Class TextMeasurer

java.lang.Object

java.awt.font.TextMeasurer

All Implemented Interfaces:

Cloneable

public final class TextMeasurer
extends Object
implements Cloneable

The TextMeasurer class provides the primitive operations needed for line break: measuring up to a given advance, determining the advance of a range of characters, and generating a TextLayout for a range of characters. It also provides methods for incremental editing of paragraphs.

A TextMeasurer object is constructed with an AttributedCharacterIterator representing a single paragraph of text. The value returned by the getBeginIndex method of AttributedCharacterIterator defines the absolute index of the first character. The value returned by the getEndIndex method of AttributedCharacterIterator defines the index past the last character. These values define the range of indexes to use in calls to the TextMeasurer. For example, calls to get the advance of a range of text or the line break of a range of text must use indexes between the beginning and end index values. Calls to insertChar and deleteChar reset the TextMeasurer to use the beginning index and end index of the AttributedCharacterIterator passed in those calls.

Most clients will use the more convenient LineBreakMeasurer, which implements the standard line break policy (placing as many words as will fit on each line).

Since:

1.3

See Also:

• LineBreakMeasurer

Constructor Summary

Constructors

Constructor	Description
TextMeasurer(AttributedCharacterIterator text, FontRenderContext frc)	Constructs a TextMeasurer from the source text.

Method Summary

Modifier and Type	Method	Description
protected Object	clone()	Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.
void	deleteChar(AttributedCharacterIterator newParagraph, int deletePos)	Updates the TextMeasurer after a single character has been deleted from the paragraph currently represented by this TextMeasurer.
float	getAdvanceBetween(int start, int limit)	Returns the graphical width of a line beginning at start and including characters up to limit.
TextLayout	getLayout(int start, int limit)	Returns a TextLayout on the given character range.
int	getLineBreakIndex(int start, float maxAdvance)	Returns the index of the first character which will not fit on on a line beginning at start and possible measuring up to maxAdvance in graphical width.
void	insertChar(AttributedCharacterIterator newParagraph, int insertPos)	Updates the TextMeasurer after a single character has been inserted into the paragraph currently represented by this TextMeasurer.

Methods declared in class Object

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

Modifier and Type	Method	Description
boolean	equals(Object o)	Compares the argument to the receiver, and answers true if they represent the same object using a class specific comparison.
protected void	finalize()	Deprecated, for removal: This API element is subject to removal in a future version. May cause performance issues, deadlocks and hangs.
final Class<? extends Object>	getClass()	Answers the unique instance of java.lang.Class which represents the class of the receiver.
int	hashCode()	Answers an integer hash code for the receiver.
final void	notify()	Causes one thread which is waiting on the receiver to be made ready to run.
final void	notifyAll()	Causes all threads which are waiting on the receiver to be made ready to run.
String	toString()	Answers a string containing a concise, human-readable description of the receiver.
final void	wait()	Causes the thread which sent this message to be made not ready to run pending some change in the receiver (as indicated by notify or notifyAll).
final void	wait(long time)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.
final void	wait(long time, int frac)	Causes the thread which sent this message to be made not ready to run either pending some change in the receiver (as indicated by notify or notifyAll) or the expiration of the timeout.

Constructor Details

TextMeasurer

public TextMeasurer(AttributedCharacterIterator text,
 FontRenderContext frc)

Constructs a TextMeasurer from the source text. The source text should be a single entire paragraph.

Parameters:

text - the source paragraph. Cannot be null.

frc - the information about a graphics device which is needed to measure the text correctly. Cannot be null.

Method Details

clone

protected Object clone()

Description copied from class: Object

Answers a new instance of the same class as the receiver, whose slots have been filled in with the values in the slots of the receiver.

Classes which wish to support cloning must specify that they implement the Cloneable interface, since the native implementation checks for this.

Overrides:

clone in class Object

Returns:

Object a shallow copy of this object.

getLineBreakIndex

public int getLineBreakIndex(int start,
 float maxAdvance)

Returns the index of the first character which will not fit on on a line beginning at start and possible measuring up to maxAdvance in graphical width.

Parameters:

start - the character index at which to start measuring. start is an absolute index, not relative to the start of the paragraph

maxAdvance - the graphical width in which the line must fit

Returns:

the index after the last character that will fit on a line beginning at start, which is not longer than maxAdvance in graphical width

Throws:

IllegalArgumentException - if start is less than the beginning of the paragraph.

getAdvanceBetween

public float getAdvanceBetween(int start,
 int limit)

Returns the graphical width of a line beginning at start and including characters up to limit. start and limit are absolute indices, not relative to the start of the paragraph.

Parameters:

start - the character index at which to start measuring

limit - the character index at which to stop measuring

Returns:

the graphical width of a line beginning at start and including characters up to limit

Throws:

IndexOutOfBoundsException - if limit is less than start

IllegalArgumentException - if start or limit is not between the beginning of the paragraph and the end of the paragraph.

getLayout

public TextLayout getLayout(int start,
 int limit)

Returns a TextLayout on the given character range.

Parameters:

start - the index of the first character

limit - the index after the last character. Must be greater than start

Returns:

a TextLayout for the characters beginning at start up to (but not including) limit

Throws:

IndexOutOfBoundsException - if limit is less than start

IllegalArgumentException - if start or limit is not between the beginning of the paragraph and the end of the paragraph.

insertChar

public void insertChar(AttributedCharacterIterator newParagraph,
 int insertPos)

Updates the TextMeasurer after a single character has been inserted into the paragraph currently represented by this TextMeasurer. After this call, this TextMeasurer is equivalent to a new TextMeasurer created from the text; however, it will usually be more efficient to update an existing TextMeasurer than to create a new one from scratch.

Parameters:

newParagraph - the text of the paragraph after performing the insertion. Cannot be null.

insertPos - the position in the text where the character was inserted. Must not be less than the start of newParagraph, and must be less than the end of newParagraph.

Throws:

IndexOutOfBoundsException - if insertPos is less than the start of newParagraph or greater than or equal to the end of newParagraph

NullPointerException - if newParagraph is null

deleteChar

public void deleteChar(AttributedCharacterIterator newParagraph,
 int deletePos)

Updates the TextMeasurer after a single character has been deleted from the paragraph currently represented by this TextMeasurer. After this call, this TextMeasurer is equivalent to a new TextMeasurer created from the text; however, it will usually be more efficient to update an existing TextMeasurer than to create a new one from scratch.

Parameters:

newParagraph - the text of the paragraph after performing the deletion. Cannot be null.

deletePos - the position in the text where the character was removed. Must not be less than the start of newParagraph, and must not be greater than the end of newParagraph.

Throws:

IndexOutOfBoundsException - if deletePos is less than the start of newParagraph or greater than the end of newParagraph

NullPointerException - if newParagraph is null