public class

ZoneView

extends BoxView

java.lang.Object
↳	javax.swing.text.View
	↳	javax.swing.text.CompositeView
		↳	javax.swing.text.BoxView
			↳	javax.swing.text.ZoneView

Class Overview

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 controled 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.

Summary

[Expand]

Inherited Constants

From class javax.swing.text.View

From interface javax.swing.SwingConstants

Public Constructors
	ZoneView(Element elem, int axis) Constructs a ZoneView.

Public Methods
int	getMaxZonesLoaded() Get the current setting of the number of zones allowed to be loaded at the same time.
int	getMaximumZoneSize() Get the current maximum zone size.
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.
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	setMaxZonesLoaded(int mzl) Sets the current setting of the number of zones allowed to be loaded at the same time.
void	setMaximumZoneSize(int size) Set the desired maximum zone size.

Protected Methods
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	getViewIndexAtPosition(int pos) Returns the child view index representing the given position in the model.
boolean	isZoneLoaded(View zone) Determine if a zone is in the loaded state.
void	loadChildren(ViewFactory f) Loads all of the children to initialize the view.
void	unloadZone(View zone) Unload a zone (Convert the zone to its memory saving state).
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.
void	zoneWasLoaded(View zone) Called by a zone when it gets loaded.

[Expand]

Inherited Methods

From class javax.swing.text.BoxView

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.
SizeRequirements	baselineRequirements(int axis, SizeRequirements r) Calculates the size requirements for this `BoxView` by examining the size of each child view.
SizeRequirements	calculateMajorAxisRequirements(int axis, SizeRequirements r) Calculates the size requirements for the major axis `axis`.
SizeRequirements	calculateMinorAxisRequirements(int axis, SizeRequirements r) Calculates the size requirements for the minor axis `axis`.
void	childAllocation(int index, Rectangle alloc) Allocates a region for a child view.
boolean	flipEastAndWestAtEnds(int position, Position.Bias bias) Determines in which direction the next view lays.
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.
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.
int	getSpan(int axis, int childIndex) Fetches the span of a particular childs current layout.
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.
boolean	isAfter(int x, int y, Rectangle innerAlloc) Determines if a point falls after an allocated region.
boolean	isAllocationValid() Are the allocations for the children still valid?
boolean	isBefore(int x, int y, Rectangle innerAlloc) Determines if a point falls before an allocated region.
boolean	isLayoutValid(int axis) Determines if the layout is valid along the given axis.
void	layout(int width, int height) Perform layout on the box
void	layoutChanged(int axis) Invalidates the layout along an axis.
void	layoutMajorAxis(int targetSpan, int axis, int[] offsets, int[] spans) Performs layout for the major axis of the box (i.e.
void	layoutMinorAxis(int targetSpan, int axis, int[] offsets, int[] spans) Performs layout for the minor axis of the box (i.e.
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.
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, Bias[] bias) Provides a mapping from the view coordinate space to the logical coordinate space of the model.

From class javax.swing.text.CompositeView

abstract void	childAllocation(int index, Rectangle a) Returns the allocation for a given child.
boolean	flipEastAndWestAtEnds(int position, Position.Bias bias) Determines in which direction the next view lays.
short	getBottomInset() Gets the bottom inset.
Shape	getChildAllocation(int index, Shape a) Fetches the allocation for the given child view to render into.
Rectangle	getInsideAllocation(Shape a) Translates the immutable allocation given to the view to a mutable allocation that represents the interior allocation (i.e.
short	getLeftInset() Gets the left inset.
int	getNextEastWestVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Bias[] biasRet) Returns the next visual position for the cursor, in either the east or west direction.
int	getNextNorthSouthVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, 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, Bias[] biasRet) Provides a way to determine the next visually represented model location that one might place a caret.
short	getRightInset() Gets the right inset.
short	getTopInset() Gets the top inset.
View	getView(int n) Returns the n-th view in this container.
abstract View	getViewAtPoint(int x, int y, Rectangle alloc) Fetches the child view at the given coordinates.
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.
int	getViewIndexAtPosition(int pos) Fetches the child view index representing the given position in the model.
abstract boolean	isAfter(int x, int y, Rectangle alloc) Tests whether a point lies after the rectangle range.
abstract boolean	isBefore(int x, int y, Rectangle alloc) Tests whether a point lies before the rectangle range.
void	loadChildren(ViewFactory f) Loads all of the children to initialize the view.
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.
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	replace(int offset, int length, View[] views) Replaces child views.
void	setInsets(short top, short left, short bottom, short right) Sets the insets for the view.
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.
int	viewToModel(float x, float y, Shape a, Bias[] bias) Provides a mapping from the view coordinate space to the logical coordinate space of the model.

From class javax.swing.text.View

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.
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.
void	forwardUpdateToView(View v, DocumentEvent e, Shape a, ViewFactory f) Forwards the `DocumentEvent` to the give child view.
float	getAlignment(int axis) Determines the desired alignment for this view along an axis.
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.
Shape	getChildAllocation(int index, Shape a) Fetches the allocation for the given child view.
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.
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.
int	getNextVisualPositionFrom(int pos, Position.Bias b, Shape a, int direction, Bias[] biasRet) Provides a way to determine the next visually represented model location at which one might place a caret.
View	getParent() Returns the parent of the view.
abstract float	getPreferredSpan(int axis) Determines the preferred span for this view along an axis.
int	getResizeWeight(int axis) Determines the resizability of the view along the given axis.
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.
View	getView(int n) Gets the nth child view.
int	getViewCount() Returns the number of views in this view.
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.
int	getViewIndex(int pos, Position.Bias b) Returns the child view index representing the given position in the model.
void	insert(int offs, View v) Inserts a single child view.
void	insertUpdate(DocumentEvent e, Shape a, ViewFactory f) Gives notification that something was inserted into the document in a location that this view is responsible for.
boolean	isVisible() Returns a boolean that indicates whether the view is visible or not.
Shape	modelToView(int p0, Position.Bias b0, int p1, Position.Bias b1, Shape a) Provides a mapping, for a given region, from the document model coordinate space to the view coordinate space.
Shape	modelToView(int pos, Shape a) This method is deprecated. No replacement.
abstract Shape	modelToView(int pos, Shape a, Position.Bias b) Provides a mapping, for a given character, from the document model coordinate space to the view coordinate space.
abstract void	paint(Graphics g, Shape allocation) Renders using the given rendering surface and area on that surface.
void	preferenceChanged(View child, boolean width, boolean height) Child views can call this on the parent to indicate that the preference has changed and should be reconsidered for layout.
void	remove(int i) Removes one of the children at the given position.
void	removeAll() Removes all of the children.
void	removeUpdate(DocumentEvent e, Shape a, ViewFactory f) Gives notification that something was removed from the document in a location that this view is responsible for.
void	replace(int offset, int length, View[] views) Replaces child views.
void	setParent(View parent) Establishes the parent view for this view.
void	setSize(float width, float height) Sets the size of the view.
boolean	updateChildren(DocumentEvent.ElementChange ec, DocumentEvent e, ViewFactory f) Updates the child views in response to receiving notification that the model changed, and there is change record for the element this view is responsible for.
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) This method is deprecated. No replacement.
abstract int	viewToModel(float x, float y, Shape a, Bias[] biasReturn) Provides a mapping from the view coordinate space to the logical coordinate space of the model.

From class java.lang.Object

Object	clone() Creates and returns a copy of this object.
boolean	equals(Object obj) Indicates whether some other object is "equal to" this one.
void	finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
final Class<?>	getClass() Returns the runtime class of this `Object`.
int	hashCode() Returns a hash code value for the 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 another thread invokes the `notify()` method or the `notifyAll()` method for this object.
final void	wait(long timeout, int nanos) Causes the current thread to wait until another thread invokes the `notify()` method or the `notifyAll()` method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed.
final void	wait(long timeout) Causes the current thread to wait until either another thread invokes the `notify()` method or the `notifyAll()` method for this object, or a specified amount of time has elapsed.

Public Constructors

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

Public Methods

public int getMaxZonesLoaded ()

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

public int getMaximumZoneSize ()

Get the current maximum zone size.

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).

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

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).

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

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

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.

Protected Methods

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.

protected int getViewIndexAtPosition (int pos)

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

Parameters

pos	the position >= 0

Returns

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

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.

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.

Parameters

f	the view factory

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.

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.

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

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 imlemented 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.

Interfaces

Classes

Exceptions

ZoneView

Class Overview

See Also

Summary

Public Constructors

public ZoneView (Element elem, int axis)

Parameters

Public Methods

public int getMaxZonesLoaded ()

public int getMaximumZoneSize ()

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

Parameters

See Also

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

Parameters

See Also

public void setMaxZonesLoaded (int mzl)

Parameters

Throws

public void setMaximumZoneSize (int size)

Parameters

Protected Methods

protected View createZone (int p0, int p1)

Parameters

protected int getViewIndexAtPosition (int pos)

Parameters

Returns

protected boolean isZoneLoaded (View zone)

protected void loadChildren (ViewFactory f)

Parameters

protected void unloadZone (View zone)

Parameters

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

Parameters

Returns

protected void zoneWasLoaded (View zone)

Parameters