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
* {@link java.text.AttributedCharacterIterator AttributedCharacterIterator}
* representing a single paragraph of text. The value returned by the
* {@link AttributedCharacterIterator#getBeginIndex() getBeginIndex}
* method of AttributedCharacterIterator
* defines the absolute index of the first character. The value
* returned by the
* {@link AttributedCharacterIterator#getEndIndex() 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
* {@link #insertChar(java.text.AttributedCharacterIterator, int) insertChar}
* and
* {@link #deleteChar(java.text.AttributedCharacterIterator, int) 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).
*
* @author John Raley
* @see LineBreakMeasurer
* @since 1.3
*/
public final class TextMeasurer implements Cloneable {
// Number of lines to format to.
private static float EST_LINES = (float) 2.1;
/*
static {
String s = System.getProperty("estLines");
if (s != null) {
try {
Float f = new Float(s);
EST_LINES = f.floatValue();
}
catch(NumberFormatException e) {
}
}
//System.out.println("EST_LINES="+EST_LINES);
}
*/
private FontRenderContext fFrc;
private int fStart;
// characters in source text
private char[] fChars;
// Bidi for this paragraph
private Bidi fBidi;
// Levels array for chars in this paragraph - needed to reorder
// trailing counterdirectional whitespace
private byte[] fLevels;
// line components in logical order
private TextLineComponent[] fComponents;
// index where components begin
private int fComponentStart;
// index where components end
private int fComponentLimit;
private boolean haveLayoutWindow;
// used to find valid starting points for line components
private BreakIterator fLineBreak = null;
private CharArrayIterator charIter = null;
int layoutCount = 0;
int layoutCharCount = 0;
// paragraph, with resolved fonts and styles
private StyledParagraph fParagraph;
// paragraph data - same across all layouts
private boolean fIsDirectionLTR;
private byte fBaseline;
private float[] fBaselineOffsets;
private float fJustifyRatio = 1;
/**
* Constructs a TextMeasurer from the source text.
* The source text should be a single entire paragraph.
* @param text the source paragraph. Cannot be null.
* @param frc the information about a graphics device which is needed
* to measure the text correctly. Cannot be null.
*/
public TextMeasurer(AttributedCharacterIterator text, FontRenderContext frc) {
fFrc = frc;
initAll(text);
}
protected Object clone() {
TextMeasurer other;
try {
other = (TextMeasurer) super.clone();
}
catch(CloneNotSupportedException e) {
throw new Error();
}
if (fComponents != null) {
other.fComponents = (TextLineComponent[]) fComponents.clone();
}
return other;
}
private void invalidateComponents() {
fComponentStart = fComponentLimit = fChars.length;
fComponents = null;
haveLayoutWindow = false;
}
/**
* Initialize state, including fChars array, direction, and
* fBidi.
*/
private void initAll(AttributedCharacterIterator text) {
fStart = text.getBeginIndex();
// extract chars
fChars = new char[text.getEndIndex() - fStart];
int n = 0;
for (char c = text.first(); c != text.DONE; c = text.next()) {
fChars[n++] = c;
}
text.first();
fBidi = new Bidi(text);
if (fBidi.isLeftToRight()) {
fBidi = null;
}
text.first();
Map paragraphAttrs = text.getAttributes();
NumericShaper shaper = AttributeValues.getNumericShaping(paragraphAttrs);
if (shaper != null) {
shaper.shape(fChars, 0, fChars.length);
}
fParagraph = new StyledParagraph(text, fChars);
// set paragraph attributes
{
// If there's an embedded graphic at the start of the
// paragraph, look for the first non-graphic character
// and use it and its font to initialize the paragraph.
// If not, use the first graphic to initialize.
fJustifyRatio = AttributeValues.getJustification(paragraphAttrs);
boolean haveFont = TextLine.advanceToFirstFont(text);
if (haveFont) {
Font defaultFont = TextLine.getFontAtCurrentPos(text);
int charsStart = text.getIndex() - text.getBeginIndex();
LineMetrics lm = defaultFont.getLineMetrics(fChars, charsStart, charsStart+1, fFrc);
fBaseline = (byte) lm.getBaselineIndex();
fBaselineOffsets = lm.getBaselineOffsets();
}
else {
// hmmm what to do here? Just try to supply reasonable
// values I guess.
GraphicAttribute graphic = (GraphicAttribute)
paragraphAttrs.get(TextAttribute.CHAR_REPLACEMENT);
fBaseline = TextLayout.getBaselineFromGraphic(graphic);
Font dummyFont = new Font(new Hashtable(5, (float)0.9));
LineMetrics lm = dummyFont.getLineMetrics(" ", 0, 1, fFrc);
fBaselineOffsets = lm.getBaselineOffsets();
}
fBaselineOffsets = TextLine.getNormalizedOffsets(fBaselineOffsets, fBaseline);
}
invalidateComponents();
}
/**
* Generate components for the paragraph. fChars, fBidi should have been
* initialized already.
*/
private void generateComponents(int startingAt, int endingAt) {
if (collectStats) {
formattedChars += (endingAt-startingAt);
}
int layoutFlags = 0; // no extra info yet, bidi determines run and line direction
TextLabelFactory factory = new TextLabelFactory(fFrc, fChars, fBidi, layoutFlags);
int[] charsLtoV = null;
if (fBidi != null) {
fLevels = BidiUtils.getLevels(fBidi);
int[] charsVtoL = BidiUtils.createVisualToLogicalMap(fLevels);
charsLtoV = BidiUtils.createInverseMap(charsVtoL);
fIsDirectionLTR = fBidi.baseIsLeftToRight();
}
else {
fLevels = null;
fIsDirectionLTR = true;
}
try {
fComponents = TextLine.getComponents(
fParagraph, fChars, startingAt, endingAt, charsLtoV, fLevels, factory);
}
catch(IllegalArgumentException e) {
System.out.println("startingAt="+startingAt+"; endingAt="+endingAt);
System.out.println("fComponentLimit="+fComponentLimit);
throw e;
}
fComponentStart = startingAt;
fComponentLimit = endingAt;
//debugFormatCount += (endingAt-startingAt);
}
private int calcLineBreak(final int pos, final float maxAdvance) {
// either of these statements removes the bug:
//generateComponents(0, fChars.length);
//generateComponents(pos, fChars.length);
int startPos = pos;
float width = maxAdvance;
int tlcIndex;
int tlcStart = fComponentStart;
for (tlcIndex = 0; tlcIndex < fComponents.length; tlcIndex++) {
int gaLimit = tlcStart + fComponents[tlcIndex].getNumCharacters();
if (gaLimit > startPos) {
break;
}
else {
tlcStart = gaLimit;
}
}
// tlcStart is now the start of the tlc at tlcIndex
for (; tlcIndex < fComponents.length; tlcIndex++) {
TextLineComponent tlc = fComponents[tlcIndex];
int numCharsInGa = tlc.getNumCharacters();
int lineBreak = tlc.getLineBreakIndex(startPos - tlcStart, width);
if (lineBreak == numCharsInGa && tlcIndex < fComponents.length) {
width -= tlc.getAdvanceBetween(startPos - tlcStart, lineBreak);
tlcStart += numCharsInGa;
startPos = tlcStart;
}
else {
return tlcStart + lineBreak;
}
}
if (fComponentLimit < fChars.length) {
// format more text and try again
//if (haveLayoutWindow) {
// outOfWindow++;
//}
generateComponents(pos, fChars.length);
return calcLineBreak(pos, maxAdvance);
}
return fChars.length;
}
/**
* According to the Unicode Bidirectional Behavior specification
* (Unicode Standard 2.0, section 3.11), whitespace at the ends
* of lines which would naturally flow against the base direction
* must be made to flow with the line direction, and moved to the
* end of the line. This method returns the start of the sequence
* of trailing whitespace characters to move to the end of a
* line taken from the given range.
*/
private int trailingCdWhitespaceStart(int startPos, int limitPos) {
if (fLevels != null) {
// Back up over counterdirectional whitespace
final byte baseLevel = (byte) (fIsDirectionLTR? 0 : 1);
for (int cdWsStart = limitPos; --cdWsStart >= startPos;) {
if ((fLevels[cdWsStart] % 2) == baseLevel ||
Character.getDirectionality(fChars[cdWsStart]) != Character.DIRECTIONALITY_WHITESPACE) {
return ++cdWsStart;
}
}
}
return startPos;
}
private TextLineComponent[] makeComponentsOnRange(int startPos,
int limitPos) {
// sigh I really hate to do this here since it's part of the
// bidi algorithm.
// cdWsStart is the start of the trailing counterdirectional
// whitespace
final int cdWsStart = trailingCdWhitespaceStart(startPos, limitPos);
int tlcIndex;
int tlcStart = fComponentStart;
for (tlcIndex = 0; tlcIndex < fComponents.length; tlcIndex++) {
int gaLimit = tlcStart + fComponents[tlcIndex].getNumCharacters();
if (gaLimit > startPos) {
break;
}
else {
tlcStart = gaLimit;
}
}
// tlcStart is now the start of the tlc at tlcIndex
int componentCount;
{
boolean split = false;
int compStart = tlcStart;
int lim=tlcIndex;
for (boolean cont=true; cont; lim++) {
int gaLimit = compStart + fComponents[lim].getNumCharacters();
if (cdWsStart > Math.max(compStart, startPos)
&& cdWsStart < Math.min(gaLimit, limitPos)) {
split = true;
}
if (gaLimit >= limitPos) {
cont=false;
}
else {
compStart = gaLimit;
}
}
componentCount = lim-tlcIndex;
if (split) {
componentCount++;
}
}
TextLineComponent[] components = new TextLineComponent[componentCount];
int newCompIndex = 0;
int linePos = startPos;
int breakPt = cdWsStart;
int subsetFlag;
if (breakPt == startPos) {
subsetFlag = fIsDirectionLTR? TextLineComponent.LEFT_TO_RIGHT :
TextLineComponent.RIGHT_TO_LEFT;
breakPt = limitPos;
}
else {
subsetFlag = TextLineComponent.UNCHANGED;
}
while (linePos < limitPos) {
int compLength = fComponents[tlcIndex].getNumCharacters();
int tlcLimit = tlcStart + compLength;
int start = Math.max(linePos, tlcStart);
int limit = Math.min(breakPt, tlcLimit);
components[newCompIndex++] = fComponents[tlcIndex].getSubset(
start-tlcStart,
limit-tlcStart,
subsetFlag);
linePos += (limit-start);
if (linePos == breakPt) {
breakPt = limitPos;
subsetFlag = fIsDirectionLTR? TextLineComponent.LEFT_TO_RIGHT :
TextLineComponent.RIGHT_TO_LEFT;
}
if (linePos == tlcLimit) {
tlcIndex++;
tlcStart = tlcLimit;
}
}
return components;
}
private TextLine makeTextLineOnRange(int startPos, int limitPos) {
int[] charsLtoV = null;
byte[] charLevels = null;
if (fBidi != null) {
Bidi lineBidi = fBidi.createLineBidi(startPos, limitPos);
charLevels = BidiUtils.getLevels(lineBidi);
int[] charsVtoL = BidiUtils.createVisualToLogicalMap(charLevels);
charsLtoV = BidiUtils.createInverseMap(charsVtoL);
}
TextLineComponent[] components = makeComponentsOnRange(startPos, limitPos);
return new TextLine(fFrc,
components,
fBaselineOffsets,
fChars,
startPos,
limitPos,
charsLtoV,
charLevels,
fIsDirectionLTR);
}
private void ensureComponents(int start, int limit) {
if (start < fComponentStart || limit > fComponentLimit) {
generateComponents(start, limit);
}
}
private void makeLayoutWindow(int localStart) {
int compStart = localStart;
int compLimit = fChars.length;
// If we've already gone past the layout window, format to end of paragraph
if (layoutCount > 0 && !haveLayoutWindow) {
float avgLineLength = Math.max(layoutCharCount / layoutCount, 1);
compLimit = Math.min(localStart + (int)(avgLineLength*EST_LINES), fChars.length);
}
if (localStart > 0 || compLimit < fChars.length) {
if (charIter == null) {
charIter = new CharArrayIterator(fChars);
}
else {
charIter.reset(fChars);
}
if (fLineBreak == null) {
fLineBreak = BreakIterator.getLineInstance();
}
fLineBreak.setText(charIter);
if (localStart > 0) {
if (!fLineBreak.isBoundary(localStart)) {
compStart = fLineBreak.preceding(localStart);
}
}
if (compLimit < fChars.length) {
if (!fLineBreak.isBoundary(compLimit)) {
compLimit = fLineBreak.following(compLimit);
}
}
}
ensureComponents(compStart, compLimit);
haveLayoutWindow = true;
}
/**
* 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.
*
* @param start the character index at which to start measuring.
* start is an absolute index, not relative to the
* start of the paragraph
* @param maxAdvance the graphical width in which the line must fit
* @return 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.
*/
public int getLineBreakIndex(int start, float maxAdvance) {
int localStart = start - fStart;
if (!haveLayoutWindow ||
localStart < fComponentStart ||
localStart >= fComponentLimit) {
makeLayoutWindow(localStart);
}
return calcLineBreak(localStart, maxAdvance) + fStart;
}
/**
* 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.
*
* @param start the character index at which to start measuring
* @param limit the character index at which to stop measuring
* @return the graphical width of a line beginning at start
* and including characters up to limit
* @throws IndexOutOfBoundsException if limit is less
* than start
* @throws IllegalArgumentException if start or
* limit is not between the beginning of
* the paragraph and the end of the paragraph.
*/
public float getAdvanceBetween(int start, int limit) {
int localStart = start - fStart;
int localLimit = limit - fStart;
ensureComponents(localStart, localLimit);
TextLine line = makeTextLineOnRange(localStart, localLimit);
return line.getMetrics().advance;
// could cache line in case getLayout is called with same start, limit
}
/**
* Returns a TextLayout on the given character range.
*
* @param start the index of the first character
* @param limit the index after the last character. Must be greater
* than start
* @return a TextLayout for the characters beginning at
* start up to (but not including) limit
* @throws IndexOutOfBoundsException if limit is less
* than start
* @throws IllegalArgumentException if start or
* limit is not between the beginning of
* the paragraph and the end of the paragraph.
*/
public TextLayout getLayout(int start, int limit) {
int localStart = start - fStart;
int localLimit = limit - fStart;
ensureComponents(localStart, localLimit);
TextLine textLine = makeTextLineOnRange(localStart, localLimit);
if (localLimit < fChars.length) {
layoutCharCount += limit-start;
layoutCount++;
}
return new TextLayout(textLine,
fBaseline,
fBaselineOffsets,
fJustifyRatio);
}
private int formattedChars = 0;
private static boolean wantStats = false;/*"true".equals(System.getProperty("collectStats"));*/
private boolean collectStats = false;
private void printStats() {
System.out.println("formattedChars: " + formattedChars);
//formattedChars = 0;
collectStats = false;
}
/**
* 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.
*
* @param newParagraph the text of the paragraph after performing
* the insertion. Cannot be null.
* @param 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
* @throws NullPointerException if newParagraph is
* null
*/
public void insertChar(AttributedCharacterIterator newParagraph, int insertPos) {
if (collectStats) {
printStats();
}
if (wantStats) {
collectStats = true;
}
fStart = newParagraph.getBeginIndex();
int end = newParagraph.getEndIndex();
if (end - fStart != fChars.length+1) {
initAll(newParagraph);
}
char[] newChars = new char[end-fStart];
int newCharIndex = insertPos - fStart;
System.arraycopy(fChars, 0, newChars, 0, newCharIndex);
char newChar = newParagraph.setIndex(insertPos);
newChars[newCharIndex] = newChar;
System.arraycopy(fChars,
newCharIndex,
newChars,
newCharIndex+1,
end-insertPos-1);
fChars = newChars;
if (fBidi != null || Bidi.requiresBidi(newChars, newCharIndex, newCharIndex + 1) ||
newParagraph.getAttribute(TextAttribute.BIDI_EMBEDDING) != null) {
fBidi = new Bidi(newParagraph);
if (fBidi.isLeftToRight()) {
fBidi = null;
}
}
fParagraph = StyledParagraph.insertChar(newParagraph,
fChars,
insertPos,
fParagraph);
invalidateComponents();
}
/**
* 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.
*
* @param newParagraph the text of the paragraph after performing
* the deletion. Cannot be null.
* @param 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
* @throws NullPointerException if newParagraph is
* null
*/
public void deleteChar(AttributedCharacterIterator newParagraph, int deletePos) {
fStart = newParagraph.getBeginIndex();
int end = newParagraph.getEndIndex();
if (end - fStart != fChars.length-1) {
initAll(newParagraph);
}
char[] newChars = new char[end-fStart];
int changedIndex = deletePos-fStart;
System.arraycopy(fChars, 0, newChars, 0, deletePos-fStart);
System.arraycopy(fChars, changedIndex+1, newChars, changedIndex, end-deletePos);
fChars = newChars;
if (fBidi != null) {
fBidi = new Bidi(newParagraph);
if (fBidi.isLeftToRight()) {
fBidi = null;
}
}
fParagraph = StyledParagraph.deleteChar(newParagraph,
fChars,
deletePos,
fParagraph);
invalidateComponents();
}
/**
* NOTE: This method is only for LineBreakMeasurer's use. It is package-
* private because it returns internal data.
*/
char[] getChars() {
return fChars;
}
}