range of this objects responsibility).
int	getMaximumZoneSize()	Get the current maximum zone size.
int	getMaxZonesLoaded()	Get the current setting of the number of zones allowed to be loaded at the same time.
protected int	getViewIndexAtPosition(int pos)	Returns the child view index representing the given position in the model.
void	insertUpdate(DocumentEvent changes, Shape a, ViewFactory f)	Gives notification that something was inserted into the document in a location that this view is responsible for.
protected boolean	isZoneLoaded(View zone)	Determine if a zone is in the loaded state.
protected void	loadChildren(ViewFactory f)	Loads all of the children to initialize the view.
void	removeUpdate(DocumentEvent changes, Shape a, ViewFactory f)	Gives notification that something was removed from the document in a location that this view is responsible for.
void	setMaximumZoneSize(int size)	Set the desired maximum zone size.
void	setMaxZonesLoaded(int mzl)	Sets the current setting of the number of zones allowed to be loaded at the same time.
protected void	unloadZone(View zone)	Unload a zone (Convert the zone to its memory saving state).
protected boolean	updateChildren(DocumentEvent.ElementChange ec, DocumentEvent e, ViewFactory f)	The superclass behavior will try to update the child views which is not desired in this case, since the children are zones and not directly effected by the changes to the associated element.
protected void	zoneWasLoaded(View zone)	Called by a zone when it gets loaded.

Methods declared in class BoxView

baselineLayout, baselineRequirements, calculateMajorAxisRequirements, calculateMinorAxisRequirements, childAllocation, flipEastAndWestAtEnds, forwardUpdate, getAlignment, getAxis, getChildAllocation, getHeight, getMaximumSpan, getMinimumSpan, getOffset, getPreferredSpan, getResizeWeight, getSpan, getViewAtPoint, getWidth, isAfter, isAllocationValid, isBefore, isLayoutValid, layout, layoutChanged, layoutMajorAxis, layoutMinorAxis, modelToView, paint, paintChild, preferenceChanged, replace, setAxis, setSize, viewToModel

Modifier and Type	Method	Description
protected void	baselineLayout(int targetSpan, int axis, int[] offsets, int[] spans)	Computes the location and extent of each child view in this BoxView given the targetSpan, which is the width (or height) of the region we have to work with.
protected SizeRequirements	baselineRequirements(int axis, SizeRequirements r)	Calculates the size requirements for this BoxView by examining the size of each child view.
protected SizeRequirements	calculateMajorAxisRequirements(int axis, SizeRequirements r)	Calculates the size requirements for the major axis axis.
protected SizeRequirements	calculateMinorAxisRequirements(int axis, SizeRequirements r)	Calculates the size requirements for the minor axis axis.
protected void	childAllocation(int index, Rectangle alloc)	Allocates a region for a child view.
protected boolean	flipEastAndWestAtEnds(int position, Position.Bias bias)	Determines in which direction the next view lays.
protected void	forwardUpdate(DocumentEvent.ElementChange ec, DocumentEvent e, Shape a, ViewFactory f)	Forwards the given DocumentEvent to the child views that need to be notified of the change to the model.
float	getAlignment(int axis)	Determines the desired alignment for this view along an axis.
int	getAxis()	Fetches the tile axis property.
Shape	getChildAllocation(int index, Shape a)	Fetches the allocation for the given child view.
int	getHeight()	Returns the current height of the box.
float	getMaximumSpan(int axis)	Determines the maximum span for this view along an axis.
float	getMinimumSpan(int axis)	Determines the minimum span for this view along an axis.
protected int	getOffset(int axis, int childIndex)	Fetches the offset of a particular child's current layout.
float	getPreferredSpan(int axis)	Determines the preferred span for this view along an axis.
int	getResizeWeight(int axis)	Gets the resize weight.
protected int	getSpan(int axis, int childIndex)	Fetches the span of a particular child's current layout.
protected View	getViewAtPoint(int x, int y, Rectangle alloc)	Fetches the child view at the given coordinates.
int	getWidth()	Returns the current width of the box.
protected boolean	isAfter(int x, int y, Rectangle innerAlloc)	Determines if a point falls after an allocated region.
protected boolean	isAllocationValid()	Are the allocations for the children still valid?
protected boolean	isBefore(int x, int y, Rectangle innerAlloc)	Determines if a point falls before an allocated region.
protected boolean	isLayoutValid(int axis)	Determines if the layout is valid along the given axis.
protected void	layout(int width, int height)	Perform layout on the box
void	layoutChanged(int axis)	Invalidates the layout along an axis.
protected void	layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans)	Performs layout for the major axis of the box (i.e. the axis that it represents).
protected void	layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans)	Performs layout for the minor axis of the box (i.e. the axis orthogonal to the axis that it represents).
Shape	modelToView(int pos, Shape a, Position.Bias b)	Provides a mapping from the document model coordinate space to the coordinate space of the view mapped to it.
void	paint(Graphics g, Shape allocation)	Renders the BoxView using the given rendering surface and area on that surface.
protected void	paintChild(Graphics g, Rectangle alloc, int index)	Paints a child.
void	preferenceChanged(View child, boolean width, boolean height)	This is called by a child to indicate its preferred span has changed.
void	replace(int index, int length, View[] elems)	Invalidates the layout and resizes the cache of requests/allocations.
void	setAxis(int axis)	Sets the tile axis property.
void	setSize(float width, float height)	Sets the size of the view.
int	viewToModel(float x, float y, Shape a, Position.Bias[] bias)	Provides a mapping from the view coordinate space to the logical coordinate space of the model.

Methods declared in class CompositeView

getBottomInset, getInsideAllocation, getLeftInset, getNextEastWestVisualPositionFrom, getNextNorthSouthVisualPositionFrom, getNextVisualPositionFrom, getRightInset, getTopInset, getView, getViewAtPosition, getViewCount, getViewIndex, modelToView, setInsets, setParagraphInsets, setParent

Modifier and Type	Method	Description
protected short	getBottomInset()	Gets the bottom inset.
protected Rectangle	getInsideAllocation(Shape a)	Translates the immutable allocation given to the view to a mutable allocation that represents the interior allocation (i.e. the bounds of the given allocation with the top, left, bottom, and right insets removed.
protected short	getLeftInset()	Gets the left inset.
protected int	getNextEastWestVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)	Returns the next visual position for the cursor, in either the east or west direction.
protected int	getNextNorthSouthVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)	Returns the next visual position for the cursor, in either the north or south direction.
int	getNextVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Position.Bias[] biasRet)	Provides a way to determine the next visually represented model location that one might place a caret.
protected short	getRightInset()	Gets the right inset.
protected short	getTopInset()	Gets the top inset.
View	getView(int n)	Returns the n-th view in this container.
protected View	getViewAtPosition(int pos, Rectangle a)	Fetches the child view that represents the given position in the model.
int	getViewCount()	Returns the number of child views of this view.
int	getViewIndex(int pos, Position.Bias b)	Returns the child view index representing the given position in the model.
Shape	modelToView(int p0, Position.Bias b0, int p1, Position.Bias b1, Shape a)	Provides a mapping from the document model coordinate space to the coordinate space of the view mapped to it.
protected void	setInsets(short top, short left, short bottom, short right)	Sets the insets for the view.
protected void	setParagraphInsets(AttributeSet attr)	Sets the insets from the paragraph attributes specified in the given attributes.
void	setParent(View parent)	Sets the parent of the view.

Methods declared in class View

append, breakView, changedUpdate, createFragment, forwardUpdateToView, getAttributes, getBreakWeight, getContainer, getDocument, getElement, getEndOffset, getGraphics, getParent, getStartOffset, getToolTipText, getViewFactory, getViewIndex, insert, isVisible, modelToView, remove, removeAll, updateLayout, viewToModel

Modifier and Type	Method	Description
void	append(View v)	Appends a single child view.
View	breakView(int axis, int offset, float pos, float len)	Tries to break this view on the given axis.
void	changedUpdate(DocumentEvent e, Shape a, ViewFactory f)	Gives notification from the document that attributes were changed in a location that this view is responsible for.
View	createFragment(int p0, int p1)	Creates a view that represents a portion of the element.
protected void	forwardUpdateToView(View v, DocumentEvent e, Shape a, ViewFactory f)	Forwards the DocumentEvent to the give child view.
AttributeSet	getAttributes()	Fetches the attributes to use when rendering.
int	getBreakWeight(int axis, float pos, float len)	Determines how attractive a break opportunity in this view is.
Container	getContainer()	Fetches the container hosting the view.
Document	getDocument()	Fetches the model associated with the view.
Element	getElement()	Fetches the structural portion of the subject that this view is mapped to.
int	getEndOffset()	Fetches the portion of the model for which this view is responsible.
Graphics	getGraphics()	Fetch a Graphics for rendering.
View	getParent()	Returns the parent of the view.
int	getStartOffset()	Fetches the portion of the model for which this view is responsible.
String	getToolTipText(float x, float y, Shape allocation)	Returns the tooltip text at the specified location.
ViewFactory	getViewFactory()	Fetches the ViewFactory implementation that is feeding the view hierarchy.
int	getViewIndex(float x, float y, Shape allocation)	Returns the child view index representing the given position in the view.
void	insert(int offs, View v)	Inserts a single child view.
boolean	isVisible()	Returns a boolean that indicates whether the view is visible or not.
Shape	modelToView(int pos, Shape a)	Deprecated.
void	remove(int i)	Removes one of the children at the given position.
void	removeAll()	Removes all of the children.
protected void	updateLayout(DocumentEvent.ElementChange ec, DocumentEvent e, Shape a)	Updates the layout in response to receiving notification of change from the model.
int	viewToModel(float x, float y, Shape a)	Deprecated.

Methods declared in class Object

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

Modifier and Type	Method	Description
protected Object	clone()	Creates and returns a copy of this object.
boolean	equals(Object obj)	Indicates whether some other object is "equal to" this one.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. Finalization is deprecated and subject to removal in a future release.
final Class<?>	getClass()	Returns the runtime class of this Object.
int	hashCode()	Returns a hash code value for this object.
final void	notify()	Wakes up a single thread that is waiting on this object's monitor.
final void	notifyAll()	Wakes up all threads that are waiting on this object's monitor.
String	toString()	Returns a string representation of the object.
final void	wait()	Causes the current thread to wait until it is awakened, typically by being notified or interrupted.
final void	wait(long timeoutMillis)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
final void	wait(long timeoutMillis, int nanos)	Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.

Constructor Details

ZoneView

public ZoneView(Element elem,
 int axis)

Constructs a ZoneView.

Parameters:

elem - the element this view is responsible for

axis - either View.X_AXIS or View.Y_AXIS

Method Details

getMaximumZoneSize

public int getMaximumZoneSize()

Get the current maximum zone size.

Returns:

the current maximum zone size

setMaximumZoneSize

public void setMaximumZoneSize(int size)

Set the desired maximum zone size. A zone may get larger than this size if a single child view is larger than this size since zones are formed on child view boundaries.

Parameters:

size - the number of characters the zone may represent before attempting to break the zone into a smaller size.

getMaxZonesLoaded

public int getMaxZonesLoaded()

Get the current setting of the number of zones allowed to be loaded at the same time.

Returns:

current setting of the number of zones allowed to be loaded at the same time

setMaxZonesLoaded

public void setMaxZonesLoaded(int mzl)

Sets the current setting of the number of zones allowed to be loaded at the same time. This will throw an IllegalArgumentException if mzl is less than 1.

Parameters:

mzl - the desired maximum number of zones to be actively loaded, must be greater than 0

Throws:

IllegalArgumentException - if mzl is < 1

zoneWasLoaded

protected void zoneWasLoaded(View zone)

Called by a zone when it gets loaded. This happens when an attempt is made to display or perform a model/view translation on a zone that was in an unloaded state. This is implemented to check if the maximum number of zones was reached and to unload the oldest zone if so.

Parameters:

zone - the child view that was just loaded.

unloadZone

protected void unloadZone(View zone)

Unload a zone (Convert the zone to its memory saving state). The zones are expected to represent a subset of the child elements of the element this view is responsible for. Therefore, the default implementation is to simple remove all the children.

Parameters:

zone - the child view desired to be set to an unloaded state.

isZoneLoaded

protected boolean isZoneLoaded(View zone)

Determine if a zone is in the loaded state. The zones are expected to represent a subset of the child elements of the element this view is responsible for. Therefore, the default implementation is to return true if the view has children. param zone the child view

Parameters:

zone - the zone

Returns:

whether or not the zone is in the loaded state.

createZone

protected View createZone(int p0,
 int p1)

Create a view to represent a zone for the given range within the model (which should be within the range of this objects responsibility). This is called by the zone management logic to create new zones. Subclasses can provide a different implementation for a zone by changing this method.

Parameters:

p0 - the start of the desired zone. This should be >= getStartOffset() and < getEndOffset(). This value should also be < p1.

p1 - the end of the desired zone. This should be > getStartOffset() and <= getEndOffset(). This value should also be > p0.

Returns:

a view to represent a zone for the given range within the model

loadChildren

protected void loadChildren(ViewFactory f)

Loads all of the children to initialize the view. This is called by the setParent method. This is reimplemented to not load any children directly (as they are created by the zones). This method creates the initial set of zones. Zones don't actually get populated however until an attempt is made to display them or to do model/view coordinate translation.

Overrides:

loadChildren in class CompositeView

Parameters:

f - the view factory

See Also:

• CompositeView.setParent(View)

getViewIndexAtPosition

protected int getViewIndexAtPosition(int pos)

Returns the child view index representing the given position in the model.

Overrides:

getViewIndexAtPosition in class CompositeView

Parameters:

pos - the position >= 0

Returns:

index of the view representing the given position, or -1 if no view represents that position

updateChildren

protected boolean updateChildren(DocumentEvent.ElementChange ec,
 DocumentEvent e,
 ViewFactory f)

The superclass behavior will try to update the child views which is not desired in this case, since the children are zones and not directly effected by the changes to the associated element. This is reimplemented to do nothing and return false.

Overrides:

updateChildren in class View

Parameters:

ec - the change information for the element this view is responsible for. This should not be null if this method gets called

e - the change information from the associated document

f - the factory to use to build child views

Returns:

whether or not the child views represent the child elements of the element this view is responsible for. Some views create children that represent a portion of the element they are responsible for, and should return false. This information is used to determine if views in the range of the added elements should be forwarded to or not

See Also:

• View.insertUpdate(DocumentEvent, Shape, ViewFactory)
• View.removeUpdate(DocumentEvent, Shape, ViewFactory)
• View.changedUpdate(DocumentEvent, Shape, ViewFactory)

insertUpdate

public void insertUpdate(DocumentEvent changes,
 Shape a,
 ViewFactory f)

Gives notification that something was inserted into the document in a location that this view is responsible for. This is largely delegated to the superclass, but is reimplemented to update the relevant zone (i.e. determine if a zone needs to be split into a set of 2 or more zones).

Overrides:

insertUpdate in class View

Parameters:

changes - the change information from the associated document

a - the current allocation of the view

f - the factory to use to rebuild if the view has children

See Also:

• View.insertUpdate(DocumentEvent, Shape, ViewFactory)

removeUpdate

public void removeUpdate(DocumentEvent changes,
 Shape a,
 ViewFactory f)

Gives notification that something was removed from the document in a location that this view is responsible for. This is largely delegated to the superclass, but is reimplemented to update the relevant zones (i.e. determine if zones need to be removed or joined with another zone).

Overrides:

removeUpdate in class View

Parameters:

changes - the change information from the associated document

a - the current allocation of the view

f - the factory to use to rebuild if the view has children

See Also:

• View.removeUpdate(DocumentEvent, Shape, ViewFactory)