Class ComponentView

java.lang.Object

javax.swing.text.View

javax.swing.text.ComponentView

All Implemented Interfaces:

SwingConstants

Direct Known Subclasses:

FormView, ObjectView

public class ComponentView
extends View

Component decorator that implements the view interface. The entire element is used to represent the component. This acts as a gateway from the display-only View implementations to interactive lightweight components (ie it allows components to be embedded into the View hierarchy).

The component is placed relative to the text baseline according to the value returned by Component.getAlignmentY. For Swing components this value can be conveniently set using the method JComponent.setAlignmentY. For example, setting a value of 0.75 will cause 75 percent of the component to be above the baseline, and 25 percent of the component to be below the baseline.

This class is implemented to do the extra work necessary to work properly in the presence of multiple threads (i.e. from asynchronous notification of model changes for example) by ensuring that all component access is done on the event thread.

The component used is determined by the return value of the createComponent method. The default implementation of this method is to return the component held as an attribute of the element (by calling StyleConstants.getComponent). A limitation of this behavior is that the component cannot be used by more than one text component (i.e. with a shared model). Subclasses can remove this constraint by implementing the createComponent to actually create a component based upon some kind of specification contained in the attributes. The ObjectView class in the html package is an example of a ComponentView implementation that supports multiple component views of a shared model.

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
ComponentView(Element elem)	Creates a new ComponentView object.

Method Summary

Modifier and Type	Method	Description
protected Component	createComponent()	Create the component that is associated with this view.
float	getAlignment(int axis)	Determines the desired alignment for this view along an axis.
final Component	getComponent()	Fetch the component associated with the view.
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.
float	getPreferredSpan(int axis)	Determines the preferred span for this view along an axis.
Shape	modelToView(int pos, Shape a, Position.Bias b)	Provides a mapping from the coordinate space of the model to that of the view.
void	paint(Graphics g, Shape a)	The real paint behavior occurs naturally from the association that the component has with its parent container (the same container hosting this view).
void	setParent(View p)	Sets the parent for a child 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 View

append, breakView, changedUpdate, createFragment, forwardUpdate, forwardUpdateToView, getAttributes, getBreakWeight, getChildAllocation, getContainer, getDocument, getElement, getEndOffset, getGraphics, getNextVisualPositionFrom, getParent, getResizeWeight, getStartOffset, getToolTipText, getView, getViewCount, getViewFactory, getViewIndex, getViewIndex, insert, insertUpdate, isVisible, modelToView, modelToView, preferenceChanged, remove, removeAll, removeUpdate, replace, setSize, updateChildren, 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	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.
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.
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.
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 at which one might place a caret.
View	getParent()	Returns the parent of the view.
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 pos, Shape a)	Deprecated.
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.
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	setSize(float width, float height)	Sets the size of the view.
protected 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.
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

ComponentView

public ComponentView(Element elem)

Creates a new ComponentView object.

Parameters:

elem - the element to decorate

Method Details

createComponent

protected Component createComponent()

Create the component that is associated with this view. This will be called when it has been determined that a new component is needed. This would result from a call to setParent or as a result of being notified that attributes have changed.

Returns:

the component that is associated with this view

getComponent

public final Component getComponent()

Fetch the component associated with the view.

Returns:

the component associated with the view

paint

public void paint(Graphics g,
 Shape a)

The real paint behavior occurs naturally from the association that the component has with its parent container (the same container hosting this view). This is implemented to do nothing.

Specified by:

paint in class View

Parameters:

g - the graphics context

a - the shape

See Also:

• View.paint(Graphics, Shape)

getPreferredSpan

public float getPreferredSpan(int axis)

Determines the preferred span for this view along an axis. This is implemented to return the value returned by Component.getPreferredSize along the axis of interest.

Specified by:

getPreferredSpan in class View

Parameters:

axis - may be either View.X_AXIS or View.Y_AXIS

Returns:

the span the view would like to be rendered into >=0. Typically the view is told to render into the span that is returned, although there is no guarantee. The parent may choose to resize or break the view.

Throws:

IllegalArgumentException - for an invalid axis

getMinimumSpan

public float getMinimumSpan(int axis)

Determines the minimum span for this view along an axis. This is implemented to return the value returned by Component.getMinimumSize along the axis of interest.

Overrides:

getMinimumSpan in class View

Parameters:

axis - may be either View.X_AXIS or View.Y_AXIS

Returns:

the span the view would like to be rendered into >=0. Typically the view is told to render into the span that is returned, although there is no guarantee. The parent may choose to resize or break the view.

Throws:

IllegalArgumentException - for an invalid axis

See Also:

• View.getPreferredSpan(int)

getMaximumSpan

public float getMaximumSpan(int axis)

Determines the maximum span for this view along an axis. This is implemented to return the value returned by Component.getMaximumSize along the axis of interest.

Overrides:

getMaximumSpan in class View

Parameters:

axis - may be either View.X_AXIS or View.Y_AXIS

Returns:

the span the view would like to be rendered into >=0. Typically the view is told to render into the span that is returned, although there is no guarantee. The parent may choose to resize or break the view.

Throws:

IllegalArgumentException - for an invalid axis

See Also:

• View.getPreferredSpan(int)

getAlignment

public float getAlignment(int axis)

Determines the desired alignment for this view along an axis. This is implemented to give the alignment of the embedded component.

Overrides:

getAlignment in class View

Parameters:

axis - may be either View.X_AXIS or View.Y_AXIS

Returns:

the desired alignment. This should be a value between 0.0 and 1.0 where 0 indicates alignment at the origin and 1.0 indicates alignment to the full span away from the origin. An alignment of 0.5 would be the center of the view.

setParent

public void setParent(View p)

Sets the parent for a child view. The parent calls this on the child to tell it who its parent is, giving the view access to things like the hosting Container. The superclass behavior is executed, followed by a call to createComponent if the parent view parameter is non-null and a component has not yet been created. The embedded components parent is then set to the value returned by getContainer. If the parent view parameter is null, this view is being cleaned up, thus the component is removed from its parent.

The changing of the component hierarchy will touch the component lock, which is the one thing that is not safe from the View hierarchy. Therefore, this functionality is executed immediately if on the event thread, or is queued on the event queue if called from another thread (notification of change from an asynchronous update).

Overrides:

setParent in class View

Parameters:

p - the parent

modelToView

public Shape modelToView(int pos,
 Shape a,
 Position.Bias b)
                  throws BadLocationException

Provides a mapping from the coordinate space of the model to that of the view.

Specified by:

modelToView in class View

Parameters:

pos - the position to convert >=0

a - the allocated region to render into

b - the bias toward the previous character or the next character represented by the offset, in case the position is a boundary of two views; b will have one of these values:

• Position.Bias.Forward
• Position.Bias.Backward

Returns:

the bounding box of the given position is returned

Throws:

BadLocationException - if the given position does not represent a valid location in the associated document

See Also:

• View.modelToView(int, Shape, Position.Bias)

viewToModel

public 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.

Specified by:

viewToModel in class View

Parameters:

x - the X coordinate >=0

y - the Y coordinate >=0

a - the allocated region to render into

bias - the returned bias

Returns:

the location within the model that best represents the given point in the view

See Also:

• View.viewToModel(float, float, Shape, Position.Bias[])