- java.lang.Object
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- java.awt.font.TextMeasurer
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- All Implemented Interfaces:
Cloneable
public final class TextMeasurer extends Object implements Cloneable
TheTextMeasurerclass provides the primitive operations needed for line break: measuring up to a given advance, determining the advance of a range of characters, and generating aTextLayoutfor a range of characters. It also provides methods for incremental editing of paragraphs.A
TextMeasurerobject is constructed with anAttributedCharacterIteratorrepresenting a single paragraph of text. The value returned by thegetBeginIndexmethod ofAttributedCharacterIteratordefines the absolute index of the first character. The value returned by thegetEndIndexmethod ofAttributedCharacterIteratordefines the index past the last character. These values define the range of indexes to use in calls to theTextMeasurer. 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 toinsertCharanddeleteCharreset theTextMeasurerto use the beginning index and end index of theAttributedCharacterIteratorpassed 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
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Constructor Summary
Constructors Constructor Description TextMeasurer(AttributedCharacterIterator text, FontRenderContext frc)Constructs aTextMeasurerfrom the source text.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description voiddeleteChar(AttributedCharacterIterator newParagraph, int deletePos)Updates theTextMeasurerafter a single character has been deleted from the paragraph currently represented by thisTextMeasurer.floatgetAdvanceBetween(int start, int limit)Returns the graphical width of a line beginning atstartand including characters up tolimit.TextLayoutgetLayout(int start, int limit)Returns aTextLayouton the given character range.intgetLineBreakIndex(int start, float maxAdvance)Returns the index of the first character which will not fit on on a line beginning atstartand possible measuring up tomaxAdvancein graphical width.voidinsertChar(AttributedCharacterIterator newParagraph, int insertPos)Updates theTextMeasurerafter a single character has been inserted into the paragraph currently represented by thisTextMeasurer.
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Constructor Detail
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TextMeasurer
public TextMeasurer(AttributedCharacterIterator text, FontRenderContext frc)
Constructs aTextMeasurerfrom 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.
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Method Detail
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getLineBreakIndex
public int getLineBreakIndex(int start, float maxAdvance)Returns the index of the first character which will not fit on on a line beginning atstartand possible measuring up tomaxAdvancein graphical width.- Parameters:
start- the character index at which to start measuring.startis an absolute index, not relative to the start of the paragraphmaxAdvance- 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 thanmaxAdvancein graphical width - Throws:
IllegalArgumentException- ifstartis less than the beginning of the paragraph.
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getAdvanceBetween
public float getAdvanceBetween(int start, int limit)Returns the graphical width of a line beginning atstartand including characters up tolimit.startandlimitare absolute indices, not relative to the start of the paragraph.- Parameters:
start- the character index at which to start measuringlimit- the character index at which to stop measuring- Returns:
- the graphical width of a line beginning at
startand including characters up tolimit - Throws:
IndexOutOfBoundsException- iflimitis less thanstartIllegalArgumentException- ifstartorlimitis not between the beginning of the paragraph and the end of the paragraph.
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getLayout
public TextLayout getLayout(int start, int limit)
Returns aTextLayouton the given character range.- Parameters:
start- the index of the first characterlimit- the index after the last character. Must be greater thanstart- Returns:
- a
TextLayoutfor the characters beginning atstartup to (but not including)limit - Throws:
IndexOutOfBoundsException- iflimitis less thanstartIllegalArgumentException- ifstartorlimitis not between the beginning of the paragraph and the end of the paragraph.
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insertChar
public void insertChar(AttributedCharacterIterator newParagraph, int insertPos)
Updates theTextMeasurerafter a single character has been inserted into the paragraph currently represented by thisTextMeasurer. After this call, thisTextMeasureris equivalent to a newTextMeasurercreated from the text; however, it will usually be more efficient to update an existingTextMeasurerthan 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 ofnewParagraph, and must be less than the end ofnewParagraph.- Throws:
IndexOutOfBoundsException- ifinsertPosis less than the start ofnewParagraphor greater than or equal to the end ofnewParagraphNullPointerException- ifnewParagraphisnull
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deleteChar
public void deleteChar(AttributedCharacterIterator newParagraph, int deletePos)
Updates theTextMeasurerafter a single character has been deleted from the paragraph currently represented by thisTextMeasurer. After this call, thisTextMeasureris equivalent to a newTextMeasurercreated from the text; however, it will usually be more efficient to update an existingTextMeasurerthan 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 ofnewParagraph, and must not be greater than the end ofnewParagraph.- Throws:
IndexOutOfBoundsException- ifdeletePosis less than the start ofnewParagraphor greater than the end ofnewParagraphNullPointerException- ifnewParagraphisnull
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